Water quality, nutrient budget, and pollutant loads in Chinese mitten crab (Eriocheir sinensis) farms around East Taihu Lake

To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.

Analysis on the Pollution Load of Non-point Source Pollution and Surface Runoff of A Typical Village in Baiyangdian Lake Basin

[Objective] The characteristic of non-point source pollution of a typical village in Baiyangdian Lake basin was studied.[Method] The discharge of domestic sewage and solid wastes of the typical village was investigated,and both pollutant and nutrient element content were monitored,as well as the water quality and quantity of rainfall runoff.[Result] The non-point source pollution of livestock manure was far more serious than the sum of domestic sewage and domestic waste in this village,and the annual emission of total organic carbon(TOC),total nitrogen(TN) and total phosphorus(TP) was 37 794.0,4 102.9 and 1 923.7 kg,respectively.The event mean concentration(EMC)of chemical oxygen demand COD,TN and TP in rainfall runoff was 44.5,78.8,1.3 mg/L,respectively,and annual pollution load was 7.6,13.4 and 0.2 kg/hm2,respectively,while the annual pollution load of COD accounted for 5.1% of standard farmland,and that of TN and TP occupied 4.5% and 0.49% of slope farmland.[Conclusion] Livestock manure was the main source of non-point source pollution in the village and the annual pollution load of non-point source pollution was obtained.

Gross Pollutants Study in Urban Areas under Tropical Climates

Gross pollutants are the primary targeted pollutants in urban catchment management for urban water quality improvement as well as mitigation of flood. Apart from aesthetically unattractive because of its visibility, gross pollutants also contributes to degradation of river water quality and loss of aquatic habitat as it carries harmful pollutants such as oxygen demanding material, hydrocarbons and heavy metals. This study analyzed trend of gross pollutant generated from two urban residential areas located in Selangor, Malaysia. The median value of gross pollutant load obtained fi＇om the Amanah Apartment and Bandar Botanic are 347.41 kg/ha/year and 32.46 kg/ha/year, respectively. Relationship between gross pollutant wet load with rainfall depths was derived using regression equation. A significant trend of increasing gross pollutant wet load into drainage system with increasing rainfall depth was observed. The behavior of pollutant load is related to the one observed in Australia.

Drivers of Regional Environmental Pollution Load and Zoning Control:A Case Study of the Yangtze River Economic Belt,China

The high environmental pollution load caused by the massive pollutant emissions and the accumulation of endogenous and cross-regional pollution has become an important obstacle to the current ecological civilization construction in the Yangtze River Economic Belt(YREB)in China.Taking the YREB as an example,by using four environmental pollutant emission indicators,including chemical oxygen demand(COD),ammonia nitrogen(NH_(3)-N),sulfur dioxide(SO_(2)),and nitrogen oxides(NO_(x)),this paper established an environmental pollution load index(EPLI)based on the entropy-based measurement.Moreover,the Spatial Durbin Model was used to quantitatively analyze the drivers and spatial effects of environmental pollution load.Finally,specific scientific references were provided for formulating environmental regulations of pollution source control in the YREB.The results showed that:1)During2011-2015,the EPLI in the YREB was reduced significantly and the environmental pollution load increased from upstream to downstream.Among them,the pollution load levels in the Upper Mainstream subbasin,Taihu Lake subbasin,and Lower Mainstream subbasin were the most prominent.2)The environmental pollution load situation in the YREB was generally stable and partially improved.High load level areas were mainly concentrated in the Yangtze River Delta Region and the provincial borders in upstream,midstream,and downstream areas.The high load level areas already formed in Chengdu and Chongqing were also the key regulatory points in the future.3)The degree of local environmental pollution load was apparently affected by the adjacent cities.The population size,industrialization level,and the fiscal decentralization not only drove the increase of the local environmental pollution load level,but also affected the adjacent areas through the spatial spillover effects.The land development intensity mainly drove the increase in the local EPLI in the YREB.While factors such as economic development level and agricultural economic share could only act on the environmental pollution load process in adjacent cities.4)According to the differentiation characteristics of drivers of each city,the YREB was divided into seven zones based on k-medoids cluster method,and targeted zoning control policy recommendations for alleviating environmental pollution load in the YREB were proposed.

