Impact of pond and fence aquaculture on reservoir environment

With the rapid development of aquaculture in lakes and reservoirs, its negative effects on water quality and aquatic organisms are clearly emerging. Toward a better understanding of these effects, chemical and biological monitoring was conducted in the Fangbian Reservoir to study the relationship between aquaculture and eutrophication. As a domestic water supply source, this reservoir has reached the mesotrophic level. The concentrations of total nitrogen （TN） and total phosphorus （TP） in the Fangbian Reservoir have frequently exceeded the prescriptive level according to the Environmental Quality Standardgfor SurJace Water （GB3838-2002）. Pond and fence aquaculture feeding is the main cause of high levels of nitrogen and phosphorus, accounting for nearly half of the total pollution, and causing the reservoir environmental capacity to be exceeded. The amounts of nitrogen and phosphorus that went directly to the reservoir through the residual bait and fish droppings in fence aquaculture were 42 768 kg per year and 10 856 kg per year respectively, from 2007 to 2009. About 2 913 kg of nitrogen and 450 kg of phosphorus were imported to the reservoir through the exchange of water from the culturing ponds at the same time. Therefore, controlling the aquaculture scale and promoting eco-aquaculture are key measures for lessening the eutrophication degree and improving the water quality.

Research on the environmental capacity of a reservoir by using the conceptual net method

The aquatic environment capacity possesses the largest tolerance to pollutants. We can improve the calculating precision using the conceptual net method. Its basic ways involved in calculation include the following aspects: first, to establish the flow continuity equation, flow motion equation, water quality equation and other mathematical models; at the same time, to conceptualize the reservoir studied, divide the reservoir into several functional areas, and use the one-dimensional section-beginning calculation model to calculate all cross-sections of each functional area; then, to superimpose the environmental capacity of each functional section to get the aquatic environment capacity of the entire two-dimensional space; and finally, to introduce how to make use of the conceptual net to calculate the aquatic environment capacity in terms of the actual reservoir's situation.

Study on the Relationship between Chlorophyll-a and Environmental Impact Factors in Deep Reservoir in Karst Areas——Taking Aha Reservoir for Example

[Objective] The aim was to study the relationship between chlorophyll-a and environmental impact factors in deep reservoir in Karst Areas.[Method] Taking Aha Reservoir for example,the changes of chlorophyll-a content and its relationship with environmental impact factors were researched,and the water quality of Aha Reservoir was assessed by means of modified Carlson trophic state index.[Result] Chlorophyll-a content in Aha Reservoir was higher in March,April,May and September and lower from June to August,and there was obvious seasonal variation,namely its variation trend was spring>summer>autumn>winter.In addition,chlorophyll-a content showed extremely significant correlation with transparency and dissolved oxygen (P<0.01) and significant correlation with ammonia nitrogen (P<0.05).Meanwhile,trophic state index was higher in whole year in Aha Reservoir which was in moderate trophic state in August,October and November and eutrophic state in other months.[Conclusion] The study could provide scientific reference for discussing the mechanism of lake eutrophication.

Multi-Reservoir Optimization for Maximization of Releases for Hydropower Generation Considering Environmental Flow

Water is the soul of the world. It is the most important element for the survival of humans, animals, birds, plants and all other living things on earth. Water is essential for the beginning of life as well as regular availability of water ensuring the survival, growth and overall nourishment. Thus, proper planning and use of reservoir water are essential for all. To tackle this issue different optimization techniques underline their need and importance in the reservoir operations. In the present study, multi-reservoir optimization model is developed using Python programing language considering the objective of maximization of total annual release for hydropower generation. Model is applied to 3 reservoirs from Godavari River basin from Maharashtra state India. Water essential for conservation of environment has also been made available in river as environmental flow as per the recommendations of Central Water Commission (CWC) India. Developed optimization model provides optimal monthly operation policies.

