Emerging contaminants and legacy pollutants in freshwater ecosystems


Emerging contaminants and legacy pollutants in freshwater ecosystems
Convener: Stefan Krause | Co-Conveners: Alena Bartosova, Anne Jaffrezic, Françoise Elbaz-Poulichet
| Thu, 02 Jun, 10:30–12:00|Room Rondelet 2
| Attendance Thu, 02 Jun, 15:00–16:30|Poster area

Orals: Thu, 2 Jun | Room Rondelet 2

Chairpersons: Stefan Krause, Françoise Elbaz-Poulichet
David Hannah, Benjamin Abbot, Kieran Khamis, Christa Kelleher, Iseult Lynch, Stefan Krause, and Adam Ward

Human activities are threatening resilience of vital, interconnected components of our Earth system. Consequences for freshwaters are missing often from this debate. Yet, a functioning terrestrial water cycle is essential with healthy rivers essential for the sustainable provision of freshwater for humans and ecosystems alike. Major international reports released very recently have evidenced concerning trends in river water pollution, with poor water quality shown to be a global and persistent problem – still responsible for 2M deaths each year. Across Europe, 34% of the 130,000 waterway surveyed fail to meet “good” chemical status. In the most current national assessment for the USA, less than a third of rivers received a “good” grade. Deteriorating water quality is apparent for rivers across much of Asia, Africa and South America. Therefore, global river water pollution is a very timely and high profile topic for science and society.

Our contribution aims: (1) to explore current water quality challenges, which vary across regions and with economic development; and (2) to consider future prospects for moving from this crisis towards more sustainable solutions.

We propose a framework (based on distinct contaminant types and mitigation methods) that conceptualises the differences in experiences of upper-income countries versus lower- and middle-income countries. We consider the factors that have made the global water quality increasingly visible and impossible to ignore. Leveraging our framework and understanding of driving factors, we propose solutions to global water pollution challenges based on: latest scientific thinking and data sources; empowering decision makers across different levels of governance; regulating more smartly; and encouraging international cooperation and data/ knowledge sharing between places with varied status of economic development.


How to cite: Hannah, D., Abbot, B., Khamis, K., Kelleher, C., Lynch, I., Krause, S., and Ward, A.: Global river water pollution: exploring current challenges and future prospects, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-399, https://doi.org/10.5194/iahs2022-399, 2022.

Ophelie Fovet, Laurent Strohmenger, Remi Dupas, Patrick Durand, Mikael Faucheux, Yannick Hamon, Laurent Jeanneau, Patrice Petitjean, Laurent Ruiz, and Chantal Gascuel-Odoux

The effects of climate change on the quality of freshwaters remains poorly investigated while these effects are likely to be ambiguous. Indeed, such effects are partly direct such as temperature control on reaction rates, and partly indirect such as decrease of dilution processes with drier low flows. How the fate of a given pollutant responds to climate change can differ depending on its sources, reactivity and mobilization processes. Therefore, investigating the hydrochemical response of streams to climate change requires considering several elements that differ in their sources and pathways, and in their sensitivity to local and global forcings.

A cross-analysis of hydro-climatic variables and the dynamics of three solutes - carbon (C), nitrogen (N) and phosphorus (P) - was conducted at multiple temporal scales using the long-term data sets from a Critical Zone Observatory in Western France (AgrHyS). We identified trends on climatic variables (air temperature increased, winters became wetter and summers drier) and stream concentrations (NO3 concentrations decreased, DOC concentrations increased). However, no effect of air temperature and radiation was observed on stream-water concentrations for the three solutes and there was no clear response of seasonal water-quality signals to increased contrast among hydrological seasons. Therefore, despite observed inter and intra-annual effects of climate on water quality, long-term changes of stream-water concentrations seemed to be more related to agricultural changes than to climate variations.  

In such a temperate and humid region, the seasonal amplitude of climatic variables is higher than the magnitude of their long-term changes. In addition, agricultural catchments of Western Europe have received high inputs of nutrients since the 1960s that led to create legacy storages in particular N and P in the soil, the vadose zone and/or the groundwater. The damped response of water quality may then be related to legacy storage, leading to lower sensitivity to climatic than to agricultural drivers. Disentangling the respective effects of climate and human activities on stream water quality is particularly challenging, even more in such contexts dealing with legacy storages. As a perspective, we show how using ratios of elements with contrasted properties or origin can help addressing this challenge.  

