Sulfate radical-based advanced oxidation processes (SR-AOPs) for antibiotic degradation are often hindered by the aggregation and toxic leaching of cobalt catalysts. Herein, we engineered a supramolecular cucurbit[7]uril (CB[7])-derived Co/Ca bimetallic nitrogen-doped carbon (CoCa/CN) catalyst. During pyrolysis, the earth-abundant calcium acted as an in-situ porogen and structural pillar, yielding a hierarchical porous C/N framework that spatially confined Co nanoparticles and prevented sintering. The optimized CoCa/CN exhibited exceptional peroxymonosulfate (PMS) activation, achieving outstanding degradation efficiency across various antibiotics. Tetracycline hydrochloride (TCH) was selected for detailed investigation, achieving 97.3% removal within 30 minutes. Mechanistic studies revealed a highly efficient singlet oxygen (1O2)-dominated non-radical pathway, alongside minor radical contributions. Density functional theory (DFT) calculations demonstrated that Ca incorporation optimized the electronic environment, significantly enhancing PMS adsorption and accelerating interfacial electron transfer to stabilize the Co0/Co2+/Co3+ redox cycle. Furthermore, the system demonstrated robust pH adaptability, excellent anti-interference in complex water matrices, and successfully eliminated TCH developmental toxicity in zebrafish embryos. This study offers a sustainable paradigm for designing highly stable, eco-friendly bimetallic catalysts for environmental remediation.

There is a significant gap in understanding how crop residues with varying carbon-to-nitrogen (C/N) ratios mitigate soil acidification in acidic soils, particularly considering the complex interplay between soil C chemistry, pH, nutrient dynamics, and their subsequent effects on microbial community composition and enzymatic activities. Here, a 65-day incubation experiment was conducted using four crop residues with varying C/N ratio (rapeseed cake 7.6; peanut straw 27.0; rice straw 48.6 and wheat straw 93.6), aiming to fill these knowledge gaps in the two typical acidic long-term tea garden soils. Results showed that the incorporation of crop residues significantly enhanced edaphic characteristics and mitigated soil acidification. In strongly acidic soil (pH 4.12), rapeseed cake increased SOC recalcitrance, while promoting SOC decomposition in slightly acidic soil (pH 4.75). Furthermore, residue incorporation markedly altered microbial community composition, notably reducing fungal-to-bacterial and G+-to-G− ratios in slightly acidic soil. Soil C chemistry, the primary factor, interacting with pH and nutrients influenced microbial composition and enzymatic activities. Specifically, in strongly acidic soils, microbial composition was determined by the interaction of pH and C chemistry, whereas in slightly acidic soils, it was driven by the interaction between C chemistry and phosphorus content. Correspondingly, enzyme activities were influenced by the interaction of C chemistry with phosphorus in the former soils and nitrogen in the latter soils. Overall, our findings confirm the importance of rapeseed cake in enhancing soil multifunctionality, especially in strongly acidic soil, and highlight the critical role of C chemistry, soil pH, and nutrient interactions in shaping microbial composition and function in acidic soils.

Due to its high nutrient utilization efficiency, liquid organic fertilizer has become a research hotspot in the field of agricultural planting. Artificial humic acids, which are near-nature products, can be deemed as a green liquid organic fertilizer, but few studies have been reported, which has limited their further application. In this study, artificial humic acids were derived from municipal sludge, and their effect on rice growth, soil fertility, and dissolved organic matter was investigated using multi-chamber root box experiments. The shoot and root biomass of rice can be significantly enhanced by artificial humic acids, and the heavy metal concentration in rice was within safe limits. Artificial humic acids can limit the decrease in soil pH, especially in the far-rhizosphere zone, and improve the distribution of nutrients in the rhizosphere, near-rhizosphere, and far-rhizosphere zones. The use of artificial humic acids led to a significant decrease in soil electrical conductivity. The dissolved organic carbon content in the root zone was significantly increased, and the fluorescence intensity of dissolved organic matter in the rhizosphere was significantly increased. The proportion of specific components of dissolved organic matter was just slightly changed in the rhizosphere and near-rhizosphere zones. Artificial humic acids promoted the humification of dissolved organic matter in the near-rhizosphere and far-rhizosphere zones. The findings indicate that the environmental impact of artificial humic acids is significantly different from conventional chemical fertilizers, and they show huge potential in the agriculture field.

