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1.
Key issues in the implementation of the Water Framework Directive are classification of lakes using biological quality parameters and type-specific reference conditions. This work is one of three studies considering different metrics of phytoplankton in the classification of ecological status. Phytoplankton was studied in a total of 55 Finnish boreal lakes, including 32 reference lakes. We tested the suitability of taxonomic composition and abundance of phytoplankton groups for biological classification. We also preliminarily determined the type-specific taxa for the studied lakes. The type-specific taxa for reference conditions are coincidently the indicator species/taxa for high ecological status. Interestingly, some taxa type-specific for impacted oligo-humic lakes proved to be the type-specific taxa for humic reference lakes. The pressure of human impact was observed not only as increase of biomass but also as changes in the species composition. The phytoplankton composition indicated the ecological status of impacted lakes moderately well. There was some variation in the indications given by different algal groups, probably due to the preliminary class boundaries used. However, the preliminary combination of indicative parameters to estimate the ecological status of the studied impacted lakes was in general in accordance with earlier classification of water quality in Finnish lakes.  相似文献   

2.
Spatial and temporal variations in a trichloroethylene (TCE) plume at an industrial complex in Wonju, Korea, were examined based on hydrogeological data and seven rounds of groundwater quality data collected over a year. The site has considerable vertical heterogeneities; the top layer of soil is covered by impermeable paving material at several locations, followed by a series of reclaimed or residual soil layers, and with weathered rocks to the crystalline biotite granite at the bottom. Areal heterogeneity in the surface conditions plays an important role in controlling groundwater recharge. The heterogeneity structure is influenced by complex surface conditions paved with asphalt and concrete. Owing to the presence of limited recharge area and concentrated summer precipitation events, the effects of seasonal variations on groundwater hydraulics tend to diminish with distance from the recharge area. This result was established by analysing the influence of the contrasting surface recharge conditions between the near‐source zone and the far zone, and the seasonally concentrated precipitation on the transport patterns of a TCE plume. In addition, variations in the plume's downstream contaminant flux levels were also analysed along a transect line near the source zone. The results show that the general tendency of the TCE plume contaminant concentration and mass discharges were reproducible if we account for seasonal recharge variations and the associated changes in the groundwater level. During recharge events, the TCE concentration variations appear to be influenced by leaching of the residual dense non‐aqueous‐phase liquid (DNAPL) TCE trapped in the unsaturated zone. This result shows that seasonal variations in contaminant plume near the source zone is inevitable at this site, and that these variations indicate the presence of residual DNAPL at or above the water table, at least in some isolated locations. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

3.
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   

4.
枯水期咸潮入侵已经严重威胁到了感潮河流区域供水安全.本文通过构建避咸蓄淡供水模型,耦合了咸度预测、河库联合供水调度和供水安全分析模块,为依赖感潮河流为水源地的区域供水安全管理提供了一种整体思路和决策方法.以面向粤港澳大湾区珠海东部及澳门的珠江三角洲磨刀门水道取供水为例,基于潮汐、径流和风等因子及咸度实测数据,较好地拟合了基于BP神经网络的咸度预测模型,及含氯度与超标时间的曲线函数,建立了上游来水和咸度超标时间之间的联系,得到了避咸蓄淡取水时机.咸度预测与当地河库联合供水调度相结合,得到了上游枯水期来水过程的当地区域供需平衡状况.枯水期不考虑水库调蓄的资源性缺水临界需水量为3.22亿m3,水库参与调蓄的工程性缺水临界需水量为3.75亿m3.通过供水安全分析模块,基于设定的风险阈值和临界阈值识别出了不同需水规模的上游来水临界流量特征.对于当地规划的需水规模4.23亿m3,期望上游枯水期临界流量均值约为3372 m3/s.整体上来说,需水规模越大,对上游来水期望的临界流量越大,但同时还与枯水期流量分布有关.  相似文献   

5.
The assessment of ecological status of marine fish communities required by the marine strategy framework directive (MSFD) emphasises the need for fish-based ecological indices in marine waters. In this study we adapt five estuarine multimetric indices to the marine environment and apply them in three types of substrates, analysing the metrics responsible for the obtained patterns of ecological status. The results show inefficiency of the community degradation index (CDI) and the biological health index (BHI) in ecological status assessment and disagreement between the estuarine biotic integrity index (EBI), the estuarine fish community index (EFCI) and the transitional fish classification index (TFCI). Analysis of individual metrics suggests lack of representativeness and consideration for the particularities of each substrate’s typical fish communities. None of the tested indices were efficient on the marine environment, urging the need for new marine indices that account for differences between types of substrate and depth.  相似文献   

