The study employed the PML (Penman–Monteith–Leuning) model to simulate the evolution law of long-sequence evapotranspiration in the mountainous region of the Luan River basin. Additionally, this study conducted a quantitative analysis to determine the effect of restoration on evapotranspiration water consumption. From 1981 to 2020, the results indicated that there were significantly less fluctuations in precipitation in the mountainous region of the Luan River basin than there were fluctuations in discharge. The restoration of vegetation in the mountainous region of the Luan River basin caused a mean annual growth rate of 3.47 mm in evapotranspiration. A linear positive correlation was observed between the evapotranspiration and vegetation NDVIs (normalized difference vegetation indexes) in mountainous regions. Specifically, for each 0.01 increase in the NDVI, there was an approximate 8.3 mm increase in evapotranspiration. When comparing the time periods of 1995–2001 and 2002–2020, it was observed that evapotranspiration increased by 70 mm. Furthermore, the evapotranspiration rate in the southeastern region exhibits significant variation, peaking at over 50 mm per year. In contrast, the northwest experiences variations of less than 10 mm per year. A quantitative analysis of the relationship between the evolution of mountain evapotranspiration and the response law of vegetation restoration is presented in this study; this information can be used as a guide when developing practical vegetation restoration strategies.

ObjectiveThe low-carbon operation of sewage treatment systems has received significant attention globally as an important source of greenhouse gas emissions. However, existing research shows a deficiency in the prognostic analysis of future trends in urban sewage treatment systems, and insufficient attention is devoted to greenhouse gases from the sewage pipe network and sludge treatment facilities in greenhouse gas accounting. Consequently, the calculated results fall significantly below the actual values, thus impeding the formulation of targeted emission reduction measures. Although Beijing is one of the cities in China with the highest level of wastewater reuse, the large-scale use of wastewater could significantly increase greenhouse gas emissions. Researching greenhouse gas emissions from Beijing's wastewater treatment system could bear reference significance for other cities under the strategic backdrop of China's carbon peaking by 2030 and carbon neutrality by 2060.MethodsA greenhouse gas accounting system of the sewage treatment system was established to measure the scale of greenhouse gas emissions from 2010 to 2020 based on the sewage treatment process in Beijing. The greenhouse gas accounting system for Beijing's sewage treatment system consisted of three stages: sewage pipeline network, sewage treatment, and sludge disposal. The accounting scope comprised direct emissions of CH4, N2O, and fossil fuel CO2, as well as indirect emissions of CO2 resulting from equipment operation and chemical consumption. Greenhouse gas emissions for each stage were computed using the emission factor method. Additionally, various calculation formulas and parameters were introduced, such as CH4 emission factors, N2O emission factors, and chemical emission factors. Therefore, the greenhouse gas emissions of each stage were calculated and aggregated, using the sewage treatment plant as the calculation unit, to obtain the overall greenhouse gas emissions of Beijing's sewage treatment system. Additionally, the scenario analysis method was used in this study to predict the characteristics of greenhouse gas emissions under different scenarios in 2035.ResultsThe following research results are presented: (1) From 2010 to 2020, there has been a significant increase in the level of greenhouse gas emissions emitted by Beijing's sewage treatment system, rising from 1.191 3 to 2.269 1 million tons. Sewage treatment is the most significant stage, accounting for 51.27% of total emissions, followed by sludge disposal (39.92%) and sewage pipeline network (8.81%). (2) The sources of greenhouse gas emissions vary significantly across different stages. The sewage pipeline network is mainly associated with electricity consumption and CH4 emission, whereas sewage treatment is primarily associated with electricity consumption and N2O emission. The sludge disposal stage mainly contributes to CH4 and N2O emissions. Generally, it can be observed that indirect emissions, which include the consumption of electricity and chemical, constitute 62.79% of the total greenhouse gas emissions from Beijing's sewage treatment system. (3) The emission intensities of different treatment standards and processes are different: the emission intensity of the Beijing landmark exceeds the national standard, and the emission intensity of the membrane bio-reactor technology is 1.77 times that of anaerobic-anoxic-oxic technology. (4) The greenhouse gas emissions of Beijing's sewage treatment system in 2035 will increase in the baseline, high standard effluent, and low carbon emission scenarios by 59.87%, 110.69%, and 41.37% compared with 2020. Although the low carbon emission scenario has the smallest increase, its realization requires an additional investment of 4.995 billion Yuan and an area of 1.92 million m2.ConclusionsThe research results show a significant increase in greenhouse gas emissions from Beijing's sewage treatment system and provide pertinent emission reduction recommendations.