Sustainable Multi-Objective Multi-Reservoir Optimization Considering Environmental Flow

Increasing demand for water from all sectors presents a challenge for policy makers to improve water allocation policies for storage reservoirs. In addition, there are many other organisms and species present in river waters that also require water for their survival. Due to the lack of awareness many times the minimum required quantity and quality of water for river ecosystem is not made available at downstream of storage reservoirs. So, a sustainable approach is required in reservoir operations to maintain the river ecosystem with environmental flow while meeting the other demands. Multi-objective, multi-reservoir operation model developed with Python programming using Fuzzy Linear Programing method incorporating environmental flow requirement of river is presented in this paper. Objective of maximization of irrigation release is considered for first run. In second run maximization of releases for hydropower generation is considered as objective. Further both objectives are fuzzified by incorporating linear membership function and solved to maximize fuzzified objective function simultaneously by maximizing satisfaction level indicator (λ). The optimal reservoir operation policy is presented considering constraints including Irrigation release, Turbine release, Reservoir storage, Environmental flow release and hydrologic continuity. Model applied for multi-reservoir system consists of four reservoirs, i.e., Jayakwadi Stage-I Reservoir (R1), Jayakwadi Stage-II Reservoir (R2), Yeldari Reservoir (R3), Siddheshwar Reservoir (R4) in Godavari River sub-basin from Marathwada region of Maharashtra State, India.

Multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory-based environmental risk evaluation for tailings reservoirs

Environmental risk assessment of tailings reservoir assessment system is complex and has many index factors.In order to accurately judge surrounding environmental risks of tailings reservoirs and determinate the corresponding prevention and control work,multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory are implemented to evaluate them and find out the rules of this evaluation system with 14 representative cases.The methods of multi-hierarchical fuzzy evaluation can overall consider each influence factor of risk assessment system and their mutual impact,and the index weight based on the analytic hierarchy process is relatively reasonable.Rough set theory based on dominance relation reduces each index attribute from the top down,largely simplifies the complexity of the original evaluation system,and considers the preferential information in each index.Furthermore,grey correlation theory is applied to analysis of importance of each reducted condition attribute.The results demonstrate the feasibility of the proposed safety evaluation system and the application potential.

Influence of Reservoir on Groundwater Environment in the Ecologically Fragile Area, Northwest of China

As the research proposed reservoirs after impact on the surrounding ecological fragile areas of groundwater level and scope, through the proposed reservoir area and its surrounding data collecting, hydrogeology survey and related test, for Modflow system simulation platform, through to the boundary conditions, initial conditions and source sink term and related hydrogeological parameters, the model identification and verification, The model of hydrogeological parameters in the study area is constructed. The simulation results show that the groundwater depth near the reservoir area will be higher than the critical value (1.8 m) of secondary salinization of soil. At the same time, according to the investigation and experiment, if the reservoir does not do seepage treatment, the water infiltration in the reservoir will aggravate the environmental hydrogeological problems in the ecologically fragile area.

Reservoir operation schemes for water pollution accidents in Yangtze River

After the Three Gorges Reservoir starts running, it can not only take into consideration the interest of departments such as flood control, power generation, water supply, and shipping, but also reduce or eliminate the adverse effects of pollutants by discharge regulation. The evolution of pollutant plumes under different operation schemes of the Three Gorges Reservoir and three kinds of pollutant discharge types were calculated with the MIKE 21 AD software. The feasibility and effectiveness of the reservoir emergency operation when pollution accidents occur were investigated. The results indicate that the emergency operation produces significant effects on the instantaneous discharge type with lesser effects on the constant discharge type, the impact time is shortened, and the concentration of pollutant is reduced. Meanwhile, the results show that the larger the discharge is and the shorter the operation duration is, the more favorable the result is.

Diurnal variations of pCO_2 in relation to environ-mental factors in the cascade reservoirs along the Wujiang River, China

We have investigated the diurnal variations of the pCO2 and related environmental factors in the cascade reservoirs with different trophic levels along Wujiang River. In surface water the pCO2 was 357±11 μatm in Hong-jiadu Reservoir, 338±48 μatm in Dongfeng Reservoir, 682±303 μatm in Wujiangdu Reservoir, and 1677±429 μatm in Liuguang, respectively. The results indicated that these cascade reservoirs had much lower pCO2 values in surface water than river did, and hypereutrophic reservoir showed larger diurnal variations of pCO2 than meso-eutrophic reservoir. In water column, pCO2 tended to increase with the depth. Phytoplankton and the environmental factors such as temperature and pH had different influences on pCO2 diurnal variations due to different trophic levels, and the effect of phytoplankton on pCO2 variation increased with the increase of trophic level in these reservoirs.

