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Drivers of soil pollution in agricultural fields
The document discusses the drivers of soil pollution in agricultural fields, focusing on both geogenic and anthropogenic sources of contaminants, particularly from fertilizers. Key contaminants such as cadmium and fluorine are highlighted, with emphasis on their impact on soil quality, crop uptake, and potential human health risks. The document underscores the importance of managing inputs and agronomic practices to mitigate these risks, especially in regions with high natural contaminant levels.
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Drivers of soil pollution in agricultural fields
- 2. Mike McLaughlin The Universityof Adelaide, Australia /fertiliser Drivers of Soil Pollution in Agricultural Fields
- 3. Outline • Agricultural footprinton the globe • Geogenic sources of soil contamination • Anthropogenic sources of soil contamination • Fertiliser contaminants in agricultural soils • Cadmium • Fluorine • Take home messages
- 4. Global land use Source:FAO Cropland + Grassland = 25.6%
- 5. Irrigation water Fertilizers Soil amendments & wastes Weathering Atmospheric inputs (volcanic,energy/nuclear) Sources of soil pollution in agricultural fields Agricultural chemicals Geogenic Anthropogenic
- 6. Geogenic contaminants • Weathering(e.g. As, Cd, Ni, Se) and agricultural perturbation of soil chemistry (e.g. pH, salinity) • Volcanic eruptions (e.g. F) • Irrigation with water from aquifers contaminating high concentrations of natural contaminants (e.g. As, F) Contaminants introduced by
- 7. Geogenic contaminants –e.g. arsenic (groundwater) Ravenscroft, P. 2011. Arsenic pollution of groundwater in Bangladesh, pp. 181-192 in Encyclopedia of Environmental Health, Elsevier B.V. http://www.novaquatis.eawag.ch
- 8. Geogenic contaminants –e.g. fluorine (volcanic) freemeteo.co.nz Gronvold, K., Larsen, G., Einarsson, P., Thorarinsson, S. & Saemundsson, K. 1983. The Hekla eruption 1980–1981. Bulletin Volcanologique, 46, 349-363.
- 9. Reimann, C., Filzmoser,P., Fabian, K., Hron, K., Birke, M., Demetriades, A., Dinelli, E., Ladenberger, A., Albanese, S., Andersson, M., Arnoldussen, A., Baritz, R., Batista, M. J., Bel-lan, A., Cicchella, D., De Vivo, B., De Vos, W., Duris, M., Dusza-Dobek, A., Eggen, O. A., Eklund, M., Ernstsen, V., Finne, T. E., Flight, D., Forrester, S., Fuchs, M., Fugedi, U., Gilucis, A., Gosar, M., Gregorauskiene, V., Gulan, A., Halamic, J., Haslinger, E., Hayoz, P., Hobiger, G., Hoffmann, R., Hoogewerff, J., Hrvatovic, H., Husnjak, S., Janik, L., Johnson, C. C., Jordan, G., Kirby, J., Kivisilla, J., Klos, V., Krone, F., Kwecko, P., Kuti, L., Lima, A., Locutura, J., Lucivjansky, P., Mackovych, D., Malyuk, B. I., Maquil, R., McLaughlin, M. J., Meuli, R. G., Miosic, N., Mol, G., Négrel, P., O'Connor, P., Oorts, K., Ottesen, R. T., Pasieczna, A., Petersell, V., Pfleiderer, S., Ponavic, M., Prazeres, C., Rauch, U., Salpeteur, Schedl, A., Scheib, A., Schoeters, I., Sefcik, P., Sellersjö, E., Skopljak, F., Slaninka, I., Šorša, A., Srvkota, R., Stafilov, T., Tarvainen, T., Trendavilov, V., Valera, P., Verougstraete, V., Vidojevic, D., Zissimos, A. M. & Zomeni, Z. 2012. The concept of compositional data analysis in practice - Total major element concentrations in agricultural and grazing land soils of Europe. Science of the Total Environment, 426, 196-210. Geogenic contaminants – cadmium (weathering) Tóth, G., Hermann, T., Szatmári, G. & Pásztor, L. 2016. Maps of heavy metals in the soils of the European Union and proposed priority areas for detailed assessment. Science of the Total Environment, 565, 1054-1062.