Poly- and perfluoroalkyl substances (PFASs) have garnered extensive attention due to their dissolubility, stability, hydrophobicity, and oleophobicity, contributing to long-range transport of PFASs in the water. As an important part of the blue-green space system, freshwater plays a decisive role in ensuring environmental health. Hence, a comprehensive analysis of the current studies regarding the transportation of PFASs in freshwater is highly important for ecotoxicological assessment and pollution control. To explore research progress and hotspots of transportation of PFASs in freshwater, CiteSpace software was utilized in this literature to conduct publication growth, analysis of countries/regionss, analysis of publishing institutions, co-citation analysis, keywords bursting analysis, and keywords timeline analysis. The publication trends of the transportation of PFASs in freshwater were divided into the embryonic period (2005-2014) and the developing period (2015-2023). Institutions and authors from China were found to publish most literature, indicating China places a significant emphasis on the assessment of risks of PFASs in freshwater environments. Research hotspots shifted from transport behaviors and mechanisms to risk assessment and multimedia transportation. Understanding the transportation of PFASs in freshwater is crucial for assessing environmental impacts, ensuring water resource sustainability, and contributing to the development of management practices prioritizing sustainability, energy efficiency, and environmental responsibility.

改善城市河湖生态环境是提升区域生态环境质量的基础.传统的引调水工程对城市河湖水环境问题抑制成效有限,结合城市河湖自身特点与补水需求,在生态补水的基础上,丰富了生态补水的科学内涵与目标,确定影响城市河湖生态环境的关键指标体系,构建生态补水技术框架,阐述补水过程中涉及到的工程措施、评估指标体系、运行维护管理及优化调配机制.充分考虑生态系统与水文要素变化的响应过程,并对其关键技术问题进行详细阐述,用以辅助城市河湖恢复自身生态系统调节功能,抑制水环境问题,以期为我国城市河湖水生态保护提供参考.

Under the requirement of the national recovery of the ecological environment of rivers and lakes,the analysis of the historical long series of water surface area changes in the Beijing-Tianjin-Hebei Plain area and the causes of changes is helpful for scientific formulation of regional ecological water recharge and prediction of water recharge effect.In this study,the water area of the Beijing-Tianjin-Hebei plain was determined by three periods of land use data fusion.The water surface area of the Beijing-Tianjin-Hebei plain from 1985 to 2020 was extracted based on GEE（Google Earth Engine） cloud platform,and the filling rate of water area and the reason for the evolution of water surface area were analyzed.The results show that the water surface area of the Beijing-TianjinHebei Plain has been increasing since 1985,and the filling rate of the water area has increased from 1985 to 2020.Ecological water refill is the main reason for the increase of the water surface area of the river and lake.In 2020,the water surface area of the central plain has increased by 176 km~2 compared with 2001.The contribution of local and external ecological water replenishment accounted for 84%.Aiming at the recovery of rivers and lakes,different scenarios were set up from the perspective of water area filling rate,and the ecological water requirements of rivers and lakes under different scenarios were estimated respectively.The research results systematically analyzed the water surface status and the effect of ecological water replenishment in the Beijing-Tianjin-Hebei Plain,which is of great significance for carrying out reasonable river and lake recovery measures in the Beijing-Tianjin-Hebei Plain.

城乡河湖水系在防洪排涝、水量保障、水质改善、景观文化等方面发挥着巨大的功能和价值.在高强度人类活动和气候变化影响下,河湖水系受到了多重胁迫,严重影响了河湖生态功能的正常发挥.为了复苏河湖生态,国内外开展了大量的河湖水系连通工程实践.尽管城乡河湖水系连通工程取得了系列成就,但其直接或间接带来的滞后性的生态环境负面影响也相继显现,在部分区域加剧了原有的生态环境问题.因此,以城乡河湖水系演变与驱动为切入点,重点关注城乡河湖水系连通工程对水量、水质、水热、水盐、水生态等带来的正负生态环境效应,并提出了未来的主要研究趋势.研究可为未来城乡河湖水系连通工程减缓或消除负效应、强化正效应提供科学基础.

