以北运河（北京段）为例模拟评估北京市“水十条”水质改善效果

基于MIKE11构建北运河(北京段)一维水质模型,以氨氮、COD为目标污染物,建立污染源与水质响应关系。以2013年为基准年,考虑不同人口疏解情景预测2020年北运河(北京段)流域人口,并结合北京市"水十条"设置减排情景方案,对2020年水质改善效果进行量化评估。模拟结果表明:北京市"水十条"可实现显著的水质改善效果,到2020年,在中人口疏解方案下,北运河氨氮、COD平均质量浓度相比2013年分别下降40.8%~77.7%、39.3%~59.7%。COD质量浓度可稳定达标,氨氮质量浓度离达标还有一定差距,但日浓度可稳定在8mg/L以下,基本消除了黑臭水体。     

淮河支流污染物综合降解系数动态测算

确定河流污染物综合降解系数动态变化规律对提高水环境容量测算精度和水环境管理具有重要意义。通过现场模拟法,采用一维稳态模型测算了淮河支流洪河五沟营-塔桥乡河段COD、氨氮和总磷在枯水期、平水期和丰水期的综合降解系数,COD、氨氮和总磷降解系数在各水期的关系为枯水期平水期丰水期,提出了建议值并利用实测浓度对计算结果进行了检验,结果表明,不同水期综合降解系数吻合情况较好。     

基于神经网络模型对城市空气质量预报方法的优化研究

基于郑州市2017年1月1日—2022年2月28日环境空气细颗粒物(PM_(2.5))逐日质量浓度监测数据和同期气象数据,利用反向传播(BP)神经网络构建了环境空气PM_(2.5)质量浓度预报模型,实现了对郑州市后1日环境空气PM_(2.5)质量浓度日均值进行预报。构建了考虑大气氧化性因素(情景一)和不考虑大气氧化性因素(情景二)这2种情景,并对2种情景下的预报效果进行评价。结果显示,在情景一下,各季节PM_(2.5)预报质量浓度与实况质量浓度的标准化平均偏差(NMB)和均方根误差(RMSE)均处于较低水平,表明预报效果均具有较好的稳定性;各季节PM_(2.5)实况质量浓度与预报质量浓度之间的相关系数(r)、一致性指数(IA)、准确率(Q)和级别预报准确率(G)均处于较高水平,其中Q值均>79%,G值均>80%,表明各季节PM_(2.5)实况质量浓度与预报质量浓度趋势的吻合程度较高。情景一各季节PM_(2.5)预报质量浓度与实况质量浓度的NMB和RMSE均低于情景二,降幅分别为0.8%~2.3%和2.3~4.2μg/m 3;r值、IA、Q值和G值均高于情景二,增幅分别为3.5%~36.1%,2.2%~14.6%,6.4%~9.4%和3.5%~9.1%,表明考虑大气氧化性因素能够优化该模型。     

CALRoads模式在上海市典型道路CO扩散预测中的应用

根据上海市市区、郊区典型主干道的气象条件、车流量、车型比例,以及CO小时质量浓度的监测资料,采用CALRoads模式中CALINE4和CAL3QHC模块,对郊区主干道和市区典型路口的适用条件分别进行了验证.结果表明,在稳定的气象条件下,CALINE4模式在模拟周围相对空旷主干道附近的CO质量浓度时,具有较好的结果,将CAL3QHC模式应用于市区典型交叉口,可以得到同监测值相对吻合的模拟结果,但准确性低于郊区.应用CALRoads模型对未来城郊典型道路附近CO高峰小时质量浓度的发展趋势进行了预测,并基于情景分析给出了减少交通污染的对策建议.     

