Displays

Activities of microorganisms can lead to formation of biominerals. This biomineralization has been described to be either 'microbially controlled' or 'microbially induced'. The control over crystalization can work intracellularly, e.g. with magnetosomes, or extracellularly like in mammals. With increasing evidence for intermediate processes with specific proteins inducing different crystalloid (macro)morphology even at a distance to a colony, and processes involving both bioweathering and formation of new minerals, the concept of biomineralization should be re-visited and a more detailed classification of biomineralization processes is needed including formation of a stable backbone determining the macromorphology of biominerals even at distance from cell surfaces.

Here, the supply of mineral components (e.g. phosphate, reduced nitrogen compounds, etc.) through microbial exudation and matrix provided by bacteria or fungi are discussed. Especially with respect to metal resistance mechanisms, this is an active process, costly to the cells. Examples are given for microbial biomineralization processes in metal rich environments on  a former heap site. The formation of manganese hydroxides, like birnessite, leading to massive hardpan formation, is one of the examples derived from the former uranium mining site in Thuringia, Germany. Other examples with different macromorphologies include carbonates, (magnesium) calcite or vaterite, formed under laboratory conditions with strains of streptomycetes in dependence of excreted amphipathic surface proteins of the bacteria. And as a third example, the formation of (nickel) struvite, switzerite and nickel phosphate formation on soil from the former mining site under laboratory conditions will be discussed.

From the original research, a new concept for microbially aided, extracellular biomineral formation is developed. The concept thus extends the previous distinction of biomineralization on the part of the 'microbially induced' formation in a process oriented way, including microbial physiology and secondary metabolism into a unified concept of biomineralization.

How to cite: Kothe, E., Meier, A., Kirtzel, J., and Costa, F.: microbial mechanisms in biomineralization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22012, https://doi.org/10.5194/egusphere-egu2020-22012, 2020.

Wales has a long history of coal and metal mining, with over 1,300 abandoned metal mines across the country. These mines pollute a number of rivers and lead to the failure of Water Framework Directive (WFD) standards for heavy metals. This includes Nantymwyn, an abandoned lead mine, which has two streams that flow into the River Tywi, and metal loads can be traced downstream for 65km. Nantymwyn, in common with many of Wales’ lead mines, has complex and poorly understood underground workings, which have degraded in the 90 years since closure. The mine is believed to have been worked during pre-Roman times and, is noted historically from AD 1530. The Nant y Bai stream flows through extensive spoil heaps, as well as over old workings, and has inflows from adits, over ground and subterranean inputs. Consequentially, conventional spot sampling of the metal concentrations as has been historically carried out by government agencies does not accurately convey the problems caused by the mine.

Tracer dilution and synoptic sampling was determined at Nantymwyn in July 2019 to calculate stream flow and heavy metal loadings and their variation downstream. Sodium bromide was injected upstream of the mine site, and once it reached a ‘plateau state’ in the stream it was sampled at 34 points over the 2km of stream. These samples were analysed for metal and bromide concentrations using Inductively coupled plasma mass spectrometry (ICP-MS), which allowed One-Dimensional Transport with Inflow and Storage (OTIS) modelling to predict pollutant flows. Additionally, monthly sampling and salt dilution flow gauging at 12 sites along the stream has been conducted since February 2019. The second, smaller stream at Nantymwyn is monitored monthly at six points.

Preliminary results show a large temporal variation in flows and concentrations across both streams, with varying loads of lead, but a consistent zinc load in the smaller stream. Initial results from the synoptic sampling show flows consistent with the salt gauging carried out after the stream had been sampled. This research will determine the extent of unseen inflow and outflows upon metal pollution on the River Tywi and allow mitigation strategies to be evaluated.

How to cite: Brown, A. M. L., Robertson, I., Walsh, R. P. D., Byrne, P., Edwards, P., Williams, T., and De-Quincey, H.: Tracing Heavy Metals at Nantymwyn, Wales, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21879, https://doi.org/10.5194/egusphere-egu2020-21879, 2020.

Mercury dispersion in the Paglia and Tiber river catchments (Central Italy) from the abandoned Monte Amiata mining district has long been documented (Rimondi et al., 2019, and references therein). However, there are comparatively fewer data on fluxes of the metal across the basin to the Tyrrhenian sea. The only published estimates (Rimondi et al., 2014) refer to the first 40 km of the Paglia River between Abbadia San Salvatore and Allerona Scalo. They reported highly variable total (dissolved + suspended particulate) Hg loads, up to 34 g/day, strongly depending on river discharge. We report here unpublished data from a sampling campaign of September 2014 (Millacci, 2016), that included three samples along the Tiber river. The data refer to low flow conditions at the end of the dry season. As expected, loads progressively increase with discharge from 1-5 g/day near the source of the Paglia river to about 100 g/day in the city of Rome. There is an anomalous value of 220 g/day just south of the Alviano dam (near Orvieto): a possible explanation is a release of Hg-rich sediments from the dam during maintenance operations.

Millacci G. (2016) – Unpublished thesis (Laurea magistrale) in Geological sciences, Università di Firenze

Rimondi V., et al. (2014) – Environmental Science and Pollution Research, 21:5575–5585

Rimondi V., et al. (2019) - Environmental Pollution 255, 113191

How to cite: Lattanzi, P., Benvenuti, M., Chiarantini, L., Colica, A., and Costagliola, P.: Mercury fluxes from the abandoned Monte Amiata mining district in the Paglia and Tiber river catchments, Central Italy: preliminary estimates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11361, https://doi.org/10.5194/egusphere-egu2020-11361, 2020.

As a result of the open-cast lignite mining in Lusatia (Eastern Germany), large quantities of iron (Fe) and sulphate (SO₄^2-) are fed into small streams discharging into the Spree river system. The study examined whether the inputs of Fe and SO₄^2- lead to longitu­dinal and depth-dependent gradients in the riverine sediments downstream the mining region in terms of element composition and mineral formations.

We sampled the surface (upper 0-3, 3-6 cm) sediment using a gravity corer at 18 sites from the heavily mining impacted Spreewald region downstream 200 km to the Bänke at Lake Müggelsee. We also included sampling sites at a pit water purification system in Vetschau, one neutral mining lake and a reference site without mining impact. Sedi­ments were analysed for total C, N using an element analyser, for various elements (incl. Fe, S, Mn, Al, P, heavy metals) by ICP-OES after digestion with hot aqua regia. A sequential Fe-extraction from fresh sediments and XRD was performed to differenti­ate solid iron forms and other minerals, respectively.  Characteristic sediment signatures are investigated with the help of a Principal Component Analysis (18 sites, 19 parameters).

We discovered a decreasing sedimentary Fe-content in flow direction from 300 mg g-1 in Vetschau, 130 mg g-1 close to the mining region in Lübbenau down to 30 mg g-1 at Bänke near Lake Müggelsee. In contrast, the S-content increased with decreasing mining impact from 3 mg g-1 in Vetschau up to 35 mg g-1. Minimum Fe- and S-contents are similar to Bautzen reservoir as a non-mining impacted reference location with Fe 28 mg g-1 and S 4 mg g-1. The statistical analysis with the PCA revealed the longitudinal influence of mining products within Spree river. Two major groups emerge from the score plot. First, there are those samples, which are clearly influenced by mining activities. Second, there are samples, which include the reference point and samples more distant from mining, where we expect no or only minor mining impact. This separation becomes even more apparent after taking heavy metals into account. Furthermore, the Fe binding shifts from more easily reducible Fe/amorphous minerals to less easily reducible Fe/more crystalline minerals in flow direction, which probably has consequences for the microbial degradability of organic matter and the strength of the ability of Fe to bind phosphorus.  

