Study of water quality distribution in Lake Biwa in consideration of runoff pollutant loads from its catchment basin.

Many strategies for water quality conservation in Lake Biwa are being carried out mainly by reducing runoff pollutant loads into the lake. But influence of the runoff load reduction on the water quality in Lake Biwa has not been clarified enough so far. This study is aimed at discussing methodology to estimate water quality distribution in Lake Biwa using runoff pollutant loads from its basin. The runoff loads from the basin are calculated by Macro Model with GIS database of the Lake Biwa basin, and the water quality distribution in the lake is estimated by the spline technique with the calculated runoff loads. As a result, it has been proved that the methodology has enough reproducibility to estimate the water quality distribution in Lake Biwa and is available to examine the water quality in the lake.     

The characteristics and measuring technique of refractory dissolved organic substances in urban runoff.

It is considered that refractory dissolved organic substances have caused an increase in the COD concentration in Lake Biwa in recent years. We investigated the organic matter in the first flush of stormwater runoff from a road in the watershed area of the lake, and studied the possibility of improvement in the water environment from that aspect. After percolating the stormwater through soil, we analyzed organic substances fractionated by using GPC-TC. And we examined the effect of removal of organic substances by comparing the peak height before and after percolation. In the result of the experiments, we found that soil infiltration reduced the refractory dissolved organic substance and we successfully designed a system for a simple and easy experimental facility to treat urban runoff.     

千岛湖现状污染负荷分析与限制排污总量研究

根据千岛湖水质现状和水功能区划,确定2015年和2020年千岛湖水质保护目标的污染物浓度,核算现状污染负荷量。将现状CODMn、NH3-N和TP污染负荷量作为千岛湖CODMn、NH3-N和TP的纳污能力,即千岛湖湖区CODMn、NH3-N和TP指标纳污能力分别为16420 t/a、2225 t/a和434 t/a。采用狄龙模型核算千岛湖TN指标的纳污能力,2015年千岛湖TN质量浓度目标值为0.88 mg/L,对应湖区限排总量为3468 t/a;2020年将千岛湖TN质量浓度目标值进一步提高至0.8 mg/L,此时对应湖区TN限排总量为3176 t/a。     

浅水湖泊水质系统滤波模型

本文建立了浅水湖泊水质系统滤波模型和相应算法。根据滇池流场比较稳定等特点。对湖泊进行单元分区，考虑模型误差扰动和观测误差扰动的存在，建立系统的状态方程和观测方程，用吉尔（ＧＩＬＬ）算法求解微分方程，进行系统多点连续模拟和实时预报，用此法对滇池１９８８年的ＢＯＤ、ＣＯＤ时空变化进行连续预报，取得满意效果。     

南四湖水质空间分布特征分析与改善效果评估

根据南四湖2006年、2007年、2010年和2011年4次90个采样点的水质空间分布监测数据,采用Surfer 8.0软件绘制南四湖水质空间分布等值线图,进行南四湖及分湖区水质指标的综合比较分析和平均综合污染指数的计算与污染控制效果评估。结果表明:南四湖COD、NH3-N、TP、TN和CODMn等指标的空间分布具有北高南低的非均一性特点;2010—2011年比2006—2007年枯水期各水质指标的平均浓度下降率为38.3%,整体提高了1～2个水质类别;按GB 3838—2002《地表水环境质量标准》中Ⅲ类标准相应的平均综合污染指数进行评价,达标和基本达标湖区的比例达到63.3%;2010—2011年枯水期南四湖主要污染物分担率由大到小排序依次为TP、COD、TN、CODMn、NH3-N;水质平均综合污染指数与电导率存在很好的相关性和北高南低的污染特点,说明南四湖水污染物仍然以外源排放为主。     

内外源共同作用对太湖营养盐贡献量研究

本文根据环太湖25条主要入湖河流的监测结果对入湖水量及污染物输入量进行分析,计算了不同季节外源对太湖营养物质的贡献量。分别于春、夏、秋、冬4个季节对太湖梅梁湾水体开展5次野外试验,利用沉积物捕获器收集沉积物,采用Gansith公式法计算沉积物的再悬浮通量,并建立其与风速的关系;对代表不同风浪作用下的太湖悬浮物进行7次静沉降试验,计算悬浮物的静沉降通量,并建立其与风速关系。以3.7m/s为界对底泥悬浮沉降过程进行分解和概化,并利用近10年的风速资料估算太湖年均内源释放量。计算结果表明,全年外源负荷和内源释放对太湖营养盐的贡献总量COD为24.23万t、总氮为3.80万t、总磷为2 045.20t,其中内源所占比例分别为20.47%,20.44%和13.47%外源、内源对太湖的贡献量在不同季节有较大差异,夏季贡献量最大,春季次之。风浪作用下的COD、TN释放量只相当于外源输入量的25.7%,而TP释放量仅相当于外源输入量的15.6%。外源输入量对营养盐的贡献占据相当高的比重,太湖河道入湖污染负荷的增加是太湖水质恶化的根本原因。     

