Integrated approach for evaluating sources and apportionment of agro-contaminants in soil and water bodies

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.