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1.
Evaluation of geochemical impact of tsunami on Pichavaram mangrove ecosystem,southeast coast of India 总被引:1,自引:0,他引:1
The 26 December 2004-tsunami has deposited sediments in the Pichavaram mangrove ecosystem, east coast of India. Ten surface
and three core sediment samples were collected within 30 days of the event and analyzed for nutrients. Water samples were
also analyzed to see the impact of tsunami on the geochemical behavior of nutrients. An increase in the concentration of various
nutrients namely nitrate and phosphate was observed. The geochemistry of the mangrove forest was observed to be influenced
by a number of factors like rapid increase of aquaculture farms, agricultural practices and the anthropogenic discharge from
the nearby-inhabited areas. Further the sediment column was disturbed due to energetic tsunami waves, which has caused a sheer
increase in the dissolved oxygen in water. As a result, the change in the redox potential has resulted in change in the nutrients
absorbed/associated with the sediments. In addition, role of retreating water after tsunami on the nutrient geochemistry was
also evaluated. 相似文献
2.
The concentrations of twenty four chemical elements in the surface layer of natural desert soils and the cultivated farmland soils were measured at a desert-oasis ecotone in the middle of Heihe river basin, north-west China. Background values were estimated for (a) major elements (Si 335.3 g kg− 1, Al 49.4 g kg− 1, Fe 19.1 g kg− 1, Ca 29.4 g kg− 1, Mg 8.9 g kg− 1, K 20.1 g kg− 1, Na 17.5 g kg− 1 and P 0.338 g kg− 1), (b) heavy metals and non-metals (Cr 55.8 mg kg− 1, Mn 404.8 mg kg− 1, Ni 17.7 mg kg− 1, Cu 5.1 mg kg− 1, Zn 33.7 mg kg− 1, Pb 15.5 mg kg− 1 and As 5.2 mg kg− 1) and (c) other trace elements (Ti 2.0 mg kg− 1, V 55.3 mg kg− 1, Co 5.7 mg kg− 1, Rb 82.4 mg kg− 1, Sr 232.9 mg kg− 1, Y 14.7 mg kg− 1, Zr 194.9 mg kg− 1, Nb 7.8 mg kg− 1 and Ba 720.6 mg kg− 1). After natural desert soil was cultivated for agricultural use, significant changes in element concentrations occurred under tillage, irrigation and fertilisation management. Compared to natural soil, the for the levels of Si, K, Na, Sr, Zr and Ba decreased, and no changes were observed for Rb, while the values of the other 17 elements increase in agricultural soil from 1.2 to 3.5 times. However, their absolute concentrations are still low, suggesting that the arable soil in this region remains comparatively a clean soil. The increased silt, clay and organic carbon content, under long-term irrigation, enriched the fine-grained materials, and application of fertilisers and manure contributed to the accumulation of most elements in arable soil. The accumulation of elements in agricultural soil increased with increasing cultivation years and extent of soil development. 相似文献
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Copper complexing ligand concentrations in the Daya Bay, Qingdao coast, Jiaozhou Bay, South China Sea and Huanghe Estuary waters were determined by the anodic stripping voltammetry technique. The distribution regularity and the relationship with other parameters were discussed. The results were as follows: Copper complexing ligand concentrations of the South China Sea were a little higher than those of other sea areas, and they were apparently higher than those of the ocean. Compared with the subsurface layer (SSL) in the sea surface microlayer copper complexing ligand concentrations showed an enrichment phenomenon, of which the mechanism is similar to dissolved organic matter. The metal complexing ligand concentration profiles of the South China Sea showed that the value in the sea surface was the highest, then it decreased with depth accruing, and a higher value appeared at the bottom. Copper complexing ligand concentrations were higher than those of cadmium and lead. Ligands in each sea area exhibited a complicated property. In short, the distribution regularity of copper complexing ligand concentrations in China' s coastal waters was consistent with that of other regions in the world. Meanwhile, the positive relationship between the copper complexing ligand concentrations and biological oxygen demand, chemical oxygen demand, dissolved organic carbon, and viscosity were found clearly. 相似文献
7.