基于QUAL2K模型的鹤壁卫河水质模拟预警研究

水质预报预警对于防范水污染、降低水污染风险及其带来的损失、保障用水安全及水环境质量等具有重大意义。提出了一种基于QUAL2K模型的水质模拟预警方法,包括水质模拟预测、预警指数计算和警情确定,以海河流域鹤壁市卫河为例进行实证研究。研究结果表明:基于QUAL2K模型模拟精度分别为COD 97.7%、NH_3-N 98.5%,水质模拟效果较好;所选河段预警时段内COD基本处于无警和轻警2个级别,氨氮大多是巨警,浓度严重超标,是导致监测断面预警指数高的主要原因。     

北运河流域河流沉积物中氮磷污染物释放规律

北京市北运河流域属于典型缺水型城市纳污河流,沉积物释放的氮磷污染物已成为阻碍水环境质量持续改善的主要因素。利用自制环形水槽,对不同流速下沉积物中氮磷的动态释放规律进行研究,结果表明,静态条件下,沉积物中氨氮平均释放速率1 136 mg/(m~2·d),磷酸盐平均释放速率为145 mg/(m~2·d),在流速0.05 m/s的缓流水体中,氨氮平均释放速率为1 408 mg/(m~2·d),而磷酸盐平均释放速率为125 mg/(m~2·d)。流速增加会显著促进氮素的硝化作用,使水体中氨氮浓度降低,硝酸盐氮浓度上升。同时,流速增加导致水体中颗粒物含量增加,促进磷吸附行为,水体中磷酸盐浓度下降。     

北京市主要水污染物排放特征及水质改善对策

污染排放信息是环境决策的重要依据。分析了北京市水环境质量的现状,基于最新源排放清单,解析北京市当前主控污染物COD、氨氮排放的结构特征和空间特征,以期为北京市开展基于流域综合治理的水污染控制和水环境管理提供依据。按照工业源、农业源、生活源和集中处理设施的环境统计口径,2013年,COD、氨氮的排放构成分别为2.7%、37.1%、35.0%、25.3%和1.5%、20.1%、54.8%、23.6%。其中,农业源中畜禽养殖排放是主要来源,COD、氨氮总排放分别占农业源总排放量的94.7%和87.0%。在北京市五大水系中,北运河流域排放量最大,COD、氨氮排放量分别占全市总排放量的53.3%和57.4%。为改善北京市水环境质量,建议从加快污水处理厂提标改造、推动面源污染治理、加强水利联通、合理规划城市规模布局等4个方面入手。     

基于去耦合直接法的兰江流域地表水水质预测方法研究

针对影响因素众多、耦合机制复杂情况下的地表水污染物浓度预测问题，将河道污染物浓度的变化量表示为各种影响因子一阶偏导项和二阶偏导项的线性叠加。其中，一阶偏导项可描述影响因子变化与污染物浓度变化的直接关系，二阶偏导项可描述影响因子之间交互作用对污染物浓度变化的影响。在此基础上，提出了用以模拟地表水污染物浓度的去耦合直接法。采用2014—2016年兰江流域将军岩、低田、半潭、沈村、焦岩5个断面的水文和氨氮、高锰酸盐指数、总氮、总磷4项污染指标逐日实测数据，通过差分法求解了一阶和二阶偏导项，并采用2017—2019年实测数据对模型进行了验证和评价。结果表明：去耦合直接法能够有效预测地表水主要污染物浓度的变化方向和变化量，且模拟结果和实测结果的符合情况较好，4项污染指标模拟值的Nash-Sutcliffe系数为0.479～0.654,模拟值与实测值的偏差为0.070～0.352;汇流区面积增加后，影响因子不确性对污染物浓度的扰动减小，污染物浓度变化的规律性增强，去耦合直接法的模拟精度升高。与SWAT模型的对比分析结果显示，在污染成因不发生显著变化的情况下，去耦合直接法的模拟精度优于SWAT模型。     

基于SHERPA的环境空气质量减排情景模拟评估

分析了SHERPA综合评价模型的基本原理和主要建模理念,重点介绍了其在环境空气质量减排情景模拟评估方面的作用,以及在排放源与受体关系(SRR)方面的处理方法,比较了其与欧盟常用的其他情景模拟模型的优缺点。SHERPA模型的特点是空间灵活性较好,对于任何给定地点,可以快速评估不同地区对该研究地点空气质量的影响。SHERPA模型的3个主要功能为污染物来源分析、决策支持和情景模拟。基于SHERPA模型对法国环境空气中PM_(2.5)、PM_(10)和NO_2年均浓度进行污染来源分析、决策支持分析和减排情景模拟评估,展示了模型在环境治理措施优先级筛选和政府间联合治理措施协调建议方面的功能和作用,以期为中国环境空气质量预测预报、环境质量管理措施的制定和成效评估等环境服务与管理工作提供借鉴。     