We were able to prove that the sedimentary ele­ment composition and especially the Fe mineral characteristics are influenced by mining activities at least 100 km downstream the Spree river system, probably affecting the phosphorus availability and carbon turnover.

How to cite: Friedland, G., Grüneberg, B., and Hupfer, M.: Impact of mining on geochemical signatures of riverine sediments in adjacent ecosystems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9159, https://doi.org/10.5194/egusphere-egu2020-9159, 2020.

Uranium (U) is a toxic radionuclide which environmental dissemination must be limited. In this regard, understanding U immobilization mechanisms in reducing environments is essential for improving the management of radioactive waste and the remediation of contaminated sites. In particular, determining the long-term behavior of non-crystalline U(IV) species in (sub-)surface conditions is of growing importance, as these environmentally-relevant species have been recently showed to play a major role in U mobility. For this purpose, we investigated the evolution of U speciation over a pluri-millennial period in naturally U-enriched sediments from Lake Nègre (alt. 2354 m, Mercantour, France) as an analogue of contaminated systems. Several sediment cores were sampled at 24 m of water depth and preserved under anoxic conditions. Bottom sediments were dated back to 8700 cal BP. These organic- and Si-rich sediments display increasing U concentration with depth, from 350 to more than 1000 µg/g. Sequential ultrafiltration of surface waters and uranium isotopic ratios (²³⁸U/²³⁵U and (²³⁴U/²³⁸U)) of sediments and waters suggest that the deposition mode of U did not vary significantly with time, thus giving the opportunity to follow the effect of diagenesis on U speciation over more than 1000 years. Uranium L_III-edge X-Ray Absorption Near-Edge Structure (XANES) analysis shows that U is rapidly reduced in the upper sediment layers and is fully reduced at depth. Preliminary Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy data at the U L_III-edge reveals that U speciation evolved with depth in the sediment core, suggesting an effect of diagenesis in anoxic conditions on U solid speciation. Our results may help to design long-term storage conditions that are able to enhance the formation of poorly soluble U species in U-contaminated soils and sediments.

How to cite: Lefebvre, P., Gourgiotis, A., Mangeret, A., Le Pape, P., Diez, O., Sabatier, P., Louvat, P., Merrot, P., Baya, C., Zebracki, M., Malet, E., Jézéquel, D., Reyss, J.-L., Bargar, J., Gaillardet, J., Cazala, C., and Morin, G.: Pluri-millenial evolution of uranium speciation in lacustrine sediments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19811, https://doi.org/10.5194/egusphere-egu2020-19811, 2020.

Nitrate contamination in groundwater is a widespread problem in Europe, Northern America, Asia, and elsewhere due to adverse health effects if the water is used for drinking purposes. The objectives of this study were to a) assess the occurrence of nitrate in groundwater throughout the province of Alberta (Canada), b) to use isotope techniques to assess the predominant sources of nitrate in groundwater, and c) to use a combination of chemical and multi-isotopic techniques to assess the fate of groundwater nitrate. The study utilized >60,000 NO₃-N concentration data points from domestic water wells supplemented by 986 chemical and isotopic data points collected from groundwater monitoring water wells in Alberta.

In Alberta, nitrate has been detected in 34% (22,943 out of 66,421 samples) of the groundwater samples collected from domestic wells and NO₃-N concentrations range from <0.005 to 421 mg NO₃-N/L. Nitrate was detected in 18% (180 out of 986 samples) of the groundwater samples collected from monitoring wells with nitrate concentrations ranging from <0.004 to 300 mg NO₃-N/L. Nitrate levels in 3.4% (2279 of 66,421 samples) of groundwater samples from domestic wells and <1% (8 out of 986 samples) of groundwater samples from monitoring wells were above the maximum allowable concentration (MAC) in drinking water of 10 mg/L NO₃-N. To determine the sources of nitrate in groundwater, we used a multi-isotope approach on a subset of groundwater samples (n < 70) from monitoring wells. Three different potential sources of nitrate in groundwater were identified: 1) nitrate from microbial nitrification of soil organic matter and/or synthetic fertilizers represented by samples with δ¹⁵N <+6‰ and δ¹⁸O <+5‰; 2) manure-derived nitrate characterized by δ¹⁸O values <+5‰ and elevated δ¹⁵N values of >+10‰ combined with elevated nitrate concentrations; and 3) in a few cases geogenic nitrate in weathered glacial tills where clay-derived ammonium was oxidized to nitrate resulting in the highest nitrate concentrations and unique isotopic compositions of nitrate with δ¹⁵N_NO3values near 26 ‰ and δ¹⁸O_NO3 values of +5 ‰. We also found that the occurrence and concentration of groundwater nitrate was critically dependent on the redox conditions in the aquifers. Geochemical analyses revealed that 66% of all groundwater samples were moderately to highly reducing suggesting that denitrification is a widespread NO₃ removal process in groundwater in Alberta. Compiling geochemical and multi-isotopic data enabled us to assess the occurrence and the origins of nitrate in groundwater in Alberta and identify denitrification as an important natural attenuation process that has the potential to remove nitrate from the investigated aquifers.

How to cite: Mayer, B., Humez, P., Wilson, L., Nightingale, M., and McClain, C.: A regional assessment of occurrences, sources and fate of nitrate in groundwater of Alberta, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12008, https://doi.org/10.5194/egusphere-egu2020-12008, 2020.

Although nitrogen is not a traditional contaminant when considering the detrimental impacts of mine waste leachate on aquatic ecosystems, it is a common pollutant of concern in underground iron ore mining where waste rock leachate has a neutral pH and a low metal content. This is the case in northern Sweden, where environmental authorities, supported by the EU Water Framework Directive, have imposed strict regulations on nitrogen discharges to oligotrophic surface water systems. Requirements for lower nitrogen releases has driven the development and application of a bioreactor technology for nitrate removal at LKAB’s Kiruna iron ore mine.

A full-scale woodchip denitrifying bioreactor has been in operation since September 2018 in Kiruna for the removal of nitrate (NO₃^-) from waste rock leachate. Drainage from the waste rock pile is intercepted in a subsurface groundwater collection reservoir at the toe of the waste rock pile and pumped at an average rate of 22 m³/d into the bioreactor. Leachate from the low-sulfur waste rock is characterized by neutral pH (average pH 7), moderate alkalinity (108 mg/L HCO₃^-), and elevated concentrations of sulfate, NO₃^- and chloride (average concentrations 670, 61 and 102 mg L^-1 respectively).

During 2019, and average nitrogen removal efficiency was 77%: during the 165 day sampling period, 189 kg NO₃-N were removed in the bioreactor, which is primarily attributed to denitrification. A net production of 26 kg of NO₂-N was measured. Nitrous oxide (N₂O) emissions in gas and aqueous phase are low from the bioreactor and the primary product of denitrification is assumed to molecular nitrogen (N₂). Dissolved N₂O concentrations were on average greater at the bioreactor inlet (277 µg L^-1) than at the outlet (179 µg L^-1), although variations were substantial during the summer months with a net dissolved N₂O export from the bioreactor on one occasion in late summer. The flux as N₂O from the bioreactor surface varied from 1 – 28 mg N₂O m^-2 d^-1. In addition to nitrate removal, zinc concentrations were reduced by, on average, 88%. 

