How are Results from Critical Load Calculations Reflected in Lake Water Chemistry?

The Steady State Water Chemistry Model (SSWCM) is a common method for determinations of critical loadof acid and subsequently of critical loadexceedance for lakes. One way to verify the modeloutput, is to compare with chemical indicatorssuch as pH-value, alkalinity or ANC. When themedian chemical status (as ANC) is used 65% ofthe lakes responded according to the exceedancevalue. For these the calculated exceedanceresulted in violation of the critical chemicalvalue while non-exceedance gave no violation.Since biota react on extreme conditions a morecorrect evaluation should be based on minimumvalues for the chemical indicator. This raises thefraction of lakes responding to 78%. Non-exceedance is seldom found inlakes with acid conditions. The evaluationindicates that the calculation of critical load ofacidity by means of SSWCM is very reliable.     

Urban Land-Use Influences on Transport of Heavy Metals to Lakes and Concentrations in Fish

Water, Air, &; Soil Pollution: Focus - To investigate the urban land-useinfluences on transport of heavy metals to lakesand metal concentrations in fish liver (perch andcrucian carp), ten lakes...     

Prediction of the concentration of chlorophyll-a for Liuhai urban lakes in Beijing City

The weekly water quality monitor data of Liuhai lakes between April 2003 and November 2004 in Beijing City were used as an example to build an artificial neural networks （ANN） model and a multi-varieties regression model respectively for predicting the fresh water algae bloom. The different predicted abilities of the two methods in Liuhai lakes were compared. A principle analysis method was first used to select the input variables of the models to avoid the phenomenon of collinearity in the data. The results showed that the input variables for the artificial neural networks were T, TP, transparency（SD）, DO, chlorophyll-a （Chl-a）,pH and the output variable was Chl-a. A three layer Levenberg-Marguardt feed forward leaming algorithm in ANN was used to model the eutrophication process of Liuhai lakes. 20 nodes in hidden layer and 1 node of output for the ANN model had been optimized by trial and error method. A sensitivity analysis of the input variables was performed to evaluate their relative significance in determining the predicted values. The correlation coefficient between predicted value and observed value in all data and in test data were 0.717 and 0.816 respectively in the artificial neural networks. The stepwise regression method was used to simulate the linear relation between Chl-a and temperature, of which the correlation coefficient was 0.213. By comparing the results of the two models, it was found that neural network models were able to simulate non-linear behavior in the water eutrophication process of Liuhai lakes reasonably and could successfully estimate some extreme values from calibration and test data sets.     

云南省九大高原湖泊水污染现状调查与分析

从云南九大高原湖泊水污染综合防治"十一五"规划编制入手,对九湖水污染情况进行系统汇编和整理,分析九湖存在的主要环境问题,为水污染综合防治工作提供参考和借鉴.     

Pollution assessment of the lower basin of Lakes Kainji/Jebba, Nigeria: heavy metal status of the waters, sediments and fishes

The objective of this investigation was to examine the heavy metal status of the lower basin of Kainji dam (used for hydroelectricity generation), which includes Lakes Kainji/Jebba, Nigeria, and the potential for human exposure to heavy metals from eating fish caught in the lakes. Water, sediments and fish were sampled from the lakes and evaluated for As, Cu, Co, Cr, Fe, Hg, Mn, Ni, Pb, Sb, Ti, V and Zn using the EDXRF technique. Fe and Mn were found to be present at high mean concentrations in the water (13 and 9 μg L^-1), sediment (7092 and 376 μg g^-1) and fish (11.4 and 4.6 μg g^-1) samples. Sb (3.2 μg L^-1), Ti (4.1 μg L^-1), Cr (2.2 μg L^-1), Co (1.2 μg L^-1), Cu (1.3 μg L^-1) and Pb (1.2 μg L^-1) in the water samples and Sb (29 μg g^-1), Ti (27 μg g^-1), V (27 μg g^-1), Cr (27 μg g^-1), Co (40 μg g^-1), Ni (33 μg g^-1), Cu (25 μg g^-1), Zn (59 μg g^-1) and Pb (19 μg g^-1) in the sediment samples were found to be of medium mean concentrations. The other metals were present at trace levels (<1 μg), including As and Hg in the fish and sediment samples. There was an appreciable increase in␣metal concentrations in going from the water to the sediment samples. The probable source of the pollutants is anthropogenic, arising from agricultural activities, corrosion/abrasion of the ferrous steel material and additives in the lubricants and insulation used for auxiliary services on the turbine floor of the dam constructed on the lakes. However, natural geological sourcing from the underlying lake rock cannot be totally ignored, particularly the high levels of Fe and Mn in the sediment samples. The potential risk for human exposure to these metals emanates from the fish caught in the lakes and subsequently consumed, as there are already significant levels of these metals in the two fish species analysed, Tilapia (Oreochromis niloticus) and Chrysicthys (Chrysicthys auratus).     

