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151.
广东沿海牡蛎体Ni含量水平及其时空变化趋势 总被引:3,自引:0,他引:3
198 9~ 1997年间 ,为实施“南海贻贝观察”计划 ,对广东沿海 12个地点近江牡蛎体内的 Ni含量水平进行了连续监测 ,结果全部牡蛎样品均检出 Ni,含量范围为 0 .17~ 2 .37mg/kg(湿重 ) ,总平均值为0 .58mg/kg。污染评价结果显示 ,广东沿海 Ni含量总体上处于微污染—轻污染水平。牡蛎体 Ni平均含量呈珠江口海区 >粤西海区 >粤东海区的分布格局 ,其最高值出现在深圳湾、唐家湾和湛江港。 70年代后期至 1991年 ,牡蛎体的 Ni含量呈明显下降趋势 ,此后 Ni含量年际间虽有波动 ,但无显著差异 相似文献
152.
Abstract The trends of annual, seasonal and monthly precipitation in southern China (Guangdong Province) for the period 1956–2000 are investigated, based on the data from 186 high-quality gauging stations. Statistical tests, including Mann-Kendall rank test and wavelet analysis, are employed to determine whether the precipitation series exhibit any regular trend and periodicity. The results indicate that the annual precipitation has a slightly decreasing trend in central Guangdong and slight increasing trends in the eastern and western areas of the province. However, all the annual trends are not statistically significant at the 95% confidence level. The average precipitation increases in the dry season in central Guangdong, but decreases in the wet season, meaning that the precipitation becomes more evenly distributed within the year. Furthermore, the analysis of monthly precipitation suggests that the distribution of intra-annual precipitation changes over time. The results of wavelet analysis show prominent precipitation with periods ranging from 10 to 12 years in every sub-region in Guangdong Province. Comparing with the sunspot cycle (11-year), the annual precipitation in every sub-region in Guangdong province correlates with Sunspot Number with a 3-year lag. The findings in this paper will be useful for water resources management. Editor Z.W. Kundzewicz; Associate editor Sheng Yue Citation Dedi Liu, Shenglian Guo, Xiaohong Chen and Quanxi Shao, 2012. Analysis of trends of annual and seasonal precipitation from 1956 to 2000 in Guangdong Province, China. Hydrological Sciences Journal, 57 (2), 358–369. 相似文献
153.
新寮岽铜多金属矿是近年来在粤东地区新发现的一个铜矿床,在该矿区绿泥石化十分强烈,并与铜矿化关系密切。按照矿物共生组合关系,矿区绿泥石可分为与硫化物共(伴)生及未与硫化物共(伴)生呈单独产出两类,两类绿泥石主要呈叶片状、纤维状、蠕虫集合体状等形态产出。本文在岩矿鉴定的基础上,以矿区绿泥石为研究对象,利用电子探针技术,对其微区化学成分进行了研究。结果表明:随着孔深的增加,与矿化有关绿泥石的Si和Mg元素含量逐渐升高,Al、Fe、Mn元素含量逐渐降低,而与矿化无关的绿泥石成分变化规律不明显。两类绿泥石主要为富铁种属的蠕绿泥石、铁镁绿泥石;绿泥石为泥质岩或者铁镁质岩受热液交代蚀变的产物,绿泥石结构的离子置换主要体现为Fe对Mg的置换,反映其可能形成于富铁及相对酸性环境;由绿泥石地质温度计估算得出两类绿泥石形成温度为166.32~245.62℃,平均为219.15℃,且与硫化物共(伴)生的绿泥石的形成温度相对较高,但两者均属中-低温范围。绿泥石的形成机制主要表现为溶蚀-结晶和溶蚀-迁移-沉淀结晶2种。 相似文献
154.
155.
基于多套全球海温再分析数据和2种线性趋势分析方法,评估了1958-2014年中国近海海表温度(SST)的变化及其对全球气候变化的响应特征,并与全球平均地表温度特别是与若干重要海区的SST做了比较。研究表明:在全球变暖的显著加速期(1980年代和1990年代),中国近海区域年平均SST表现出更快速的升温特征,其速率达0.60℃/10a,是同期全球平均升温速率的5倍以上;在变暖暂缓期(1998-2014年),中国近海SST出现显著的下降趋势。研究还表明,中国近海区域SST的年代际变化与太平洋年代际涛动(PDO)的位相转换一致,前者SST的快速上升(下降)期与PDO正(负)位相最大值的时期相对应,PDO可能是通过东亚季风和黑潮影响中国近海SST的年代际变化。 相似文献
156.
Benthic faunal data is regularly collected worldwide to assess the ecological quality of marine environments. Recently, there has been renewed interest in developing biological indices able to identify environmental status and potential anthropogenic impacts. In this paper we evaluate the performance of a general polychaete/amphipod ratio along the Norwegian continental shelf as an environmental indicator for offshore oil and gas impacts. Two main trends are apparent: first, a contamination gradient is discernible from where production takes place compared to stations 10,000 m away. Second, the quality of the marine environment has improved over time. These results are consistent with monitoring reports employing a combination of uni- and multi-variate statistics. Thus, we consider this ratio as a relatively simple, useful and potentially cost-effective complement to other more demanding assessment techniques. Because of its strong theoretical basis, it may also be useful for detecting ecological change as a result of other activities. 相似文献
157.
《China Geology》2020,3(4):633-642
Oil and gas resources are short in Pakistan and no commercially viable oil and gas sources have been yet discovered in its offshore areas up to now. In this study, the onshore-offshore stratigraphic correlation and seismic data interpretation were conducted to determine the oil and gas resource potential in the Offshore Indus Basin, Pakistan. Based on the comprehensive analysis of the results and previous data, it is considered that the Cretaceous may widely exist and three sets of source rocks may be developed in the Offshore Indus Basin. The presence of Miocene mudstones has been proven by drilling to be high-quality source rocks, while the Cretaceous and Paleocene–Eocene mudstones are potential source rocks. Tectonic-lithologic traps are developed in the northwestern part of the basin affected by the strike-slip faults along Murray Ridge. Furthermore, the Cretaceous and Paleocene–Eocene source rocks are thick and are slightly affected by volcanic activities. Therefore, it can be inferred that the northwestern part of Offshore Indus Basin enjoys good prospects of oil and gas resources. 相似文献
158.
Suction buckets differ with their easy and cost-efficient installation technique from other foundation types for offshore wind turbines. For successful completion of their installation process, suction is essential, but the imposed seepage leads to the changes in states of the soil in and around the bucket. Especially, a loosening of soil inside the bucket affects the load carrying behaviour of bucket subjected to repetitive loading resulting from environmental conditions. In this study, the behaviour of buckets under cyclic axial compressive loads with considering a possible loosening and related changes in permeability of soil inside the bucket is investigated numerically. In the framework of finite element analysis, a fully coupled two-phase model and a hypoplastic constitutive model are used to describe the saturated sandy soil behaviour under repetitive loading. The porosity-permeability variation is taken into account by Kozeny–Carman relationship. Special attention is dedicated to load carrying behaviour of bucket top plate, inner and outer skirt as well as base and their changes resulting from a loosening of soil inside the bucket with variable aspect ratio. For this purpose, cyclic axial compressive loads which cause an attenuation and progressive failure of soil-bucket system response are considered. The main findings on the changes in load carrying behaviour of bucket are presented and discussed. 相似文献
159.
160.