How to cite: Herbert, R., Hellman, M., and Hallin, S.: Nitrogen removal from waste rock drainage in northern Sweden with denitrifying woodchip bioreactor, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21885, https://doi.org/10.5194/egusphere-egu2020-21885, 2020.

Antimicrobials (AM) play a critical role in the treatment of human and animal (aquatic and terrestrial) diseases, which has led to their widespread application and use. Antimicrobial resistance (AMR) is the ability of microorganisms (e.g. bacteria, viruses and some parasites) to stop an antibiotic, such as an antimicrobial, antiviral or antimalarial, from working against them. Globally, about 700 000 deaths per year arise from resistant infections as a result of the fact that antimicrobial drugs have become less effective at killing resistant pathogens. Antimicrobial chemicals that are present in environmental compartments can trigger the development of AMR. These chemicals can also cause antibiotic-resistant bacteria (ARB) to further spread antibiotic resistance genes (ARG) because they may have an evolutionary advantage over non-resistant bacteria. Thus, AMR is a global threat to health, livelihoods and the achievement of the Sustainable Development Goals, both in developing and developed countries. For some time now, antimicrobial resistance (AMR) has been approached mainly from the human and animal health angles, however little is known about the impacts that AMR in the environment may have on health. A better understanding of how antimicrobial resistance moves from agricultural areas to the environment through soil and water is important if we are to develop guidance to managing it cost effectively. We examined the potential of nuclear techniques—the application of compound-specific stable isotope analysis (CSIA)—as a powerful tool to determine the source and fate of antibiotics in the environment and detect the degradation of antibiotics by transformation-induced isotopic effects. CSIA can be used to qualify and quantify in situ transformations. The latest methodological advances even allow the analysis of several elements (H, C, Cl, N) within a molecule This multi-element isotope information is used to elucidate in-situ transformation pathways and underlying reaction mechanisms.

How to cite: Seidel, M., Göpfert, L., Elsner, M., Nijenhuis, I., Adu-Gyamfi, J., Heng, L., and De Souza, M.: Nuclear techniques for surveillance and monitoring of antimicrobial and antimicrobial resistance in soil and the environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5746, https://doi.org/10.5194/egusphere-egu2020-5746, 2020.

Water pollution from agricultural activities has direct negative impacts on human health, as the well-known blue-baby syndrome —a potentially fatal illness —deriving from nitrate intake in infants. Inefficient farming practices, farming systems discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies results in pollution poses demonstrated risks to aquatic ecosystem, human health and productive activities including agriculture. In order to design effective remediation strategies there is a need to target sources of excess nutrients, and sediments in an efficient way. Standard operating procedures (SOP) that provides step-by step instructions on how to collect, prepare and prepare soil samples from agriculture watersheds for multi-isotope analysis were evaluated and standardized in agricultural catchments in Asia (Australia, China, India, Sri Lanka, Vietnam), Europe (Austria, France, Germany, Ireland, Romania, Slovenia, Switzerland, United Kingdom) and Africa (Morocco and Ghana) in a coordinated research project managed by the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. The δ¹⁸O, δ²H, δ¹⁵N-NO₃, δ¹⁸O-NO₃ stable isotope values in water samples were used to apportion the contributions of the different sources (chemical fertilizers, organic fertilizers from livestock, and rural domestic sewerage). The compound specific isotope analysis (CSIA)-based monitoring approach (δ¹³C and δ¹⁵N) was used to evaluate in-situ degradation, transport, transformation and fate of pesticides. Information gained will fill knowledge gaps for catchment scale predictive models and provide guidelines and decision trees to develop an isotopic analytical toolbox that could be adapted to different agricultural management situations.

How to cite: Adu-Gyamfi, J., Heng, L., and Halder, J.: Integrated approach for evaluating sources and apportionment of agro-contaminants in soil and water bodies , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8242, https://doi.org/10.5194/egusphere-egu2020-8242, 2020.

In contaminated agroecosystems, the rhizosphere at the soil/plant interface may act as a hotspot of pesticide transformation. However, results based on pesticide concentrations only may not be conclusive because degradative and non-degradative (e.g. sorption) processes simultaneously dissipate pesticides. Compound-specific stable isotope analysis (CSIA) allows to identify degradation processes by analyzing changes of natural stable isotope abundances of isotopic elements (e.g., ¹³C, ¹⁵N) during (bio)degradation of pesticides.

The purpose of this study was to evaluate and compare the contribution of processes responsible for pesticide dissipation in planted and unplanted soil mesocosms using CSIA. Five widely used aniline herbicides and fungicides (i.e., acetochlor, alachlor, S-metolachlor, metalaxyl and butachlor) were spiked at 25 µg g^-1 in planted (with Lolilum multiflorum sp.) and unplanted mesocosms with contrasted forest and vineyard soils. The mesocosms were incubated in a climate chamber for 75 days under controlled humidity, light and temperature. Three successive rainfalls (15 mm) were applied at on day 45, 60 and 75 days to collect soil leachate. Bulk soil and rhizosphere samples were collected at the end of the experiment. Pesticides were extracted from leachate and soil for quantification using GC-MS and pesticide CSIA (δ¹³C and δ¹⁵N) using GC-IRMS. Pesticide uptake by plants was negligible.

Pesticides concentrations in leachate ranged from 0.9 (acetochlor in planted mesocosms) up to 7.1 mg L^-1 (metalaxyl in unplanted vineyard soil). Pesticide concentrations were higher in unplanted microcosms, in particular in the vineyard soil microcosms. This suggests that plants and higher organic content in forest soil limited pesticide leachate. In total, 3, 3, 13, 8 and 4% of acetochlor, alachlor, metalaxyl, S-metolachlor and butachlor were exported in leaching, respectively. In addition, the first rainfall accounted for 70 to 99% of total leaching losses, indicating large export in both soil types during the first event following application. CSIA of pesticides in leachate confirmed that in situ degradation occurred in both planted and unplanted microcosms, although degradation extent may be larger in planted than in unplanted mesocosms. Isotope fractionation in alachlor, acetochlor, S-metolachlor and butachlor was more pronounced in planted mesocosms for both soils (Δδ¹³C up to 9.5‰), while it was only observed in planted forest microcosms for metalaxyl (Δδ¹³C = 5.9‰). This suggests that soil physico-chemical properties and/or the rhizosphere (i.e., root exudates and uptake) influenced pesticide degradation.

Up to 6, 8, 29, 20 and 5% of acetochlor, alachlor, metalaxyl, S-metolachlor and butachlor, respectively, persisted in soil at the end of the experiment. This corresponds to pesticide dissipation ranging from 58 to 91% due to both sorption and degradation in soil. Accordingly, the isotopic fractionation in acetochlor and alachlor in soil and rhizosphere was only observed after 75 days in both soils (Δδ¹³C = 8.2 and 3.2‰, respectively), and remained low or insignificant for the other pesticides. Our results emphasize variability in the extent of pesticide dissipation in soils, and CSIA of pesticides indicates that pesticide degradation mainly occurs in the soil solution leached during rainfall events rather than in bulk soil or the rhizosphere.

How to cite: Imfeld, G., Pérez-Rodríguez, P., Gangloff, S., and Schmitt, A.-D.: Dissipation and leaching of pesticides in planted and unplanted soil mesocosms: insights from compound-specific isotope analysis (CSIA) , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17983, https://doi.org/10.5194/egusphere-egu2020-17983, 2020.