氨气敏电极法和纳氏试剂分光光度法对地表水中氨氮的比对测试

采用不同质量浓度的氨氮标准样品和实际样品,用氨气敏电极法和纳氏试剂分光光度法进行同步测试。结果表明,2种分析方法在水样氨氮质量浓度在0. 159～2. 81 mg/L范围内具有良好的可比性、精密性和准确性。氨气敏电极法的检出限为0. 03 mg/L,平行6次测定样品的相对标准偏差为0. 4%～4. 2%,加标回收率为85. 0%～110%;纳氏试剂分光光度法的检出限为0. 025 mg/L,平行6次测定样品的相对标准偏差为0. 5%～6. 4%,加标回收率为93. 0%～99. 8%。同时氨气敏电极法在样品预处理、试剂配制和分析时间上要优于纳氏试剂分光光度法。氨气敏电极法能够满足地表水自动监测在线比对实际工作的需求,该方法具有良好的适用性。     

Study of the Climate Change Impacts on Water Quality in the Upstream Portion of the Cau River Basin,Vietnam

This paper presents simulations of climate change impacts on water quality in the upstream portion of the Cau River Basin in the North of Vietnam. The integrated modeling system GIBSI was used to simulate hydrological processes, pollutant and sediment wash-off in the river basin, and pollutant transport and transformation in the river network. Three projections for climate change based on emission scenarios B1, B2, and A2 of IPCC Special Report on Emission Scenarios (SRES) were considered. By assuming that the input pollution sources and watershed configuration were constant, based on 2008 data, water quality in the river network was simulated up to the terminal year 2050. For each climate change scenario, patterns of precipitation in wet and dry year were considered. The change in annual and monthly trends for dissolved oxygen (DO), biochemical oxygen demand (BOD), and ammonium ions (NH4+) load and concentration for different portions of the watershed have been analyzed. The results of these simulations show that climate change has more impact on changing the seasonal water quality parameters than on altering the average annual load of the pollutants. The percent change and change pattern in water quality parameters are different for wet and dry year, and the changes in wet year are smaller than those in dry year.     

Environmental water demand assessment under climate change conditions

Measures taken to cope with the possible effects of climate change on water resources management are key for the successful adaptation to such change. This work assesses the environmental water demand of the Karkheh river in the reach comprising Karkheh dam to the Hoor-al-Azim wetland, Iran, under climate change during the period 2010–2059. The assessment of the environmental demand applies (1) representative concentration pathways (RCPs) and (2) downscaling methods. The first phase of this work projects temperature and rainfall in the period 2010–2059 under three RCPs and with two downscaling methods. Thus, six climatic scenarios are generated. The results showed that temperature and rainfall average would increase in the range of 1.7–5.2 and 1.9–9.2%, respectively. Subsequently, flows corresponding to the six different climatic scenarios are simulated with the unit hydrographs and component flows from rainfall, evaporation, and stream flow data (IHACRES) rainfall-runoff model and are input to the Karkheh reservoir. The simulation results indicated increases of 0.9–7.7% in the average flow under the six simulation scenarios during the period of analysis. The second phase of this paper’s methodology determines the monthly minimum environmental water demands of the Karkheh river associated with the six simulation scenarios using a hydrological method. The determined environmental demands are compared with historical ones. The results show that the temporal variation of monthly environmental demand would change under climate change conditions. Furthermore, some climatic scenarios project environmental water demand larger than and some of them project less than the baseline one.     

