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351.
352.
Black carbon (BC) in surface sediments from Henan section of Yellow River and Huaihe River, China, was determined. Average content of BC in Huaihe River was 0.33%, higher than that in Yellow River (n?=?23) with mean value of 0.15%. Distribution patterns of BC in Yellow River and Huaihe River were similar, namely that tributaries had higher BC content than main stream. In addition, BC content in the mainstream of Yellow River and Huaihe River decreased with altitude. The BC content presented a significant positive correlation with clay (r?=?0.672; p?<?0.01) content in Yellow River, while neither did in Huaihe River. The ratio of BC/TOC ranged from 1.8–57.4% (median 29.6%), evidencing pyrogenic fossil fuel source of BC in Yellow River. Relatively low values of BC/TOC in Huaihe River (5.3%–28.8%, median 7.5%,) reflected that the origin of BC is from burning of biomass. In addition, Pearson rank correlation analysis showed that BC was in strong correlation with lighter PAH in Yellow River, while BC was in significant correlation with heavier PAH in Huaihe River. The ratio of BC/TOC indicated that BC in Yellow River mainly came from fossil fuel combustion, while BC in Huaihe River was primarily from biomass burning. 相似文献
353.
讨论了以河道底泥和生活污泥为原料烧制陶粒比表面的测定原理、方法和结果,并对生活污泥添加量、粘结刑添加量和烧结温度对陶粒比表面的影响作了进一步分析。 相似文献
354.
Contamination of the environment from atmospheric deposition during the twentieth century is pervasive even in areas ostensibly considered pristine or remote from point sources. In this study, Pb concentrations in a 210Pb-dated peat core collected from the Okefenokee Swamp, GA were used to assess historical contaminant input via atmospheric deposition. Lead isotope ratios were determined by dynamic reaction cell ICP-MS (DRC-ICP-MS). Increases in Pb concentration occurred in the late nineteenth century and a marked rise in Pb concentrations pre-dated the widespread use of leaded gasoline within the US. The 206Pb/207Pb ratios of 1.19 during this period were consistent with coal combustion emissions. A later increase in Pb concentration, concurrent with a trend toward more radiogenic 206Pb/207Pb ratios in gasoline is consistent with an increased input of Pb from leaded gasoline emissions. However, it appears that coal combustion emissions remain a major source of Pb to the Okefenokee. 相似文献
355.
356.
Anaerobic degradation of diethyl phthalate, di-n-butyl phthalate, and di-(2-ethylhexyl) phthalate from river sediment in Taiwan 总被引:5,自引:0,他引:5
We investigated anaerobic degradation rates for three phthalate esters (PAEs), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP), from river sediment in Taiwan. The respective anaerobic degradation rate constants for DEP, DBP, and DEHP were observed as 0.045, 0.074, and 0.027 1/day, with respective half-lives of 15.4, 9.4, and 25.7 days under optimal conditions of 30 °C and pH 7.0. Anaerobic degradation rates were enhanced by the addition of the surfactants brij 35 and triton N101 at a concentration of 1 critical micelle concentration (CMC), and by the addition of yeast extract. Degradation rates were inhibited by the addition of acetate, pyruvate, lactate, FeCl3, MnO2, NaCl, heavy metals, and nonylphenol. Our results indicate that methanogen, sulfate-reducing bacteria, and eubacteria are involved in the degradation of PAEs. 相似文献
357.
Bioassays are widely used to estimate ecological risks of contaminated sediments. We compared the results of three whole sediment bioassays, using the midge larva Chironomus riparius, the water louse Asellus aquaticus, and the mayfly nymph Ephoron virgo. We used sediments from sixteen locations in the Dutch Rhine-Meuse Delta that differed in level of contamination. Previously developed protocols for each bioassay were followed, which differed in sediment pretreatment, replication, and food availability. The Chironomus bioassay was conducted in situ, whereas the other two were conducted in the laboratory. The measured endpoints, survival and growth, were related to contaminant levels in the sediment and to food quantity in water and sediment.
Only the response of A. aquaticus in the bioassay was correlated with sediment contamination. Food availability in overlying water was much more important for C. riparius and E. virgo, thereby masking potential sediment contaminant effects. We conclude that growth of A. aquaticus was depressed by sediment contamination, whereas growth of E. virgo and C. riparius was stimulated by seston food quantity. We discuss that the trophic state of the ecosystem largely affects the ecological risks of contaminated sediments. 相似文献
358.
Hollert H Dürr M Holtey-Weber R Islinger M Brack W Färber H Erdinger L Braunbeck T 《Environmental science and pollution research international》2005,12(6):347-360
Goal, Scope and Background In order to evaluate the estrogenic activity of sediments and XAD water extracts of selected sites of the catchment area
of the River Neckar, a river system in Southern Germany, an integrative assessment approach was used to assess the ecological
hazard potential of endocrine-disrupting compounds in sediment and water.