SUPREME’s goal is to support the safe and efficient use of microbial inocula to assist crops growth. We aim at scaling up the use of autochthonous microbes from greenhouse experiments to field scale pilot plants. Different soils and crops meaningful for the regional economies (tomatoes, sunflowers, onions, legumes such as faba beans and vetch, barely, wheat or high biomass leading grasses like sorghum, health crops and cereals as konjac, orchidaceae, amaranth and quinoa) will be considered in the test sites. Test sites are distributed over 6 different areas of the Mediterranean (figure 1). Leading edge characterization and monitoring techniques will be set up to measure: i) soil biodiversity before and after inoculation, ii) crop growth, iii) water and fertilizer consumption, iv) and mineral consumption and formation through biosphere-geosphere interactions allowing to long term assessment of soil mineral.

Bacteria and fungi can effectively influence plant physiology, growth, defence mechanisms and nutrient uptake (1-5). Mycorrhizal fungi associated with plant roots increase the absorption of nutrients, particularly phosphorus and nitrogen, and distribution of water between different plants is achieved through the hyphal networks. As a result, growth of crops and trees is enhanced or even only possible as in the case of mycoheterotrophy in ectomycorrhizas. Inocula of PGP bacteria can be used to improve soil functions and the resistance of plants to drought periods contributing to reduce irrigation needs. Especially on arid and bare soils, bacterial inoculants can positively influence biogeochemical element cycles and formation of soil. Thus, they can help to reduce water, N and P requirements by augmenting the soil functions, and to reduce the effect of climate change on crop production. In this work, the first results of the project will be shown.

1                 Gianinazzi-Pearson and Gianinazzi (1983)-Plant Soil, 71, 211–215

2                  Smith and Read (1997)- Academic Press

3                  Gianinazzi et al. (2002) Basel. Switzerland: BirkhäuserVerlag

4                  Van der Heijden et al. (2008) Ecol. Let., 11, 296–310

5                  Peterson et al. (1984 )Biotech. Adv., 2, 101-12

How to cite: De Giudici, G., Sprocati, A. R., Tasso, F., Alisi, C., Paganin, P., Miglior, G., Podda, F., Medas, D., Dore, E., Fancello, D., Cau, P., and Cidu, R.: SUPREME : developping tools for SUstainable food PRoduction in mEditerranean area using MicrobEs, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22507, https://doi.org/10.5194/egusphere-egu2020-22507, 2020.

The intensive farmland in north China accounts for more than 17% of China's arable land, which is main wheat and corn production area in China. Consequently, excessive use of chemical fertilizers and pesticides, as well as rural household waste, are the environmental problems in this region. How the surface water quality responses to large scale of intensive agricultural activities in north China remains unclear. The study aims to identify the sources of nitrogen (N) pollutant in the surface water and to understand the contributions of different land use types to sediment at catchment scale. The study site is in a representative agricultural catchment (Jiangou catchment), which located in north China intensive farming areas. The main stream in the catchment, the Hai river system, is one of China's seven big rivers. The topography, land use and agricultural management practices and precipitation of the catchment were investigated using field observations and remote sensing. Fertilizer types applied in the farmland in the upstream area was investigated, and water samples along the tributary of Hai river (Ju river) from upstream at different sites representing different sources and samples of water entering Ju river were collected. The compound specific stable isotope (CSSI) analysis for soil samples collected under different land use types was done. Stable isotopic (δ¹⁸O, δ²H, δ¹⁵N-NO₃ and δ¹⁸O-NO₃) techniques to identify the N pollutant sources in the catchment surface water, and CSSI fingerprinting techniques were used to identify the contribution of different land use types to catchment sediment production. The δ¹⁸O and δ²H values of collected water samples suggested that the water source of these samples dominantly came from the local precipitation. Source contribution of N pollutant in water body of the Jiangou catchment identified by δ¹⁵N-NO₃ and δ¹⁸O-NO₃ data using IsoSource model and chemical fertilization from maize farmland (38±2%) and excrements of livestock from dairy (32±7%) were the dominant nitrate pollutant sources in the water body. Approximately 20±11% and 11±7% were attributed to discharge of manure from vegetable farmland and rural domestic sewage from village, respectively. Based on the CSSI data, the sediment source was mainly derived from maize farmland which contributed by 71%, the followed were bean and vegetable farmlands which accounted for 14% and 10%, respectively, and least contribution from forest land (5%). The combined use of CSSI fingerprinting and stable isotopic techniques could quantitatively identify the source contribution of N pollutant in surface water and sediment in the catchment, which is critical to the assessment and implementation of optimised agricultural and land management practices.

How to cite: Yu, H. and Adu-Gyamfi, J.: The integrated use of stable isotopic and CSSI fingerprinting techniques to identify the sources of N pollutant in surface water and sediment in an agricultural catchment, north China , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6705, https://doi.org/10.5194/egusphere-egu2020-6705, 2020.

Groundwater is the main source of drinking water in Slovenia, but nitrate pollution originating from agriculture and urban areas is threatening its quality in several areas of the country. The aim of this study is to assess the vulnerability of three different unconfined aquifers in Slovenia (Ljubljansko polje, Dravsko-ptujsko polje and Krško-brežiško polje). All three study areas are located on alluvial plains with shallow groundwater levels and similar soil types, but different ratios of urban and agricultural land use. Soil types and land use were analyzed in each area as they contribute strongly to leaching of nitrate. Along with this we performed the analysis of stable isotopes of O, H and N to determine the origin of groundwater recharge and trace the possible sources of nitrate pollution. Results will give us an overview of nitrate pollution pathways through better understanding of nitrate sources, vulnerable areas, and groundwater recharge characteristics.

How to cite: Curk, M., Glavan, M., Adu-Gyamfi, J., Halder, J., Cerar, S., and Zupanc, V.: Study of groundwater vulnerability in three unconfined aquifers in Slovenia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7028, https://doi.org/10.5194/egusphere-egu2020-7028, 2020.

Mining activities generate a large amount of waste materials that are often very unstable and represent a source of pollution. Phytomanagement, in terms of phytostabilization, is considered a suitable method to decrease environmental risks of metal-enriched mine wastes (Parraga-Aguado et al. 2013). This technique employs plants to achieve the surface stabilization of the wastes by acting as a barrier which decreases wind borne dust and water erosion, reduces metal-enriched leaching through metal accumulation in plant roots and provides metal immobilization in the rhizosphere (Robinson et al. 2009; Sun et al. 2016).

Most of the research has focused on the selection of the best spontaneously adapted plant species (endemic pioneer plants) for each specific mining site (Parraga-Aguado et al. 2013), because they may respond better and can survive easily compared to introduced alien species (Bradshaw 1997; Pandey 2015). Pioneer vegetation may improve edaphic conditions by increasing soil nutrient content (Rodríguez et al. 2007) or ameliorating soil acidity (Rufo and de la Fuente 2010), and thus may favor further establishment of other plant species.

The investigation of metal transfer from the geosphere to the vegetal tissues helps to understand the adaptive strategies of plant species and may be useful for soil remediation actions. Synchrotron radiation-based techniques represent the state of the art tools to investigate the microscopic processes occurring in plant-soil systems (Kopittke et al. 2017). X-ray diffraction, X-ray fluorescence and X-ray absorption spectroscopy (XAS), are particularly suited to determine the finest complementary details about the atomic and crystallographic structure, distribution of elements, their chemical speciation and their valence state. Here, we report a review of selected researches performed on different plant species (Pistacia lentiscus L., Euphorbia pithyusa subsp. cupanii, Phragmites australis, and Helichrysum microphyllum Cambess. subsp. tyrrhenicum), growing on metal contaminated substrates in abandoned mining areas in Sardinia (Italy).