How to cite: Fovet, O., Strohmenger, L., Dupas, R., Durand, P., Faucheux, M., Hamon, Y., Jeanneau, L., Petitjean, P., Ruiz, L., and Gascuel-Odoux, C.: Climate change and water quality responses in agricultural catchments with high legacy storages of nutrients, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-470, https://doi.org/10.5194/iahs2022-470, 2022.

Maryam Khalilzadeh Postegal, Mojtaba Noury, and Seyed Ahmad Mirbagheri

Based on the deep studies of existing mathematical models, a mathematical model that expresses the dynamic of transport and transformation of heavy metals in the rivers has been presented. In this model, the basic principles of chemistry in the environment, hydraulic and fluid transfer dynamics have been used as well as seasonal variations of the studied heavy metals and influence of the mentioned physicochemical parameters on concentration variations of the heavy metals were investigated. The results of sediment effect can be investigated by the proposed models on the transfer and evolution of heavy metals pollution. For example, the transmutation and transport of heavy metal pollutants in a steady state flow containing sediment are studied using the present model. The results indicated that, the transportation of heavy metals not only have common characteristics of general pollutant but also have features of transport and transformation induced by the movement of sediments. The seasonal variations could be resulted from natural or anthropogenic sources and ambient conditions such as water temperature, EC, DO, pH, etc. Significant relationships were observed between concentration of some heavy metals and physicochemical parameters during wet and dry periods.

Keywords: Numerical Simulation; Heavy Metal; Pollution; Sediment; Physicochemical parameters; Seasonal variation

How to cite: Khalilzadeh Postegal, M., Noury, M., and Mirbagheri, S. A.: Seasonal variation of Heavy Metal Pollution and numerical Modeling in the River and Dam(Case study: Zarineh river and Bookan dam in Iran), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-739, https://doi.org/10.5194/iahs2022-739, 2022.

Conceptualization of Uranium Sources in the alluvial aquifers of North-West India & Extent of Contamination.
Ritu Bala, Debabrata Das, and Karan veer
Uwe Schneidewind, Holly Nel, Jennifer Drummond, Anna Kukkola, Iseult Lynch, Greg Sambrook-Smith, and Stefan Krause

Microplastics have been found to be an emerging contaminant of concern in many ecosystems worldwide. While microplastics have been around for many decades, only recently have studies started to improve understanding of their transport and fate in riverine environments, toxicity to aquatic organisms and distribution throughout riverine food chains. Microplastics of various size, shapes and polymer types have been identified in water and sediment samples in streams and rivers on a global scale with the potential to accumulate in river sediments for extended periods of time. As this accumulation often occurs and increases downstream from where microplastics enter a stream, they can well be considered legacy pollutants.

While earlier studies assumed that microplastics deposit on the streambed mostly by gravitational settling, recent research indicates that turbulent flow processes near the sediment-water interface and groundwater-surface water interactions can greatly influence particle deposition patterns and retention times. In order to directly assess the deposition, accumulation and resuspension of polyamide (PA) particles in a more controlled setting we conducted experiments in mesocosms (recirculating flumes with dimensions of 200 x 42 x 15 cm).

Flumes were filled with either gravel (10-20 mm) or mixed sediment (ranging from silt to fine gravel) and freshwater and were spiked with PA fibres (500 μm length, 14 μm diameter), pre-crushed fragments (size ranges: 150-250 μm and 400-600 μm, pre-stained with Nile Red) or both. Sampling over 24 hours at three locations in each flume allowed us to study the deposition behaviour and we found that due to turbulent flow especially fibres remained in the water column much longer than would be the case for gravitational settling. Deposition rates and retention times of deposited particles were estimated by fitting flume data to a mobile-immobile model that provide insight into the differential transport between polymer types, sizes, and sediment grain size distribution. Subsequent resuspension experiments with variable flow velocities achieved by using one or several pumps per flume indicated significant differences in resuspension with respect to polymer shape and sediment type in the flume. Results will help us better understand and predict microplastic fate in streams and improve current models.  