The global food crisis provides an impetus for agricultural green transformation via optimized fertilization methods. While organic substitution, green manure incorporation, and targeted fertilization sites have individually shown promise in enhancing rice yield, there is still a gap between optimized fertilization methods and achieving sustainable rice production. To explore the factors influencing rice yield across different fertilization strategies, we conducted a field experiment in Southern China encompassing five treatments, such as CK (no N input), RN (broadcasting urea with recommended N rates), RON (broadcasting organic-inorganic fertilizer with recommended N rates), RONS (side-deep placement of organic-inorganic fertilizer with recommended N rates), and RONSA (coupled RONS with Azolla [Azolla pinnata R. Brown]). Using a Minimum Data Set approach, we identified the primary variables influencing soil properties and rice production, with a focus on soil physicochemical characteristics and bacterial communities. Further, the soil properties index (SPI), calculated by multiplying the linear score with the weight of each variable, served as an indicator of soil properties variations. Our findings revealed that RONSA significantly increased the SPI by 21.1% compared with RN, predominantly because of higher soil labile organic carbon (LOC) and available N (SAN) fractions (p < .05). N uptake in rice plants (23.9%-28.4%) increased dramatically under RONSA leading to higher rice yield (11.0%-16.9%) and NUE (30.2%-36.1%) than RN (p < .05). The enhancement in soil properties, characterized by increased LOC, SAN fractions, and bacterial community diversity, was essential in boosting rice yields, with dissolved inorganic N emerging as the dominant contributor. In summary, our results highlight the effectiveness of integrated fertilization approaches in enhancing soil properties, subsequently leading to improved rice yields and NUE. This fertilizer strategy holds promise for guiding field fertilization practices and advancing sustainable rice production.

Urban ecological spaces are effective thermoregulators under global warming. However, the cooling efficiency of urban ecological spaces during the urbanization has not been studied comprehensively. Here, we investigate the spatio-temporal dynamics of Urban Cold Island (UCI) intensity in 11 typical cities of the Yangtze River Economic Belt (YREB). We determined the impact of ecological landscape trends on these dynamics by using GlobalLand and MODIS 8 d mean land surface temperature (LST) data for three periods (2000, 2010, and 2020), and the landscape pattern index and diversity index. We found that in the past 20 years, the built-up area has increased by sixfold; 62.53 % and 37.47 % of YREB were warming or cooling, with 71.22 % of the daytime cooling and 93 % of the nighttime warming. The average UCI intensity of YREB has increased from 0.518 to 0.847 and is negatively correlated with LST with a decreasing slope. As the UCI intensity of green spaces increased, that of blue spaces decreased. Surface area and landscape pattern are the key determinants of UCI intensity in blue and green spaces, respectively, especially the landscape shape index (LSI). Therefore, maintaining ecological spaces, enriching the structural integrity of green spaces, and improving blue space connectivity can help cities at different development levels cope with heat stress during regional urbanization.

Biochar and hydrochar have garnered widespread attention owing to their excellent performance in environmental remediation, carbon sequestration, and resource utilization from biowaste. Studies on the release potential of dissolved organic matter (DOM) have been limited, and the distinction between biochar and hydrochar remains unclear. In this study, pine sawdust was utilized as a model precursor with the aim of comparing the release quantity, components, and properties of DOM from biochar (BDOM) and hydrochar (HDOM) under various simulated conditions. The amount of DOM released by hydrochar (38.20-190.49 g/kg) was significantly greater than that released by biochar (0.57-11.96 g/kg), and more DOM was released at higher temperatures and pH values. BDOM consists of three categories of components, namely, humic-like, protein-like, and benzoic acid-like and tyrosine-like substances compounds, whereas HDOM consists of four categories of components, namely, two categories of humic-like compounds and two categories of protein-like compounds. By using ESI-FT-ICR-MS technology, 8586 compounds in BDOM and 6428 compounds in HDOM were identified. A total of 4665 unique compounds were found in BDOM, 1416 unique compounds were found in HDOM under alkaline release conditions, and HDOM contained more unique compounds than those found in other environments. CRAM/lignin-like compounds made up the majority of the released DOM and reached 31.01-65.35 % for BDOM and 54.79-73.05 % for HDOM. These findings revealed significant differences in the release potential of DOM from biochar and hydrochar, and further behavior research is needed to guide future applications of char materials in the environment and agriculture fields.