Our results demonstrate that these plant species have developed their own adaptation strategy to grow and to survive in polluted environments, making them potential candidates to develop low-cost and self-sustainable vegetative covers aimed at reducing the dispersion of metals in soils and waters around these mine polluted sites.

Acknowledgments

The authors acknowledge CESA (E58C16000080003) from RAS and RAS/FBS (F72F16003080002) grants, FP7 ERANETMED2 72094 SUPREME, the POR FESR Sardegna 2014-2020 (project cluster Top-Down: TESTARE), the Grant of Excellence Departments, MIUR (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016), and the CeSAR (Centro Servizi d'Ateneo per la Ricerca) of the University of Cagliari, Italy, for SEM analysis.

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How to cite: Medas, D., Meneghini, C., Carlomagno, I., and De Giudici, G.: Synchrotron microscopic and spectroscopic techniques to reveal the fate of Zn in pioneer plants from abandoned mining sites, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15021, https://doi.org/10.5194/egusphere-egu2020-15021, 2020.

The Chindwin River, a major tributary of the Ayeyarwady River in Myanmar, is approximately 850 km long with a watershed area of 115,300 km². The Chindwin River is essential for local livelihoods, drinking water, ecosystems, navigation, agriculture, and industries such as logging and mining. Over the past two decades, Myanmar’s rapid economic development has resulted in drastic changes to socio-economic and ecological conditions in the basin. Water users in the basin reported that there is a rapid extension of gold and jade mining and they observed a noticeable decline in water quality along with increased sedimentation and turbidity. So far, however, Myanmar has not undertaken a comprehensive scientific study in the Chindwin River Basin to assess water quality and sources of water pollution and to effectively address issues of river basin degradation and concerns for public health and safety. This study aims to assess the status of water quality in the Chindwin River and the potential impact of mining activities on the water quality and loading through monitoring program and modeling approach. 17 locations in the upper, middle and lower parts of the Chindwin River Basin were selected for water quality monitoring. These sites are located near Homalin, Kalewa, Kani and Monywa townships where human activities and interventions could affect water quality. Water quality sampling and testing in the Chindwin River was conducted two times per year: in the dry season (May-June) and in the wet season (September-October) during 2015-2017. We monitored 21 parameters including heavy metals such as Lead (Pb), Mercury (Hg), Copper (Cu) and Iron (Fe). The observed values of Mercury in Uru River in the upper Chindwin River Basin which located nearby gold mining sites shown higher than the WHO drinking standard. This area also has high values of turbidity and Total Suspended Solid. The SHETRAN hydrological model, PHREEQC geochemical model and LOADEST model were used to quantify the heavy metal loads in the Uru River. Results from scenario analysis indicate an increase in Arsenic and Mercury load under increment of concentration due to expansions in mining areas. In both baseline and future climate conditions, the Uru downstream area shows the highest load effluent in both Arsenic and Mercury. These heavy metal loads will intensify the declining water quality condition in Chindwin River and can impact negatively on human health who use water for drinking. Therefore, we recommend that water quality monitoring should continue to provide scientific-evidence for decision-makers to manage water quality and mining activities properly.  Water treatment systems for drinking water are required to remove turbidity, Total Suspended Solid, and Mercury from raw water sources. Raising awareness of relevant stakeholders (local people, farmers, private sectors, etc.) is necessary as many people living in the Chindwin River Basin are using water directly from the river and other waterways without proper water treatment.

How to cite: Piman, T., Krittasudthacheew, C., K. Gunawardanaa, S., and Shresthaa, S.: Monitoring and modelling mining impacts on water quality in Chindwin River Basin, Myanmar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15824, https://doi.org/10.5194/egusphere-egu2020-15824, 2020.

Mining activity is cause of deep landscape morphology modifications and often leaves critical legacy represented by huge volumes of mine wastes and residues of metallurgical processes. These wastes are usually made up by highly reactive materials which lead to the mobilization and dispersion of harmful elements in soils and waters, up to several kilometers from the source of contamination, representing a serious threat for health of humans, animals and environment.

The Iglesiente and Arburese mine districts, in South West Sardinia (Italy), have been interested by intensive mine exploitation lasting for centuries. The mine activity was mainly addressed to zinc (Zn) and lead (Pb) extraction from primary sulphides and secondary non-sulfide mineralizations (calamine ores). After the mine closure (1968−1995), no real actions addressed to mitigate the environmental impact have been adopted; therefore, either surface or underground waters can interact with minerals present in the flooded adits, mining wastes and tailings, causing the mobilization and dispersion of high amounts of contaminants.

Several studies have been carried out to understand the processes ruling the fate of metals, with particular interest for Zn, the most important contaminant of the study areas. Results of hydrological tracer techniques show that the Zn load of the investigated rivers differs up to 3 orders of magnitude, from about 6 kg/day (Rio San Giorgio) up to about 2000 kg/day (Rio Irvi). These differences do not seem to be linked to a substantially different discharge, but appear to be related to the peculiarity of each river in terms of riverbed morphology, vegetal coverage, water flow and sedimentation/erosional rates, that may favor, in the hyporheic zone, the onset and development of processes limiting the metal mobility. For example, scanning electron microscopy (SEM) analyses of core sample collected from the riverbed has shown the presence of metal sulphides (FeS₂, ZnS) attributable to the supergene formation of secondary phases promoted by the microbial sulphate reduction. Moreover, the metal intake/immobilization in roots and stems of plants (e.g. Phragmites australis and Juncus acutus) and in their rizosphere, have been observed.

These processes constitute natural biogeochemical barriers, that can effectively limit the metal dispersion and whose understanding can help in planning effective remediation strategies.

The authors acknowledge CESA (E58C16000080003) from RAS and RAS/FBS (F72F16003080002) grants, FP7 ERANETMED2 72094 SUPREME, the Grant of Excellence Departments, MIUR (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016),  the CeSAR (Centro Servizi d'Ateneo per la Ricerca) of the University of Cagliari, Italy, for SEM analysis, and the POR FESR Sardegna 2014-2020 (project cluster Top-Down: TESTARE)

How to cite: Dore, E., Fancello, D., Rigonat, N., Medas, D., Cidu, R., Da Pelo, S., Frau, F., Lattanzi, P., Marras, P. A., Meneghini, C., Podda, F., and De Giudici, G.: Impact of biogeochemical barriers on the fate of zinc (Zn) in the metal-polluted Iglesiente and Arburese mine districts (SW-Sardinia, Italy) , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18313, https://doi.org/10.5194/egusphere-egu2020-18313, 2020.