6.
Thespatialtemporalevolutioncharacteristicsoftheload/unloadresponseratio(LURR)anditsimplicationsforpredictingthethreeelementso...  相似文献   

7.
目前定量研究下垫面不均匀性对大孔径闪烁仪(LAS)、涡动相关仪(ECS)观测感热通量差异的影响还比较少.本文利用黄土高原庆阳观测站2012年6、7月典型晴天两主风向范围E-SE和SW-W的陆面过程数据,在建立了下垫面不均匀性定量化指标的基础上,分析了下垫面不均匀性与地表温度变率的关系及其对LAS、ECS观测感热通量差异的影响.结果表明:庆阳站下垫面不均匀性大小η和地表温度变率г具有很好的相关性,相关系数达到0.566以上,证明了新建立指标的合理性.下垫面不均匀性大小η和LAS、ECS观测的感热通量差异HLAS-HECS具有很好的一致性,相关系数达到0.634.下垫面不均匀性对LAS和ECS的感热通量差异影响显著,下垫面越不均匀LAS和ECS测量的感热通量差异越大.对两主风向分别进行分析,在E-SE风向范围η和HLAS-HECS的相关系数为0.430,HLAS和HEC拟合的线性趋势系数为1.279,在SW-W风向范围η和HLAS-HECS的相关系数为0.680,HLAS和HEC拟合的线性趋势系数为1.297.下垫面不均匀性的影响程度越大,LAS和ECS观测的感热通量差异越大.  相似文献   

8.
The Cercis siliquastrum tree leaves are introduced as a low cost biosorbent for removal of Ag(I) from aqueous solution in a batch system. FT‐IR, XRD analysis, and potentiometric titration illustrate that the adsorption took place and the acidic functional group (carboxyl) of the sorbent was involved in the biosorption process. In addition, it was observed that the pH beyond pHpzc 4.4 is favorable for the removal procedure. The effect of operating variables such as initial pH, temperature, initial metal ion concentration, and sorbent mass on the Ag(I) biosorption was analyzed using response surface methodology (RSM). The proposed quadratic model resulting from the central composite design approach (CCD) fitted very well to the experimental data. The optimum condition obtained with RSM was an initial concentration of Ag(I) of 85 mg L?1, pH = 6.3 and sorbent mass 0.19 g. The applicability of different kinetic and isotherm models for current biosorption process was evaluated. The isotherm, kinetic, and thermodynamic studies showed the details of sorbate‐sorbent behavior. The competitive effect of alkaline and alkaline earth metal ions during the loading of Ag(I) was also considered.  相似文献   

9.
目前遥感干旱监测方法的精度普遍不高,探求新的遥感干旱监测方法有助于干旱监测预警技术的提升与发展.波文比是感热通量与潜热通量之比,能综合反映地表水热特征,可尝试将其引入到遥感干旱监测领域加以利用.应用甘肃河东地区的EOS-MODIS卫星资料和同步地面气象资料,基于地表能量平衡原理构建了波文比干旱监测模型,对比分析了波文比(β)指数、温度植被指数(TVX)与土壤水分的相关性,并以典型晴空影像(2014年10月5日)为例初步建立了β的干旱分级标准,对研究区进行了旱情评估.结果表明:β与土壤相对湿度呈现出高度负相关,相比于当下广泛应用的TVX,β与0~20 cm平均土壤相对湿度具有更好的相关性,监测精度得到了显著提高.用β干旱分级标准评估的研究区干湿状况与前期降水空间分布吻合得相当好,评估表明2014年10月5日研究区基本为适宜(无旱),与2014年9月的降水距平百分率特征一致.基于地表能量平衡的波文比(β)指数在干旱监测中效果突出,具有很好的应用前景.  相似文献   

10.
长江中下游地区湖泊硅藻-总磷转换函数   总被引:19,自引:8,他引:19  
硅藻转换函数的研究为湖泊环境指标的定量重建提供了有效途径.在长江中下游45个湖泊水质和表层沉积硅藻调查的基础上,利用典型对应分析方法开展了表层硅藻与营养态指标的关系研究.15个水质指标中总磷解释了硅藻数据的最大变率,是影响硅藻种群分布的最重要最显著的环境变量.通过对不同加权平均回归方法的比较,选择了反向还原加权平均回归与校正方法建立了研究区硅藻一总磷转换函数模型.依据刀割法统计检验,该模型提供了较低的推导误差(RMSEPjack=0.157).在删除异常样品后,该硅藻一总磷转换函数的推导能力明显增强,实测值与推导值的回归相关系数大大提高(R^2jackk=0.82),推导误差(RMSEPjack=0.12)也较原来降低了近21%.该转换函数同世界上其它区域的硅藻-总磷模型相比具有更强的推导能力.长江中下游地区硅藻-总磷转换函数的建立,为今后开展研究区内不同营养类型湖泊营养本底的定量重建奠定了基础,可望为湖泊治理参考目标的制定提供有效的技术支撑.  相似文献   

