Impact of phosphorus load reduction on water quality in a stratified reservoir-eutrophication modeling study

Monitoring data collected from the Mingder Reservoir in Taiwan indicate that the water quality is between mesotrophic and eutrophic. Chlorophyll a concentration is higher in the summer and anoxic conditions occur in the bottom. The data also reveal that a pronounced vertical thermal gradient in summer and vertical mixing the end of fall. A vertical two-dimensional, laterally averaged hydrodynamic and water quality model (CE-QUAL-W2) was adopted to simulate the water surface elevation, water temperature, and water quality conditions in the water column. The modeling effort was supported with monitoring data collected in the field for a 2-year period in the reservoir. The hydrodynamic model reproduced the time series water surface elevation. Spatial and temporal distributions of temperature in the water column of the reservoir were also well reproduced by the hydrodynamic model. Model-calculated concentrations of key water quality constituents such as nutrients, dissolved oxygen, and algal biomass matched the measured values closely in the reservoir. The calibrated model was then applied to simulate water quality response to various nutrient reduction scenarios. Results of the model scenario runs reveal that a 20% and 80% reduction of the phosphorus loads will improve the water quality from eutrophic to mesotrophic and oligotrophic conditions, respectively. The modeling effort has yielded valuable information that can be used by decision makers for the evaluation of different management strategies of reducing watershed nutrient loads.     

核算间接冷却水污染当量数的研讨

针对间接冷却水的特点和核算其污染当量数过程中存在的问题,阐述了间接冷却水的界定,水源水的采样监测技术,本底值的扣除以及超标排放的判别等环节的技术要求和注意事项,并就与之密切相关的几个问题进行了讨论,为核算间接冷却水的污染当量提供了一定的参考依据,并建议增加水温排放指标,以切实控制间接冷却水造成的主要污染－热污染。     

An appraisal of changes in seasonal water quality during passage through a shallow reservoir in Western Poland

Following restoration changes in Antoninek Reservoir physico-chemical and biological processes in the water column and bottom sediments were measured to outline mechanisms of changes in nitrogen, phosphorus and organic matter concentrations during water flow through this reservoir. Intensive mineralisation of organic matter in the shallow sediments stimulated primary production and influenced increasing ammonia and nitrite nitrogen concentrations. Two main factors affected concentrations of phosphorus: (1) its presence in the external loads of river waters entering the reservoir, more important in the colder seasons as the water discharge was higher and (2) from the internal loads coming from bottom sediments. The quality of the river water during its flow through this reservoir improved for most parameters and seasons. However, concentrations of nutrients were still high in waters flowing out from the reservoir and in some months they were higher in the outflow than in waters entering the reservoir.     

Toxicity Identification Evaluation (Phase I) of water and sediment samples from a tropical reservoir contaminated with industrial and domestic effluents

The Funil Reservoir (Rio de Janeiro State, Brazil) is an environment degraded by constant discharge of nutrients and pollution coming from the most industrialized region of the country. As a consequence of eutrophication, there are continuous cyanobacteria blooms, which cause acute and chronic toxicity to zooplankton. In this context, Phase I of Toxicity Identification Evaluation (TIE) was performed on Daphnia similis using water and interstitial water from the reservoir, with the aim of identifying classes of compounds responsible for toxicity. The results indicated that water toxicity was due to cyanobacteria resulting from blooms in the reservoir and surfactants. Metals, especially copper, contributed to sediment toxicity. This research is the first attempt to describe the nature of toxicity in this reservoir using this method.     