How to cite: Schneidewind, U., Nel, H., Drummond, J., Kukkola, A., Lynch, I., Sambrook-Smith, G., and Krause, S.: What can we learn from flume experiments about the transport of polyamide microplastics in streams?, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-442, https://doi.org/10.5194/iahs2022-442, 2022.

Georgios Niarchos, Dan Berggren Kleja, Lutz Ahrens, and Fritjof Fagerlund

 Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic chemicals that have extensively been used for more than five decades worldwide, resulting in their ubiquitous spreading . In the light of their toxicity, recalcitrance and bioaccumulation potential, their use and disposal are increasingly being limited. Groundwater is one of the environmental pathways critical for PFAS dispersal and subsequent human exposure. Case studies on PFAS groundwater contamination are lacking and remediation efforts applied in full-scale are limited. In this context, the main objective of this study was to quantify the extent of PFAS contamination in the subsurface and evaluate the effectiveness of a trap-and-treat in-situ soil remediation method with the use of colloidal activated carbon. A PFAS-contaminated site was selected for investigation in Sweden, that has previously been used for fire-fighting training with PFAS-containing aqueous fire-fighting foam (AFFF).

 PFAS concentrations and hydrological properties of the contaminated site were investigated. Groundwater was sampled through five monitoring wells, while surface water samples were collected at four different locations in a stream adjacent to the site monthly-bimonthly. PFAS concentrations were quantified for 11 individual PFASs. Colloidal activated carbon was injected in the subsurface, aiming for a good distribution of the sorbents in the treatment zone. Monitoring wells were drilled upstream and downstream to the injection well, identifying variations in concentrations through time. Total oxidizable precursor concentrations were also quantified in two observation wells. Other parameters that were monitored in the wells included pH, conductivity and metals concentrations. Groundwater levels were measured by manual sounding as well as by automated logging with barometric compensation. Aquifer characteristics were defined by slug tests and the site’s geological characteristics were investigated.

Prior treatment, groundwater concentrations of ∑PFASs were up to 24 μg L-1, while two significant hotspots were identified. ∑PFASs concentrations decreased by ~74% based on the original concentration within and directly downstream of the treatment zone approximately three months after applying the colloidal activated carbon. Differences in the PFAS composition profile after injection, indicated a stronger reduction for PFOS in comparison to, for example, PFOA. However, long-term monitoring is needed to assess the treatment’s efficiency over time.

How to cite: Niarchos, G., Berggren Kleja, D., Ahrens, L., and Fagerlund, F.: Remediation of Per- and Polyfluoroalkyl Substance (PFAS) Contaminated Soil with Colloidal Activated Carbon: Lessons Learned from a Swedish Case Study, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-410, https://doi.org/10.5194/iahs2022-410, 2022.

Posters: Thu, 2 Jun, 15:00–16:30 | Poster area

Chairpersons: Alena Bartosova, Anne Jaffrezic
Moussa Boubacar Moussa, Amadou Abdourhamane Touré, Bruno Lartiges, Emma Rochelle Newall, Laurent Kergoat, Elodie Robert, Marielle Gosset, Bachir Alkali Tanimoun, and Manuela Grippa

130 million residents use the Niger River water for agriculture, fishing, transport and domestic activities. Suspended particulate matter (SPM) and other waste, washed into the river during rainy events,  constitute a favorable environment for bacteria proliferation since it provides protection from ultraviolet radiation, offers nutrients and ideal living environment. The objectives of this work are to: characterize the concentration and nature of SPM in the middle Niger River and analyze their spatio-temporal variability; study the link between SPM and indicator of fecal bacteria contamination (E. coli); quantify the part of fecal pollution that the Niamey city brings into the Niger River.

Two regular monitoring sites were set up on the Niger River and two periurban lakes east of Niamey. Measurements of SPM were made by filtering water samples acquired during two full years. Water color was monitored by above-surface radiometer operating in red and infrared bands and Sentinel-2 satellite. E. coli content and physico-chemical water parameters were also monitored and SPM were analyzed using electronic microscopy and laser granulometry.

