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151.
以安徽涡河流域为研究区域,通过采集涡河地表水、浅层地下水和中深层地下水样品,运用Gibbs图、离子比例和MixSIAR模型等方法对各类水体的水化学参数和氢氧同位素进行分析,揭示并量化了各类水体之间的转化关系.结果表明,研究区地表水和地下水主要呈现中性至弱碱性,地表水的水化学类型以Cl·SO4 ·HCO3 -Na和Cl·SO4 -Na型为主,浅层地下水以HCO3 -Ca·Mg和HCO3 -Mg·Na型为主,中深层地下水主要为Cl·HCO3 -Na型.各类水体的水化学特征受到岩石风化、蒸发浓缩及正向阳离子交换等多重因素共同影响.地表水和地下水的δ18O和δ2H分布特征表明大气降水是该区域水体的主要补给来源,且地下水δ18O和δ2H值与K+、Na+、Cl-、SO4 2-和NO 3-浓度存在显著相关性.根据MixSIAR模型分析结果,地表水接受大气降水和浅层地下水的贡献率分别为46.5 %和53.5 %;浅层地下水的补给来源分别为大气降水(57.4 %)和地表水(42.6 %);中深层地下水的补给主要来自上游地下水的侧向径流补给. 相似文献
152.
Lars W. Clement Stephan C. W. Köppen Willi A. Brand Martin Heil 《Behavioral ecology and sociobiology》2008,62(6):953-962
Mutualisms can be exploited by parasites—species that obtain resources from a partner but provide no services. Though the
stability of mutualisms in the presence of such parasites is under intensive investigation, we have little information on
life history traits that allow a species to be a successful mutualist or rather a parasite, particularly in cases where both
are closely related. We studied the exploitation of Acacia myrmecophytes by the ant, Pseudomyrmex gracilis, contrasting with the mutualistic ant Pseudomyrmex ferrugineus. P. gracilis showed no host-defending behavior and had a negative effect on plant growth. By preventing the mutualist from colonization,
P. gracilis imposes opportunity costs on the host plant. P. gracilis produced smaller colonies with a higher proportion of alates than did the mutualist and thus showed an “r-like” strategy. This appears to be possible because P. gracilis relies less on host-derived food resources than does the mutualist, as shown by behavioral and stable isotope studies. We
discuss how this system allows the identification of strategies that characterize parasites of mutualisms. 相似文献
153.
研究泉水氢氧稳定同位素时空变化特征,探究泉水的补给来源,对水资源管理及旅游业可持续发展具有重要指导意义。以百脉泉泉群为研究区,通过分析降水及泉水中的氢氧稳定同位素特征,获取了本地大气降水线、泉水同位素时空变化特征及蒸发线,并探究了百脉泉泉水的补给来源。结果表明:大气降水中δ2H的波动范围为-151.55‰δ18O—-4.28‰,δ18O的波动范围为-19.93‰δ18O—-0.52‰,δ2H和δ18O在时间上的分布规律相似,均呈现双峰状(“M”型),本地大气降水线(LMWL)为:δ2H=7.58×δ18O+4.17。百脉泉泉水的δ2H的波动范围为-65.23‰δ18O—-37.01‰,δ18O的波动范围为-8.99‰δ18O—-4.04‰。泉水δ2H—δ18O均落在本地大气降水线上或... 相似文献
154.
为了识别鄱阳湖湿地水体中硝酸盐污染的来源,转化特征和各污染来源的贡献比例,选取枯水期这一典型时期,于2019年1月份对鄱阳湖中的蚌湖湿地,沙湖山湿地和庐山湿地的地表水进行取样,并测定了水样中的离子组成和硝酸盐氮氧同位素值.研究结果显示, NO3-/Cl-物质的量浓度比值与Cl-浓度的关系表明3处湿地中硝酸盐来源可能受到农业活动和降雨的影响.蚌湖,沙湖山和庐山湿地水体中δ15N-NO3-和δ18O-NO3-值的范围分别为-6.19‰~4.67‰和3.41‰~39.95‰,-4.14‰~1.45‰和31.54‰~68.30‰,-6.98‰~3.83‰和2.80‰~30.43‰,硝酸盐氮氧同位素值表明3处湿地硝酸盐来源可能受到降水NO3-,硝酸盐氮肥,氨态氮肥和土壤有机氮的影响.利用硝酸盐氮氧同位素之间的关系,并结合NO3-与Cl-比值关系判断湿地中无明显反硝化作用的发生.SIAR模型结果显示:蚌湖湿地,沙湖山湿地,庐山湿地硝酸盐来源中降水NO3-贡献占比最大,其次是化肥,土壤有机氮,粪便和生活污水贡献占比最小. 相似文献
155.
156.
Rosenfelder N Bendig P Vetter W 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2706-2712
Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the δ13C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in 13C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in 13C because of more stable bonds between 13C and bromine. As a result, the δ13C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the δ13C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products. 相似文献
157.
158.
Isotopes of uranium in the sea-water sediments collected from two different areas (El Hamraween harbour and Ras El Behar) on the Egyptian coast of the red sea have been studied using radiochemical separation procedures and alpha-particle spectrometry. Activity concentrations of 238U, 235U, 234U were calculated. The activities observed indicated enhanced radioactivity levels in sea-water sediments of El Hamraween harbour area due to the activities of phosphate shipment operation. Secular equilibrium between 234U and 238U was found in the analyzed samples. The average activity ratio of 235U/238U was close to the value 0.046 for uranium in nature. 相似文献
159.
K. Hirose Y. Igarashi M. Aoyama Y. Inomata 《Journal of environmental radioactivity》2010,101(2):106-112
Monthly plutonium and thorium depositions at Tsukuba (28 m asl) and Mt. Haruna (1370 m asl) were measured during 2006 and 2007 (Jan 2006-Dec 2007 at Tsukuba, Nov 2006-Dec 2007 at Mt. Haruna). The monthly 239,240Pu depositions ranged from 0.044 to 2.67 mBq m−2 at Tsukuba and from 0.05 to 0.9 mBq m−2 at Mt. Haruna during the measurement periods. Monthly 239,240Pu deposition did not differ markedly between the two sites except in April 2007. Seasonal pattern of monthly 239,240Pu depositions at both sites showed high in spring and low in summer, and typical of seasonal variations in northeastern Asia. Thorium deposition at Tsukuba was higher than that at Mt. Haruna except in May and June 2007. 230Th/232Th activity ratios were used to partition deposition samples into locally and remotely derived fractions. The results revealed that a major proportion of total 239,240Pu and Th deposits are derived from remote sources, especially in spring. 相似文献
160.
Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock–pedosphere–irrigated riverwater–cereal–atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of 208Pb/206Pb = −1.157 × 206Pb/207Pb + 3.46 (r2 = 0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb (208Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower 206Pb/207Pb and higher 208Pb/206Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7–52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb. 相似文献