丹江口水库流域氮素时空分布特征

为全面了解丹江口水库流域氮素污染状况,对库区26个点位及10条主要入库河流入库口处的表层水样进行了丰水期、平水期、枯水期采样与监测,探讨了氮素时空分布特征。入库口总氮检出范围为1.31~10.96 mg/L,其中泗河和神定河入库口总氮最高。总氮为库区水质主要限制因子,年均总氮质量浓度为1.13~2.71 mg/L;汉江库区整体上总氮污染水平略高于丹江库区,且与丹江库区相比,汉江库区受点源排放的影响较大。10条入库河流总氮的总年均输入量为63 347.31 t/a,其中汉江的总氮输入量最大;入库河流总氮控制的关键在于溶解性有机氮和硝酸盐氮的控制。     

Fuzzy Logic Model to Estimate Seasonal Pseudo Steady State Chlorophyll-A Concentrations in Reservoirs

A fuzzy logic model is developed to estimate pseudo steady state chlorophyll-a concentrations in a very large and deep dam reservoir, namely Keban Dam Reservoir, which is also highly spatial and temporal variable. The estimation power of the developed fuzzy logic model was tested by comparing its performance with that from the classical multiple regression model. The data include chlorophyll-a concentrations in Keban lake as a response variable, as well as several water quality variables such as PO₄ phosphorus, NO₃ nitrogen, alkalinity, suspended solids concentration, pH, water temperature, electrical conductivity, dissolved oxygen concentration and Secchi depth as independent environmental variables. Because of the complex nature of the studied water body, as well as non-significant functional relationships among the water quality variables to the chlorophyll-a concentration, an initial analysis is conducted to select the most important variables that can be used in estimating the chlorophyll-a concentrations within the studied water body. Following the outcomes from this initial analysis, the fuzzy logic model is developed to estimate the chlorophyll-a concentrations and the advantages of this new model is demonstrated in model fitting over the traditional multiple regression method.     

A Three-Dimensional, Integrated Seasonal Separate Advection–Diffusion Model (ISSADM) to Predict Water Quality Patterns in the Chahnimeh Reservoir

Seasonal rivers are the main sources of discharge for many lakes and reservoirs. These rivers can deliver pollutants into these water bodies, especially during large events. The fate and distribution of these pollutants within lakes is difficult to predict. Here, a three-dimensional, finite-volume model for predicting lake water quality is used to account for internal advection and diffusion, including the impacts of the inflowing rivers on the velocity field. We used parsimonious sub-models for the source/sink terms for temperature, dissolved oxygen, ammonia nitrogen, phosphorous, phytoplankton, and zooplankton concentrations and tested the model predictions against field measurements from the Chahnimeh Reservoir in Iran. The modeled water quality parameters were in good agreement with the measured values. Results were notably poorer when the three-dimensionality of the model was removed. This study suggests that properly simulating three-dimensional advection is important to properly predict the distribution of pollutants within some lakes and reservoirs and that this model may be directly applicable to systems similar to Chahnimeh Reservoir.     

模糊数学在丹江口水库富营养化评价中的应用

丹江口水库是南水北调中线工程水源地,其水质安全将直接影响调水工程的成败。基于2013年6月的水质监测结果,通过对水质指标的聚类,将丹江口水库划分子库区,并尝试使用模糊数学方法进行水质富营养化评价。结果表明,丹江口库区可分为6个子库区,各库区在透明度、溶解氧、浊度、高锰酸盐指数、总磷、硝酸盐氮和叶绿素a等理化指标均有显著差异;富营养化评价显示,库区总体营养状态级别为中营养。其中,坝前区域(库区Ⅰ)和丹库主体部分(库区Ⅵ)营养状态级别为贫营养,汉库原河道区(库区Ⅱ)为中营养,汉江入库口(库区Ⅲ)、汉库最大库湾(库区Ⅳ)、丹江入库口(库区Ⅴ)为轻度富营养。模糊综合评价法较好反映出水质的模糊性、连续性,使评价结果更加准确可靠。     

Factors dominating stratification cycle and seasonal water quality variation in a Korean estuarine reservoir

A comprehensive monitoring program was conducted during 2005-2007 to investigate seasonal variations of hydrologic stability and water quality in the Yeongsan Reservoir (YSR), located at the downstream end of the Yeongsan River, Korea. A principal component analysis (PCA) was performed to identify factors dominating the seasonal water quality variation from a large suite of measured data--11 physico-chemical parameters from 48 sampling sites. The results showed that three principal components explained approximately 62% of spatio-seasonal water quality variation, which are related to stratifications, pollutant loadings and resultant eutrophication, and the advective mixing process during the episodic rainfall-runoff events. A comparison was then made between YSR and an upstream freshwater reservoir (Damyang Reservoir, DYR) in the same river basin during an autumn season. It was found that the saline stratification and pollutant input from the upstream contributed to greater concentrations of nutrients and organic matter in YSR compared to DYR. In YSR, saline stratification in combination with thermal stratification was a dominant cause of the longer period (for two consecutive seasons) of hypoxic conditions at the reservoir bottom. The results presented here will help better understand the season- and geography-dependent characteristics of reservoir water quality in Asian Monsoon climate regions such as Korea.     