The analysis of SPM revealed extremely fine (0.2 µm) particles of mineral origin (kaolinite) with some iron oxide/hydroxide during the red flood. Radiometric measurements by both the in-situ radiometer and Sentinel-2 were found to be well suited to monitor SPM dynamics in this area. SPM and discharge showed a complex relationship : SPM increases before the discharge increase at the beginning of the red flood but they are at their lowest during the black flood. SPM concentration and E. coli somewhat co-vary at the beginning of the rainy season but E. coli values remain relatively high during the black flood, despite low SPM at that time. E. coli concentration at the downstream station reveals an important fecal pollution from the Niamey city with E. coli values on average 10 times higher than the upstream station. Maintaining and developing monitoring tools in this area is particularly important in the context of  global environmental changes, as for example the increase in the red flood discharge observed  in Niamey since the 90’s, that may deeply modify the transfer of contaminants in surface waters.

How to cite: Boubacar Moussa, M., Abdourhamane Touré, A., Lartiges, B., Rochelle Newall, E., Kergoat, L., Robert, E., Gosset, M., Alkali Tanimoun, B., and Grippa, M.: Suspended particulate matter and water fecal pollution in the Niger River at Niamey, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-184, https://doi.org/10.5194/iahs2022-184, 2022.

Mahougnon Fidèle Ahéhéhinnou Yêdo, Ernest Amoussou, Maurice Mathieu Ahouansou, Japhet Domiho Kodja, and Sourou Henry Totin Vodounon

Coastal areas are areas where a very large number of laguno-marine species reproduce, grow or transit, which are most often the subject of fishing exploitation. The purpose of this study is to analyse the risk of contamination of fisheries ecosystems and its consequences on the evolution of aquatic resources in the coastal zone and more specifically from south-west Benin to south-east Togo.

The methodology adopted is based on the collection and processing of raw data such as: hydrometric data, particle size data, climatological data, data from fauna and flora inventories, supplemented by those from in situ measurements and those from laboratory analyses made from sediment samples and some species caught during fisheries during the different hydrological seasons.

Analysis of the results revealed that pollution of the lagoon channel in Cd, As, Pb and some major ions such as Cl -, NO3- and PO43- are responsible for its eutrophication. In addition, organic matter and MES in high concentrations lead to the covering of aquatic habitats, particularly spawning grounds and suffocation of eggs by reducing essential metabolic exchanges (supply of oxygen and nutrients, evacuation of metabolic waste) through the decrease in the concentration of dissolved oxygen within the substrate. Analysis of trace elements in the flesh of samples of Captain fish (Polydactylus quadrifilis), white grouper (Epinephelus aeneus), Tilapia zillii, and white catfish revealed their rate of contamination with metallic trace elements. Behavioural effects (abandonment of shelter areas and avoidance reaction) are thus recorded; subletal effects (short-term reduction in feeding rate; minor physiological stress; increased cough frequency; increased breathing rate; moderate physiological stress; major; delayed outbreak; reduction of population density; mortality). According to 89% of fishermen, the decline in fish species caught is recorded during dry periods, when the channel has a high rate of contamination with heavy metals and major ions.

How to cite: Ahéhéhinnou Yêdo, M. F., Amoussou, E., Ahouansou, M. M., Kodja, J. D., and Totin Vodounon, S. H.: Inland Fisheries and Risk of Contamination of Fisheries Ecosystems in the Gbaga Lagoon Channel (Benin-Togo Coastal Zone), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-404, https://doi.org/10.5194/iahs2022-404, 2022.

Eléa Crayol, Frédéric Huneau, Emilie Garel, Alexandra Mattei, Sébastien Santoni, and Vanina Pasqualini

Coastal Mediterranean hydrosystems, especially Mediterranean lagoons provide a wide range of ecosystem goods and services that human societies take advantage from. Those socio-hydro-eco-systems are most of the time groundwater dependent ecosystems, however their hydrogeological functioning, essential for their management is still little-known.

Catchment anthropization is one of the highest pressure for the lagoons and can increase their ecological vulnerability, especially by the pollutants flowing to the lagoons via groundwater and surface water. The consideration of the groundwater as an inertial system with the ability to store pollutants is not yet taken into account by the water resource managers. South of Corsica is an interesting study area due to the presence of numerous small lagoons and a high rate of urbanization. The catchments of the Balistra, Santa Ghjulia and Arasu lagoons were investigated to explore the types and concentrations of contaminants of emerging concerns. These specific pollutants being considered here as relevant tracers of the coastal Mediterranean anthropization phenomenon with high population increase due to strong seasonal touristic activity.