11.
本文努力探索地震活动性定量化前兆的检测方法,针对Region-Time-Length(RTL)算法在空间异常分析中的不足,根据新提出的综合衡量区域地震活动水平的物理参数——RTL面积分(I_(RTL)),定量分析了2014年鲁甸M_S6.5地震前地震活动时空变化,并与2012年彝良M_S5.7、5.6地震作了对比,研究结果显示这些地震前都检测到地震活动增强.彝良地震前地震活动增强异常主要分布在则木河断裂和昭通—莲峰断裂带西段的交汇区,鲁甸地震前异常主要分布在昭通—莲峰断裂带、马边断裂带及周边地区.以上地震活动增强异常区的I_(RTL)随时间呈现由小变大,至峰值后回落的特征.彝良地震和鲁甸地震均发生于I_(RTL)峰值后数月,这表明I_(RTL)峰值对地震发生可能有一定的指示意义.鲁甸地震后,对周边地区地震活动跟踪研究检测到地震活动增强现象,且自2015年I_(RTL)呈上升趋势,目前I_(RTL)值已超过鲁甸地震前的峰值水平,也许更强的地震正在孕育,所以川滇交界东边界中部仍存在发生强震的可能.以上研究为我们认识鲁甸地震的孕震过程和地震前兆研究提供了新的认识.  相似文献   

12.
In this paper we present a novel method for deseasonalizing TOC data using non-linear models, with evolutionary computation techniques, and its performance with a neural network as regression approach. Specifically, the proposed deseasonalization method uses an evolutionary programming (EP) approach to carry out a curve fitting problem, where a given function model is optimized to be as similar as possible to an objective curve (a real TOC measurement in this case). Different non-linear models are proposed to be optimized with the EP algorithm. In addition, we test the possibility of deseasonalizing the TOC measurement and also the meteorological input data. The deseasonalized series is then used to train a neural network (multi-layer perceptron). We test the proposed models in the prediction of several TOC series in the Iberian Peninsula, where we carry out a comparison against a reference deseasonalizing model previously proposed in the literature. The results obtained show the good performance of some of the deseasonalizing models proposed in this paper.  相似文献   

13.
This study evaluates the ship of opportunity (Ferrybox) concept for both sustained monitoring of UK shelf sea waters and numerical model validation. Release of phosphate from the wreck of a chemical tanker (MV Ece) in the western English Channel (49.73 degrees N, 3.25 degrees W) in March 2006 is used to demonstrate the importance of sustained observations in decision support systems and policy development. The Ferrybox system continuously collects sea surface (5m) data from a suite of autonomous electronic sensors installed on a passenger ferry operating year-round between Portsmouth (UK) and Bilbao (Spain). The detection of anomalously high concentrations of phosphate (1.54mmolm(-3), four times the usual level) and onset of phytoplankton growth close to the wreck site in March 2006 was placed in the context of multiple years of measurements (phosphate, nitrate, silicate and chlorophyll) collected from the Ferrybox system (2003-2006) and the long-term time series station E1 (50.03 degrees N, 4.65 degrees W, 1930-1987) in the English Channel. With regard to decision support, release of phosphate from the tanker is unlikely to pose a threat as phytoplankton growth at the end of winter is not unusual in this region and dissolved inorganic nitrogen rather than phosphate (DIN:DIP=10-18) is likely to ultimately limit algal growth in spring 2006. With regard to policy development, the Oslo and Paris (OSPAR) commissions recommendation of sampling every three years in "non-problem areas" is likely to provide statistically inadequate data, given the interannual and decadal variability identified in the Ferrybox and E1 data: the Ferrybox data show that oceanic winter nutrient concentrations varied by 35-50% between 2003/2004 and 2005/2006 due to deeper mixing of water off-shelf in early 2005/2006 and comparisons between the Ferrybox and E1 years show that the western English Channel is currently experiencing a low in phosphate concentrations similar to those in the 1960s. The importance of Ferrybox data in evaluating the reliability of predictive operational models needed in decision support is also demonstrated, by highlighting both strengths and weaknesses in a state-of-the-art ecosystem model designed for UK shelf waters.  相似文献   

14.
2009年姚安6.0级地震震害特征分析   总被引:1,自引:1,他引:1  
介绍了姚安6.0级地震震区的土木结构、砖木结构、砖混结构和框架结构房屋、生命线系统的概况及震害特征。分析了各种破坏产生的机理,提出了震区在恢复重建与规划发展时的建议、各类建(构)筑物加强抗震的措施。  相似文献   

