Sources of lead in surface waters

Lead is deposited from the atmosphere directly onto water surfaces. It is also contributed by effluents arising from industrial, domestic and transport activities, as well as being derived from natural sources, in particular areas of lead mineralization. 

Direct deposition, either by dry or wet pathways (Section 4.2) is only significant in the case of larger water bodies such as lakes or oceans. It has been estimated that more lead now enters the North Sea via atmospheric input, 15 000 tonne y than is contained in the known water-borne inputs of 3600 tonne y [1]. The estimated magnitude of different pathways of lead input to all the worlds oceans, including both industrial and natural sources is shown in Table 3.1. 

The remaining sources of lead are in the form of liquid effluents. These may be usefully considered in terms of point sources — readily identified large discharges — and as diffuse or non-point sources, which are smaller in scale and more widespread, and hence harder to quantify. A rigid distinction should not, however, be drawn between these two types of source. 

Rivers and sewers (soluble, mainly from aerosols) 60 000 

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Sources of lead in surface water or sediment include deposits of lead-containing dust from the atmosphere, waste water from industries that handle lead (primarily iron and steel industries and lead producers), urban runoff, and mining piles. 

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