Ecological operation for Three Gorges Reservoir

The traditional operation of the Three Gorges Reservoir has mainly focused on water for flood control, power generation, navigation, water supply, and recreation, and given less attention to the negative impacts of reservoir operation on the river ecosystem. In order to reduce the negative influence of reservoir operation, ecological operation of the reservoir should be studied with a focus on maintaining a healthy river ecosystem. This study considered ecological operation targets, including maintaining the river environmental flow and protecting the spawning and reproduction of the Chinese sturgeon and four major Chinese carps. Using flow data from 1900 to 2006 at the Yichang gauging station as the control station data for the Yangtze River, the minimal and optimal river environmental flows were analyzed, and eco-hydrological targets for the Chinese sturgeon and four major Chinese carps in the Yangtze River were calculated. This paper proposes a reservoir ecological operation model, which comprehensively considers flood control, power generation, navigation, and the ecological environment. Three typical periods, wet, normal, and dry years, were selected, and the particle swarm optimization algorithm was used to analyze the model. The results show that ecological operation modes have different effects on the economic benefit of the hydropower station, and the reservoir ecological operation model can simulate the flood pulse for the requirements of spawning of the Chinese sturgeon and four major Chinese carps. According to the results, by adopting a suitable re-operation scheme, the hydropower benefit of the reservoir will not decrease dramatically while the ecological demand is met. The results provide a reference for designing reasonable operation schemes for the Three Gorges Reservoir.

Sedimentary Characteristics and Response to Climate Change and Human Activities in Shilianghe Reservoir,Jiangsu Province

Reservoirs,as artificial lakes,suffer from silting inevitably since being constructed,the sediments from surrounding environment can provide a continuous record of environmental change.Shilianghe Reservoir,the largest artificial lake in Jiangsu Province,was constructed in 1959,and plays an important role in flood control,irrigation,water supply,and so on.Nevertheless,the silting situation of the reservoir is also quite serious.In this paper,the grain-size distribution of core from Shilianghe Reservoir and its response to environmental changes were studied.It is due to two driving factors:climate variability and human activities.Based on the analysis of the grain size distribution data,the sediments were mainly composed of clayey silt and silty clay with a clear tendency of upward fining.But a grain-size peak appeared at 86 cm,and the sand proportion was also very big,indicating that hydrodynamic force was stronger.There was a consistent trend of change between sediment record in Shilianghe Reservoir and historical precipitation in the basin.According to the dating mark of137 Cs,it can be determined primarily that the abnormal grain-size at 86 cm reflected possibly the rainstorm and flood event occurring in 1970.Human activities reduced the hydrodynamics of depositional environment.Hydraulic projects are direct human activities,and land use/cover changes are indirect human activities.It turned out that sediment yield and sediment load were more and more less,and sedimentation rate showed a decreasing trend.Furthermore,sediments tended to become smaller and had better sorting property.

尾矿的特性、灾害及其资源潜力

尾矿是矿石磨细选别后残余的固体废弃物,尾矿物理化学特性及尾矿库的常规地表堆存共同导致尾矿库存在较大的安全与环境风险。低品位矿体高强度开采趋势下,我国尾矿年排放量维持在10亿t以上的高位,累计堆存规模超200亿t,细粒尾矿堆存方式、潜在灾害防治及综合利用面临新挑战,采选新技术装备及政策利好因素推动尾矿资源潜力亟待释放。因此,以尾矿物理化学特性、排放堆存方法、溃坝灾害、尾矿资源潜力为主线,综述了尾矿物理化学特性、尾矿堆存形式、尾矿溃坝灾害防治等方面的研究进展,系统梳理了尾矿空区充填、尾矿制备材料、尾矿二次利用、超积累植物提取金属元素、尾矿固碳等资源综合利用方法,可为研究者及工业界系统全面地重新审视尾矿废弃物特性、尾矿库灾害防治、矿产可持续开发利用提供启示。

基于不同评价方法的小浪底水库水质分析及来源解析

水质评价是水生态系统保护和水污染治理的重要基础。为探究小浪底水库不同水期水质特征,于2021年对3个断面的15个水质指标进行监测与分析。采用三种方法对研究区水环境质量进行评价,厘清水质变化规律,确定最佳的评价方法,探讨不同水期影响水质的关键环境因子并解析其来源。研究表明:库区水质总氮浓度超出地表水Ⅴ类标准,其他水质指标均达到Ⅲ类标准及以上;三种方法受指标权重影响,评价结果存在差异,综合比较与分析,确定基于TOPSIS的信息加权和排序法更适用于评价研究区水质状况;相关性分析表明,不同水期影响水质的环境因子及其来源不同,枯水期受人类活动影响,平水期水质变化与上游输入有关,丰水期受降水和水动力条件影响显著。研究结果可为小浪底水库的水环境治理提供科学依据,为库区水质评价提供新的思路。

