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181.
Individuals of the subtidal gastropod Babylonia lutosa were exposed to three sublethal concentrations of copper (0.02, 0.06 and 0.20 ppm) for four weeks. The percentage of normally active individuals (body extended and moving with the foot attached) decreased and the percentage of snails retracted (body extended, foot not attached, unable to move) and in a distressed stage (body retracted within the shell) increased with increase in copper concentration. Exposure to copper also decreased significantly the ability of an individual to move, and to burrow, but the effect was only observed in week 1, individuals were fully recovered in week 2. Feeding, however, was not affected, both in terms of the percentage number of individuals which fed, and the time spent feeding. Results were discussed with respect to the potential of using this animal as a bioassay tool in monitoring the effect of environmental perturbations on the subtidal community in Hong Kong. 相似文献
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Subbarao Pichuka 《水文科学杂志》2017,62(3):467-482
An attempt is made to assess the future trend of spatio-temporal variation of precipitation over a medium-sized river basin. The Statistical Downscaling Model (SDSM, version 4.2) is used to downscale the outputs from two general circulation models (GCMs) for three future epochs: epoch-1 (2011–2040), epoch-2 (2041–2070) and epoch-3 (2071–2100). Considering the Upper Mahanadi Basin as a test bed, the study results indicate a “wetter” monsoon (June–September) and the annual increase in precipitation is 12% during epoch-3, which is consistent for both GCMs. Monthly analyses indicate that the precipitation totals are likely to increase and the magnitude of increase is greater during monsoon months than non-monsoon months. The number of month-wise daily extremes increases in most months in the year. However, the maximum percentage increase (with respect to baseline period, 1971–2000) in the number of extreme events is found in the non-monsoon months (specifically before and after the monsoon). 相似文献
186.
Water temperature has a significant influence on aquatic organisms, including stenotherm fish such as salmonids. It is thus of prime importance to build reliable tools to forecast water temperature. This study evaluated a statistical scheme to model average water temperature based on daily average air temperature and average discharge at the Sainte-Marguerite River, Northern Canada. The aim was to test a non-parametric water temperature generalized additive model (GAM) and to compare its performance to three previously developed approaches: the logistic, residuals regression and linear regression models. Due to its flexibility, the GAM was able to capture some of the nonlinear response between water temperature and the two explanatory variables (air temperature and flow). The shape of these effects was determined by the trends shown in the collected data. The four models were evaluated annually using a cross-validation technique. Three comparison criteria were calculated: the root mean square error (RMSE), the bias error and the Nash-Sutcliffe coefficient of efficiency (NSC). The goodness of fit of the four models was also compared graphically. The GAM was the best among the four models (RMSE = 1.44°C, bias = ?0.04 and NSC = 0.94). 相似文献
187.
《Limnologica》2017
Feeding interactions among functional feeding groups (FFGs) of macroinvertebrates are robust indicators of aquatic ecosystem interactions. They provide information regarding organic matter processing, habitat condition and trophic dynamics. In tropical rivers with pronounced wet and dry seasons, macroinvertebrate based ecological monitoring tools are explicitly focused on metrics and indices, while ignoring interactions of FFGs. Therefore, the objective of this study was to investigate the functional feeding type metrics, diversity indices and feeding interactions among FFGs of macroinvertebrates along the water pollution gradient in Gilgel Gibe watershed, Ethiopia. Water quality parameters and macroinvertebrate community attributes were assessed for samples collected from upstream sites (15 sites), urban-impacted stretches (12 sites) and wetland-affected river zones (7 sites) of the watershed during the rainy (July) and dry (February) seasons. To understand the effect of pollution on the feeding interactions, stable carbon and nitrogen isotopes were analyzed. Macroinvertebrate-based diversity indices and functional feeding type metric showed deterioration of ecological integrity at the urban-impacted sites and substantial recovery in the wetland-affected downstream sites. Omnivorous feeding behavior of macroinvertebrates was noted for the upstream sites, whereas clear trophic guilds of FFGs were suggested for the wetland-affected river zones by the stable isotope results. The results of pollution gradient analysis and feeding interactions among FFGs revealed that the urban-impacted sites showed weaker interactions when compared to upstream and wetland influenced sites. This affirms the potential importance of feeding interactions among FFGs of macroinvertebrates in water quality monitoring. 相似文献
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结合夏县中心地震台CIC-200型离子色谱仪实际观测,从仪器输液系统、分离系统、基线、管路等方面详细阐述色谱仪常见故障,逐一分析原因,并给出相应故障排除方法,为同类仪器维护提供参考,并为获得准确观测数据,延长仪器使用寿命,提出日常维护方法及建议。 相似文献
189.
2012年6月13日和7月10日华东地区部分地磁台垂直分量日变形态出现双低点异常,首次异常出现后37天,于7月20日发生江苏扬州M 4.9地震,震中位于低点位移分界线附近。分析认为,在强震前由于应力变化,引起孕震体环境中介质电导率等电磁性质发生改变,区域地磁场垂直分量日变曲线出现相位和幅度变化,说明地磁垂直分量日变双低点异常与地震的孕育和发生相关。 相似文献
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为了直观展示大地电场日变幅年度变化趋势,获取多年尺度下数据变化形态及特征,选取2012-2015年,4个地电台网8个存在潮汐地电场变化的地电台站观测数据,进行去除台阶、异常数据及滤波处理,计算地电场日变幅。结果显示:①2012-2013年大多数台站存在春冬低、夏秋高的日变幅趋势性特征;②2014-2015年存在几种不同日变幅年度变化趋势,同时同一台站不同测道间日变幅变化趋势存在差异性,该变化趋势和差异性的存在可能与地下介质结构变化和介质的非均匀性有一定关系。 相似文献