湿地具有涵养水源等重要生态服务功能,但在人类活动与气候变化的多重胁迫下出现萎缩与退化,其中湿地补给水量不足是其主要生态问题之一.随着跨区域、跨流域调水工程的实施运行,生态补水目前已成为湿地修复与水资源配置的关键技术组成.因此,关注多水源补给湿地的补水路径优化,基于湿地补水水动力过程提出了生态补水方式的优化方案.2021年在潮白河流域全线通水的背景下,以北京市仅存的大型芦苇沼泽湿地——汉石桥湿地为案例区,构建了潮白河流域SWAT模型模拟径流变化规律,利用MIKE21模型模拟湿地补水水量-水动力耦合过程,比较了6种湿地补水情景的水动力变化特征.结果表明:汉石桥湿地内部水系连通受阻造成的湿地南部与北部分隔是限制生态补水效率的主要瓶颈,湿地南北区多流路同时补水,以及改造湿地水文连通结构是改善补水水动力条件,提升生态补水效应的优化方案.该研究结论可为湿地的长期管理和生态修复提供参考,有利于首都城市生态水系建设.

城市景观缓滞水体水华控制及水力条件改善是当前城市湖泊、河流等景观水体生态健康恢复的关键问题.永定河生态补水措施用于缓解莲石湖8号湖等景观缓滞水体面临的水华易发问题,然而该补水过程对景观水体的水华控制成效尚不明确.基于2019-2021年水质、水文、藻类实测数据,通过构建莲石湖8号湖水动力-水质二维耦合数值模型,结合现场监测数据对耦合数值模型进行率定与验证,探讨了在不同补水条件下8号湖叶绿素a含量和缓流区域的变化特征,定量分析了不同外调补水条件下缓滞区空间分布、叶绿素a浓度与典型景观缓滞水体水文条件的响应关系.结果表明:不同外调补水流量能够有效控制缓滞水体内叶绿素a含量,当外调补水流量为0.23～0.96 m3/s时,莲石湖8号湖表层水体中叶绿素a浓度较低且缓流区域面积较小.该研究结果可为城市景观水体水华控制及外调补水优化方案的制定提供技术支撑.

Microplastics (MPs) present in non-negligible amounts in urban environments, where urban rivers serve as important transport channels for MPs. However, the footprint of MPs in urban rivers under the influence of natural and anthropogenic factors is poorly understood. This study investigated the MPs organization, stability and pollution risk before and after rainfall in the Qing River, Beijing. Rainfall potentially diluted the MPs abundance, attributed to opening of barrages and increase of flow velocity. The proportion of small-sized MPs (SMPs, 48-300 mu m) decreased slightly, whereas that of normal-sized MPs (NMPs, 300-1000 mu m) and large-sized MPs (LMPs, > 1000 mu m) increased. However, SMPs dominantly presented in the Qing River before and after rainfall. Polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polystyrene (PS) were main polymers observed in the Qing River. The proportions of PET and PS decreased, while PP and PE increased after rainfall. The main types of MPs introduced by stormwater were PP and PE. The elevated MP diversity integrated index after rain suggested that rainfall enriched the local sources of MPs. Rainfall reduced the stability and fragmentation of MPs owing to the introduction of large debris. NMPs and LMPs were susceptible to further fragmentation and downsizing, implying that MPs abundance in the Qing River tended to rise and SMPs might enriched. In addition, alteration of MPs fragmentation and stability reflected that the likely input source was wastewater treatment plant and atmospheric deposition before rainfall, whereas soil and road dust were possible sources after rainfall. The pollution risk assessment defined the MPs pollution risk of Qing River as low level and decreased after rainfall. This study demonstrated that rainfall substantially influences MPs organization in urban river and provided empirical support for MPs environmental behavior under influence of natural and anthro-pogenic factors.

Building inland waterways affects the natural structure, formation, and extent of the riverbed and riparian zone. It alters the hydrology and sediment deposition conditions and hence damages the aquatic ecosystem. To address the effects of the construction of inland waterways on the riverine biome, benthic macroinvertebrate communities were compared at different building stages of inland waterways along a gradient of shipping traffic density at two montane rivers in China. The Shannon–Wiener diversity index of the benthic macroinvertebrate communities ranged from 0.4 to 1.6; the lowest value was recorded in the completed inland waterway, while the highest value was recorded in the unaffected stretch. Principal component analysis and canonical correlation analysis showed the communities in the inland waterways to be distinct from those in the natural riparian habitats. Our results suggest that benthic macroinvertebrate communities can reflect the damage done by the hydromorphological modifications caused by building inland waterways. Benthic macroinvertebrate diversity and abundance should therefore be included when assessing the impact of building and operating inland waterways.