15.
在石油、天然气的勘探和开发研究中,涉及到深部空间的介质、结构和属性,在沉积建造上涉及到陆相沉积、海相沉积和火山岩相,在油、气成因理论上涉及到有机成因和无机成因,在机制上涉及到深部流体的分异、调整、运移和动力作用.这些本质性问题的研究和探讨是人们十分关注的科学领域.基于油、气生、储和形成的理论、应用和成效的研究提出,有几个基础性的理念问题必须重新认识,特别是沉积建造与古老变质岩结晶基底;双相(海相和陆相)沉积建造与盆地的内涵和双基(有机和无机)混合油、气成因理念.清晰地厘定这些认识不仅有益于对油、气形成、聚集和勘探及开发给出一个更为科学的深部空间,即第二深度空间(5000~10000 m)的油、气勘探,而更为重要的是基于对这些理念的重新认识和深化研究可构建新的思路或理论,且在新的理念导向下,强化油、气深部勘探,以期能在理论研究和实践应用中取得新的成效,发现大型与超大型油、气田.  相似文献   

16.
滕吉文  杨辉 《地球物理学报》2013,56(12):4164-4188
在当今全球各国对油、气能源的需求和我国在工业化进程中油气能源十分紧缺的前提下,共享世界油、气能源的同时,必须立足于本土,迅速建立起安全、稳定,且可保证持续供给的油、气能源战略后备基地.油、气田勘探和开采中,尚存在着大于或远大于通常所规范的油、气生成稳定温度和深度限定,而向深部勘察油、气的理念又受到传统油、气成因理论的严峻挑战.为此,近些年来,通过对沉积建造、结晶基底,深部油气生成的物理(主指温度、压力)条件、物源和聚集储存空间的研究,提出:①沉积盆地中存在双相(陆相+海相)沉积建造,而基底则分为中、新生代沉积基底和古老的变质岩结晶基底,即双层基底;②地壳深部介质的物理-化学属性和变质岩及存储空间为油、气的生成和聚集提供了物质基础;③厘定了在有机成因主导下,油、气混合成因(有机+无机)的新理念;④第二深度空间(5000~10000 m)的油、气探查和开发将必是未来深部发现大型和超大型油、气田和深化研究的必然轨迹.  相似文献   

17.
The parameters of Earth free core nutation (FCN) are two relatively significant geophysical parameters. Sasao et al. (1980) and Wahr and Bergen (1986) provided the theoretical estimation values of FCN parameters. Gwinn, Herring and Shapiro (1987) first obtained the observational values of FCN parameters by very long base Interference (VLBI) at Cambridge University. In the same year, Neuberg and Zürn in former West Germany and Hinderer in France began to retrieve FCN parameters by the observation of gravity tides and introduced the stacking method. The other scholars who researched into the same geophysical problems by applying the data of gravity tides basically followed the stacking method. The results they reached were similar to the observational result of FCN parameters given by Neuberg et al. in 1987. But the observational results of FCN parameters gained from gravity tides were not identical with those from VLBI, mainly because of the large difference of quality of FCN. So there was not an affirmative observational result of FCN parameters since then. In this paper, The authors firstly introduce the tri-frequency spectrum method with clearly geometrical and geophysical meaning for the resolution of FCN parameters, and the observational results of FCN parameters obtained from tide data at three superconducting gravity stations were accordant with those from VLBI, which will be relatively important to arriving at a certain observational result of FCN parameters.  相似文献   

18.
The parameters of Earth free core nutation (FCN) are two relatively significant geophysical parameters. Sasao et al. (1980) and Wahr and Bergen (1986) provided the theoretical estimation values of FCN parameters. Gwinn, Herring and Shapiro (1987) first obtained the observational values of FCN parameters by very long base Interference (VLBI) at Cambridge University. In the same year, Neuberg and Zürn in former West Germany and Hinderer in France began to retrieve FCN parameters by the observation of gravity tides and introduced the stacking method. The other scholars who researched into the same geophysical problems by applying the data of gravity tides basically followed the stacking method. The results they reached were similar to the observational result of FCN parameters given by Neuberg et al. in 1987. But the observational results of FCN parameters gained from gravity tides were not identical with those from VLBI, mainly because of the large difference of quality of FCN. So there was not an affirmative observational result of FCN parameters since then. In this paper, The authors firstly introduce the tri-frequency spectrum method with clearly geometrical and geophysical meaning for the resolution of FCN parameters, and the observational results of FCN parameters obtained from tide data at three superconducting gravity stations were accordant with those from VLBI, which will be relatively important to arriving at a certain observational result of FCN parameters.  相似文献   

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