An original multi-tracer approach, combining physico-chemical parameters, major ions and trace elements as well as, stable isotopes of the water molecule was carried out on 48 points divided in surface water (16 points), groundwater (18 points) and lagoon water (14 points) on the 3 watersheds. On selected relevant points, the analysis of emerging compounds was also realized to identify potential sources of pollutions.

Emerging compounds analysis shows that the three sites are concerned by contamination, nevertheless at very low content. DEET- diethyltoluamid have been found on 78% of the sampling points with concentrations between 16.2 ng/l to 198 ng/l. It is the most commonly found compounds in groundwater with caffeine and benzotriazoles.

The presence of emerging compounds in groundwaters of the 3 catchments with different level of anthropization reveals a high human footprint due to sewage system leakage which is a vector of pollution to the lagoons. In a context of global change, the hydrological balance of such systems is fragile and the degradation of the quality of groundwaters highlighted by the emerging compounds is increasing the vulnerability of the Mediterranean lagoons.

How to cite: Crayol, E., Huneau, F., Garel, E., Mattei, A., Santoni, S., and Pasqualini, V.: Contaminants of emerging concerns in groundwater as tracers of antropization to small Mediterranean lagoons hydrosystems, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-444, https://doi.org/10.5194/iahs2022-444, 2022.

Frédéric Huneau, Emilie Garel, Sébastien Santoni, Alexandra Mattei, Caroline Tafani, and Vanina Pasqualini

Micro-estuaries are very common in the Mediterranean. Their ecological role is also of uppermost importance for the preservation of biodiversity as well as for the nutrient input towards the coastal marine environment. Strong seasonal contrasts are characteristic of the Mediterranean regions, for the hydrological behaviour of rivers but also for activities in relation with the tourism industry. Therefore, in coastal regions water bodies can be exposed to very strong impacts due to the very focused touristic activity especially along the most appreciated zones like beaches, sand dunes and sand bands where micro-estuaries are very frequently also located. Due to the very short duration of the highest touristic season and to the very frequently under-calibrated capacities of sanitation infrastructures, it is frequent to observe wastewaters releases towards the surface waters which can contaminate groundwaters and in the end micro-estuaries. It is then of major interest to evaluate what type of emerging contaminants can be found in these regions, and if a clear seasonality in the contaminant release can be observed.

The strategy is to investigate the emerging contaminant content in waters of micro-estuaries and other types of connected waters (river waters, groundwaters) from a coastal areas of North-Western Corsica characterized by a very dynamic seasonal touristic activity. Sampling were organized before the touristic period and after in order to appreciate the impact of the high season peak on the water quality. 102 molecules were analyses on 20 water samples from 4 different coastal watersheds.

Results show a clear impact of the increase in the population due to the touristic activity, but a baseline contamination is also observed for the winter season. 11 molecules are present for each sampling and mostly composed of pharmaceuticals, nicotine and caffeine metabolites as well as artificial sweeteners. A tendency towards the reduction of concentrations is observed in rivers along the flow due to dilution processes and degradation of contaminants. Groundwater contamination appear as really more stable and mostly in relation with the immediate vicinity of boreholes and wells. Micro-estuaries, which are the final collector all the watershed pollution sources, are the most contaminated water bodies of the survey.

How to cite: Huneau, F., Garel, E., Santoni, S., Mattei, A., Tafani, C., and Pasqualini, V.: Impact of seasonal touristic activity on emerging contaminants of micro-estuaries and hydraulically connected water bodies in North-Western Corsica, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-497, https://doi.org/10.5194/iahs2022-497, 2022.

Nabil Bougherira, Azzedine Hani, Hicham Chaffai, Marnik Vanclooster, Larbi Djabri, Dounia Nechem, Badreddine Saadali, Salim Boubelli, and Ahmed Nahal

Algeria has established a growing urban pole, therefore urbanization and urban dynamics are increasing from year to another, and it occurs a flow of excessive urban wastewater discharges from these agglomerations.

