Organic anthropogenic contaminants

Figure 1. Conceptual model illustrating examples of major anthropogenic contaminant sources and contaminants, their distribution within the abiotic environmental media, their movement into biota with potential food chain contamination, and potential effects at the organismal, population, conmiunity and ecosystem level of organization.

Currently available CRMs Calibrants are available for TBT (very evident, as TBT is an anthropogenic contaminant) and for a number of other organic tin compounds. There is also an interesting choice of environmental CRMs (sediment and mussel tissue) certified for TBT content. 

Field-collected sample of presumably clean (uncontaminated) sediment, selected for properties (e.g., particle size, compactness, total organic content) representing sediment conditions that closely match those of the sample(s) of test sediment except for the degree of chemical contaminants. It is often selected from a site that is uninfluenced or minimally influenced by the source(s) of anthropogenic contamination but within the general vicinity of the site(s) where samples of test sediment are collected. A reference sediment should not produce a toxic effect (or have a minimum effect) on a test species. A sample of reference sediment should be included in each series of toxicity tests with test sediment(s). See also Artificial sediment, Positive control sediment and Test sediment. Volume 1(2,13), Volume 2(8). 

Over the past few decades the Black Sea has been seriously perturbed by climatic change and intensive anthropogenic contamination. Some nutrients have increased (e.g., NO3 due to eutrophication) while others have decreased (e.g., Si due to Danube river dams construction) [22]. Organisms imported as part of international shipping (e.g., Mnemiopsis and Beroe) have contributed to modification of the natural ecosystem. Understanding the natural temporal variability of the hydrochemistry of the Black Sea is important when trying to determine the effects of these anthropogenic perturbations. 

The amount of organic load associated with anthropogenic contamination and redox conditions also controls the reactivity of the unsaturated zone, and consequently the salinity of associated water. In aerobic conditions, the degradation of organic matter results in accumulation of HCOj" and Ca due to dissolution of the carbonate matrix of the host aquifer. In addition, the contents... 

Estuarine environments in particular are often sites of intense human and animal activity (e.g. sites of leisure pursuits and breeding grounds for many species of birds) so the level of contamination of intertidal sediments is of particular interest in relation to environmental health. Total concentrations of individual trace elements in UK estuaries, for example, vary widely (Table 2.1), reflecting the natural sediment characteristics (e.g. organic content and surface area), and the level of anthropogenic contamination of individual systems (Bryan Langston, 1992). The order of variability of concentrations of individual elements in Table 2.1 is Sn > As > Cu > Pb > Hg > Ag > Zn > Cd > Se > Cr > Mn > Co > Ni > Fe, which to some extent can be considered as the order of anthropogenic influence. 

In summaiy, the scientific research on the anthropogenic pollution of groundwater and riverine systems, especially by organic substances, comprising the sources, emission pathways, distribution and fate of anthropogenic contaminants still remains as an important challenge in environmental sciences. 

Aquatic particulate matter is an important sink for numerous lipophilic anthropogenic contaminants as the result of adsorption and accumulation processes. In the adsorbed state organic contaminants can be subject to transformation as well as to transportation processes within the river system. The anthropogenic contribution to the organic load of river systems can be attributed mainly to sewage effluents derived from industrial and domestic point sources, to agricultural emissions or to shipping activities. Numerous specific compounds reflect the different sources of pollution and, therefore, are frequently detected in river systems. 

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