Sewage sludge application as a vehicle for microplastics in eastern Spanish agricultural soils

Periodo de realización: 1900/01/01 al 2020/01/01

Tipo: Artículo científico

Resumen: "Plastic has taken up an important role in current society, with global annual use exceeding 260 million tons. A possible pathway for plastic to enter the environment, potentially damaging ecosystems, is through the use of sewage sludge of wastewater treatment plants. Spain recycles 65% of the sewage sludge through agricultural soils, the highest rates within Europe. However, the content of microplastics in sewage sludge and its contribution to the overall content of microplastics in the soil is largely unknown. The objective of this study was to quantify microplastic pollution in agricultural soils and the contribution of sewage sludge to this. Four wastewater treatment plants and 14 agricultural fields, located in the vicinity of Valencia, were sampled. Plastic particles were extracted using a flotation and filtration method while making a distinction between light density plastic particles (density <1 g cm -3) and heavy density plastic particles (density >1 g cm -3). It was found that sewage sludge, on average, has a light density plastic particle load of 18,003 ± 15,940 kg-1 and a heavy density plastic particle load of 32,070 ± 19,076 kg-1. Soils without application of sewage sludge had an average light density plastic particle load of 928 ± 744 kg-1 and a heavy density particles load of 1,099 ± 567 kg- 1. Soils with sewage sludge application had an average light density plastic particle load of 2,130 ± 946 kg-1and a heavy density particle load of 3,060 ± 1,683 kg-1. Findings show that there is a big variance in microplastic concentration, but overall there are more microplastics in soils with the application of sewage sludge. This confirmed that sewage sludge application further pollutes agricultural soils and indicates that legislation surrounding the application of sewage sludge as a fertilizer ought to be reconsidered"

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