Zinc

Although Zn is known as an ubiquiteous element in nature, it is supposed that about 96 of its release into the global environment is the result of anthropogenic activities, like electroplating, smelting and ore processing, corrosion from alloys and galvanized surfaces as well as erosion from agricultural land (see chapters 2-3 before). It is supposed that dissolved Zn in Canadian and Scandinavian freshwaters rarely exceeds 40 g l. High concentrations are likely to occur in acid surface waters...

Permitted trace metal loads to agricultural soils

The existing EU Directive regulating the use of sewage sludge in agriculture (86 278 EEC) stipulates the highest permitted loading rate for trace metals as follows 12 kg copper, 3 kg nickel and 30 kg zinc per ha and year as mean value over a period of 10 years. However, due to increasing concerns, several EU member states have set national limits well below the EU Directive (see Table 4.6). A recent EU initiative (Third Draft to the Working Document on the Revision to the Sewage Sludge...

Toxicity to aquatic organisms in the water column

In recent years, it has - again and again - been recognized that the toxicity, e.g. the acute median lethality, LC50, of a trace metal to a single aquatic species can vary widely between different bioassays. This has become a problem, because results of toxicity tests are often used to establish Water Quality Criteria or as inputs into environmental risk assessments, and with variable toxicity data it is difficult to apply criteria based thereon with any certainty. Therefore, environmental...

Speciation Bioavailability and effects of trace metals in the environment

Assessments of the fate and biological effects of trace metals in the environment based solely on total concentrations of the metals in the various media (water, sediment or soil) is no longer state-of-the-art or scientifically justified. Although water, sediment and soil quality criteria for metals in most countries are still based on the total concentrations, it is now becoming more and more evident also for regulatory authorities that it is the actual metal species that determines mobility,...