Nitrogen forms and pollution load of Dianchi Lake inflow river runoff in rainy season

With the control of point source pollution in Dianchi Lake basin, and the expansion of Kunming city, non-point source pollution has become the main source pollution of urban water environment and Dianchi Lake. To reveal the nitrogen pollution characteristics in watershed, this research selected key monitoring points and sections at Baoxiang river basin in rainy season which is the peak transported time of non-point source pollution, the nitrogen and hydrological indicators are monitored systematically. The different forms of nitrogen are analyzed, the pollution load of nitrogen are calculated and studied at cardinal sections; combined with the literature data, we compared the water nitrogen characteristics of Dianchi basin and Taihu basin, the main results are as follows:(1) In summer, water nitrogen form of Baoxiang river in the Caohe area is dominated by nitrate nitrogen, while in other areas it is dominated by ammonia nitrogen which is accounted for 31%-50% of total nitrogen;(2) The water pollution loads of Baoxiang river tended to increase from upstream to downstream, from June to August the total nitrogen pollution mainly comes from urban areas and the pollution load is 166.408 t;(3) In Dianchi Lake watershed and Taihu Lake watershed nitrogen concentration of inflow river is higher than that of the lake, nitrate nitrogen concentration between inflow river and lake shows a little difference, while ammonia nitrogen concentration of inflow river is higher than that of the lake. The results can provide the theoretical basis for nonpoint source pollution control and urban water environment planning and improvement in Dianchi Lake Basin.

Modified Weighting for Calculating the Average Concentration of Non-Point Source Pollutant

The concentration of runoff depends upon that of soil loss and the latter is assumed to be linear to the value of EI that equals the product of total storm energy E times the maximum 30-min intensity I 30 for a given rainstorm. Usually, the maximum accumulative amount of rain for a rainstorm might bring on the maximum amount of runoff, but it does not equal the maximum erosion and not always lead the maximum concentration. Thus, the average concentration weighted by amount of runoff is somewhat unreasonable. An improvement for the calculation method of non-point source pollution load put forward by professor Li Huaien is proposed. In replacement of the weight of runoff, EI value of a single rainstorm is introduced as a new weight. An example of Fujing River watershed shows that its application is effective.

Research on the Non-Point Pollution Loads in the Lake Uluabat Basin

Lake Uluabat, having an international significance and subject to the Ramsar Convention, is fed by the basin of Mustafakemalpasa Stream which runs through fertile lands utilized for livestock breeding and agriculture. In this study, total amount of nitrogen (TN) and phosphorus (TP) loads of non-point pollutants (agriculture, livestock breeding, vegetation, surface runoff and small settlements) was calculated. It was found out that most intensive pollution load stemmed from livestock breeding which causes dispersion of 13653.57 tons·year-1 of TN and 3224.45 tons·year-1 of TP into the Lake Uluabat. Additionally, seasonal changes in concentration of TN and TP were observed during the period of 2008-2009 in Lake Uluabat. It was concluded that the rise of agricultural activities in summer months was the reason underlying the increase in pollution during the months in question.

Analysis on the Status of Agricultural Non-point Source Pollution in Xinan River Basin

Taking Xinan River basin as research object,the status of agricultural non-point source pollution was analyzed based on field survey,as well as the effect of fertilizer and pesticide leaching and runoff,livestock and poultry breeding and rural domestic pollution on non-point source TN and TP.At last,some technical countermeasures of controlling non-point source pollution were put forward according to the characteristics of agricultural non-point source pollution in Xinan River basin.

Size distribution and diffuse pollution impacts of PAHs in street dust in urban streams in the Yangtze River Delta

Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs in street dust particles, the potential risks of the particles in urban streams, and the sources and sinks of PAHs in the stream network. This assessment was based on measurements of 16 PAHs from the USEPA priority list in street dust particles and river sediments in Xincheng, China. The content of total PAHs ranged from 1629 to 8986 Dg/kg in street dust particles, where smaller particles have a higher concentrations. Approximately 55% of the total PAHs were associated with particles less than 250 μm which accounted for 40% of the total mass of street dust. The PAH quantities increased from 2.41 to 46.86 μg/m2 in the sequence of new residential, rising through main roads, old town residential, commercial and industrial areas. The sediments in stream reaches in town were found to be sinks for street dust particle PAHs. The research findings suggested that particle size, land use and the hydrological conditions in the stream network were the factors which most influenced the total loads of PAH in the receiving water bodies.