Reactive transport in porous media involves a complex interplay of multiple processes relative to flow of water and gases, transport of elements, chemical reactions and microbial activities. In surface-groundwater interfaces, the role of the capillary fringe is of particular interest as water table variations can strongly impact the transfer of gases (e.g. oxygen), the evolution of redox conditions and the evolution/adaptation of bacterial/microbial populations that control biodegradation pathways of contaminants. Although the understanding of individual processes is advanced, their interactions are not yet fully understood challenging the development of efficient reactive transport models (RTM) for predictive applications. In this context, the combination of microbial approaches with isotope measurements and modelling may be useful to understand reactive transport of halogenated pollutants in hydrogeological dynamic systems, to improve processes representation in RTMs, and to reduce model equifinality. Dichloromethane (DCM) is a toxic and volatile halogenated compound frequently detected in multi-contaminated aquifers. Although mechanisms of DCM microbial degradation under both aerobic and anaerobic conditions have been described, little is known about the relationships between the hydrogeochemical variations caused by water table fluctuations, as well as their effects on the diversity and distribution of bacterial communities and degradation pathways.
            In this study, two laboratory aquifers fed by contaminated groundwater from the industrial site Thermeroil (France) were designed to collect water samples at high-resolution to investigate the reactive transport of DCM in porous media under steady and dynamic hydrogeological conditions. The effect of water table variations on hydrochemical, microbial and isotopic composition (δ¹³C and δ³⁷Cl) was examined to derive DCM mass removal and potential changes in degradation pathways. For the latter, Compound-Stable Isotope Analysis (CSIA) has been used as a tool to evaluate natural degradation of halogenated hydrocarbons. A RTM model (CubicM) is currently being developed to include dual-element CSIA and biological processes - such as growth, decay, attachment, detachment or dormancy – and relate changes in redox conditions with the evolution of DCM degrading populations. A two-phase flow model (i.e. water and gas) has been developed to account for the volatilization and the associated transport processes of halogenated volatile compounds in porous media. Currently, the model is tested on the experimental results to assist in the interpretation of DCM dissipation and the observed biogeochemical and microbial processes to determine the best-suited formalism to address the effect of water table fluctuations on DCM reactive transport in porous media. Such model will enable to assess natural attenuation of DCM at contaminated sites accounting for dynamic hydrogeological conditions.

How to cite: Prieto Espinoza, M., Weill, S., Di chiara, R., Belfort, B., Lehmann, F., Muller, E. M., Vuilleumier, S., Masbou, J., and Imfeld, G.: Reactive transport of dichloromethane in porous media under dynamic hydrogeological conditions: from experiments to modelling , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21997, https://doi.org/10.5194/egusphere-egu2020-21997, 2020.

Modern agriculture utilises large quantities of fertilisers which are applied to maximise food production. However, these high loads of agricultural chemicals are not always fully utilised by plants or decomposed in the soil; therefore, they frequently leach out from agriculture systems and pollute surface and ground waters. Farms and facilities that process agriculture products and wastes also release high loads of organic pollutants to the environment. These environmental problems are a subject of concern in many regions around the world, including the Swan Coastal Plains of Western Australia where agricultural production has been intensive over the last 150 years.

The Nambeelup Brook catchment (~143 km²) of Western Australia, which is characterised by diverse land use, was selected as an experimental study site. On average, ~9.7 GL/y of water is discharged from this catchment to costal lagoons and contributes to their eutrophication. However, the surface water flows are highly seasonal and the nutrient loads vary widely. Apart from the traditional hydrochemical techniques, multi-tracer stable isotope analyses of water molecules [δ²H(H₂O) and δ¹⁸O(H₂O)], nitrates [δ¹⁵N(NO₃) and δ¹⁸O(NO₃)] and sulphate ions [δ³⁴S(SO₄) and δ¹⁸O(SO₄)] were used in the present study to partition different sources of pollutants in the catchment.

During the wet season of 2018, all surface waters were fresh, with Total Dissolved Solids varying between 100 and 1,000 mg/L and δ¹⁸O(H₂O) and δ²H(H₂O) between 0.8 and ‑4.2 ‰ and 4.5 and -19.4 ‰, respectively. These values reflected the time since the last rainfall and differences in evaporations with respect to differences between water retention times in different parts of the catchment. Sulphate concentrations ranged 6–140 mg/L and δ³⁴S(SO₄) 14.3 to 26.3 ‰, reflecting inputs from fertilisers, natural acid rock drainage and sulphur reduction. Nitrates had relatively low concentrations in surface waters (<1.3 mg/L, except one location 6.5 mg/L) but diverse δ¹⁵N(NO₃), ranging -5.4 to 15.3 ‰ and δ¹⁸O(NO₃) -6.7 to 19.4 ‰ and displaying general denitrification trend.

These stable isotope results provide important supplementary information about possible sources of agro-pollutants across the catchment, but they must be analysed in conjunction with water hydrochemical composition. The major challenge is to clarify the ambiguous signatures and to partition the mix from other processes, such as denitrification and sulphate reduction. These challenges, to a large extent, can be addressed using the multi-tracer approach and analysing oxygen stable isotope composition of various molecules: δ¹⁸O(H₂O), δ¹⁸O(NO₃) and δ¹⁸O(SO₄).

How to cite: Skrzypek, G. and Degens, B.: Stable isotope fingerprints of agro-contaminant inputs in a nutrients-limited catchment, Western Australia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3220, https://doi.org/10.5194/egusphere-egu2020-3220, 2020.

Surface water resources in Peru show high spatio-temporal variability, being the prediction of streamflow at ungauged sites, one of the fundamental challenges today.  This research presents a methodology for regional parameter estimation at national scale using SWAT (Soil and Water Assessment Tools) model, with the goal of estimating the streamflow for three hydrographic regions in Peru: the Pacific, Titicaca and Amazonas. Hydrological models were calibrated using observed discharge data which is sparse and poorly distributed over Peru. In this context, we design a regional parameter estimation following the next steps: i) First, a regionalization of 3394 hydrological response units (HRU) in the whole country were built through Ward’s hierarchical cluster criterion, in which 14 calibration regions were defined. ii) A calibration procedure to obtain the best calibration parameters was made with Non-dominated Sorting Genetic Algorithm (NSGA-II) optimization using the Kling-Gupta (KGE) and Nash Sutcliffe Logarithmic (LogNSE) statistics. A total of 31 hydrological stations were selected to calibration and validation procedure with the condition of leaving at least one in each region defined at point i) iii) Using the physical similarity approach, each set of calibrated parameters was averaged in each region to get the regional parameter sets.

The Pacific drainage was grouped into 6 regions, in which the results of daily flows estimations showed a good performance (KGE varies between -0.89 and 0.79) with some exceptions in the central zone; and acceptable results in the low- flow estimation (logNSE varies between -1.66 and 0.82), whose performance declines in some stations in northern and southern areas. On the other hand, the Amazon and Titicaca drainages regions were grouped into 7 and 1 region respectively. The calibration in the Amazon resulted in a very good performance in the Andean part (KGE> 0.5 and LogNse> 0.3), however in the north (region shared with Ecuador), the results are moderately satisfactory (KGE varies 0.0 and 0.4). In the Titicaca region, very acceptable KGE calibration values ​​were obtained (KGE> 0.75, LogNSE> 0.6). This first stage of the research will allow evaluating the climate change impacts on the water resources availability in Peru.

How to cite: Asurza Véliz, F. A., Traverso-Yucra, K. A., Lavado-Casimiro, W. S., Felipe-Obando, O., Montesinos-Cáceres, C. A., and Llauca-Soto, H. O.: Surface water resources assessment in Peru through SWAT hydrological model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6308, https://doi.org/10.5194/egusphere-egu2020-6308, 2020.

In the semi-active treatment process of mine drainage, neutralized mine drainage flows into settling pond to form sedimentary layer. The sedimentation layer is increased in thickness over time by the continuous inflow of sediment, and the bottom  of the sediment layer is compressed by the load of the upper layer. Thus, the physical characteristics of the sedimentary layers change depending on the depth over time. In this study, the sedimentation layers of four semi-active treatment facilities in South Korea were sampled by depth to measure physical properties and chemical composition. As a result of the analysis, the density and water content of the sludge did not change significantly, while the particle size distribution and viscosity were different according to the depth. As a result of statistical analysis, there was a significant correlation between depth, water content, and viscosity of the sediments. In addition, the content of Mn and Fe contained in the sediments was correlated with the content of Ca and Mg.