- 10. Geogenic contaminants –cadmium (weathering) Barry, G. A. & Rayment, G. E. 1997. Heavy metals and nutrients in soils and sediments of Raine Island, Great Barrier Reef. In: Land Contamination and Reclamation. pp. 281-285. “Background” Cd concentrations 37 mg/kg (Barry and Rayment 1977)
- 11. Geogenic contaminants –e.g. nickel (weathering) Anderson, A. J., Meyer, D. R. & Mayer, F. K. 1973. Heavy metal toxicities: levels of nickel, cobalt, and chromium in the soil and plants associated with visual symptoms and variation in growth of an oat crop. Australian Journal of Agricultural Research, 24, 557-571.
- 12. Anthropogenic contaminant sources •Fertilisers • Wastes (agricultural, urban and industrial) • Agricultural chemicals (pesticides, herbicides, plant regulators/promotants, veterinary chemicals, etc.) • Atmospheric diffuse sources (combustion, radiogenic) Contaminants introduced from multiple sources
- 13. Fertilisers • Phosphatic fertilisers– through impurities either in the phosphate rock used or in the sulphuric acid used for acidulation • Trace element fertilisers – through use of by-product metals with high levels of impurities e.g. smelting wastes Fertilizer contaminants introduced by 2 main groups of fertiliser Nitrogen, potash and sulphur fertilisers mostly pure with low levels of contaminants
- 14. Contaminant concentrations infertilisers related earth’s crust concentrations Rock phosphate Earth crust Element Minimum Maximum average value As 2 300 5 Cd 1 90 0.5 Co 0.2 21 30 Cr 6 327 200 Cu 20 98 100 F 1900 42400 270 Hg 0.4 2.1 <0.1 Mn 5 524 900 Mo <1 5 3 Ni 9 51 80 Pb <1 51 16 Sb 0.1 3 <1 Se <1 12 <1 Sn <1 52 40 Sr 420 24800 400 Ti 265 1471 6000 V 10 248 150 Zn <2 2412 50 Th 1 110 8 U <1 280 3 1 2 Sauerbeck, D. 1992. Conditions controlling the bioavailability of trace elements and heavy metals derived from phosphate fertilizers in soils. In: Proceedings of the International IMPHOS Conference on Phosphorus, Life and Environment., Institute Mondial du Phosphate, pp. 419-448.
- 15. Predicted increases incontaminant concentrations McLaughlin, M. J., Tiller, K. G., Naidu, R. & Stevens, D. G. 1996. Review: The behaviour and environmental impact of contaminants in fertilizers. Australian Journal of Soil Research, 34, 1-54.
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- 17. Cadmium – uptakeinto food crops • Cadmium is unique amongst the trace elements in that it is taken up readily by plants (despite being non-essential) • Removal from soil is not agronomically feasible • Minimisation of Cd accumulation in soil, and control of Cd transfer to crops (especially for geogenic Cd), is therefore prudent en.Wikipedia.org
- 18. Fish, freshwater Molluscs Shrimp, freshwater Shrimp,sea Crab, freshwater Crab, sea Purple seaweed Kelp Kelp, dry Meat, stock Meat, poulty Liver Kidney Egg, fresh Egg, preserved Milk (excl. milk powder) Milk powder anim a China ke th) 25 30 25 30 China Europe 1990 1992 2000 2015 Japan Korea Thailand Bangladeshis USA Australia Europe(avg.) Lebanon Canada Germany UK France DietaryCdintake (µg/kgBW/month) 0 5 10 15 20 25 30 Crab, freshw Crab Purple seaw Kelp Meat, s Meat, p Ki Egg, f Egg, prese Milk (excl. milk pow Milk po China 1990 1992 2000 2017 Japan Korea Thailand gladeshis USA Australia ope(avg.) Lebanon Canada Germany UK France DietaryCdintake (µg/kgBW/month) 0 5 10 15 20 25 30 (a) (b) (d) WHO 2010 EFSA opinion, 2009 ATSDR, 2008 Cadmium • There is considerable divergence in critical Cd intakes established to minimise risks of Cd disease to human populations (EFSA vs. FAO/WHO JECFA), which drives concern for soil Cd contamination • Important to note that exposure of populations in Asia to dietary Cd is much higher than in the EU (Wang et al., 2017) Wang, P., Kopittke, P. M., McGrath, S. P. & Zhao, F. J. 2017. Cadmium transfer from soils to plants and its potential risk to human health. In: The Nexus of Soils, Plants, Animals and Human Health. eds B. R. Singh, M. J. McLaughlin & E. Brevik), Catena- Schweizerbart, Stuttgart, Germany, pp. 138-147.