趸船式水质自动监测站建站模式的技术可行性分析

分析大胜关水质自动监测站建成运行后2015-2018年每月实际水样比对数据,并与同期建设固定式水站水样比对结果比较,探讨趸船式水站的技术可行性。结果表明:趸船式水站自动监测的pH值、溶解氧、电导率、氨氮指标与实验室数据有较好一致性,相关性均>0.7,且显著性概率<0.01,存在非常显著的相关关系,pH值、电导率、高锰酸盐指数3个指标的实际水样比对合格率均超过80%,其中高锰酸盐指数和氨氮指标的误差范围与固定式水站监测结果的误差范围相当。     

Monitoring cyclical air/water elemental mercury exchange

Previous experimental work has demonstrated that elemental mercury evasion from natural water displays a diel cycle; evasion rates during the day can be two to three times evasion rates observed at night. A study with polychlorinated biphenyls (PCBs) found that diurnal PCB air/water exchange rates exceeded nocturnal exchange rates by 32%. Given that the exchange rates of both PCBs and elemental mercury are dominated by the resistance in the aqueous thin film at the air/water interface and that water column elemental mercury concentrations in natural water bodies also display a diel cycle (and water column PCB concentrations do not) the findings here suggest that PCBs can serve as a tracer to assess the relative contribution of diel atmospheric temperature variations on elemental mercury air/water exchange rates. Using previously published data describing water column elemental mercury concentrations and the previously published diel mercury evasion model, four evasion scenarios are examined within the context of monitoring air/water toxicant exchange: constant atmospheric temperatures and constant water column elemental mercury concentrations; variable atmospheric temperatures and constant water column elemental mercury concentrations; constant atmospheric temperatures and variable water column elemental mercury concentrations; and variable atmospheric temperatures and variable water column elemental mercury concentrations. A scenario of monthly elemental mercury air/water exchange also is examined (at constant atmospheric and water column elemental mercury concentrations). Some of the findings include: (1) atmospheric temperature variations do have a significant effect on air/water toxicant exchange; (2) diel atmospheric temperature variations become more significant to overall diel toxicant exchange rates the closer the air/water system is to equilibrium conditions; (3) for refractory toxicants, average diel exchange rates are best estimated by averaging datasets obtained over a 24 h period or, at minimum, by measuring exchange rates at average atmospheric temperature values; (4) for elemental mercury, variable diel water column concentrations are likely to be the dominant contributor to variations in diel evasion rates; (5) diel atmospheric temperature variations amplify the magnitudes of both diel mercury evasion and absorption events and can shift maximum evasion rates to later in the day; (6) variations in monthly elemental mercury air/water exchange rates may exceed diel variations: and (7) 24 h and monthly monitoring efforts will likely be required to accurately describe diel and annual elemental mercury air/water exchange in a given system.     

New Unstructured Mesh Water Quality Model for Cooling Water Biocide Discharges

A new unstructured mesh coastal water and air quality model has been developed that includes species transport, nonlinear decay, by-product formation, and mass-exchange between sea and atmosphere. The model has been programmed with a graphical user interface and is applicable to coastal seawater, lakes, and rivers. Focused on species conversion and interaction with the atmosphere, the water and air quality model follows a modular approach. It is a compatible module which simulates distributions based on fluid dynamic field data of underlying existing hydrodynamic and atmospheric simulations. Nonlinear and spline approximations of decay and growth kinetics, by-product formation, and joint sea–atmosphere simulation have been embedded. The Windows application software includes functions allowing error analysis concerning mesh and finite volume approximation. In this work, a submerged residual chlorine cooling water discharge and halogenated matter by-product formation has been simulated. An error analysis has been carried out by varying vertical meshing, time-steps and comparing results based on explicit and implicit finite volume approximation. The new model has been named 3D Simulation for Marine and Atmospheric Reactive Transport, in short 3D SMART.     

一次监测值用于水质评价的研究

以2003年长江和淮河水系为例,通过计算各个评价项目的单月监测值分别与季均值和年均值的相对误差及其分布,以及水质类别相同的断面比例,认为对于旬报、月报短期水质评价,采用一次监测的数据评价水质是可靠的;对于季报和年报中、长期水质评价,采用一次监测数据评价的可靠程度较差,应采用2次或2次以上的监测数据平均值进行评价。     

Sensitivity Analysis and Water Quality Modeling of a Tidal River Using a Modified Streeter–Phelps Equation with HEC-RAS-Calculated Hydraulic Characteristics