How to cite: Lee, D.-K., Cheong, Y.-W., Yim, G.-J., Ji, W. H., and Cho, S.: Characteristics of neutralized mine drainage sediment depending to the depth in semi-active treatment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6411, https://doi.org/10.5194/egusphere-egu2020-6411, 2020.

Air striping on an acid mine drainage was conducted to measure dissolved CO₂ concentration and acidity. The raw water and the disturbed water were neutralized to pH 7.5 and to compare the amount of lime added and sludge volume generated between two waters. The concentration of dissolved CO₂ in the raw water was 49 mg/L and the total acidity was 1,018 CaCO₃ mg/L. For disturbed water, the CO₂ concentration was below 1 mg/L and the total acidity was 882 - 909 CaCO₃ mg/L. This was the result of the release of dissolved CO₂ into the air. As a result of the removal of CO₂, 11% less lime was used and 85% less sludge generation occurred.

How to cite: Cheong, Y., Cho, D.-W., Ji, W. H., and Cho, S.: Effect of air stripping on acidity of mine drainage and the amount of neutralizing agent usage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6457, https://doi.org/10.5194/egusphere-egu2020-6457, 2020.

Among the variables affecting the volume and composition sludge generated in the semi-active mine drainage treatment facility operating in Korea, the effect of CO₂ dissolved in the mine drainage on the sludge composition was studied.

The water quality change was analyzed by neutralizing 1m³ of mine drainage from the Ilkwang abandoned mine. The neutralization with lime slurry resulted in removal of Fe, Al, Cu and SiO₂, and an increase in Ca content in neutralized water. The dissolved CO₂ in raw water was 56 mg/L but decreased to <1 mg/L after neutralization. The dissolved CO₂ in the mine drainage can be consumed to form calcite or be removed by degassing before neutralization. There is also a possibility that gypsum may be produced depending on pH due to the high concentration of Ca and SO₄ enriched.

The amount of sludge generated through the neutralization test was insufficient for analysis. Therefore, chemical analysis and mineral assessment were performed on the effluent, sludge and cakes generated in the settling pond in the Ilkwang abandoned mine. XRD analysis showed that calcite (CaCO₃) and Bassanite (CaSO₄ · H₂O) were commonly found in red and white sludge. CO₂ in the mine drainage reacted with CaO to affect the sludge composition. As a result of the XRF, white sludge contained 35.57% of CaO, indicating that a large amount of slaked lime was included. Red sludge and cakes had a Fe₂O₃ content of more than 35%, so iron was the main ingredient. In addition, the CaO content was analyzed as 15.28%, the second major component. As a result of measuring the paste pH of the dehydrated cake, it can be seen that the pH is in the range of 9 to 10 due to CaO. The sludge shows strong alkali characteristics, indicating that slaked lime remains in the sludge. The remaining slaked lime will increase the sludge volume and increase the sludge management costs.

How to cite: Yim, G., Cheong, Y., Lee, J., Cho, S., and Ji, W.: Effect of Dissolved CO2 in Acid Mine Drainage on Sludge Composition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7233, https://doi.org/10.5194/egusphere-egu2020-7233, 2020.

Arsenic pollution was recognized to be an important environmental problem. Most relevant studies have focused on the groundwater systems in alluvial fans. This study aims to assess the spatial and temporal distributions of arsenic concentration and the variations of arsenic species along Lao-jie Stream in Taoyuan City, Taiwan. The river sediment, pore water, and surface water (river) samples were taken at fixed locations along Lao-jie stream. There were 10 surface water, 8 pore water, and 8 shallow river sediment samples included in the analysis. s (n = 8). Results show that the arsenic concentration changes significantly in summer (June) and autumn (September). The phase characteristic is also different in different seasons. There is no obvious concentration change in rivers. The averaged concentration in June and September were 1.609μg / L and 1.067μg / L. However, the averaged pore water concentration was 4.089μg / L in June and was 4.829μg / L in September. The averaged concentration in shallow riverbed sediment samples were 4.435 mg / Kg in June and 6.223 mg / Kg in September. Because of stream discharge rates at different sampling times, the total arsenic concentration in autumn was generally higher than that in summer. Additionally, and the arsenic concentration for surface water and pore water showed significantly different pattern along the stream. The correlation of arsenic concentration was obtained based on samples taken from surface water and pore water in summer time. However, in the summer time the inverse proportional relation was obtained as compared with the arsenic concentration obtained from the shallow sediments. In autumn, the arsenic concentration in the pore water samples is proportional to the arsenic concentration in the sediment samples. The spatial distributions of pore water and sediment samples along the stream are similar. The results also showed that the arsenic concentration of sediments in the autumn was higher than that in the summer, which might be influenced by the content of iron oxide. The concentration ratios of As (III) with As (V) for pore water is 23.8: 76.2 and for sediments is 15:85 in summer. However, the ratios for pore water is 51.4: 48.6 and for sediment is 11.4: 88.6 in autumn. The As (III) in pore water increased 27.6% in autumn and As (V) in sediments increased 3.6% in winter.

How to cite: Tzu-Jung, L., Chuen-Fa, N., Jiin-Shuh, J., and Chu-Ching, L.: The spatial and temporal distribution of Arsenic speciation along Lao-Jie stream on Taoyuan tableland, Taiwan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7901, https://doi.org/10.5194/egusphere-egu2020-7901, 2020.

A silver phosphate comparison material (Ag₃PO₄) for measurement of the stable oxygen isotope composition was prepared by the University of Natural Resources and Life Science (BOKU) and distributed to four international isotope laboratories frequently measuring the δ¹⁸O value in Ag₃PO₄. The contributing laboratories were the University of Natural Resources and Life Science (BOKU), The University of Western Australia (UWA), the ETH Zurich (ETH), the University of Helsinki (UH) and the Helmholtz Centre for Environmental Research (UFZ). Each laboratory analysed the comparison material in a minimum of two independent measuring rounds with a minimum of 10 individual measurements. The instrument used to perform the measurements were high-temperature conversion elemental analyzers coupled with continuous flow isotope ratio mass spectrometers: TC/EA with Thermo Finnigan Delta XP (BOKU), a TC/EA with a Thermo Scientific Delta V Plus (UWA), an Elementar Pyrocube with a Isoprime 100 (ETH), a Flash IRMS EA with a Thermo Scientific Delta V Plus (UH) and a TC/EA with a Finnigan Delta S (UFZ). The working gas δ¹⁸O was set to 0 ‰ and the normalization was done by a three-point linear regression calibration (Paul et al., 2007) using the reference material IAEA-601 (δ¹⁸O_VSMOW = +23.14 ± 0.17 ‰), IAEA-602 (δ¹⁸O_VSMOW = +71.28 ±0.42 ‰) (both benzoic acid) and NBS 127 (barium sulfate) (δ¹⁸O_VSMOW = +8.59 ± 0.20 ‰) (Brand et al., 2009). BOKU, UH and ETH had experienced inhomogeneity of the IAEA-602 as already mentioned in Brand et al. (2009). The weighted arithmetic mean and standard deviation (1σ) of the new BOKU Ag₃PO₄ comparison material from the single measurements has a δ¹⁸O value of 13.80 ± 0.40 ‰ on the VSMOW scale (n=131), while the median of the single rounds was 13.76 ‰ (n=11) and the median of the laboratories was 13.79 ‰ (n=5). The arithmetic means of two measuring rounds were outside ± 1σ. When excluding data from these rounds from the statistics the weighted arithmetic mean has a δ¹⁸O value of 13.80 ± 0.32 ‰ on the VSMOW scale (n = 111) and the median of the single valid rounds (n=9) remained at 13.76 ‰ and the median of the labs at 13.79 ‰ (n=5). Excluding NBS127 from the normalization slightly reduced the δ¹⁸O value to 13.74 ± 0.31 ‰ (n = 111). The BOKU Ag₃PO₄ comparison material is available for stable isotope research laboratories to facilitate the calibration of their lab comparison material.

