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951.
太湖梅梁湾水体中可见光的衰减、吸收及散射 总被引:1,自引:0,他引:1
对太湖梅梁湾沿岸带和敞水区的水体进行了光学特性研究。结果发现,沿岸带的水下光辐射衰减系数(Kd)值较敞水区小;400nm与500nm向上辐照度比值(Eu440/Eu550),沿岸带在1m左右最小,敞水区在0.5m左右最小;沿岸带的水面下向上辐照度与向下辐照度的比值(R)低于敞水区:440、550、670nm的后向散射与吸收的比值(b/a),在沿岸带的1m处最大,敞水区在0.5m处最大。这些结果说明,相对于敞水区而言,沿岸带的光衰减较弱,无机悬浮颗粒的含量较少,最大叶绿素a分布较深。 相似文献
952.
R Burt M.A WilsonT.J Keck B.D Dougherty D.E StromJ.A Lindahl 《Advances in Environmental Research》2003,8(1):51-67
Long-term copper smelting in the Anaconda and Deer Lodge Valley area of Montana has resulted in an extensive area of trace element contamination. Aerial extent of contamination is generally established, but total analysis of soils does not correlate to relative degree of impact on vegetation growth. Three pedons (Beaverell, Cetrack and Judco) were analyzed by routine soil characterization methods, aqua regia microwave digestion, sequential chemical extraction, and X-ray diffraction analysis with the objective of providing a better understanding of chemical forms and potential reactivity of selected trace elements (Cd, Co, Cr, Cu, Hg, Mn, Ni, P, Pb). Surface horizons of soils are more acidic than subsoils, with pH for all horizons ranging from 4.0 to 8.7. Beaverell is the most contaminated in the upper 20 cm with the sum of total extractable (SUMTE) trace elements by microwave digestion ranging from 1836 to 3605 mg kg−1, largest H2O-soluble (WS) and exchangeable (EX) fractions (e.g. 1.6 and 9.3%, respectively), and smallest residual (RES) fraction (e.g. 14.3%). Cetrack has greater SUMTE elements than Judco, though a lower WS+EX fraction due to the effects of alkaline pH, carbonates and high P. Oxide (OX), organic matter/sulfide (OM/S), and RES fractions predominate over WS, EX, and specially-sorbed/carbonate-bound fractions (SS/CAR) for all horizons. Copper, Zn, Pb and Cd are elevated in surface over subsurface horizons in these latter fractions, indicating these elements were anthropogenic additions. X-ray data indicate that Pb, Cu, Cr and Cd partially exists as both OX and sulfide mineral forms. 相似文献
953.
在印度洋中部查戈斯礁群的大多数珊瑚死亡之后3年,对30m水深以浅珊瑚的侵蚀和恢复情况进行了研究.北部环礁15m水深以浅、中部和南部环礁>35m处的珊瑚差不多全部死亡.由于密集珊瑚丛的损失,一些礁体"表面"下降了1 5m.珊瑚的生物侵蚀情况严重,减少了三维礁体"结构"并形成松散的碎石.幼年珊瑚数量众多,尽管大部分是在侵蚀的或不稳定的基底上,并且稳定种较少.在15m的深度,礁体间鱼类丰度和多样性仍旧较高;依赖于珊瑚生存的物种减少,而一些食草动物和食碎屑动物则增加.一个新的海面温度(SST)数据集表明,平均SST自1950年以来升高了0.65℃.造成查戈斯珊瑚礁死亡的临界SST是29.9℃. 相似文献
954.
采用基于 16SrDNA序列分析方法 ,在长度多态 (LPM)和 16SrDNA的GC含量二维水平分析了受重金属污染的活性污泥系统内细菌的优势种类和多样性 .设计的PCR引物可以将细菌分为三大类 :即 1)proteobacterialα&δ(变形杆菌α&δ) ,2 )pro teobacterialβ&γ(变形杆菌 β&γ) ,以及 3)flexibacter(屈桡杆菌 )和革兰氏阳性菌 .分析了未受重金属驯化和受重金属驯化的两类活性污泥系统在重金属作用下优势种和多样性的变化 ,结果显示未驯化的活性污泥系统多样性减少但优势种的变化微小 ,而驯化系统优势种有较大的变化 ,但多样性基本不变 .这一结果证实驯化有助于提高微生物对重金属的抗性 相似文献
955.
活性炭吸附-光催化氧化深度净水工艺实验研究 总被引:6,自引:0,他引:6
以光催化氧化作为活性炭吸附工艺出水通常存在的亚硝酸盐、余氯与细菌总数超标等问题,并能去除铁穿透炭层的极性短链有机污染物,使出水达到《饮用净水水质标准》(CJ94-1999)。与目前常用的活性炭-反渗透组合工艺相比,该工艺具有可保留水中有益的矿物成分的特点,具有良好的应用前景。 相似文献
956.
Gamergates (i.e. mated reproductive workers) are mostly known from ant species within the Ponerinae. We report here the discovery of gamergates in two species of the subfamily Myrmicinae. Until now, mated reproductive females in colonies of myrmicine species have been considered morphologically distinct from the worker caste. However, in two species of the myrmicine Metapone (Metapone madagascarica and a newly discovered, not yet described Metapone species) all workers have six ovarioles and a spermatheca; and some of them are mated. There are no morphological differences between mated and non-mated workers. Field observations and laboratory studies indicate that colonies of the Metapone species can reproduce with gamergates only. 相似文献
957.
IntroductionCleaningthefineparticlesinhightemperature (450℃ -950℃ )andhighpressureconditioncanenhancethethermalefficiencyofcleancoaltechnologiessuchasIGCCorPFBC .Rigidceramicfiltersofavarietyofstructuresareunderdevelopmentinprogramsaroundtheworld ,whichcanfi… 相似文献
958.
959.
Geng Jinju Wang Qiang Niu Xiaojun Wang Xiaorong 《Frontiers of Environmental Science & Engineering in China》2007,1(1):120-124
Effects of pH, temperature, and oxygen on the production and release of phosphine in eutrophic lake sediments were investigated
under laboratory tests. Results indicated that the elimination of matrix-bound phosphine was accelerated under initial pH
1 or 12. Phosphine levels could reach maximum under initial pH 10. The contents of phosphine increased with the addition of
alkali under pH 4–12. The rates of phosphine production and release from lake sediments varied with temperature. 20°C was
the most favorable temperature for the production of matrix-bound phosphine. Oxygen showed little effect on matrix-bound phosphine.
Matrix-bound phosphine concentrations in lake sediments were concluded to be dependent on a balance of natural generation
and depletion processes.
Translated from Acta Scientise Circumstantiae, 2005, 25(5): 681–685 [译自: 环境科学学报] 相似文献
960.
In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate
the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of
granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH
of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable
pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri,
had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their
acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its
body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge
was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule.
Translated from Acta Scientiae Circumstantiae, 2004, 24(4): 633–636 [译自: 环境科学学报] 相似文献