Monitoring of non-point source pollutants load from a mixed forest land use

The aim of this study was to determine the unit load of NPS （non-point source） pollutants including organic variables such as BOD （biochemical oxygen demand）, COD （chemical oxygen demand） and DOC （dissolved organic carbon）, nitrogen and phosphorus constituents, and suspended solids （SS） and their event mean concentration （EMC） of runoff flows from a water-shed of mixed forest land use by intensive field experiments. Field monitoring for continuous measurements of rainfall, flow, and water quality was conducted over 12 storm events during 2008-2009 using automated and manual sampling methods. The EMCs of individual runoff event were estimated for each water quality constituent based on the flow rate and concentration data of runoff discharge. The average EMCs of BOD, COD, DOC, SS, TN （total nitrogen）, NH4^＋-N, NO3^--N, TP （total phosphorus）, PO4^3-P from the mixed forest land were 1.794, 3.498, 1.462, 10.269, 0.862, 0.044, 0.634, 0.034, and 0.005 mg/L, respectively. The annual unit loads of BOD, COD, DOC, SS, TN, NH4^＋-N, NO3^--N, TP and PO4^3--P were estimated as 66.9, 133.2, 55.5, 429.8, 36.5, 1.6, 26.9, 1.3 and 0.1 kg/（ha·yr）, respectively. In addition, affecting parameters on the EMCs were investigated by statistic analysis of the field data. As a result, significant correlations with precipitation, rainfall intensity, and total runoff flows were found in most constituents.

Pollution control of outfall of rainwater-sewage confluence in old town

In order to improve water quality of middle ancient canal in Zhenjiang city a pollution control project was carried out.The research area is the middle catchment area of the ancient canal river system in the old town of Zhenjiang. The specific research object is the runoff of the outfall of rainwater-sewage confluence in the area. On the basis of detecting and analyzing the water yield and water quality of the runoff of rainwater-sewage confluence a combined technology which contains four independent continuous processes for lowering pollution load was developed and system equipment was established and put into operation. The processing effects of the project were monitored and analyzed.The results show that the pollution control project of outfall runoff is efficient which decreases the pollution load including chemical oxygen demand COD total phosphorus TP suspended solids SS and ammonia-nitrogen NH3-N .As a result the water environment of the ancient canal is protected.

Total pollution effect of urban surface runoff

For pollution research with regard to urban surface runoff, most sampling strategies to date have focused on differences in land usage. With single land-use sampling, total surface runoff pollution effect cannot be evaluated unless every land usage spot is monitored. Through a new sampling strategy known as mixed stormwater sampling for a street community at discharge outlet adjacent to river, this study assessed the total urban surface runoff pollution effect caused by a variety of land uses and the pollutants washed off from the rain pipe system in the Futian River watershed in Shenzhen City of China. The water quality monitoring indices were COD （chemical oxygen demand）, TSS （total suspend solid）, TP （total phosphorus）, TN （total nitrogen） and BOD （biochemical oxygen demand）. The sums of total pollution loads discharged into the river for the four indices of COD, TSS, TN, and TP over all seven rainfall events were very different. The mathematical model for simulating total pollution loads was established from discharge outlet mixed stormwater sampling of total pollution loads on the basis of four parameters： rainfall intensity, total land area, impervious land area, and pervious land area. In order to treat surface runoff pollution, the values of MFF30 （mass first flush ratio） and FF30 （first 30% of runoff volume） can be considered as split-flow control criteria to obtain more effective and economical design of structural BMPs （best management practices） facilities.

Multi-indicator assessment of water environment in government environmental auditing

This study focused on a multi-indicator assessment methodology for governmental environmental auditing of water protection programs. The environmental status of Wuli Lake in China was assessed using the global indicators （driver-status-response） developed by the Commission on Sustainable Development, and four additional indicators proposed by the author： water quality, pollution load, aquatic ecosystem status, and lake sediment deposition. Various hydrological, chemical, biological and environmental parameters were used to estimate the values of the indicators for assessment of environmental status of the lake based on time series data sets for twenty years. The indicators proposed can be customized to meeting the needs for particular assessment of water protection programs. This method can be used to evaluate the performance of national environmental protection programs and provide technical support for environmental auditors.

