水源水中不同分子量区间有机物的分布及控制对策

通过超滤膜法研究了澳门水源水中不同分子量区间有机物的分布特性 .结果显示 :1)澳门水源水中总有机碳 (TOC)的主体有机物分子量在 10 0 0以下 ,传统工艺对这类水体的有机物去除效率较低 .2 )澳门水源水中可生物降解溶解性有机碳(BDOC)主要与分子量小于 10 ,0 0 0的有机物相关 .3)三种水源水中不同分子量区间BDOC TOC比率的变化也非常大 ,表明能有效控制TOC的水处理工艺未必能够导致相同的BDOC处理效果 ,所以不一定可以有效保证饮用水的生物稳定性 .4 )澳门水源水中有机物含量很低 ,不必增加其它工艺来控制水中有机物 ;如果在水源水质恶化的突发事件情况下 ,可以采用投加粉末活性炭的方法加以控制 .     

Presence of DDT metabolites in water,sediment and fish muscle tissue from Lake Prespa,Republic of Macedonia

Organochlorine pesticides were determined in water and sediment samples collected from the littoral zone of Lake Prespa, as well as from its three main tributaries (the rivers Golema, Brajcinska and Kranska), during the period 2004 to 2006. In addition, muscle tissue samples of barbus fish (Barbus prespensis Karaman, 1928) collected from the littoral zone of Lake Prespa were also analysed. The obtained results give an overview of the contamination levels of these problematic compounds at their potential sources in the river mouths, in the potentially affected, species-rich littoral section of the lake and in the muscle tissue of one selected fish species, collected near the rivers’ deltas. Special attention was paid to the presence of some DDT metabolites (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′–DDE); (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (p,p′–DDD) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′–DDT). The extraction of pesticides from water samples was done by liquid-liquid partition in dichloromethane. For the sediment and fish tissue we used solid-liquid extraction. The extracted residues were analyzed on a gas chromatograph equipped with an electron capture detector (GC-ECD). The results of the respective studies indicated the presence of DDT metabolic forms in the samples of the three analysed matrixes. The highest levels of presence for these pollutants were found in the muscle tissue of the fish samples. The total DDTs content in the analysed muscle tissue samples range from 11.67 to 13.58 μg kg^?1of fresh tissue. The average total DDTs content for the sediment samples were within the range of 2.32 to 4.17 μg kg^?1 of dry sediment. Higher DDT metabolites content were found in the sediments collected from the rivers than in the samples from the littoral zone. The lowest average total concentrations of DDTs, on the other hand, were recorded in the water samples and ranged between 0.036 and 0.057 μg L^?1. The obtained results indicated that the dominant metabolic form in the samples of the three investigated matrixes (water, sediment and fish tissue) from Lake Prespa was p,p′-DDE. There was a very good linear correlation in this study between the content of DDT's (total DDT metabolites) detected and the percentage of total organic material in the sediment. The detected concentrations are clearly below the toxicity thresholds; consequently, severe effects on the endemic species of Lake Prespa are not very likely.     

Distribution of natural radionuclides in surface soils in the vicinity of abandoned uranium mines in Serbia

The activity concentrations of natural radionuclides in soils from the area affected by uranium mining at Stara Planina Mountain in Serbia were studied and compared with the results obtained from an area with no mining activities (background area). In the affected area, the activity concentrations ranged from 1.75 to 19.2 mg kg^?1 for uranium and from 1.57 to 26.9 mg kg^?1 for thorium which is several-fold higher than those in the background area. The Th/U, K/U, and K/Th activity ratios were also determined and compared with data from similar studies worldwide. External gamma dose rate in the air due to uranium, thorium, and potassium at 1 m above ground level in the area affected by uranium mining was found to be 91.3 nGy h^?1, i.e., about two-fold higher than that in background area. The results of this preliminary study indicate the importance of radiological evaluation of the area and implementation of remedial measures in order to prevent further dispersion of radionuclides in the environment.