A modified Streeter–Phelps equation and the Hydrological Engineering Centers River Analysis System (HEC-RAS) were combined to assess water quality of the Tan-Sui River and its tributaries. The Tan-Sui River is the main source of water supply for northern Taiwan, and the water quality of its stream is significantly affected by tides. In this study, HEC-RAS was employed to assess the impact of tides on water quality and to calculate reoxygenation coefficients. The modified Streeter–Phelps equation was used to calculate water quality in terms of contaminant degradation and reoxygenation. Biochemical oxygen demand (BOD) and ammonia nitrogen (NH₃–N), the most important identified sources of water pollution in the rivers investigated, were evaluated. Dissolved oxygen (DO) was also simulated, since it is often used as a staple of water quality. Results showed that employing HEC-RAS for hydraulic calculations improves the modified Streeter–Phelps simulation. In river sections without tidal influence, water quality was sensitive to the BOD and NH₃–N degradation constants. Downstream of Chin-Mei Creek, while the BOD degradation constant decreased by 80%, BOD and DO concentrations increased from 7.1?mg/L to 10.7?mg/L and 5.0?mg/L to 7.2?mg/L, respectively, indicating that water quality was not as sensitive to variations of the BOD degradation constant as expected. The concentrations of DO and BOD at the river mouth had a significant impact on water quality for the tidal sections of the investigated rivers due to mixing of tidal and river waters. The BOD and NH₃–N degradation constants in the tidal sections had little impact on water quality simulations. This study demonstrated the innovative combination of the modified Streeter–Phelps equation and HEC-RAS to assess the impact of tidal variation and to simulate the water quality of a tidal river when available data is rather limited.     

北京市河流氨氮浓度时空演变特征分析

选取2010—2017年北京市地表水监测数据,对河流氨氮(NH 3-N)浓度的时空演变特征进行分析。结果显示,空间上,全市河流NH 3-N浓度整体上保持上游优于下游的分布特征;年均浓度显著下降,由2010年的8.53 mg/L逐年下降至2017年的3.09 mg/L;河流NH 3-N浓度与化学需氧量、总磷呈显著正相关,与溶解氧显著负相关,总氮与NH 3-N的比值随着水质由差到好呈上升状态。污水收集处理和再生水利用是改善北京市河流水质的关键措施。为持续降低河流NH 3-N浓度,改善首都水环境质量,须提高污水处理能力和出水水质,有机结合再生水回用与生态治水理念。     

A distributed modelling system for simulation of monthly runoff and nitrogen sources, loads and sinks for ungauged catchments in Denmark

We validated an existing physically based 3D MIKE SHE groundwater resource model (DK-model) at 175 Danish gauging stations covering different catchment sizes in order to calculate monthly water runoff in the 50% ungauged part of Denmark. Model performance was in most cases good (61% of gauging stations had a Nash-Sutcliffe (NS) coefficient >0.60) but nevertheless showed a large seasonal and georegion specific bias. Therefore, bias correction factors had to be developed before applying the DK-model simulations of runoff in the ungauged areas. Simulated monthly runoff from ungauged areas and the measured monthly runoff from 178 gauging stations were distributed to 2663 smaller Hydrological Units (ca. 15 km(2)) and linked with a new empirical model for flow-weighted monthly total nitrogen (TN) concentrations (R(2) = 0.43; P < 0.0001) developed based on 20 years of observations (1990-2009) in 83 small catchments for calculation of monthly gross diffuse TN-loads from HU's. Nitrogen retention was calculated in streams, lakes and wetlands utilising both lake specific models and rate coefficients to calculate N retention in surface water bodies. The whole model complex was linked in the DK-QN concept for simulation of monthly TN losses from point sources and diffuse sources, TN retention and resulting loadings to Danish coastal waters. The DK-QN model was validated in 118 gauged catchments and the model simulations had for >25% of the observations of monthly discharge weighted TN concentrations a NS larger than 0.26. Catchment specific monthly TN-loadings were modelled with a higher performance as 50% of the catchments had a NS greater than 0.75. The model concept allows calculation of N retention in streams, lakes and wetlands and the average annual model calculated N retention amounted to 21% of the modelled gross riverine TN loadings. The average annual gross TN loading to surface freshwater in Denmark derived from diffuse sources amounted to 97 000 tonnes N (91% of gross TN loadings) which is 54% of the total estimated N-leaching from the root zone on the Danish land area (212 000 tonnes N) during the period 1990-2009.