Freshwaters toxic substances

Unlike the freshwater biota, POPs in local marine fish and shellfish were relatively well studied. Data were retrieved primarily from two toxic substances consultancy studies (EPD, 2003a,b), the EPD ad hoc baseline survey (EPD, 2003c), and the 2004 CEDD Environmental Monitoring and Audit for Contaminated Mud Pit IV at East Sha Chau (CEDD,... 

To reduce the inflow of toxic substances into basin waters efficiently, the Corporation required information on which effluents posed the greatest hazard to the river. While chemical data on many of the effluents were available, their diverse composition was difficult to interpret in terms of hazard potential. Moreover, hazard is not only linked to chemical composition of an effluent, but also on the toxic effects it can have on a variety of freshwater organisms. Adverse effects on biota are also influenced by the volume of wastewater discharged at different times of the year. Hence, the Corporation searched for a cost-effective approach, based on ecotoxicological principles, to rank the various effluents (there are several hundred sources), in terms of their toxic loading, so that subsequent efforts (such as clean up actions) could be prioritized. 

Toxicity data for saltwater organisms are often insufficient to assess risks. Freshwater toxicity data are usually more plentiful, and their use may provide a suitable surrogate for saltwater data. Wheeler et al. (2002b) used species sensitivity distributions to determine if freshwater data sets are adequately protective of saltwater species assemblages for 21 chemical substances. For ammonia and metal compounds, freshwater organisms tended to be more sensitive than saltwater species, whereas the opposite was true for pesticides and narcotic compounds (Wheeler et al. 2002b). De Zwart (2002), who compared 160 compounds, including 92 pesticides, concluded... 

Studies involving the adsorption of organic substances onto solid phases have largely centered around organic pesticides because of the environmental significance of these toxic substances. The extent of adsorption of Bromacil onto freshwater... 

Maryland Criteria for toxic substances in surface waters Freshwater Acute Chronic Saltwater Acute Chronic Drinking water 20 gg/L 5.0 gg/L 300 gg/L 71 gg/L 50 gg/L BNA 2001... 

The most obvious impact of sediment-associated pollutants on aquatic biota is direct acute toxicity and there is considerable literature on both laboratory and field effects of toxic substances on marine and freshwater invertebrates (Baker, 1980 Reynoldson, 1987). For example, Warwick (1980) and Wiederholm (1984) observed deformities in chironomid larvae mouthparts at polluted sites of lakes in Canada and Sweden Milbrink (1983) has shown setal deformities in oligochaetes exposed to high sediment mercury levels. Indirect effects resulting from sediment contamination oftenly include changes in benthic invertebrate community structure. For example, Lock et al. (1981) evidenced increased growth of bacterial flora and algal cells on oiled substrates and a consequent stimulation of macroinvertebrates. Chapman et al. (1982) have shown effects of life history alterations (e.g., impairment of reproduction and age selective toxicity) which have been linked to sediment contaminants. ... 

Aquatic Information Retrieval). Produced by the Environmental Protection Agency, Offlce of Pesticides and Toxic Substances, USA. AQUIRE includes data on tests performed on freshwater and saltwater organisms. At March 1990 it contained data on over 5200 diemicals in over 104,000 different assays. Compiled by J.T. Baker Inc., Phillipsbuig, New Jersey, USA. Contains MSDSs for around ISOO chemical substances, using guidelines of the U.S. Occupational Safety and Health Administration (OSHA). 

Interactions of merciuy with other toxic substances have not been studied extensively, but some information does exist with respect to copper. In studies of the antifouling properties of these two metals, Barnes and Stanbury (1948) using the copepod Nitrocra spinepes noted that copper and mercury acted synergistically. They reported that the exposure of animals to 0.4 mg/L of merciuy resulted in a 17% mortality after 24 hrs, whilst 2.6 mg/L of copper gave a mortality of 20%. However, a mixture of the two materials at these concentrations produced a mortality of 98%, i.e., a 3x increase above the expected additive value. Similar results have been reported by Corner and Sparrow (1956) and by Hunter (1949). However, Roales and Perlmutter (1974) reported that copper apparently inhibits the toxicity of methyl mercury chloride to an American freshwater fish, Trichogaster trichopterus. 

The time dependence of the acute toxicity of oil and dispersants on a sensitive freshwater organism, namely, Daphnia magna, was investigated [1805]. Two different oils were used a crude oil from the southwest of France and a gas oil free from volatile substances after being equilibrated with atmosphere. Two commercial dispersants were used British Petroleum Enersperse 1037 and Dasic Freshwater. 

USEtox (Rosenbaum et al. 2008 [42]) was used to address the continental scale. It can be applied to assess either ecotoxicity or human toxicity from different pollutants. It calculates characterization factors for human toxicity and freshwater ecotoxicity, taking into account the environmental fate, exposure and effects of the substance. 

Although this chapter focuses on applications with effluent wastewaters, all types of aquatic environmental media (freshwater, brackish, marine) can be appraised with the pT-scale procedure. Testing of liquid samples is virtually unlimited and can include untreated and treated wastewater, surface water, ground water, porewater, elutriates and organic extracts of sediments. Applications could also be extended to assess toxicity of particle-bound substances in suspended matter and sediments. In this case, sample dilutions can be made with reference sediment material (Hoss and Krebs, 2003). The pT-method can also capture the effects of both soluble and particulate toxicity in a sample, provided that appropriate bioassays are employed. 

Hutchinson T, Scholz N, Guhl W. 1998a. Analysis of the ECETOC Aquatic Toxicity (EAT) database, IV comparative toxicity of chemical substances to freshwater versus saltwater organisms. Chemosphere 36 143-153. 

For substances with specific modes of action, the SSD should be based on data for the most sensitive group (e.g., crustaceans). If there are no indications that salinity affects toxicity (see Section 4.6), SSDs can be created using combined freshwater... 

Examples of organic and inorganic substances for which toxicity is different in freshwater and marine water organisms... 

The first method for detecting water pollution is to carry out comprehensive chemical monitoring and look for concentrations that exceed water quality criteria. However, since over 1500 substances have been listed as freshwater pollutants (Mason, 1981), extensive monitoring can be costly. Additionally, acute and chronic toxicity data are limited for commonly tested organisms and are almost nonexistent for many native species. However, chemical monitoring alone may not detect water pollution... 

A9.3.2.1 For classifying substances in the harmonized system, freshwater and marine species toxicity... 

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