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31.
We have shown that there are large internanimal variations in hepatic phenol UDP-glucuronosyltransferase (UGT) activity in the plaice which may affect their capacity to detoxify metabolites of carcinogenic PAHS such as benzo(a)pyrene with obvious implications for their health and survival. By molecular studies we have only been able to identify one copy of the UGT1B1 gene coding for the major phenol-UGT in the diploid plaice genome and found that it is highly polymorphic about this locus. Sequencing of multiple UGT1B1 cDNA clones derived from RT-PCR revealed the existence of clustered SNPs, however, from their positions we contend that this is not sufficient to explain the observed phenotypic variability. We discovered a heterozygous null genotype derived from a dinucleotide deletion (and also found preliminary evidence for a corresponding phenotype) which has a much greater implication for survival not only in polluted environments but for embryonic survival if the gene product has an essential endogenous role. We propose that the observed interanimal variations are attributable to a combination of factors including genotypic variations and differential expression. 相似文献
32.
本文在1988年至1992年大量调查资料的基础上,研究了莱州湾入海污染源及海水中污染物的分布特征。认为,莱州湾主要污染物质为石油类、COD,其主要来源为西南部沿岸河口,尤其是小清河和广利河;其次为无机氮、无机磷,其主要来源为黄河口,其次为南岸河口。小清河为本区主要污染源,占本区污染物总入海量的1/3强,治理小清河、广利河是改善本区环境质量的主要环节。 相似文献
33.
Simultaneous observations of surface ozone (O3) with its precursors namely, carbon monoxide (CO) and oxides of nitrogen (NOx) have been taken on diurnal scale from a tropical semi-urban site, Pune (18.54°N, 73.81°E) in India. We present the data
for one year (2003–2004) period to study the salient features of these trace gases. The peak in amplitude of ozone is found
during the noontime whereas in CO and NOX it is observed in the morning hours between 0800 and 0900 H. The concentration of these pollutants drop down considerably
during southwest monsoon months and the diurnal pattern also become very weak. The diurnal trends of these gases are found
to be different for different seasons, which are specific to the receptor site. Model simulations using 3-D chemical-transport
model with regional emission inventories and observed winds have also been carried out. The comparison of model results with
observations, on seasonal basis yielded a reasonable qualitative agreement. The relative role of local emissions and long
range transport in the diurnal pattern for different seasons has been outlined, which reveals that the ozone is highly influenced
by regional/long range transport in this region. The effect of precursor amounts in the morning on afternoon ozone peak levels
has been investigated using the lag correlation study, which reveals that a time lag of 5–7 h is required for most of these
precursor gases to photo-chemically produce ozone to its maximum potential. Results are discussed in the light of available
topographic and meteorological conditions. 相似文献
34.
胡正林 《成都信息工程学院学报》1990,(Z1)
本文用数值解扩散方程的方法模拟了长沙市SO_2的浓度分布,并比较了两种扩散系数模型的模拟结果,认为作者曾经给出的扩散系数较取扩散系数为粘性系数时为好。最后提出了一种评价、比较模式的方法 相似文献