Chemical Products

An immense variety of chemical products are being manufactured, used, and released by agricultural and industrial activity. Some inorganic compounds include acids, alkalis, ammonia, chlorine, radionuclides, and heavy metals (e.g., cadmium, copper, iron, mercury, and zinc). Organic compounds are grouped under different names such as chlorinated hydrocarbons, hydrocarbons, pesticides, phthalates, and phenolic compounds. Perhaps 20,000–50,000 substances are manufactured or applied within industrial countries, and a few thousand are added each year. In most European countries, between 120 and 530 active pesticides are approved for agricultural use today. The annual usage is usually between 1 and 14 kg ha–1 of arable land. Substances that are applied within a country are also detected (or their degradation products) when tested for in surface waters and groundwaters. The most common pesticides in groundwater (i.e., atrazine, desethylatrazine, lindane, and simazine) are often found in concentrations exceeding the maximum allowable threshold (0.1 μg l−1 in the European Union).