Water resources carrying capacity（WRCC） is the basis for the development of townships in inland river basin. To meet the needs of sustainable utilization of water resources in township construction and based on the understanding of WRCC conception, this study established a series of evaluation system for WRCC in township level. Comprehensive WRCC evaluation was carried out in the middle reaches of Heihe River. Key advancement strategies were analyzed by using multi-source data such as statistic, remote sensing or survey data by combing regulation metrics and comprehensive index. The results show that:（1） There were significant differences in water stress index and comprehensive index between different types of irrigated areas and between different types of townships, indicating that it is necessary to implement advancement strategies to improve the WRCC in key areas;（2） At the current annual development level, water right allocation, high-standard farmland, and industrial structure adjustment can improve the WRCC in townships to some extent. Except for the output value mode, all modes can basically improve the comprehensive carrying capacity by 0.01%-1.87%. Importantly, the high-standard farmland and industrial structure adjustment can effectively increase the comprehensive carrying capacity by 1.91%-8.72% and 0.11%-3.06%, respectively.

生态文明示范区是推进区域环境保护和社会发展协同共赢的重要平台和有效载体,包括国家生态文明建设示范区和"绿水青山就是金山银山"实践创新基地(简称"两山"实践创新基地),分别着力于构建以产业生态化和生态产业化为主体的生态经济体系、探索生态产品价值实现路径和模式,特别是在快速城市化地区.以长江三角洲(简称长三角)区域77个生态文明建设示范区和22个"两山"实践创新基地为对象,综合利用土地利用、夜间灯光和MODIS数据,分别构建遥感生态指数(remote sensing ecological index,RSEI)和综合夜间灯光指数(compoun-ded night light index,CNLI)代表生态环境质量和城市化水平,并采用空间叠加分析方法和耦合协调度模型探析长三角生态文明示范区建设水平和时空差异性.结果表明:(1)生态文明示范区在长三角区域分布具有不均衡性,生态文明建设示范区分布较为集中且以平原地形为主,"两山"实践创新基地分布较分散,以山地地形为主.(2)生态文明示范区生态用地面积占比超70％,具有较好的生态环境基础,"两山"实践创新基地RSEI指数高于生态文明建设示范区,生态环境质量优越,但更具脆弱性.(3)生态文明建设示范区CNLI指数及其增速均大于"两山"实践创新基地,具有更高的城市化水平和发展速度.(4)2017-2021年,生态文明建设示范区和"两山"实践创新基地RSEI和CNLI指数的耦合协调度呈现不断增加趋势,平均增幅分别为10.55％和8.90％,生态文明建设取得一定成效,其中江浙两省交界处耦合协调度最高.

The ecological civilization demonstration area includes the national ecological civilization construction demonstration area and the "Lucid Waters and Lush Mountains Are Invaluable Assets (as Two Mountains)" practice and innovation base, which focuses on the developing of an ecological economic system with industrial ecology and ecological industrialization as the mainstay, explores the path and model of realization of ecological product value, especially in rapidly urbanized areas. Taking 77 ecological civilization construction demonstration areas and 22 "Two Mountains" practice and innovation bases in the Yangtze River Delta (YRD) as the objects, the author utilized land use products, VIIRS, and MODIS data to construct remote sensing ecological index (RSEI) and compounded night light index (CNLI) to represent the ecological environment quality and urbanization level, respectively, and explored the level and spatiotemporal variability of ecological civilization demonstration construction in the YRD by using spatial superposition analysis and coupling coordination degree model. The results show as follow: (1) The distribution of ecological civilization demonstration area in the YRD is uneven, among which, the distribution of ecological civilization construction demonstration areas is more concentrated and dominated by plain terrain, while the "Two Mountains" practice and innovation bases are more dispersed and dominated by mountainous terrain. (2) The ecological land area of the ecological civilization demonstration area exceeds 70% and has a good environment foundation, among which the RSEI index of the "Two Mountains" practice and innovation base is higher than that of the ecological civilization construction demonstration area, and the ecological environment quality is superior, but it is more fragile. (3) The CNLI and its growth rate of the ecological civilization construction demonstration areas are higher than those of the "Two Mountains" practice and innovation bases, which has a higher urbanization level and development speed. (4) From 2017 to 2021, the coupling coordination degree between ecological environment quality and urbanization level of the ecological civilization construction demonstration areas and "Two Mountains" practice and innovation base showed an increasing trend, with an average increase of 10.55% and 8.90%, respectively, indicating that the ecological civilization construction has achieved certain results, with the highest coupling coordination degree at the junction of Jiangsu and Zhejiang Provinces.