核算间接冷却水污染当量数的研讨

针对间接冷却水的特点和核算其污染当量数过程中存在的问题 ,阐述了间接冷却水的界定、水源水的采样监测技术、本底值的扣除以及超标排放的判别等环节的技术要求和注意事项 ,并就与之密切相关的几个问题展开了讨论 ,为核算间接冷却水的污染当量数提供了一定的参考依据。建议增加水温排放指标 ,以切实控制间接冷却水造成的主要污染——热污染     

温升包络线在核电站温排水监测中的应用

采用核电站温排水遥感监测影像叠加合并方法提取温升包络线,监测核电站附近海域海表温升数据,确定核电温排水的影响范围,对海面温升面积进行计算,判断核电站温排水是否符合我国相关海洋空间管理标准。以某核电站实例表明,通过遥感监测获得的温升包络线在核电站温排水监测中具有应用价值。     

Numerical Modeling of the Impact of a Pumped-Storage Hydroelectric Power Plant on the Reservoirs’ Thermal Stratification Structure: a Case Study in NW Spain

Pumped-storage hydroelectric power plants are generally perceived as an environmentally respectful technology. Nevertheless, the pumping of water from a lower reservoir to an upper impoundment, and the return of that water during power generation, can strongly affect the water quality of the reservoirs. In particular, plant operation can alter their thermal structure, deep water mixing, and water circulation characteristics. The objective of this study is to quantify, through the use of 3D hydrodynamic modeling, the potential impacts of a pumped-storage hydroelectric plant on the thermal stability and mixing of two reservoirs in Galicia, northwest of Spain. To this end, three-dimensional hydrodynamic simulations were conducted using the model Delft3D. Two different coupled models, one for each reservoir, were constructed and subsequently tested for several stratification scenarios, according to measured temperature profiles during the spring and summer season. Several reservoir minimum and maximum operation water levels were also considered. Model simulations demonstrated a high level of mixing in the vicinity of the intake-outlet structures, in particular during startup of the power plant, regardless of the water level in the reservoir. Beyond this area, the results showed a limited overall effect on stratification and mixing in the upper reservoir, owing to the relation between the inflow temperatures and the initial temperature profile of this reservoir. A more significant alteration of the thermal structure is expected in the lower reservoir due to its narrow shape and shallow depth at the structure location, as well as the temperature differences between receiving waters and inflow.     

核电站温排水遥感监测方法研究——以田湾核电站为例

以江苏省连云港田湾核电站为主要研究区,通过热红外遥感技术研究温排水热污染现象,综合应用美国Landsat卫星热红外波段数据及地面气象测站资料,定量反演核电站建成前后附近海域水温分布与变化情况。研究结果表明,遥感技术完全能够满足温排水监测要求,对于完善近岸海域生态环境保护工作具有积极意义。     

The potential effects of climate change on the distribution and productivity of Cunninghamia lanceolata in China

