Establishing minimum water level for Plastiras reservoir (Greece) combining water quality modelling with landscape aesthetics

A water quality model (MERES) is applied in the multi-purpose reservoir of Plastiras in Greece. The model was calibrated with limited field data using the standard trial and error procedure; next, it was applied for four scenarios of reservoir operation, which correspond to four values of minimum water levels (MWL). Model results were combined with landscape aesthetics to establish a “safe” MWL in the reservoir. MWL was proposed to be +784 m, a value that ensures a very good water quality by retaining the reservoir in the status of “a little beyond oligotrophic” and a very good quality of landscape with an acceptable area of dead zones; it also ensures an annual release of 127.5 hm³ of water within a reliability level of 90%. This quantity can be considered as acceptable from the water supply point of view.     

尔王庄水库水质污染特征和主要问题分析

对引滦输水调剂水库尔王庄水库的水生生态环境和富营养化情况进行了分析，剖析了水质影响因素。为改善尔王庄水库水质提供了有利技术依据。     

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.     

Using Mussel Isotope Ratios to Assess Anthropogenic Nitrogen Inputs to Freshwater Ecosystems

Stable nitrogen isotope ratios (¹⁵N) of freshwater mussels from a series of lakes and ponds wererelated to watershed land use characteristics to assess their utility in determining the source ofnitrogen inputs to inland water bodies. Nitrogen isotope ratiosmeasured in freshwater musselsfrom 19 lakes and ponds in Rhode Island, U.S.A., ranged from4.9–12.6 and were found tosignificantly correlate with the fraction of residential development in 100 and 200 m bufferzones around the ponds. Mussel ¹⁵N values in 12 of the 19 ponds also showed significantcorrelation with average dissolved nitrate concentrations, which ranged from 23–327 g L^-1.These observations, in light of previous studies which link elevated¹⁵N values of nitrogenderived from septic wastewater with those seen in biota, suggest that mussel isotope ratios mayreflect nitrogen source in freshwater ecosystems. We followed aniterative approach usingmultiple regression analysis to assess the relationship between mussel¹⁵N and the land usecategories fraction residential development, fraction feedlotagriculture, fraction row-cropagriculture, and fraction natural vegetation in 100 and 200 m bufferzones and pond watersheds.From this we developed a simple regression model to predict mussel¹⁵N from the fraction ofresidential development in the 200 m buffer zone around the pond.Subsequent testing with datafrom 16 additional sites in the same ecoregion led us to refine themodel by incorporating thefraction of natural vegetation. The overall average absolute differencebetween measured andpredicted ¹⁵N values using the two-parameter model was 1.6. Potential sources of error inthe model include differences in the scale and categorization ofland-use data used to generate andtest the model, differences in physical characteristics, such asretention time and range ofresidential development, and exclusion of sources of enrichednitrogen such as runoff from feedlot operations or increased nitrogen loading from inefficient or failed septic systems.     

辽宁省水库富营养化限制因子及风险研究

中国东北部典型水库群的富营养化风险管理是饮用水安全的重要保障。选择辽宁省15个主要水库作为研究案例,以近十年的水质数据为评价基础,采用统计学分析方法,针对春、夏、秋3个季节建立富营养化指标的回归模型,识别不同季节富营养化产生的主要限制因子。采用概率分布曲线法对各水库发生中营养化和轻度富营养化的风险进行评估,并对15座水库的风险进行排序。结果表明:水库富营养化在不同季节的环境限制因子各有不同,水库中营养化和轻度富营养化的风险特征也有显著差异。     

改性松木锯末吸附富营养化水体中磷的研究

采用改性松木锯末作为吸附剂,对富营养化水体的模拟水样中的磷进行吸附去除研究。实验结果表明,改性松木锯末对磷的吸附作用主要发生在15 min内,吸附时间超过15 min吸附量趋于平衡状态;p H值由4.0上升到6.0,改性松木锯末对磷的去除率增长较快,由6.0上升到9.0,去除率基本处于稳定状态;磷浓度在0.5~5 mg/L的低浓度范围内,改性松木锯末对磷的去除率均可达到95%以上;改性松木锯末的最佳投加量为0.4 g/L。用Freundlich吸附等温线方程能准确地描述改性松木锯末对磷吸附的特征,吸附等温线方程为q=5.11 C~(1/0.523)。     