The effects on ethoxyresorufin O-deethylase (EROD), NADPH-cytochrome c reductase and NADH cytochrorne b5 reductase activities of digestive gland in Meretrix meretrix exposed to tributyltin (TBT) at environmental levels (0.1,1.0,10.0 ng/dm as stannum concentration),in experimental condition, were evaluated. The EROD, NADH cytochrorne b5 reductase activities were significantly inhibited after exposure to 10.0 ng/dm^3 TBT for 8 and 20 d, the NADPH cytochrorne c reductase activities were significantly inhibited after exposure to 0.1,1.0 and 10.0 ng/dm TBT for 8 d and to 1.0 and 10.0 ng/dm for 20 d, as compared with the matched control, while NADH cytochrorne b5 reductases and NADPH cytochrome c reductase activities were induced after exposure to 10.0 ng/dm^3 TBT for 2 d. The EROD activity in the 10 ng/dm^3 group,and the NADH cytochrome b5 reductases activities in 1.0 and 10.0 ng/dm groups, were significantly induced when transferred to clean recovery tanks for 7 d. The three enzymic activities in the clams exposed to TBT were recovered to the level corresponding to that of the control group after transfer to clean recovery tanks for 20 d. NADPH cytochrome c reductase activity in Meretrix meretrix seems to be more sensitive to exposure of TBT than that of the EROD and NADH cytochrome b5 reductases. The results suggest that induction and inhibition by TBT to the monooxygenase system enzymic activity in Meretrix meretrix would simultaneously exist. The enzymic activities were inhibited by exposure for a long time. The results suggest that inhibition of the monooxygenase system should be an indication of the exposure to environmentally relevant concentrations of TBT for a long time. 相似文献
8.
ICES baseline survey of trace metals in European shelf waters 总被引:1,自引:0,他引:1
Balls P.; Cofino W.; Schmidt D.; Topping G.; Wilson S.; Yeats P. 《ICES Journal of Marine Science》1993,50(4):435-444
9.
本文对套子湾表层沉积物中的pH、Eh、硫化物、氮、磷、有机质、铜、铅、锌、镉地球化学特征进行了分析研究.并讨论了如下几个关系:①与沉积类型之间的关系;②其相关性与环境的关系。③与矿物的关系;④与水和风等作用的关系;⑤与水化学的关系;⑥重点分析了表层沉积物中化学要素与生物的相互关系。这不仅为该湾的开发治理.生物养殖等提供科学依据.并进一步证明沉积物地球化学.在环境化学和生态学研究等方面的理论意义。 相似文献
10.
Dissolved titanium distributions in the Mid-Atlantic Bight 总被引:1,自引:0,他引:1
Although titanium is abundant in Earth's crust, its sources and distribution in the ocean are poorly understood. To elucidate its behavior, distributions of dissolved (< 0.2 μm) Ti were determined in surface waters and vertical profiles from the Mid-Atlantic Bight (MAB). Concentrations of Ti decreased from 390 pM at the Delaware Bay mouth to < 100 pM across the Delaware continental shelf. In vertical profiles, small increases in bottom waters suggest a possible flux of Ti from shelf sediments, consistent with previous reports of pore water enrichments of dissolved Ti in MAB sediments. Concentrations in surface waters of the outer shelf and slope ranged between 30 and 140 pM, with most values below 90 pM. Concentrations in a 1000 m vertical profile in the eastern Gulf Stream ranged between 110 and 280 pM, and showed a variable distribution attributed to the mixing of water masses in the outer MAB. A simple model of Ti sources to the MAB suggests that atmospheric deposition of dissolved Ti is comparable to net riverine contributions and therefore must be considered in applications of Ti as a tracer of oceanographic processes. 相似文献