盐湖流域空-天-地立体监测系统结合VIC模型径流模拟初探

盐湖流域属于无资料地区且基础资料稀缺,使用传统方法开展水文模拟存在困难。为了研究盐湖流域生态环境、水文气象等变化,综合利用卫星遥感、无人船等技术,建立盐湖流域空-天-地立体监测系统,构建盐湖水位-面积-容积关系曲线,并通过月尺度遥感数据解译了盐湖月尺度湖泊面积,推算了盐湖蓄变量和盐湖入湖月尺度径流量。通过收集并整理中国区域地面气象要素驱动数据集CMFD和MODIS LAI叶面积指数等数据,构建了基于多源数据的VIC模型,开展盐湖流域湖泊径流模拟研究。结果表明,盐湖流域径流模拟纳什系数NSE和相对误差分别为0.87和11.81%,表现出实际径流的丰枯变化情况。盐湖流域空-天-地立体监测系统结合VIC模型能够模拟盐湖流域的月尺度径流变化过程,对无资料区域河湖水文模拟具有一定参考意义。     

鄱阳湖水质参数时空分布规律探讨

根据１９８１～１９９０年水质监测资料，全面系统地分析了鄱阳湖主要水质参数在地区大的分布、年内变化及部分水质参数的年际变化．结果表明：鄱阳湖主要水质参数在地区上的差异，年内变化及年际变化均较大，１９８６年以后ＣＯＤ在局部区域的含量有逐年上升趋势．     

Drainage basin security of hazardous chemical fluxe in the Yodo River basin.

The Yodo River basin consists of three major tributary basins (and other small river basins) namely Uji, Katsura and Kizu, which overlap respectively Shiga, Kvoto and Nara prefectures' administrative areas. Lake Biwa, the largest lake in Japan, drains water through the Uji river. The water quality of the lake, in terms of BOD, continuously improved over the last decade. However, the quality in terms of COD did not show any improvement in spite of a large amount of infrastructure finance being introduced. Eutrophication of the lake still continues, showing no improvement in the nitrogen concentration level. Non-point as well as point source control is not strong enough. There is a gap between BOD and COD evaluations of the lake water quality. Hazardous chemical fluxes are estimated based upon PRTR reports of Japan (2001). PCBs are still discharged into the lake, although the report of Shiga Prefecture showed zero discharge. Dace fish monitoring clearly showed that PCB contamination of the fish had not changed since the 1980s in spite of a ban on use and production of PCBs in the 1970s. There is still leakage of PCBs into the lake. The major exposure of dioxins to Japanese is fish rather than meat and eggs. The risk of water contamination must take into consideration not only drinking water safety but also ecological magnification of food chains in water. The ecological health aspect of hazardous chemicals is also important, such as organotins with imposex of sea snails. Finally, public participation in hazardous chemical management is very important using the method of risk communication based upon the annual report of PRTR in Japan.     

The use of a mass balance phosphorus budget for informing nutrient management in shallow coastal lakes

Eutrophication has degraded ecosystem, cultural and recreational values in Lake Forsyth, a small, shallow, coastal lake in New Zealand. To inform catchment management decisions designed to prevent algal blooms and improve water quality, a sub-catchment scale, mass-balance approach to understanding the behaviour of the critical nutrient, phosphorous (P), has been taken. To determine a P budget for the lake, and identify key P reservoirs, hydrological inflows and outflows were measured over a 15 month period. These were combined with total (TP) and dissolved reactive P (DRP) concentrations in these flows, to determine the external load of P transported to the lake. Lake water was also analysed for TP and DRP concentrations, and chemical extractions were used to determine the mass and mobility of P in the lake sediments. Biomass surveys and chemical digestions were used to quantify the mass of P contained in lake macrophytes. Changes in the lake water P reservoirs were then used to assess the contribution of external P loading relative to fluxes of P from the sediment to the lake water column (internal P loading). More than 7000 kg P per year was delivered to the lake, 68% of which came from a single sub-catchment. P associated with suspended particulate material accounted for 80% of the external P load transported into the lake and 61% of the load delivered over the study period was transported during a single flood event. A reduction of 53% in the external P load is necessary to achieve a recommended areal loading guideline. As the lake has no permanent outflow, this external load and the low flushing rates have created a large legacy reservoir of P in the lake sediments with 70% of external P loads retained in the lake. It is the release of P from these lake sediments rather than fluctuations in external loading that control P concentrations in the lake water column during the blooms of nitrogen-fixing cyanobacteria. The results indicate the importance of targeting both external and internal loading processes in the catchment. The sub-catchment scale, mass-balance approach to determining a P budget and quantifying P reservoirs enable critical source areas for external P loads to be identified, and the potential efficacy of targeted interventions to reduce P sources and minimise P transport, such as wetlands and sediment retention basins, to be assessed.     

