anthropogenic 39 aquatic 31 sludge 21 wastewater 13 terrestrial 7 lentic 6 marine 6 waste 5 benthic 5 medium temperature 5 sediment 5 anaerobic 4 sewage 4 agriculture 4 very high salinity 4 cropland 2 high salinity 2 hospital 2 saline water 2 built environment 2 subsurface 1 groundwater 1 fresh water 1