Brand, W.A., Coplen, T.B., Aerts-Bijma, A.T., Böhlke, J.K., Gehre, M., Geilmann, H., Gröning, M., Jansen, H.G., Meijer, H.A.J., Mroczkowski, S.J., Qi, H., Soergel, K., Stuart-Williams, H., Weise, S.M., Werner, R.A., 2009. Comprehensive inter-laboratory calibration of reference materials for δ¹⁸O versus VSMOW using various on-line high-temperature conversion techniques. Rapid Communications in Mass Spectrometry, 999–1009. doi:10.1002/rcm

Paul, D., Skrzypek, G., Fórizs, I., 2007. Normalization of measured stable isotopic compositions to isotope reference scales - A review. Rapid Communications in Mass Spectrometry 21, 3006–3014. doi:10.1002/rcm.3185

How to cite: Watzinger, A., Schott, K., Hood-Nowotny, R., Skrzypek, G., Tamburini, F., Arppe, L., Cristini, D., and Knöller, K.: Inter-laboratory calibration of a Ag3PO4 comparison material for oxygen stable isotope analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7910, https://doi.org/10.5194/egusphere-egu2020-7910, 2020.

The Bécancour River basin in southern Québec (Canada) has been impacted by more than a hundred years of asbestos mining activities in the Thetford Mines region. Several recreational water bodies located downstream from the city are suffering from high sediment and contaminant loads and eutrophication. In order to prepare an efficient management of the fluvial lakes, we completed paleolimnological investigations to evaluate the extent of their deterioration and identify catchment disturbances that influenced their present-day condition. Here we present the results of a multi-proxy study of sediment cores collected from a chain of 5 lakes. The sedimentary records from these lakes indicate severe perturbations associated with the complete draining of Lac Noir, a former lake near Thetford Mines excavated and drained for mining purposes between 1955-1959. Radiometric ²¹⁰Pb dating revealed extreme increases in the sediment accumulation rate following this event. Analyses of loss-on-ignition, carbon (C) and nitrogen (N) isotopes, grain-size, and X-ray microfluorescence indicated that the post-1960 sediments were enriched in fine-grained mineral matter and had higher metal and nutrient concentrations as compared to older sediments at the bottom of the cores. Changes in the δ¹³C and C/N ratios and the predominance of diatom taxa (class Bacillariophyceae) typical of nutrient-rich waters (e.g., Cyclostephanos invisitatus, Cyclotella meneghiniana) also showed that the 1955-1959 event led to a rapid eutrophication of some lakes. Results from our study illustrate that the asbestos mining activities had dramatic impacts on lake biota and contaminant levels, and suggest that major restoration efforts will be needed to improve their ecological condition.

How to cite: Pienitz, R. and Jacques, O.: Sedimentological and limnological evolution of recreational lakes in a former asbestos mining region (Québec, Canada): insights from paleolimnology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3741, https://doi.org/10.5194/egusphere-egu2020-3741, 2020.

Pollution from small abandoned mines is usually overseen compared to larger historical mining sites. Especially in the Arctic more research is needed on long-term water quality degradation from mine waste (e.g. metal leakage). We have studied changes in water quality from a historical copper (Cu) mining area, Nautanen, northern Sweden, that was shortly in operation for six years before abandonment in 1908 (~110 years ago). Water quality data from previous studies of the site (1993-2014) was compared to results from our own field campaigns in 2017, which provided us with a rare Arctic case study of 25 years of data. The results showed Cu, Zn and Cd concentrations at the mining zone being orders of magnitude larger than local background levels. This was surprising considering Nautanen’s short time of operation, the small scale of the mining site, and the long time since closure. We found no declining trend of metal concentrations over the surveyed 25-year period (1993-2017) and during the past 110 years (1907-2017) a mass flow of 43 tons of Cu was estimated to have been released to the local surface water system from the mining zone and 7 tons of Cu at 4 km downstream. Nautanen stands out with its high metal leakage relative to its small volume of mine waste compared to mass flows of other larger historical mining sites in e.g. Sweden and Canada. Small abandoned sites, which are numerous, could add disproportionately large amounts of metals to surface water systems. This information is crucial in upscaling local low-priority sites to regional assessments of total pollution pressures in sensitive Arctic environments. We are currently further investigating pollution transport pathways through oxygen and sulfur isotopes to trace water originating from the mine and other sources (e.g. atmospheric deposition, bacterial sulfate reduction). This method could give valuable information in data scares sites where e.g. groundwater data is inaccessible.

How to cite: Fischer, S., Rosqvist, G., Chalov, S., Mörth, M., and Jarsjö, J.: Small 110-year old mine in northern Sweden leaves disproportionately high metal impact on water quality, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10092, https://doi.org/10.5194/egusphere-egu2020-10092, 2020.

Mercury contamination of stream sediments in the Paglia and Tiber river catchments (Central Italy) from the abandoned Monte Amiata mining district has long been documented (Rimondi et al., 2019, and references therein). Along the river courses, fluvial sediments have been quarried for decades to obtain sand and gravel for several industrial uses, including construction of road and rail embankments. Although specific information is not available, there is a high chance that some of this material was used for two major Italian transport routes, the A1 Expressway, and the Alta Velocità (=high speed; AV) railroad.

A preliminary survey was conducted near the city of Orvieto (Umbria region, Central Italy) by taking soil samples in proximity of the embankments of A1 and AV. Both constructions occurred in the 1960s-1970s, when the Monte Amiata mines were still active; specifically, the A1 section Chiusi-Orvieto was completed in 1964, and the AV section Città della Pieve-Roma was completed in 1977. Samples from the embankment of the older railroad Orvieto-Orte (completed in 1874, when mining at Monte Amiata was just beginning) were also taken for comparison.

Samples near the A1 and AV embankments show Hg contents ranging from 1.4 to 9.2 mg/kg, and 2.7 to 5.8 mg/kg, respectively. All these values exceed the limit (1 mg/kg) established by Italian regulations for public green and civil use soil; some also exceed the limit (5 mg/kg) for industrial soil. By contrast, samples from the old railroad show values of 0.3-0.4 mg/kg, below the law limits.

The immediate risk to local inhabitants is deemed low; however, these preliminary results indicate a potential contamination of highway and railroad embankments from mine-impacted sediments, and suggest the opportunity of a more systematic study.

Rimondi V., et al. (2019) – Environmental Pollution 255, 113191

How to cite: Lattanzi, P., Costagliola, P., and Paolieri, M.: Potential risk from the use of mine-contaminated sediments for road and rail embankments: preliminary data from Central Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11394, https://doi.org/10.5194/egusphere-egu2020-11394, 2020.