In this research, we are interested in the evaluation of the current state of wastewater, which comes from 1114 residences by household activities and human metabolism, or the mixing of domestic wastewater with water runoff.

In the extreme North east of Algeria, the predominantly domestic waters of Drâa-Errich city, evacuated through collectors and without treatment they are rejected in nature, and the quality of the water at the level of the Gueridjima wadi has deteriorated and these waters currently constitute a polluted effluent which joins the waters of the El Aneb wadi to the west. 

A set of analyzes was carried out (period of April to May 2021) on domestic wastewater to assess their quality.

Sampling and analysis carried out of surface water (02 samples from Gueridjima wadi and 02 samples from El Aneb wadi) and groundwater (01 well), covering an area of 15 km.

The physic-chemical parameters measured with the WTW multiparameter are pH, temperature, electrical conductivity EC, biological demand in oxygen BOD5. In addition, the undesirable substances are Nitrates (NO3-), Nitrites (NO2-), Phosphates (PO4-), and orthophosphate.

In front of this situation, the measures proposed are the systems for treating domestic wastewater sewage, seen the advantages represented by the topography of the land in the region; remains the better solution for possible reuse recovery of wastewater, in agriculture sector. This measure will certainly improve the quality in terms of production of an acceptable quality of (purified) wastewater, and reduce environmental problems

Keywords: current state - domestic wastewater - sewage - admissible quality.

How to cite: Bougherira, N., Hani, A., Chaffai, H., Vanclooster, M., Djabri, L., Nechem, D., Saadali, B., Boubelli, S., and Nahal, A.: Identification of some water quality parameters of the liquid effluents discharged from recent urbanization, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-578, https://doi.org/10.5194/iahs2022-578, 2022.

Remegio Confesor, Marianne Bechmann, Johannes Deelstra, and Jannes Stolte

The Beale’s ratio estimator (Beale, 1962) had been proven to be an unbiased pollutant loading calculator. However, Dolan et al (1981) cited that the estimator may have poor performance due to inadequate stratification. This study evaluated the error in phosphorus annual load calculation using an automated stratified sampling Beale’s ratio estimator of weekly, bi-weekly, and baseflow + storm event sampling schedules. The uniform random sampling and genetic algorithm approaches to search the optimal stratification and the number of strata were implemented in R programming language. The data from the National Center for Water Quality Research’s (NCWQR) tributary loading program in Ohio, USA and the Norwegian Institute for Bioeconomy’s (NIBIO) JOVA monitoring program in Norway were used in this study. The minimum number of strata required in uniform random sampling and the number of sample size and iterations for the genetic algorithm were identified to obtain the stratification that has the lowest load mean square error calculation. The results of this study can be used to find the optimal pollution sampling strategy with minimal loading calculation error depending on monitoring infrastructure and constraints.

How to cite: Confesor, R., Bechmann, M., Deelstra, J., and Stolte, J.: R-Beale: an automated stratified Beale’s ratio estimator to calculate pollutant loading from measurements with missing observations., IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-628, https://doi.org/10.5194/iahs2022-628, 2022.

Zahra Abdollahi, Ataollah Kavian, and Seyed Hamid Reza Sadeghi

The ZanjanRud Basin, in north-western Iran, Zanjan Province, has recently experienced the worst drought conditions in over 50 years of records. Watershed management decisions and climatic shifts resulted in hydrological drought in the middle reaches of the ZanjanRud River from 1999 to 2018. Average River discharge (0/49 m3/s at Sarcham Hydrometric station) in the drought period (2008-2018) were approximately 0.65 m3/s lower than the long-term average (1.2 m3/s) and represented a 54.16% reduction in water discharge. The purpose of this study was to increase understanding of the water quality and ecology of the river, provide additional information for investigation of watershed management options which are compatible with climate change.

Water quality was investigated at the middle part of the river (2 sites) which were regularly (fifteen–monthly) monitored from October 2016 to March 2018. This reach has experienced municipal effluent discharge and are at risk of acidification. The water quality parameters considered in this report were general water quality parameters (EC, temperature, pH, TDS, TSS, turbidity), nutrients (total nitrogen, TN; total phosphorus, TP), dissolved oxygen, chemical oxygen demands, color, and particle metals. Hydrological parameters were also assessed as potential drivers of water quality change. The concentration of dissolved and particulate material in the study sites increased during hot and dry months driven by evaporation and the associated large reduction in water volume. The lack of runoff also resulted in the observation of a high concentration of nutrients and green-algae during the low flow period. Turbidity also increased during the drought period. The results revealed that the middle part of the river is highly influenced by effluents from the municipal area (Zanjan City). Further assessment of water quality during future low flow events is recommended in our study area.

