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Muñoz-Barbosa A Gutiérrez-Galindo EA Daesslé LW Orozco-Borbón MV Segovia-Zavala JA 《Marine pollution bulletin》2012,64(2):405-409
In 1992 and 2004, heavy metals concentrations were measured in surficial sediments from Todos Santos Bay, located in Ensenada, Baja California, Mexico. The aim was to search for relationships between metal enrichment factors and a biological adverse effects index. Unlike Ni, the elements Cd, Cu and Zn showed significant correlations (p<0.05) between enrichment factors and the biological adverse effects index. Cu showed a 0.74:1 relationship, which means that any enrichment above 0.74 could represent biological adverse effects. On the other hand, Cd and Zn enrichments must be >5.5 and >1.5, respectively, in order for the sediments to be considered toxic. In general, data showed that most of the metal concentrations in Todos Santos Bay sediments could not cause adverse effects to biota. Only Ensenada's harbor and the zone next to a dredging dumping site showed metal enrichments that could be toxic. 相似文献
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With many environments worldwide experiencing at least some degree of anthropogenic modification, there is great urgency to identify sensitive indicators of ecosystem stress. Estuarine organisms are particularly vulnerable to anthropogenic contaminants. This study presents bacterial communities as sensitive indicators of contaminant stress. Sediments were collected from multiple sites within inner and outer zones of three heavily modified and three relatively unmodified estuaries. Bacterial communities were censused using Automated Ribosomal Intergenic Spacer Analysis and analysed for a suite of metal and PAH contaminants. Shifts in both bacterial community composition and diversity showed strong associations with sediment contaminant concentrations, particularly with metals. Importantly, these changes are discernable from environmental variation inherent to highly complex estuarine environments. Moreover, variation in bacterial communities within sites was limited. This allowed for differences between sites, zones and estuaries to be explained by variables of interest such as contaminants that vary between, but not within individual sites. 相似文献
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利用1981—2020年沂沭河流域内12个气象台站逐日降水观测资料,西太平洋副热带高压(西太副高)指数、太平洋年代际振荡指数(PDO)等资料以及NCEP/NCAR逐日再分析资料,采用线性趋势分析、累积距平法联合滑动t检验、morlet小波分析、相关性分析、合成分析等方法,研究近40 a沂沭河流域极端降水事件的时空变化特征,并进一步研究极端降水指数与气候因子之间的相关性以及极端降水事件的异常环流背景。结果表明:沂沭河流域极端降水事件具有整体上增多且强度增强的特征,且近年来在频次和年极端降水量上波动峰间值增大,分别为6.2 d/a、538.2 mm/a,极端降水事件日趋严重。空间分布上南多北少,中部、北部较南部增速更明显。极端降水频次和年极端降水量均在1989年和2002年左右突增;极端降水强度在1989年突增,2000年左右突减。极端降水的频次、强度和年极端降水量分别以22 a、10 a和22 a的周期波动为主。西太副高的脊线位置跟频次和年极端降水量具有正相关性,PDO与频次和年极端降水量具有负相关性。东亚夏季风强度和西太副高的位置是影响沂沭河流域极端降水事件多寡的重要因子,在预测该流域的极端降水情况时可做参考依据。 相似文献
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Oliveira MM Silva Filho MV Cunha Bastos VL Fernandes FC Cunha Bastos J 《Marine environmental research》2007,63(4):303-312
Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis-Menten constant (K(M)) for acetylthiocholine varied from 104 to 291 microM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min=455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min=3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones. 相似文献
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桂东北豆乍山花岗岩年代学与地球化学特征 总被引:16,自引:4,他引:12
豆乍山花岗岩主要由中细粒二云母二长花岗岩构成,是桂东北苗儿山复式花岗岩体中段的一个重要产铀的岩体.单颗粒锆石SHRIMP U-Pb年龄为228±11Ma,属于印支期岩浆活动产物.地球化学特征显示该花岗岩以过铝、富硅、富碱和低CaO/Na2O比值为特征,微量元素主要富集Rb、Th、U和Ta,亏损Sr、Ba和Ti.稀土总量30.24×10-6~139.18×10-6,轻稀土轻微富集(LREE/HREE=4.00~6.35,(La/Yb)N=3.24~6.74),Eu亏损明显(δEu=0.14~0.19).结合其它相关地质资料,表明豆乍山花岗岩是壳源型花岗岩,是在印支运动晚期地壳伸展-减薄的构造背景下,成分为泥质的变质岩通过低程度部分熔融方式而形成. 相似文献
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