Climate changes may have immediate implications for forest productivity and may produce dramatic shifts in tree species distributions in the future. Quantifying these implications is significant for both scientists and managers. Cunninghamia lanceolata is an important coniferous timber species due to its fast growth and wide distribution in China. This paper proposes a methodology aiming at enhancing the distribution and productivity of C. lanceolata against a background of climate change. First, we simulated the potential distributions and establishment probabilities of C. lanceolata based on a species distribution model. Second, a process-based model, the PnET-II model, was calibrated and its parameterization of water balance improved. Finally, the improved PnET-II model was used to simulate the net primary productivity (NPP) of C. lanceolata. The simulated NPP and potential distribution were combined to produce an integrated indicator, the estimated total NPP, which serves to comprehensively characterize the productivity of the forest under climate change. The results of the analysis showed that (1) the distribution of C. lanceolata will increase in central China, but the mean probability of establishment will decrease in the 2050s; (2) the PnET-II model was improved, calibrated, and successfully validated for the simulation of the NPP of C. lanceolata in China; and (3) all scenarios predicted a reduction in total NPP in the 2050s, with a markedly lower reduction under the a2 scenario than under the b2 scenario. The changes in NPP suggested that forest productivity will show a large decrease in southern China and a mild increase in central China. All of these findings could improve our understanding of the impact of climate change on forest ecosystem structure and function and could provide a basis for policy-makers to apply adaptive measures and overcome the unfavorable influences of climate change.     

中国北方山区水库与引黄水库富营养化特征

于2012年10月—2013年8月对中国北方地区2种典型水库:山区水库(卧虎山、锦绣川)和引黄水库(鹊山、玉清)进行了采样调查,对其水质特征和富营养化现状进行分析研究。结果表明:2类水库水质的最大差异在于山区水库的氮含量显著高于引黄水库,这主要与水源、氮素来源和水库的进水方式有关。山区水库中SD与藻类生物量、TP关系密切;而引黄水库中,影响SD的环境因素较复杂,除藻类生物量和氮、磷外,碱度和水温也与SD密切相关。全年水平上,卧虎山水库营养状态指数显著高于其他水库,属中-富营养水体,锦绣川水库、鹊山水库和玉清水库均属中营养水平。时间上,同类型水库的营养状态指数季节变化基本一致。参与营养状态计算的4个因子中,Chla和TN对营养状态指数的贡献最大,表明这两者是引起2类水库营养状态加重的重要原因。典型的水源及进水方式、流域人类活动类型和强度是影响山区水库和引黄水库营养状态的主要外部因素。     

A simplified model for reservoir operation considering the water quality issues: Application of the Young conflict resolution theory

In this study, an algorithm combining a multi-objective genetic algorithm (GA)-based optimization model and a water quality simulation model is developed for determining a trade-off curve between objectives related to the allocated water quantity and quality. To reduce the run-time of the GA-based optimization model, the main problem is decomposed to long-term and annual optimization models. The reliability of water supply is considered to be the objective function in the long-term stochastic optimization model, but the objective functions of the annual models are related to both the allocated water quantity and quality. The operating policies obtained using this long-term model provide the time series of the optimum reservoir water storages at the beginning and the end of each water year. In the next step, these optimal reservoir storage values are considered as constraints for water storage in the annual reservoir operation optimization models. The epsilon-constraint method is then used to develop a trade-off curve between the reliability of water supply and the average allocated water quality. The Young conflict resolution theory, which incorporates the existing conflicts among decision-makers and stakeholders, is used for selecting the best solution on the trade-off curve. The monthly reservoir operating rules are then calculated using an Adaptive Neuro-Fuzzy Inference System, which is trained using the optimal operating policies. The proposed model is applied to the 15-Khordad Reservoir in the central part of Iran. The results show that this simplified procedure does not reduce the accuracy of the reservoir operating policies and it can effectively reduce the computational burden of the previously developed models.     

Seasonal change and correlation with environmental parameters for 2-MIB in Feng-Shen Reservoir, Taiwan

Two common drinking water earthy/musty odorants, 2-methyl-isoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin), were monitored and analyzed for their correlation with environmental conditions in Feng-Shen Reservoir (FSR), Taiwan. Long-term monitoring results, from December 2000 to July 2003, indicated that 2-MIB was present in the reservoir at concentrations between 10 and 200 ng L(-1), and those of geosmin were always smaller than 10 ng L(-1). The 2-MIB concentrations followed a trend of higher concentrations during the warm seasons. After being analyzed with 10 water quality and three meteorological parameters, 2-MIB concentration was found to correlate with corresponding air and water temperatures. An analysis of air temperature history versus 2-MIB concentration in FSR suggested that 2-MIB concentration was best correlated with the mean of average daily temperature from 1 to 9 days before sampling, with R (2) = 0.90. This correlation was further employed to predict the 2-MIB concentration observed during another sampling period in FSR. A similar degree of fit was observed between predictions and experimental data, suggesting the potential applicability of the approach. In addition to the effect of temperature, heavy rainfalls that occurred before the sampling time may also reduce the 2-MIB concentration in the reservoir. A short-term continuous monitoring of the odorants for 32 h showed that both geosmin and 2-MIB concentrations in the reservoir remained almost constant, with only about a 10% difference during the sampling period. This may suggest that the odorants were uniformly distributed in the water near the sampling location in the reservoir.     