Long-term temporal-spatial dynamics of marine coastal water quality in the Tolo Harbor,Hong Kong,China

The long-term temporal and spatial dynamics of marine coastal water quality in Tolo Harbor, Hong Kong were explored. The Harbor is divided into three zones represented as Harbor, Buffer, and Channel Subzones. The time range for the study covers the period from the 1970s to the 1990s. The selected indicators for the comprehensive assessment of water quality consist of physical, chemical and biological aspects, including suspended solids(SS), Secchi disk depth(SD), 5-day biochemical oxygen demand(BOD\-5), total nitrogen(TN), total phosphorus(TP), faecal coliform, chlorophyll-a(Chl-a), and the number of red tide occurrences. The results indicated the presence of obvious temporal and spatial trends with regard to changes in water quality. Spatially, water quality in the Channel Subzone is the best, while that in the Harbor Subzone is the worst. On a temporal basis, the average trend from bad to good was 1980s>1990s>1970s as indicated by most of the selected water quality indicators. Water quality during the late 1980s reached its worst level with the lowest SD, the highest BOD\-5, TN, TP, Chl-a concentrations, and the number of red tide occurrences. These long-term temporal-spatial water quality trends were also found in other studies of the Tolo Harbor. The large quantity of pollutants produced as a result of increasing population, industrial and commercial actives, and urbanization and industrialization trends in both Shatin and Tai Po seem to be primarily responsible for the changes in marine coastal water quality.

Method for calculating non-point source pollution distribution in plain rivers

The land area in a river network is divided into certain-scale square cells for the sake of precision, and, based on the physical mechanisms of rainfall-runoff processes and runoff pollution, the non-point source pollution from cells is estimated using the export coefficients of different land use types. The non-point source pollution from a land cell should all go into the closest fiver reach, so it is distributed according to the terrain of the plain river network area and the positions of land cells and river network reaches. A relationship between a single land cell and its pollution-receiving reach can be determined using this system. In view of the above, a spatial distribution model of the rainfall runoff and non-point source pollution in reaches of a plain river network area was established. This model can provide technological support for further research on the dynamic effects of non-point source pollution on water quality.

Field survey of a sustainable sanitation system in a residential house

Sustainable sanitation is an approach for more ecological and sustainable water resources management. In this paper, we proposed one of the new integrated waste treatment systems： an ＂sustainable sanitation system＂ that includes separation of the black water from water system by a non-flushing toilet （bio-toilet）, and a gray water treatment based on a biological and ecological concept. Sustainable sanitation system also converts the domestic waste to soil conditioners and fertilizers, for farmland use. As one of the case studies, Environmentally Symbiotic Housing in which people actually live using the bio-toilet for the black water treatment and the household wastewater treatment facility for the gray water was introduced. The availability of this system was investigated by analyzing the sawdust used in the bio-toilet and the quality of the effluent in the household wastewater treatment facility. As the result, the water content of the sawdust did not exceed 60% in any of the sampling points and the BOD and COD of the effluent of the household wastewater treatment facility were below 10 and 20 mg/L respectively, due to the low loading. Compared to the pollution load on the water environment created by the conventional system, it was found that the effluent of the house has a lower load than the tertiary treatment and the volume of the water consumption is 75% of the conventional system.

Physico-chemical characteristics and heavy metal concentrations of copper mine wastes in Zambia:implications for pollution risk and restoration

Soil characterization is a vital activity to develop appropriate and effective restoration protocols for mine wastelands while insights into the total content of heavy metals in the soil is an important step in estimating the hazards that the metals may pose to the vital roles of soil in the ecosystem.This study addressed the following research questions:(1)To what extent do the physico-chemical characteristics vary between mine waste sediments and the nearby forest soil?(2)Are the concentrations of heavy metals high enough to be considered as toxic?and(3)Are heavy metals present in mine waste sediments potential sources of pollution?We hypothesized that the physicochemical characteristics of mine waste sediments are less favorably for plant establishment and growth while the concentrations of heavy metals are very high,thus restricting the success of revegetation of mine waste lands.Mine waste sediments were sampled following a diagonal transect across tailings dams,overburden dump sites and the local forest soil from the top layer(0-20 cm)using a closed auger.Samples were analyzed for arsenic,barium,lead,cadmium,cobalt,copper,chromium,nickel,vanadium,and zinc as well as for soil physico-chemical properties.The mine waste sediments were dominated by silt whilst the forest soil by sand particles,with significantly high bulk density in the former.Both the forest soil and overburden sediments were acidic than the alkaline tailings dam sediment.Total organic carbon and nitrogen contents were significantly low in mine wasteland substrates but the concentration of Ca and Mg were significantly higher in tailings dam substrate than the forest soil.The concentrations of available P,K and Na were similar across sites.The mean concentrations of heavy metals were significantly(p<0.01)higher in mine waste sediments than the forest soil;except for cadmium(p=0.213).The order of contamination by heavy metals on the tailings was Cu>Co>Ba>Ni>As>Zn>Pb>Cr>V>Cd,and that on the overburdens was Cu>Co>Ba>Ni>Zn>Cr>Pb>V>As>Cd.The pollution load index(PLI)was nearly twice higher for the tailings dam(8.97)than the overburden(5.84).The findings show that the copper mine wastes(the tailings dams and overburden waste rock sites)are highly contaminated by heavy metals;which,in turn,might pose serious hazards to human health and agricultural productivity.In addition,poor macro-nutrient availability,substrate compaction and soil acidity(particularly on overburden sites)coupled with toxic level of heavy metals would be the main challenges for successful phytostabilization of copper mine wastelands.