The continuous advancement of urbanization and industrialization has greatly threatened the natural capital and its sustainable utilization in urban agglomeration. In order to clarify the characteristics of natural capital sustainability changes during the construction process of urban agglomerations, taking the Yangtze River Delta urban agglomerations as an example, two-dimensional and three-dimensional ecological footprint models were applied to analyze the change of ecological footprint, ecological pressure index（EPI） and ecological economic coordination index（EECI）, the natural capital stock consumption and natural capital flow occupancy, as well as the influencing factors and its related mechanisms, by adding the water resources account to the adapted ecological footprint model to reflect the water resource potential and demand in this area. The results showed that during the study period, the per capita ecological footprint and ecological carrying capacity of the Yangtze River Delta urban agglomeration were 4.46 hm~2/person and 1.59 hm~2/person, respectively; and the average per capita ecological deficit was 2.87 hm~2/person; however, the ecological footprint per unit GDP continued to decline, indicating that the utilization rate of resources continued to rise. From 2005 to 2019, the EPI value of the Yangtze River Delta urban agglomeration increased from 2.48 to 3.25, and the EECI value fell from 1.30 to 1.25. Based on the revised threedimensional ecological footprint model, it was found that the use of natural capital stock in the Yangtze River Delta urban agglomeration was increasing, and it had a significant inhibitory effect on the renewal of natural capital flows,and the consumption of natural capital stock was 2.26 times of capital flow in 2019, with the resource consumption occupied. The impact factors analysis showed that the industrial output value, total energy consumption,construction land area and urbanization rate played positive roles in promoting the ecological footprint and exerted greater pressure on the sustainability of natural capital. The relationships among the ecological pressure level,ecological environmental and economic development of the Yangtze River Delta urban agglomeration were quantitatively analyzed to provide a scientific basis and decision support for improving the ecological security and sustainable development of urban agglomerations.

Water resources play a key role in development. The research on water resources carrying capacity (WRCC) is helpful to judge the development status and provide suggestions for regional policy-making. In this study, the System Dynamics (SD) model and the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method are combined to calculate the change of WRCC of the Hangbu River basin from 2015 to 2035 under four development scenarios. The results show that WRCC of each scenario decreases first and then increases. The scenario that prioritizes water resources is the best for the Hangbu River Basin, under which the WRCC will increase to 0.631 in 2035, achieving a good level. This is different from other WRCC studies. Through analysis, the research method and the development level and focus of the study area may be the reasons for this difference. In addition, some suggestions were provided such as focusing on improving the efficiency of irrigation water use and looking at the long-term development of the region.

如何科学评估"绿水青山就是金山银山"(以下简称"两山")实践创新基地碳源碳汇的变化趋势、时空分布、影响因子,对指导新时期生态文明建设具有重要作用.以浙江省宁海县为例,基于IPCC碳排放清单,测度宁海县碳汇量与碳排放量,分析区域碳汇的空间分布规律,并基于方差分解分析探究宁海县碳排放的影响因素.结果表明,宁海县碳汇量呈现逐年增加的趋势,2003—2018年从43.91万上升至49.40万t,其中,森林碳汇量占比为88.21％～91.12％;碳源量呈现平稳—急剧上升—波动下降—保持稳定的变化趋势,由2003年的154.17万变化至2018年的508.87万t.从碳汇量的空间分布来看,宁海县县域碳汇大致呈现西部>东南部>北部>中部的西高东低格局;宁海县碳排放可被社会因素、经济因素和"两山"建设驱动因素共同解释,3个因素对碳排放的共有解释度为60.86％,各因子的解释度表现为经济因素>"两山"建设驱动因素>社会因素.该研究为国家"两山"实践创新基地的碳源碳汇量核算提供了新思路,可为下一步政策制定和县域绿色发展提供参考.

人与自然和谐共生是生态文明建设的重要内容,也是解决城镇化和城市生态环境问题的重要路径.面对城市和城市群生态安全屏障保护和绿色低碳转型发展的需求,笔者梳理了生态城市的内涵演进、城市生态系统观测现状,研究构建了基于人与自然和谐共生的生态城市建设观测指标体系,包括城市生态安全格局、生物多样性保护、人居环境健康、绿色转型发展4个方面的28项指标.从国家政策引导、地方实践创新和理论研究探索3个维度,结合我国生态城市建设实践,研究提出了生态城市功能提升路径,以期为新时期国家环境保护模范城市建设指标及测评标准制定提供理论依据和决策参考.

Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool to characterize DOM that interacts with heavy metals in MSWI bottom ash (IBA). Here, two fresh IBA samples collected from large MSWI plants were subjected to 33 days of accelerated weathering. Carbon content and fluorescence characterization of DOM and leaching behavior of heavy metals (Cu, Ba, Cr, Ni, and oxyanions) were monitored during the weathering. The mineralogical and chemical properties of IBA during the weathering process were also characterized. EEM combined with parallel factor analysis showed that fluorescent DOM could be decomposed into humic-like (C1, C2) and tryptophan-like substances (C3), while the accelerated weathering process can be further divided into three phases. Fitted cubic polynomials described well the changes in the specific intensity of fluorescence components. Humification and freshness indexes and SUVA results suggested the leached DOM contained a higher proportion of condensed aromatic structures and/or conjugation of aliphatic chains postweathering. The results also revealed that adsorption of humic-like substances onto neo-formed reactive surfaces occurred quickly in the early stage of accelerated weathering; thereafter, biodegradation of lower molecular mass-hydrophilic organic carbon fraction plays a vital role in further reduction of Cu and Cr leaching in subsequent weathering. Oxyanions (Mo and Sb) became more mobile after 3 days of accelerated weathering, but their leaching was effectively reduced after the weathering process. A novel method for an IBA weathering treatment combined with enhanced microbial degradation is proposed. These findings provide new and inspiration for improving accelerated weathering technology.

CO2排放是城市碳达峰预测研究的重要内容,准确核算碳排放对实现城市产业绿色转型发展与碳中和具有重要意义.主城区产业以生活功能、生产研发和服务业为主,缺乏独立的主城区能源消费统计,导致碳排放核查存在空白.为此,以南京某市辖区为研究对象,结合2011—2020年南京市能源统计数据,从碳排放影响因素和终端能源消费计算2个方面分析市辖区碳排放特征,并采用Kaya碳排放恒等式和LEAP模型,设置不同的情景,预测未来碳排放趋势和达峰时间.结果表明:2011—2020年研究区能源消费从108.99万增长至222.02万t(以标准煤计),CO2排放量仍处于快速增长期,2020年碳排放量相比2011年增长82.27％,但能耗强度由0.324下降到0.200 t·万元-1,化石燃料使用占比逐渐减少,用电量增加.2020年研究区碳排放强度为0.337 t·万元-1,低于南京市平均水平(0.75 t·万元-1).积极推动低碳转型发展,研究区可实现2030年前碳达峰的目标.人均生产总值和能源强度是影响主城区碳排放的最重要因素.研究结果为主城区碳达峰预测提供了一种可行的核算方法,对城市碳排放核算、减排模式优选及减排任务分解具有指导意义.

To find effective measures to control the water quality of the Hongmen Reservoir, it is necessary to better understand its phytoplankton composition, abundance and spatial and temporal distribution. Samples were collected at three sampling sites in January (dry season), May (wet season) and September (normal season) in 2019. Trophic level and stability status were assessed on the basis of the Shannon diversity index (H), species richness (S) and evenness (J) index. The different relationships between phytoplankton and the concentrations of several physicochemical parameters and the main soluble nutrients were evaluated by statistical tests. The results showed that there were 75 species belonging to seven groups of phytoplankton, including Chlorophyta (44 species), Bacillariophyta (12 species), Cyanophyta (9 species) and others (10 species). The phytoplankton community composition belongs to the Chlorophyta–Bacillariophyta–Cyanobacteria type structure; and Microcystis, Anabaena azotica Ley, Aphanizomenon, Melosira granulata were the main contributors to the dissimilarities in the temporal distributions of their communities. The phytoplankton density ranged from 4.42 × 106 to 8.99 × 106 particles/L, with an average of 6.45 × 106 particles/L, and the biomass was 4.42 × 106 ∼ 8.99 × 106 particles/L, with an average of 6.45 × 106 particles/L. The variation ranges of the Shannon–Wiener index (H′), Margalef index (D) and Pielou evenness index (J) were 2.05 ∼ 2.85, 4.12 ∼ 6.60 and 0.61–0.78, respectively. This research shows that the water in the Hongmen Reservoir is clean and that the pollution level is light. The correlation analysis shows that total phosphorus and dissolved oxygen are the main factors affecting phytoplankton community structure in the Hongmen Reservoir.