耦合水文情势及鱼类繁殖的江垭水库生态调度需求研究

为了修复河流水文情势、维持河流生态系统健康,通过环境DNA采样、IHA水文指标变动分析和文献资料总结等方法,开展了江垭水库坝下水文情势及鱼类繁殖需求关系研究,提出了水库生态调度需求与建议。结果显示,2021年9月在溇水干支流综合调查获得鱼类55种,与20世纪90年代相比,流水性种类在干流江段显著减少了51.35%;按照生态调度优先等级评估原则,确定江垭水库生态调度的主要目标物种为产漂流性卵的银鲴(Xenocypris argentea)、银鮈(Squalidus argentatus)、贝氏䱗(Hemiculter bleekeri)和产粘沉性卵的鲤(Cyprinus carpio)、鲫(Carassius auratus);江垭建坝前后下游水文情势变化较大,发生高度改变且对鱼类洄游产卵及鱼卵发育有重要作用的水文指标包括年最大1日、3日平均流量指标、年出现高流量脉冲事件的次数和持续时间以及连续日流量上涨率。研究表明,以促进坝下不同产卵类型的鱼类繁殖为目标,生态调度需要一定的高流量脉冲次数和历时,还需要控制下游水位的日降幅,通过泄放合理的生态流量来维持下游鱼类的生物多样性。

铜山源水库春夏季浮游植物群落特征及其与环境因子的关系

铜山源水库是位于浙江省衢州市的1座调蓄性水库,在农业灌溉和水利发电方面具有重要作用。为了解铜山源水库浮游植物群落特征及其与水环境因子之间的关系,于2021年3、5和7月对铜山源水库水体进行采样调查。结果表明,共检出浮游植物92种,隶属于7门57属。铜山源水库浮游植物主要优势种为硅藻门的小环藻、绿藻门的空球藻和网状空星藻以及蓝藻门的微囊藻和水华束丝藻。主坐标分析结果表明,3次调查的浮游植物群落结构具有显著差异,由硅藻/绿藻型变为蓝藻型,再变为绿藻/蓝藻型。Shannon-Wiener多样性指数(H′)表明,水库处于中污染状态。浮游植物的细胞密度和生物量在5月有所下降,但在7月又回升。典范对应分析结果显示,水温、总氮和总磷是影响铜山源水体浮游植物群落结构的主要环境因子。浮游动物的下行效应在5月更强,但浮游动物的密度和生物量对浮游植物群落结构改变无显著影响。研究结果为进一步了解铜山源水库生态特征并开展生态环境保护工作提供重要基础数据。

Evaluation of Volatile Organic Compounds and Polyaromatic Hydrocarbons in Barker Reservoir in Houston, Texas after the 2017 Hurricane Harvey

Analysis of volatile organic compounds (VOCs) and polyaromatic hydrocarbons (PAHs) in the Barker Reservoir in Houston, Texas, United States is reported. Samples were collected within one week after the August 2017 Hurricane Harvey. Using a gas chromatograph equipped with a mass spectrometer, 4 VOCs and 13 PAHs were found in the Barker Reservoir. Concentrations of acetone, benzene, chloroform, and toluene were 1500, 380, 830, and 290 parts per million (ppm), respectively. Benzene and chloroform are classified as probable human carcinogens by the U.S. Environmental Protection Agency (EPA). Six PAHs including benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, and dibenz[a,h]anthracene are probable human carcinogens. The most concentrated PAH was acenaphthylene at 0.068 ppm, while the least one was fluoranthene at 0.00046 ppm. Results revealed water contaminants in Houston and its vicinities during the flooding season and served as references for water monitoring purposes in the future.

陆水水库浮游植物群落结构特征及其影响因素

探究陆水水库浮游植物群落组成及环境因子的时空特征,对水库生态系统的管理与保护具有重要意义。2020年7月(雨季)和12月(旱季),对陆水水库10个采样点的浮游植物和水质理化因子进行了调查分析。结果表明,2次调查共采集到浮游植物6门59属63种,其中绿藻种类最多,有31种,硅藻、蓝藻次之,分别为13种、12种;优势种主要为蓝藻门的尖头藻(Raphidiopsis sp.)、水华束丝藻(Aphanizomenon flos-aquae)、长孢藻(Dolicho-spermum sp.)以及硅藻门的颗粒直链藻(Melosira granulata);细胞密度的变化范围为0.03×10^(7)~6.27×10^(7)个/L,平均值为2.08×10^(7)个/L;雨季和旱季浮游植物多样性指数差异不显著(P>0.05);变差分解和冗余分析结果显示,陆水水库浮游植物群落结构在雨季和旱季存在显著差异,该差异主要受营养盐、水温(WT)、pH的影响;环境过滤作用在驱动陆水水库浮游植物群落构建过程中占主导地位;优势物种丰度与环境因子的冗余分析显示浮游植物优势类群与WT、总氮TN、高锰酸盐指数CODMn具有显著的相关性。

