Table 1.1.

Sources and route of pollutant discharge into aquatic environs (NEST 1991; Mateo-Sagasta et al. 2017)

Contamination	Source	Route
“Oxygen-demanding wastes (organic pollutants)”	“Domestic sewage, human and animal wastes (such as wastes from canneries and wood pulp mills)”	“Thrown, dumped or released into streams and rivers or into gutters, drains from where they may get washed by run-off into water bodies”
“Infectious disease agents”	“Domestic sewage, human and animal wastes”	“Washing, swimming or working in paddy rice fields and on irrigated land”
“Plant nutrients such as nitrate, phosphate and others”	“Fertilized farm lands, ashes and detergent”	“Run-off from fertilized farmlands”
“Pesticides (insecticides and herbicides)”	“Organic and inorganic chemicals”	“Run-off from pesticides associated with farmlands”
“Industrial effluents which include DDT, dyes, mercury, cadmium”	“Textile factories, distilleries pulp and paper mills, fertilized plants, chemical and allied industry, food, beverages and tobacco industries, soap, detergents and confectionery industries”	“Human discharges”
“Eroded sediments”	“Deforestation and accelerated soil erosion”	“Soil erosion, urban storm water runoffs and dredging activities”
“Other solid wastes”	“Metals, plastics, artificial fibers etc.”	“Dumping by human beings due to poor management of waste disposal”
“Petroleum products”	“Drill cuttings,” “drilling mud (fluids used to stimulate the production processes),” accidental discharges of “crude petroleum,” “refinery effluents” which include “oil” and “grease,” “phenol,” “cyanide,” “sulphide,” “suspended solids,” “chromium,” and “biologically oxygen demanding organic matter”	“Petroleum, exploration, exploitation, refining, transportation, storage, marketing, use and ruptured oil pipelines”