How to cite: Abdollahi, Z., Kavian, A., and Sadeghi, S. H. R.: The Effect of Hydrological Drought on Water Quality in Zanjanrud River, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-741, https://doi.org/10.5194/iahs2022-741, 2022.

Alban de Lavenne, Julien Tournebize, Hocine Henine, Samy Chelil, and Vazken Andréassian

Models based on StorAge Selection (SAS) functions are emerging as promising tools for quantifying catchment-scale solute export through the understanding of factors controlling transit time distribution (TTD). SAS functions describe the sampling of different ages in catchment storage that produces river discharge. This sampling varies over time, for example in such a way that the young water fraction is generally higher during high flows and lower during low flows. Literature thus proposed different parametrization of SAS functions in order to make them dynamics according, for instance, to soil moisture or antecedent inputs.  

In the first step of this work, we investigated how the time variance of the SAS functions could be related to the different fluxes and model states of the hydrological model GR4J. Chloride concentrations are used as a conservative tracer to evaluate different modelling hypotheses. In a second step, we investigated how TTD could be used to understand the dynamics of a non-conservative solute such as nitrate. In addition to the solute transport, we described the relationship between water age and denitrification at catchment scale. We assumed that nitrate removal is higher when young water fraction is lower, and we investigated the seasonal dynamics of this assumption. These hypotheses are tested by exploring the detailed water quality record from the Orgeval catchment (ORACLE observatory, France) where it is possible to assess various scales of nested catchments (up to 104 km²). 

How to cite: de Lavenne, A., Tournebize, J., Henine, H., Chelil, S., and Andréassian, V.: Modeling Nitrate export with GR4J and StorAge Selection functions, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-65, https://doi.org/10.5194/iahs2022-65, 2022.

Anne Jaffrezic, Lise Charuaud, Marine Liotaud, Fabien Mercier, Barbara Le Bot, and Emilie Jardé

Veterinary pharmaceuticals, widely used in intensive livestock production, may contaminate surface waters. Identifying their sources and pathways in watersheds is difficult because i) most veterinary pharmaceuticals are used in human medicine as well and ii) septic or sewer wastewater treatment plants (WWTP) can release pharmaceuticals into surface water, even in agricultural headwater watersheds. This study aimed to analyze the spatiotemporal variability of animal-specific, mixed-use, and human-specific pharmaceuticals, from agricultural headwaters with intensive livestock production and a WWTP to a watershed used for Water Framework Directive monitoring. Grab sampling was performed during three hydrological year in seven nested watersheds in intensive husbandry area upstream and downstream from a WWTP with areas of 1.9-84.1 km². Twenty pharmaceuticals were analyzed. Microbial fecal indicator E. coli and fecal stanols were determined. Fecal stanols are microbial source tracking tool allowing to identify the origin of the fecal contamination (porcine, bovine or human). Animal-specific pharmaceuticals were detected at all sampling dates upstream and downstream from the WWTP and at concentrations higher than those of human-specific pharmaceuticals. Animal-specific pharmaceuticals were detected mainly during runoff events associated with bovine or porcine fecal contamination. A large percentage of mixed-use pharmaceuticals was assigned to animal sources. Mixed-use and human-specific pharmaceuticals predominated in the largest watersheds when runoff decreased. In areas of intensive livestock production, mitigation actions should focus on agricultural headwater watersheds to decrease the number of pathways and the transfer volume of veterinary pharmaceuticals, which can be the main contaminants.

How to cite: Jaffrezic, A., Charuaud, L., Liotaud, M., Mercier, F., Le Bot, B., and Jardé, E.: Veterinary pharmaceutical and fecal contamination in mixed-land use watersheds: from agricultural headwater watersheds to water-monitoring watersheds., IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-534, https://doi.org/10.5194/iahs2022-534, 2022.