Methods The approach is based on estrogen receptor-mediated vitellogenin synthesis induced in isolated hepatocytes of rainbow trout
and quantified in a non-radioactive dot blot/RNAse protection-assay in parallel to comprehensive chemical analyses of estrogenic
substances.
Results and Discussion Numerous investigated extracts revealed an estrogen activity comparable to that of the positive control (1 nM 17?-estradiol
corresponding to 270 ng/L in the test medium). Based on a concentration factor of 30 in the extracts and a recovery of XAD
resins of approximately 80 %, 17?-estradiol equivalent concentrations between 20 and 26.7 ng/L could be calculated downstream
of a sewage treatment plant (< 0.1 ng/L for a reference site). A comparison of the bioassay-derived Bio-TEQs (toxicity equivalents)
and the Chem-TEQs revealed a high correlation with a Pearson coefficient of 0.85, indicating that the same ranking of the
samples could be obtained with respect to the endocrine disrupting potential with both chemical and bioanalytical analysis.
However, the TEQ concentrations computed from chemical analyses were significantly lower than the bioassay-derived TEQ concentrations.
In fact, in none of the samples, more than 14 % of the vitellogenin-inducing potency could be attributed to the substances
(steroids, alkylphenols, bisphenol A, diethylstilbestrol) analyzed.
A comparison of the endocrine disrupting potential of sediments extracted by the solvents acetone and methanol revealed lower
biological effects for acetone-extracted samples. Possible reasons may be a masking of endocrine effects in acetone extracts
by cytotoxicity, a low extraction efficiency of the solvent acetone, or anti-estrogen potencies of some extracted sediment
compounds.
Using a mass balance approach, the contribution of the compounds analyzed chemically (Chem-TEQs) to the total endocrine activity
(Bio-TEQs) was calculated. Based on the very low detection limits, particularly of the steroids with their high TEF factors,
results revealed that a calculation of the Chem-TEQs is associated with considerable scale inaccuracy: Whereas only 7-15 %
of the biological effectiveness (Bio-TEQs) could be explained by endocrine substances identified above the detection limits,
the assumption of concentrations slightly below the given detection limits would result in a significant over estimation (137-197
%) of the Bio-TEQs. Even the interassay variation of the dot blot assay with different fish donors for primary hepatocyte
(factor 2 - 2.5) is relatively low, when compared to the large range of the Chem-TEQ concentrations (factor 20) obtained when
applying different modes of calculation.
Conclusions and Outlook Overall, only a minor portion of the endocrine activity detected by bioassays could be linked to compounds identified by
chemical analysis. In vitro assays for assessment of endocrine activities are useful as sensitive integrating methods that
provide quantitative estimates of the total activity of particular receptor-mediated responses. Although discrepancies may
also result from different bioanalytical approaches, it is overall likely that bioanalytical and not chemical analytical approaches
give the correct estimate of endocrine disrupting potencies in environmental samples. As a conclusion, assessment of endocrine
disruption based on chemical analysis alone does not appear sufficient and further research into the spectrum of substances
with potential endocrine activity as well as into additive or even synergistic effects in complex environmental samples is
urgently needed. 相似文献
359.
Feiler U Ahlf W Hoess S Hollert H Neumann-Hensel H Meller M Weber J Heininger P 《Environmental science and pollution research international》2005,12(5):257-258
- In current biotest approaches, intact organisms or in vitro systems are exposed to sediments using different exposure scenarios.
The most important issue in sediment toxicity testing protocols is the question which test phase (solid or liquid) should
be used. Whole-sediment exposure protocols represent the most realistic scenario to simulate in situ exposure conditions in
the laboratory. However, until now there is no agreement in how to acquire and to evaluate the data of the various available
sediment contact assays. The SeKT joint research project was initiated with the aim to compare recently developed sediment
contact assays by addressing reference conditions, control sediments and toxicity thresholds for limnic sediment contact tests. 相似文献
360.
Yoshitaka Yonezawa Manabu Fukui Shigeki Masunaga Yoshikuni Urushigawa 《Chemosphere》1994,28(12):2179-2184
The relation between dechlorination activities of 1,2,4-trichlorobenzene and anaerobic microbial activity were studied in the sediment collected at three sites in Ise Bay in Japan. The degradation rate of spiked 1,2,4-trichlorobenzene (3nmol ml−1) ranged from 15 to 35 pmol day−1 ml−1 wet sediment and about 1/3 to 1/2 of degraded the trichlorobenzene was recovered as dechlorinated products. Among the dichlorobenzenes, the 1,2-isomer had the highest and 1,3-isomer had the lowest production rate. Comparing the three sampling sites, the trichlorobenzene degradation and dichlorobenzenes production rates were related to the sulfate reducing activity for the unit number of sulfate reducing bacteria. Production rates of dichlorobenzenes were completely inhibited by adding molybdate (20 mM), nitrate (60 mM), and formaldehyde solution (4 %). These results indicated that dechlorination activity in the Ise Bay sediment was supported by sulfate reduction activity in the sediment, and not supported by any other anaerobic microbial activity. 相似文献