Pollutant concentrations and pollution loads in stormwater runoff from different land uses in Chongqing

To investigate the distribution of pollutant concentrations and pollution loads in stormwater runoff in Chongqing,six typical land use types were selected and studied from August 2009 to September 2011.Statistical analysis on the distribution of pollutant concentrations in all water samples shows that pollutant concentrations fluctuate greatly in rainfall-runoff,and the concentrations of the same pollutant also vary greatly in different rainfall events.In addition,it indicates that the event mean concentrations （EMCs） of total suspended solids （TSS） and chemical oxygen demand （COD） from urban traffic roads （UTR） are significantly higher than those from residential roads （RR）,commercial areas （CA）,concrete roofs （CR）,tile roofs （TRoof）,and campus catchment areas （CCA）;and the EMCs of total phosphorus （TP） and NH3-N from UTR and CA are 2.35-5 and 3 times of the class-III standard values specified in the Environmental Quality Standards for Surface Water （GB 3838-2002）.The EMCs of Fe,Pb and Cd are also much higher than the class-III standard values.The analysis of pollution load producing coefficients （PLPC） reveals that the main pollution source of TSS,COD and TP is UTR.The analysis of correlations between rainfall factors and EMCs/PLPC indicates that rainfall duration is correlated with EMCs/PLPC of TSS for TRoof and TP for UTR,while rainfall intensity is correlated with EMCs/PLPC of TP for both CR and CCA.The results of this study provide a reference for better management of non-point source pollution in urban regions.

Effect of Different Factors on Nitrogen Removal Rate in Constructed Wetlands

Factors affecting total nitrogen(TN) removal rates in constructed wetland were investigated by intermittent operation in the subsurface flow(SSF) constructed wetland system.The results demonstrated that removal rates of TN increased with the rising of TN pollution load(1.40-12.40 g/m2) when the retention time was determined by 60% TN removal efficiency(n=180,p<0.05) in SSF wetlands.The maximum TN removal rate was 1.71 g/(m2·d) in SSF Phragmites australis-soil-slag system.TN removal rates were affected by total phosphorus load in case of higher TN load.TN removal rates in SSF Phragmites australis wetlands were greater than that in SSF Calamagrostis angustifolia wetlands at the same experimental cycle.Effect of wetland substrates on TN removal rates varied with the pollutants loading in SSF constructed wetland system,plant species and plant-growing period.

An approach to calculating allowable watershed pollutant loads

To improve the management of discharge pollutants loads in the reservoirs＇ watershed, an approach of the allowable pollutants loads calculation and its allocation, based on the water environment model, was proposed. Establishment of the approach framework was described at first. Under the guidance of this framework, two major steps were as follows： modeling and scenario analysis were involved and should be applied to support the decision of discharge loads management; Environ- mental Fluid Dynamic Code （EFDC） model was selected as the kernel model in this framework. In modeling step, spatial discretization for establishing cell map in model, data preprocessing, parameter calibration and uncertainty analysis （which is considered as the significantly relevant factor of the margin of safety （MOS））, were conducted. As a result of the research, the model-based approach presented as a combination of estimation and precise calculation, which contributed to scenario analysis step. Some integrated modules, such as scenario simulation, result analysis and plan optimization were implemented as cycles in the scenario analysis. Finally, allowable pollutant loads under various conditions were calculated. The Chaihe Reservoir in Liaoning Province, China was used as a case study for an application of the approach described above. Results of the Chaihe reservoir water quality simulation, show good agreement with field data and demonstrated that the approach used in the present study provide an efficient and appropriate methodology for pollutant load allocation.