鄱阳湖流域人为氮磷输入演变及湖泊水环境响应

人类活动导致的氮磷营养盐富集是我国湖泊富营养化问题形成的重要驱动力.鄱阳湖是我国最大的淡水湖泊,随着流域经济社会的迅速发展,湖体营养盐水平上升,降低了鄱阳湖及长江中下游地区的水环境质量.然而,人类对鄱阳湖流域氮磷输入的影响程度尚不明确,湖体氮磷浓度与流域人为氮磷输入的关系也缺乏定量研究.因此,本研究基于人为净氮输入模型(NANI)、人为净磷输入模型(NAPI)和多元统计回归模型,评估了鄱阳湖流域1949—2013年人类活动导致的氮磷输入量,构建了人为氮磷输入与湖泊氮磷浓度的响应模型.结果表明,研究期内鄱阳湖流域的人为净氮输入和人为净磷输入分别增长6倍和15倍,化肥施用是20世纪80年代以来的主要增长因子;鄱阳湖氮磷浓度与流域人为氮磷输入显著相关,根据多元回归模型的可决系数,NANI可解释88%的湖体TN浓度变化,NAPI和湖泊平均水位可解释64%的TP浓度变化.提高氮磷的循环利用率同时维持湖泊生态水位对于降低鄱阳湖富营养化水平具有重要意义.     

Exponential Collapse of Benthic Depurative Capacity in A Eutrophic Tropical Marine Ecosystem: A Threshold Response to Organic Nitrogen Loading

Microbial decomposition of particulate organic matter in sediments can substantially modulate eutrophication of nearshore marine environments. Flux budgets for nitrogen compounds and quantification of rates of microbial transformation can provide important information on the process of eutrophication. This survey documents sediment nitrogen budgets for a eutrophic nearshore marine environment at La Parguera on southwest coast of Puerto Rico, including consideration of the organic fraction in addition to microbial transformations.

Sediments of the inshore channel at La Parguera denote the input of heavy organic loads with low redox potentials and high ammonium contents. Benthic fluxes of dissolved organic nitrogen are below those recorded for ammonium. These observations suggest that nearshore tropical sediments subject to heavy nitrogen loads act as a sink for organic nitrogen and that ammonification is a key process in the release of nitrogen from sediments to the water column. Nitrification and denitrification rates are low overall and inversely related to the redox potential. Depuration of excess nitrogen through denitrification is ineffective in these sediments. in contrast to more robust temperate environments, our work demonstrates that tropical marine systems are particularly susceptible to eutrophication given their limited capacity for depuration of excess nitrogen.     

人类活动在武汉东湖沉积物中的记录

研究了武汉东湖Ⅰ站90cm和Ⅱ站150cm沉积物柱芯TOC、TN、TP和硅藻的垂向分布,探讨了在东湖的发展演化中尤其是富营养化的过程中人类活动的影响.在350aBP(清朝康熙雍正年间)和20世纪60年代,由于人口增长、农业耕作发展和湖泊富营养化使区域内TOC、TN等营养物质向湖内大量输入.东湖I站沉积物中TP在0～5cm的高值区主要与建国以来东湖周围的人类活动作用加强有关,是湖泊营养程度逐步提高的结果.随着湖泊富营养化的加剧,湖泊藻类大量繁衍,沉积物中保存的硅藻也相应大量增加.     

5种水生植物去污抗逆能力的试验研究

在实验室人工模拟太湖地区初春较寒冷的气象条件下,对5种能越冬的水生植物(伊乐藻、微齿眼子菜、竹叶眼子菜、石菖蒲和水芹菜)在不同营养条件下去除氮磷的效果和一些反映其抗逆能力的生理生化指标进行了系统的对比研究.结果表明:这5种植物均能较好地吸收水中的营养物质,其中以水芹菜和微齿眼子菜的脱氮除磷效果最好;5种植物体内脯氨酸含量均与水体营养物质的质量浓度呈正相关,相同试验条件下,水芹菜和微齿眼子菜体内脯氨酸的积累倍数最高,表明二者的抗逆能力也较强;但当水体营养物质的质量浓度超过一定限值后,5种植物的生物量增长率均随水体营养等级的增高而下降.水芹菜和微齿眼子菜可作为构成双层次群落结构(FAMS)的优选植物种类,用于修复太湖地区富营养化水体.