改进综合水质指数法的乌伦古湖水质空间特征

湖泊水质状况是识别湖泊变化、评价湖泊健康的重要指标,关系流域生态环境安全。以典型干旱内陆湖泊———乌伦古湖为研究对象,采用改进综合水质指数法(WPASEQI)并结合GIS技术对乌伦古湖湖区(吉力湖、布伦托海)2017年水质状况及空间分布规律进行研究。结果表明:(1)乌伦古湖水质类别及状况为Ⅲ类、轻度污染,其中,吉力湖水质类别为Ⅱ类,布伦托海水质类别为Ⅲ类,水质空间分布特征表现出越靠近湖中心东部区域,以及越远离进水口区域水质污染越严重的基本规律;(2)乌伦古湖水质污染关键超标因子为COD、COD_(Mn)、TN、TP、氟化物,其空间分布特征表现为,COD、COD_(Mn)与氟化物指标浓度空间分布规律大致相似,呈现出吉力湖优于布伦托海、进水口优于湖心区的空间分布特征;TN、TP指标浓度变化差异较小,大体呈现出进水口优于湖心区、布伦托海西部优于东部的特征;(3)富营养物、有机物以及无机物是乌伦古湖水质主要污染来源,气候变化与人类活动是导致湖泊水质进一步恶化的驱动力。     

暴雨对梁子湖水动力和水质的影响研究

为了分析在暴雨条件下,流域面源污染对梁子湖水质的影响,采用分布式流域面源污染模型,结合湖泊二维水动力水质模型,以暴雨产生的面源径流和污染负荷作为水动力水质模型的边界条件,构建了包含暴雨径流-面源模型与二维水动力水质模型的梁子湖水质模型体系。采用梁子湖水质的实测资料对模型进行了验证,其结果为面源模型的误差在15%以内,水质模型误差在20%以内,表明模型能模拟暴雨条件下面源径流和入湖污染物输入时湖泊水动力及水质的动态响应关系。以2010年7月11日暴雨过程为例,利用所建模型对暴雨前后梁子湖水质变化进行分析。模拟结果表明,水质受暴雨及污染物的冲击影响较大。     

华阳河湖群水位变化对水质的影响

针对华阳河湖群水质变化的问题,基于典型站点水位和水质实测资料,同时运用Spearman法分析华阳河湖群水位在空间、时间变化上对水质指标的影响趋势以及水位、水质的相关性。结果表明:空间变化上,受长江来水水质影响,华阳河湖群总体呈现西部水质较差、东部水质较好的分布特征;年际变化上,在2015—2018年间,龙感湖、黄湖、泊湖、大官湖水质存在一定程度的波动,且2018年龙感湖、黄湖、泊湖水质较差;年内变化上,各湖泊污染物浓度指标总体表现出枯水期大于丰水期的特征;相关性上,华阳河湖群水位变化与TN、TP、COD浓度均呈负相关,其平均相关系数分别约为-0.43,-0.41,-0.09,但绝对值均＜0.5。研究结果可为今后华阳河流域的水环境综合治理提供参考。     

Management Options to Improve Water Quality in Lake Peipsi: Insights from Large Scale Models and Remote Sensing

Nutrient pollution causes frequent blooms of potentially harmful cyanobacteria in Lake Peipsi (Estonia/Russia). Although external nutrient loading has reduced since the 1990s, lake water quality has barely improved, and eutrophication is still considered a threat to lake biota and water usage. To understand the recovery dynamics of the lake it is necessary to analyse the effects of land use and lake management on water quality to develop mitigation strategies. Comprehensive analysis has thus far failed due to information gaps inherent to conventional monitoring strategies. We show how two large-scale hydrological models using Earth observation data provide spatial information on pollution and can help explain the causes of past and current lake eutrophication. WaterGAP3.2 provides valid estimates of present and probable future phosphorus concentration in the lake water, based on past hydrological conditions. WaterWorld models spatial potential water quality and a scenario of optimal pollution reduction. Remotely sensed optical water quality data can be used to analyse recent, spatial water quality dynamics. The spatial and temporal algae distributions and can help explain eutrophication causes at Lake Peipsi and its catchment, adding value to in situ monitoring and supporting river basin management with large scale data.

