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Investigation of the contamination of water resources by Agricultural chemicals and the Impact on environmental health volume 1: Risk assessment of Agricultural chemicals to human and animal health
Expanded Title:The project selected three agriculturally intensive catchments (Letsitele, Lomati, Vals and Renoster) representative of important commercial crops produced in South Africa and these are maize, sugarcane, citrus and subtropical fruit, where seasonal sampling for pesticides, inorganic chemistry and Endocrine Disruptive (ED) bioassays was conducted in water and sediment. These results were interpreted against guideline values or subjected to detailed risk assessment methodologies (in the case of pesticides) so as to assess the potential risk of agricultural chemicals to human and animal health. In addition, pesticides were prioritised based on the quantity of use, toxicity (to human health) and environmental mobility and their spatial distribution mapped to highlight important source areas. These resources were used to prioritised pesticides for monitoring in each of the selected study areas. This study has provided further evidence of the widespread occurrence of agricultural chemicals in water resources in South Africa. In all the study areas, the detection of pesticides was well predicted by indices used in the prioritisation procedure, particularly quantity of use and mobility. The frequency detection of atrazine, terbuthylazine and simazine in maize and sugar cane areas is undoubtedly a reflection of their high quantity of use as well as their high mobility in the environment. Similarly, imidacloprid, which was also highlighted as being highly mobile in the environment, although not detected as frequently, was also found in comparatively high concentrations when detected. Other frequently detected pesticides such as carbofuran, diuron and hexazinone were also well predicted by outputs from the prioritization procedure (i.e. crop specific use and mobility). These results indicate that indices of use and mobility are very useful in terms of prioritising specific pesticides for detailed monitoring in study areas. In addition, the qualitative screening analysis was also instructive in helping to identify specific pesticides in the selected catchment study areas for further quantitative analysis. The pesticide maps developed during this study provide an additional resource by specific pesticides is likely to occur. Additional useful resources with regards to characterising pesticide use include databases produced by CropLife South Africa and AgrilIntel which provide information on active ingredients and recommended rates of application of registered pesticides for different crops in the country. Based on the results from this project, the key messages are: (a) To use practices that minimize the movement of pesticides to surface and groundwater, (b) We need to protect water quality through releasing fewer pesticides or less toxic pesticides into the environment, (c) Improved prioritisation of environmental risk, monitoring and modelling approaches in the environment.
Date Published:01/10/2015
Document Type:Research Report
Document Subjects:Agricultural Water - Commercial irrigation, Agricultural Water - Small holder irrigation, Agricultural Water - Aquaculture
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1956/1/15
ISBN No:978-1-4312-0711-4
Authors:Dabrowski JM
Project No:K5/1956
Organizations:CSIR Natural Resources and the Environment
Document Size:11 737 KB
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