- 19. Factors affecting soilCd uptake by crops weather Soil Characteristics Soil Cd concentration Crop Rotation Fertilizer management Tillage and agronomic management Crop Genetics Irrigation and water management Grant, C. A., Bailey, L. D., McLaughlin, M. J. & Singh, B. R. 1999. Management factors which influence cadmium concentrations in crops. In: Cadmium in Soils and Plants. eds M. J. McLaughlin & B. R. Singh), Springer Netherlands, pp. 151-198.
- 20. Cadmium - management •Cadmium accumulation by crops can be managed by various agronomic factors as well as by minimising inputs (recognising that geogenic Cd inputs cannot be easily minimised) • Effective control of contamination of the food chain by Cd is therefore by a combination of farmer education, agronomic interventions and by controls on inputs to soil
- 21. Cadmium – fertiliserlimits • There is considerable debate ongoing at present regarding limit values for Cd in fertilisers as part of the CE process in the EU • Proposed reductions are driven by the concept of no net accumulation in soils – informed by scientific modelling
- 22. Cadmium – fertiliserlimits • There is a danger of focusing too much on fertiliser Cd limits, and ignoring the great reductions in food Cd concentrations that can be achieved by agronomic means • Agricultural areas with high geogenic Cd will benefit most from agronomic and remediation technologies to reduce food chain transfer, not from input management
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- 24. Fluoride • Fluorine isthe forgotten element in the quest for “safer” phosphatic fertilisers • Fluorine (as fluoride) occurs at % levels in phosphate rocks and hence P fertilisers, while Cd only occurs at trace (mg/kg) levels • Concentrations of F in soils are increasing more than Cd due to P fertilisation Loganathan, P., Hedley, M. J., Wallace, G. C. & Roberts, A. H. C. 2001. Fluoride accumulation in pasture forages and soils following long-term applications of phosphorus fertilisers. Environmental Pollution, 115, 275-282.
- 25. Fluoride • Fortunately, F-is bound strongly by soil minerals, so adverse effects on plants and soil organisms, or plant uptake, only occur at high soil F concentrations • However, the strong retention of fertiliser F- by soil results in strong accumulation at the soil surface • More acidic soils allow greater F uptake by plants and potential toxicity due to formation of (AlFx)3-x complexes • Hence, grazing animals on permanent pastures (e.g. dairy systems) are at risk of high F ingestion and potentially fluorosis McLaughlin, M. J., Stevens, D. P., Keerthisinghe, D. G., Cayley, J. W. D. & Ridley, A. M. 2001. Contamination of soil with fluoride by long-term application of superphosphates to pastures and risk to grazing animals. Australian Journal of Soil Research, 39, 627-640.
- 26. Perspectives  Geogenic sourcesof pollution (e.g As, F, Se) have had a greater global impact on human and animal health than anthropogenic sources  Nonetheless, fertilisers, mainly phosphatic fertilisers, represent an important source of potential contaminants in global agricultural systems, as they represent “new” inputs from the geosphere to the biosphere (unlike animal manures)  Cadmium and fluorine are the elements in fertilisers most likely to significantly affect soil quality and function  The food chain is protected best by a combination of limiting Cd inputs, as well as agronomic management to minimise Cd uptake  In the not too distant future, F could adversely affect grazing systems that are intensively fertilised