Research into the suitability of Microtox® for the evaluation of toxicity of surface waters and bottom sediments in Poland was conducted. Water bodies of various pollution levels were tested, including the Odra River and its tributaries, the Lower Vistula River, the Kashubian Lake District and the Gulf of Gdańsk, using a Microtox® Model 500 analyser (Microbics Corporation, USA). The majority of tested surface water samples were found to be apparently non-toxic. However, 75% of the bottom sediment samples were found to be highly toxic (EC50<2%). These results indicate that the Microtox® test is suitable for evaluating the toxicity of bottom sediments, in which pollutants tend to accumulate. It seems, however, that Microtox® lacks the sensitivity to be of use in analyzing water quality. The relationship between the toxicity of analysed sediments and their organic content was examined.
Combustion processes are considered to be the main source of the dioxin emission in the Baltic region. Pentachlorophenol (PCP) and its derivatives, pentachlorophenyl laurate (PCPL) and sodium pentachlorophenate (NaPCP) are known as precursors of dioxins. The research was conducted to obtain the first data on the concentration of PCDD/Fs and PCP in the bottom sediments of the Port of Gdansk. Toxicity (the Microtox® test) as well as several sediment parameters have been examined.In the surface layer of bottom sediments from the Port of Gdansk, all congeners of PCDD/Fs have been detected using GC-MS/MS. The positive correlation between toxicity and physicochemical properties of the analyzed bottom sediments confirms that these parameters are important in terms of environment contamination.
The toxicity of sediments in the Gulf of Gdansk is analyzed in relation to the chemical composition of interstitial and near-bottom waters, and sediment properties. The toxicity of sediments, pore waters and saline elutriates is determined by using the Microtoxm test based on changes in light production of the luminescent bacteria Vibrio fischeri. The results indicate considerable toxicity in the majority of examined sediments. Since the sediment elutriates and pore waters are toxic in some cases, the total toxicity of the sediments is likely to be due to both sediment-bound and water soluble substances. The sediment toxicity is related to the percentage contribution of the fine fraction of sediments. A significant correlation between the toxicity of the sediments and the black carbon content implies anthropogenic contamination. The toxicity of the sediments is seen to increase with the increase of hydrogen sulfide concentration in pore waters. The ammonia in pore waters was found not to be responsible for the toxicity of the sediments.
Polish rivers, which make up 20% of the Baltic Sea's catchment area, transport a load of nitrogen and phosphorus compounds into the sea. Theoretically, this load should be strongly correlated with the amount of water flowing in those rivers. However, this is not the case, especially in terms of the phosphorus compounds, since most of them come from point source pollution. The outflow load is also significantly influenced by nonpoint source pollution from farmland, which is very difficult to quantify. About 50% of nitrogen and 30% of phosphorus appear to come from nonpoint source pollution. It is important to realize that the load from nonpoint source pollution also includes the load of phosphorus and nitrogen transformed by lakes. Only recently, however, has this issue been mentioned in the specialist literature. In Polish studies on lake balance this remains a marginal issue. A limited number of observations indicate that lakes are capable of both limiting and increasing the load (mainly from the bottom sediments). This article presents some data on this issue which suggest that the roles of lakes in the transformation of the load of biogenic substances may be significant, but diverse.
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