再生水作为城市景观水体生态补水的主要水源,能够改善城市景观水体水污染状况,但水体内较高的氮磷物质易造成水体富营养化爆发水华现象,因此,研究水生植物群落对景观水体水质及水生态系统健康的维持意义重大.镜河是以再生水为补水水源的新建景观河道,为提升水环境质量,以流场、COD、氨氮及硝态氮为指标,应用MIKE 21和ECO Lab搭建流域二维水动力水质模型,探究水生植被覆盖率为0、30％、50％及70％等4种方案对湖泊水环境质量的改善效果.研究表明:水动力水质模型在研究区具有良好的适应性,水动力模拟精度优良,水位模拟Nash-Sutcliffe效率系数(NSE)为0.78,相对误差(RE)为5.75％;随着水生植物群落覆盖率增加,水体停留时间延长,有效降低了河道内COD、氨氮、硝态氮等污染物浓度.当植被覆盖率达到70％,水体表面流速速率减缓,整体处于0.15～0.30 cm·s-1,COD、氨氮、硝态氮污染物浓度降解速率减缓,模拟结果显示最佳的植被覆盖率处于50％～70％.

根据1981-2020年永定河北京段官厅水库、雁翅断面、三家店和卢沟桥等4个水位监测站点的长序列水文数据,采用线性趋势分析法和Morlet小波分析法分析永定河北京段水位变化特征和水位周期变化规律,并依据NARX神经网络模型对河道水位进行模拟预测.结果表明:(1)永定河北京段年平均水位在1981-2020年间整体呈下降趋势;(2)2019年永定河北京段实施的生态补水工程和降水量增多成为水位提升的主要原因;(3)永定河北京段年平均水位存在12～31年的主周期变化特征,其中心尺度为28年,同时在28年时间尺度存在第一主周期,在28年时间序列上水位呈枯-丰-枯-丰-枯趋势;(4)利用NARX神经网络构建预测模型预测永定河水位变化,年最小误差绝对值为0,年最大误差绝对值为0.002 1,其模拟预测精度较高,可应用于永定河水位预测并进行推广使用.

A constructed wetland (CW) coupled microbial fuel cell (MFC) system that treats wastewater and generates electricity was constructed. The total phosphorus in the simulated domestic sewage was used as the treatment target, and the optimal phosphorus removal effect and electricity generation were determined by comparing the changes in substrates, hydraulic retention times, and microorganisms. The mechanism underlying phosphorus removal was also analyzed. The experimental results showed that the best removal efficiencies of the two CW-MFC systems that used magnesia and garnet as substrates were 80.3% and 92.4%, respectively. Phosphorus removal by the garnet matrix mainly depends on a complex adsorption process whereas the magnesia system relies on ion exchange reactions. The CW-MFC system can also generate electricity. The highest output voltage and stable voltage of the garnet system were both higher than those of the magnesia system. The maximum stable voltage of the garnet device was 500 mV, while that of the magnesia device was 290 mV. The microorganisms in the soil and in the electrode within the wetland sediments also substantially changed, indicating that microorganisms positively respond to the removal of organic matter and power generation. Combining the advantages of constructed wetlands and microbial fuel cells also improves phosphorus removal in the coupled system. Therefore, when studying a CW-MFC system, the selection of electrode materials, matrix, and system structure should be taken into account in order to find a method that will improve the power generation capacity of the system and remove phosphorus.

研究了不同运行工况条件下Orbal氧化沟工艺脱氮除磷效果.在水温25℃左右时系统脱氮效果较好,NH3-N去除率在90％左右,TN去除率67.14％左右.增加污泥回流比可以提高系统脱氮效率,污泥回流比为100％和200％时,TN平均去除率分别为55％和65％.好氧区DO在2 mg/L时,TP平均去除率为88％,好氧区过量曝气时即DO>3.5 mg/L,TP去除率也由95％下降到26％.结论:提高曝气量虽能提高NH3-N硝化效果,但并不能提高TN去除率;增加回流比可以提高脱氮效率,但需综合考虑能耗、运行费用等因素;维持好氧区DO浓度为2～3 mg/L,可以实现较好的除磷效果.