     

Burrowing mayfly (Ephemeroptera: Ephemeridae: Hexagenia spp.) bioturbation and bioirrigation: A source of internal phosphorus loading in Lake Erie

Traditional lake eutrophication models predict lower phosphorus concentrations with decreased external loads. However, in lakes where decreased external phosphorus loads are accompanied by increasing phosphorus concentrations, a seeming “trophic paradox” exists. Western Lake Erie is an example of such a paradox. Internal phosphorus loads may help explain this paradox. We examined bioturbation and bioirrigation created from burrowing mayfly, Hexagenia spp., as a possible source of internal phosphorus loading. Phosphorus concentrations of experimental microcosms containing lake sediments, filtered lake water, and nymphs (417/m²) collected from western Lake Erie were compared to control microcosms containing sediments and lake water over a 7-day period. Phosphorus concentrations in microcosms containing Hexagenia were significantly greater than microcosms without nymphs. Further, we estimate the soluble reactive phosphorus flux from the sediments due to Hexagenia is 1.03 mg/m²/day. Thus, Hexagenia are a source of internal phosphorus loading. High densities of Hexagenia nymphs in western Lake Erie may help explain the “trophic paradox.” Furthermore, Hexagenia may be a neglected source of internal phosphorus loading in any lake in which they are abundant. Future studies of phosphorus dynamics in lakes with Hexagenia must account for the ability of these organisms to increase lake internal phosphorus loading.     

镜泊湖水质及富营养化现状调查

为了解镜泊湖水质及富营养化情况,于2007年4~7月,每月取水样一次,分别监测透明度、COD、TN、TP等水质指标,依据地表水水域环境功能和保护目标,按功能高低依次划分为5类,进行水质分析。结果表明:湖水的透明度较低,COD偏高,pH值小于7,略显酸性,TN、TP较高,其中TN含量严重超标;镜泊湖水质类别属于Ⅴ类,水质较差,属严重富营养化。     

高原再生水湖泊的水体透明度及其影响因素

昆明市的翠湖是一个以再生水为主要水源的高原城市景观湖泊。利用2013年5月-10月四期(每期连续一周)的翠湖水质监测数据,对其水体透明度(SD)的时空分布,及其与水温(T)、pH、DO、Chla(叶绿素a)、TP、SS、CODCr、N/P、TN、NH4-N、DTP、DTN的相关性进行了分析,并以SD为因变量,以各水环境因子为自变量进行了多元线性回归分析。结果显示,水生植物少、水质较差的湖泊西区水域透明度(平均值33.6cm)相对低于水生植物较多、水质状态较好的东区(平均值61.5cm);翠湖水体透明度与T、pH、DO、Chla、TP、SS、CODCr显著负相关(p<0.01),而与N/P、TN呈极显著正相关(p<0.01),Chla是影响翠湖水体透明度的主要直接影响因素,CODCr、TP是影响藻类生长的主要水质因子。研究结果为以高原城市再生水湖泊翠湖水体透明度的改善及景观价值的提升提供了科学依据。     

五里湖水污染治理现状及继续治理对策

污染严重的五里湖通过控制外源、生态清淤、调水、生态修复、退渔还湖、水域封闭管理、建设生态护岸和滨水区等措施,水环境明显好转。西五里湖1 km2生态修复区的水质原来为劣Ⅴ类,大部分指标改善至Ⅲ~Ⅳ类。今后继续治理对策:全部削减入湖小河道污染负荷;调贡湖水入五里湖;禁止货运,清洁航行,控制航行污染;全面生态恢复;全封闭管理。2010年水质改善到Ⅳ类,达到功能区目标。     

镇江金山湖水体污染源解析

分析了2012年金山湖各监测段的水质情况,并对金山湖水体污染源进行解析。结果表明,运粮河入流水质较差,金山湖TN值超标;降雨地表径流是金山湖的第一大污染源,并且城镇地表径流所产生的污染物的负荷及浓度要远高于农田地表径流;由于截污工程的实施,工业生产废水与城镇生活污水对污染的贡献率较低。     

Nitrogen retention in a river system and the effects of river morphology and lakes.

The mean annual transfer (loss and retention) of nitrogen in a river system was estimated using a conceptual approach based on water surface area and runoff. Two different approaches for the calculation of water surface area were applied to determine riverine nitrogen retention in four European catchments, ranging between 860-14,000 km2 in area, and differing considerably in the proportion and distribution of surface waters, specific runoff and specific nutrient emissions. The transfer rate was estimated sequentially as either the mean value for the total catchment, on a sub-catchment scale, or considering the distribution of water surface area within a sub-catchment. For the latter measure, nitrogen retention in larger lakes was calculated separately. Nitrogen emissions modelled with MONERIS and HBV-N were used to calculate nitrogen river loads and compare those with observed loads. Inclusion of the proportion of water area within a sub-catchment improved modelled results in catchment with large lakes in sub-catchments, but not where there was a homogenous distribution of surface waters among sub-catchments.