Adaptive Management, Monitoring, and the Ecological Sustainability of a Thermal-Polluted Water Ecosystem: A Case in Sw Spain

The construction of the Almaraz nuclear power plant in Spain in the 1970s posed interesting environmental problems concerning the construction of a cooling reservoir (Arrocampo reservoir) to cool the steam condensers and the consequent heating of the reservoirs water. The socio-political context forced decision makers to set up a project for the monitoring and management of the environmental impacts derived from the construction and operation of the power plant. Numerous scientific and technical specialists collaborated with the representatives of social groups towards two goals: the improvement of the biodiversity and of the efficiency of the cooling system. These goals involved the monitoring and managing of the system with respect to different biological aspects, mainly limnology, ichthyology, avian fauna and vegetation. The management plan yielded numerous results. The control of the water eutrophy is one of the most important due to its repercussion on the rest of the ecosystem, especially the fish fauna. The development of the shore vegetation slowly increased the patchwork nature of the reservoir, leading to a greater diversity of the avian species. This paper describes the monitoring and management of the Arrocampo ecosystem, the condition before and after the construction of the reservoir and the results obtained concerning some biological communities.     

右江百色水库下游断面低溶解氧形成原因分析

广西右江东笋断面溶解氧(DO)呈现5—11月浓度较低,12月及1—4月浓度较高的变化规律。从水温、藻类呼吸、沉积物耗氧、有机物耗氧、上游来水等方面分析了东笋断面低DO形成的原因。结果表明,5—11月东笋断面DO浓度较低,主要是受夏季高温和水利工程运行等非污染型因素的影响。右江流域夏秋季水温较高,限制了水体DO浓度的上限。热分层现象导致百色水库中层水体DO浓度较低,而水利枢纽发电时的下泄水正是中层水体,因此,下泄水DO浓度低是导致5—11月东笋断面DO浓度低的主要原因。东笋河段沉积物和有机物耗氧对DO浓度的影响很小,藻类呼吸作用对DO浓度的影响有限。     

Assessment of organic and inorganic contaminants in sediments of an urban tropical eutrophic reservoir

Although the Ibirité reservoir (an urban tropical eutrophic reservoir) has been the recipient of the discharge of a large volume of raw urban sewage, the key cause of ecosystem degradation has been historically solely attributed to the discharge of effluents from an oil refinery. This fact motivated an investigation to unravel the compositions of contaminants in the sediments to evaluate their distributions, possible sources, and potential impacts on sediment–water quality. The concentrations of polycyclic aromatic and aliphatic hydrocarbons and of metals and metalloids were, in general, significantly lower than some selected polluted sites used for comparison. Calculated distribution indexes showed that the hydrocarbon sources were petrogenic, pyrogenic, and biogenic. Only a few PAHs exceeded the threshold effects level (TEL) guideline. Industrial activities are the presumed sources of metals and metalloids except for copper, which is from copper sulfate used as algaecide in the reservoir. The bioavailable concentrations of some metal and metalloid exceeded the TEL–PEL guidelines. The acid volatile sulfide concentration was greater than that of the simultaneously extracted metals in the clayey–silty reservoir sediments, whereas the opposite result was observed for the sandy sediments of the tributaries. The sediment interstitial water toxic units were >1 for metals, thus indicating that metals are potentially toxic to the benthos. Considering the data set generated in this study, it can be concluded that the degradation of Ibirité reservoir and its tributaries cannot be solely attributed to the input of hydrocarbons, but predominantly to the discharge of raw urban sewage and effluents from other industrial sources.