油气储层用化学封堵材料性能室内评价方法发展方向

目前油气井储层封堵材料室内评价多以承压能力和储层保护能力为主,并以其作为入井依据。但随着技术进步和社会发展,只满足作业需求的某一项或几项指标,无法投入现场试用或应用,导致需要重复检测、评价,造成投入应用时间长,成功率低。从1000余篇国内外油气井安全性、储层保护和环境保护等相关主题词的文献中,发现封得住、稳得起、流得出、过得关和用得起等5项投入应用的性能指标需要检测,并以此为依据将检测方法分为5类。引入大数据思想分析应用成功率与测试指标数量的关系、投入应用时间与测试指标数量的关系发现,评价5类指标比评价单一指标的材料应用成功率最多高62%。5类评价方法项全部完成增加室内工作时间但投入应用的时间最多可节约77%。结果表明,封堵材料应用前评价5类指标,解决了封堵材料投入应用的时间长、效率低难题,不仅为储层封堵材料投入现场应用提供评价指标和检测方法,还为其他井筒作业材料提供了可借鉴的评价手段。

A Study of Solid-Free Drilling Fluid for Tight Gas Reservoirs

This project is explaining a laboratory development of a solid free drilling fluid formula that could be potentially used in tight gas reservoirs. The configuration of the weak gel fluid WGL-1, which is resistant to high temperature and high salt, was tested, and concluded that its gelling properties, salt and temperature resistance, and environmental protection were all in line with industry requirements. The final drilling fluid formula was developed as: water + (0.3% ~ 0.5%) NaOH + 5% KCl + 2% WGL-1 + 5% NaCl + (1.0% ~ 2.0%) HBFR Anti-high temperature fluid loss agent + 2% Polyol + (1.5% ~ 2.0%) SDL-1 Lubricant + 0.4% A4O1. The performance of the liquid was tested for temperature resistance, inhibition, gas formation protection effect, plugging performance, and static settlement stability. It was concluded that the temperature resistance performance is satisfied at 150°C, and the cuttings recovery rate is as high as 96.78%. It has good performance in inhibiting water dispersion and swelling of cuttings. The permeability recovery value reaches 88.9%, which meets the requirements of gas formation protection. The SSSI value shows that its settlement stability is good;under high temperature and high pressure, its sealing performance is good. This drilling fluid system has achieved the expected results and laid a foundation for further promoting the development of solid-free drilling fluid systems. The future development direction of solid-free drilling fluids is pointed out, to the improvement of properties to be applied in high temperature environment and have high salt resistance capacity.

新疆上游水库浮游植物群落结构与环境因子关系

本研究旨在掌握新疆上游水库浮游植物分布特征,了解库区生态情况,于2021年8月13日(丰水期)和2022年5月3日(枯水期)进行浮游植物采集,并通过冗余分析法(RDA),分析其群落结构与环境因子之间关系。结果显示:上游水库5个典型水域断面共鉴定出浮游植物6门29属40种,在门水平,两个水期中硅藻门均为主要优势种群,占总类的40.00%;其次为绿藻门和蓝藻门,占总类的27.50%、20.00%;裸藻门、金藻门和隐藻门种类较少;种水平上,优势种为梅尼小环藻、桥弯藻和谷皮菱形藻。两个水期浮游植物群落结构差异较大(P<0.05),枯水期浮游植物种类数量及生物量皆高于丰水期。通过浮游植物生物量及密度分析评价,上游水库水体呈贫营养状态。浮游生物Shannon-Wiener多样性指数为2.83,Margalef物种丰富度指数为2.97,Pielou均匀度指数为0.56。RDA结果表明电导率(EC)、水温(WT)及溶解氧(DO)是影响上游水库浮游植物群落变化的主要环境因子。本研究为新疆上游水库的可持续发展和丰富其生态多样性奠定了一定基础。