长春城市水体夏秋季温室气体排放特征

为掌握我国东北地区城市湖泊水体温室气体的释放/吸收特征,本研究分别于夏季和秋季,对位于吉林省长春市的7个城市湖泊(南湖、北湖、雁鸣湖、胜利公园、地理所内湖、天嘉公园和长春公园)表层水中的CO_2和CH_4分压[p(CO_2)和p(CH_4)]进行了监测,并对影响p(CO_2)和p(CH_4)季节变化的相关环境和水质参数进行了分析.研究结果表明在夏季和秋季这7个城市湖泊表层水体中CH_4都处于过饱和状态;除夏季的南湖和胜利公园内湖,其它湖泊CO_2也都处于过饱和状态,且不同湖泊间的温室气体分压具有显著性差异(P0.05),通量也同样具有显著性差异(P0.05).除了南湖和胜利公园内湖外,其它各湖泊在夏秋季节都是大气CO_2和CH_4的"源",且对大气中温室气体的贡献都以CO_2为主.环境参数与p(CO_2)或p(CH_4)之间的相关性分析表明,在夏季,城市湖泊表层水体中p(CO_2)和p(CH_4)都与日照时数呈显著负相关(r_(p(CO_2))=-0.48,P0.05;r_(p(CH_4))=-0.63,P0.01),日照时数通过影响水生植物的光合作用进而影响水体中CO_2和溶解氧浓度,p(CH_4)还与降水量呈显著正相关(r_(p(CH_4))=0.44,P0.05);在秋季,p(CO_2)与气温呈显著负相关(r_(p(CO_2))=-0.39,P0.05).另外,水质参数与p(CO_2)和p(CH_4)的相关性分析表明,这些城市湖泊表层水体的p(CO_2)和p(CH_4)都与水体pH显著负相关(r_(p(CO_2))=-0.51,r_(p(CH_4))=-0.82,P0.01),与盐度显著正相关(r_(p(CO_2))=0.38,P0.05;r_(p(CH_4))=0.75,P0.01),p(CH_4)还与水体DOC、TN和TP均具有显著相关性(P0.01).从研究结果可以推测在这7个富营养城市湖泊中,水体的营养物水平及其所决定的浮游植物生物量并不是影响表层水体p(CO_2)的最主要因素,而日照时数、水体pH和盐度与夏秋季表层水体中的p(CO_2)和p(CH_4)有较大关联.     

贡嘎山冷杉林带草海子小流域土壤及湖泊沉积物中磷的形态及迁移特征

磷（P）是控制水体生态系统生产力的重要元素,了解陆地与水体间P的迁移特征,是了解控制水体生态系统中P有效供给的重要途径。本研究选择青藏高原东缘贡嘎山海拔2800 m左右峨眉冷杉林带中一小湖泊——草海子及其流域,通过对流域内土壤、湖泊沉积物中P的形态组成分析,探讨流域内P的形态组成及其迁移特征。结果表明,草海子流域内土壤成土母质中的磷以Ca-P为主,表层土壤中的磷以Al、Fe结合态为主,占总磷的49%~80%,而湖泊沉积物中Al、Fe结合态P下降到46%左右。在成土作用及植物吸收的过程中P由土壤剖面下部向上迁移,迁移的主要形态为树脂提取态（或称可交换态,R-P）,而R-P还是由陆地向水体迁移的主要形态P。土壤的Al、Fe结合态P难以释放转化,因此少有随地表径流迁移向湖泊。     