对基于跨界断面水质和污水治理任务双考核的水环境区域补偿内容、核算方法、实施效果等进行了详细介绍.2015年实施以来,水环境区域补偿金逐年下降.实践表明,基于跨界断面水质和污水治理任务双考核的水环境区域制度,对于落实属地政府水环境治理主体责任,改善区域水环境质量发挥了重要作用.文章建议下一步应针对不同河道、不同区域制定差异化考核指标,需要适时进一步提高断面补偿标准,将补偿核算内容向工业废水治理、畜禽养殖废水、面源污染治理等方面进行扩展.

Burrowing crabs are main constituent of estuarine wetlands ecosystems, and provide a variety of ecosystem functions including providing food for waterbirds and fishes, promoting nutrients cycling, and processing sediments deposition. Helice tientsinensis is the dominant crab species which inhabits almost the entire intertidal marshes of the Yellow River Delta. However, for a long time we ignored the crab bioturbation in this area. We know little about whether crabs have potential effects on sediment environment. Here, we investigated the crab burrow characteristics in three marsh zones, and we also analysed the sediment parameters among crab burrow mounds (chimneys), flats (flat areas between burrows), controls (outside of crab bed) and crab fecal deposit. We found that sediment was softer in crab burrow mounds than in flat and control areas. Higher crab density indicates softer sediment. Crab burrow mounds had saltier soil than the flats. Our results showed that sediment total nitrogen, total carbon and organic matter varied among mounds, flats, controls and crab fecal deposit, which indicated that crab bioturbation have potential effects on sediments redistribution and nutrients cycling. Our study is essential to clear the roles of crabs in ecosystems and will benefit for coastal saltmarsh protection and restoration.

The abundant riparian wetlands supported by the complex river network in Pearl River Delta (PRD) are under an intensely anthropogenic disturbance that threatens the local ecological environment. This paper examined the benthic invertebrate diversity and biomass within the Pearl River through a field study. A fieldwork was conducted to assess a hydrological connectivity gradient among the main channel of the Pearl River. The responses of macroinvertebrate metrics to the connectivity gradient and the restoration history in the river channel were examined. The Shannon diversity index ranged from 0.75 to 2.08, which was the highest among most connectivity river channels. Statistical analyses (PCA and CCA) revealed that the benthic abundance in high hydrological connectivity riverine habitats is clearly distinct from the low connectivity habitats. Results demonstrated that the diversity and density of macrobenthos are determined by hydrological connectivity and time span of the restoration (river channels). Therefore, conservation and restoration efforts should focus on the macroinvertebrate response to the hydrological connectivity of the river channels in PRD.

The increasing fragmentation and degradation tendency of estuarine wetlands due to rapid urbanization in coastal areas exert the urgent need to quantify the structural characteristic of wetland network, which involves the fragmentized wetland patches for wetland restoration and conservation. Although wetland networks have already been used for conservation planning on a regional scale, the variation of connectivity and structural characteristic has not been well studied. Therefore, this study gathered data from Landsat TM/ETM + images to construct the wetland network and employed the graph theoretical analysis to characterize the network evolution, structural connectivity changes, and network integrity alteration in the Pearl River Estuary, South China. The wetland network integrity was defined in the study, including structural connectivity and several functional attributes, the variation of six generated networks during 1979 to 2009 was analyzed as well. The wetland network exhibited a weakening topology over time, which is indicated by a significant decrease in the degree distribution, connectivity, and clustering coefficient. The diminishing trends of wetland network integrity reveal that although the latest wetland network can still protect the regional environment, the weakening phenomenon in its topology and integrity would reduce the ability of estuarine wetland network to resist external interference.

It can be seen by the Deutsch formula that the size of dust particles driving velocity directly determines the level of ESP collection efficiency.This paper improve the driving speed from analyzing the relationship of the major impact factor of ESP collection efficiency and the driving velocity to get the method of improving the dedusting efficiency of an electrostatic precipitator and provides aguidance for rational design of high efficiency and energy-efficient electrostatic precipitators.