西部河湖连通水质时空演化对渔业生态环境的影响研究

吉林西部原有生态系统敏感脆弱,若采用河湖连通势必会对原有的生态系统产生一定影响.主要从河湖连通后会对养殖水域水质可能出现的现象和问题进行研究,通过对氟化物、非离子氨、凯氏氮、生化耗氧量、硫酸盐与硫化物、氮磷比、本底性污染、河流湖泊退化等多个因素分析了河湖连通后潜在的生态危机,以及灌区退水及鱼产力影响西部河湖连通生态效益的主要因素,提出了切实改善西部河湖连通生态影响的建议.     

Nutrient Sources and Transport in the Missouri River Basin,with Emphasis on the Effects of Irrigation and Reservoirs1

Brown, Juliane B., Lori A. Sprague, and Jean A. Dupree, 2011. Nutrient Sources and Transport in the Missouri River Basin, With Emphasis on the Effects of Irrigation and Reservoirs. Journal of the American Water Resources Association (JAWRA) 47(5):1034‐1060. DOI: 10.1111/j.1752‐1688.2011.00584.x Abstract: SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were used to relate instream nutrient loads to sources and factors influencing the transport of nutrients in the Missouri River Basin. Agricultural inputs from fertilizer and manure were the largest nutrient sources throughout a large part of the basin, although atmospheric and urban inputs were important sources in some areas. Sediment mobilized from stream channels was a source of phosphorus in medium and larger streams. Irrigation on agricultural land was estimated to decrease the nitrogen load reaching the Mississippi River by as much as 17%, likely as a result of increased anoxia and denitrification in the soil zone. Approximately 16% of the nitrogen load and 33% of the phosphorus load that would have otherwise reached the Mississippi River was retained in reservoirs and lakes throughout the basin. Nearly half of the total attenuation occurred in the eight largest water bodies. Unlike the other major tributary basins, nearly the entire instream nutrient load leaving the outlet of the Platte and Kansas River subbasins reached the Mississippi River. Most of the larger reservoirs and lakes in the Platte River subbasin are upstream of the major sources, whereas in the Kansas River subbasin, most of the source inputs are in the southeast part of the subbasin where characteristics of the area and proximity to the Missouri River facilitate delivery of nutrients to the Mississippi River.     

The variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes

Taking 29 Chinese lakes and 29 Italian lakes as two separate case studies, the paper presented the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. The exergies (Ex) and structural exergies (Exst) were calculated based on phytoplankton biomass (BA) and zooplankton biomass (BZ). A trophic state index (TSI) scaling from 0 to 100 was developed to classify trophic status for Chinese and Italian lakes based on three indicators, chlorophyll-a concentration (Chl-a, in mg/m³), total phosphorus (TP in mg/m³) and transparency in Secchi disk depth (SD in m). The relationships between TSI and Ex, Exst, total biomass, BZ/BA ratios were analyzed. The following results were obtained: (1) with the increase of TSI in Chinese and Italian lakes, there is an increasing trend for Ex, and a decreasing trend for Exst, generally. The obvious negative correlations exist between TSI and Exst, at the significant level of 0.01 for Italian lakes, and 0.05 for Chinese lakes. The obvious positive correlations exist between TSI and Ex, at the significant level of 0.01 for Chinese lakes, and for Italian lakes in Spring, Autumn and the all-year. (2) The structural exergy is more dependent on the ratio of phytoplankton biomass to zooplankton biomass (BZ/BA) than the exergy, and the exergy is more dependent on total biomass than the structural exergy. (3) The phytoplankton biomass (BA) and zooplankton biomass (BZ) are increased with the increasing TSI in Chinese and Italian lakes, and phytoplankton biomass (BA) increases more rapidly then zooplankton biomass (BZ) does. This results in the definite decrease of BZ/BA ratio with the increasing trophic status index. Such changes of BA, BZ and BZ/BA ratio could explain successfully the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. From the two separate case studies of Chinese lakes and Italian lakes, it could be concluded that exergy and structural exergy are feasible to serve as the system-level ecological indicators to give appropriate information on the trophic status of different lakes.