为评估"绿水青山就是金山银山"实践创新基地（"两山"基地）的"绿水青山"价值及绿水青山向金山银山的转化（"两山"转化）成效,以生态系统价值核算相关理论和方法为基础,构建了基于生态产品价值、生态调节价值和生态文化价值的"两山"基地生态系统生产总值（Gross Ecosystem Product, GEP）核算体系,并探索性地以生态产品价值和生态文化价值之和评估"两山"转化成效。以"两山"基地——浙江省宁海县为例,对2011—2018年宁海县GEP和"两山"转化价值进行核算。结果表明,2011—2018年期间宁海县GEP逐年提高,2018年GEP为1259.03亿元,较2011年增长了47.78%,是同年地区生产总值（GDP）的2.09倍,生态调节服务是宁海生态系统的最主要生态服务类型,其价值达670.59亿元,占GEP的53.26%。2018年,宁海县"两山"转化价值为588.44亿元,较2011年增长了1.39倍,其中旅游转化的贡献度最高。"森林宁海"建设、依托生态优势发展特色全域生态旅游、创新生态补偿机制开展流域生态环境整治等是宁海县GEP增长的主要驱动力。GEP核算体系可以作为"两山"基地建设成效评估和"两山"转化评估的参考依据。

随着乡村振兴战略深入推进,村镇建设正处于社会经济高质量发展转型时期.为研究村镇在快速城市化进程中经济社会发展与水资源承载力之间的关系,以南京市江宁街道为研究区,采用组合赋权法识别村镇水资源承载力关键影响因素,从空间管控、水资源利用、生态环境治理、生活宜居和经济发展5个层面构建评价指标体系,并采用主成分分析法开展水资源承载力评价研究.结果表明,2013-2018年研究区村镇水资源承载力水平存在波动,但整体呈现上升趋势,生态环境治理水平、空间管控和经济社会发展为研究区村镇水资源承载力主要影响因素,水资源利用水平是保障村镇水资源承载力的重要方面.该研究成果可为同类村镇在城市化进程中实现经济社会与水资源协调发展提供参考.

The raw water distribution systems (RWDSs) play key roles in urban water supply systems. The changes of disinfection byproducts (DBPs) precursors of trihalomethanes (THMs), haloacetic acids (HAAs) and halogenated acetaldehydes (HALs) in the RWDS in Taihu Basin were investigated by formation potentials. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) method and 454-pyrosequencing were employed to study the variation of molecular characteristics of low molecular weight-dissolved organic matter (LMW-DOM) and microbial communities of pipeline biofilms respectively, which played crucial roles in the variation of DBPs precursors. The results showed that both DBPs precursors and the molecular characteristics of LMW-DOM in the RWDS had changed. Moreover, the LMW-DOM could be an indicator due to the good positive correlation with precursors of HAAs and HALs. Specifically, the LMW-DOM showed continuous accumulation in the RWDS. The LMW-DOM tended to possess higher m/z and more CH2 or long alkyl chains while pre-chlorination controlled this trend. The LMW-DOM in the pre-chlorinated pipe section also possessed higher saturation. Additionally, lignins served as an important part of DBPs precursors and dominated the LMW-DOM. The microbial diversity decreased in the RWDS, and the abundance and diversity of the microbial community in the pre-chlorinated section were significantly lower than those in the no-chlorinated section. Finally, most DBPs precursors had positive correlation with dominant phylum and genus in RWDS. This study reveals variation of DBPs precursors, LMW-DOM and microbial pipeline biofilms as well, and provide important data for further research on raw water safety and stability in RWDSs.

Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool for characterizing dissolved organic matter (DOM), a key component of anaerobic digestion. In this study, the fluorescence characteristics of DOM during 55 days of anaerobic digestion of oil crop straw inoculated with rumen liquid were investigated. EEM spectroscopy coupled with parallel factor analysis (PARAFAC) showed that three major fluorescence components, tyrosine- (C-1), humic- (C-2) and tryptophan-like substances (C-3), were identified in all DOM samples. The F-max values of C-1 and C-3 increased rapidly during the first 5 d, decreased dramatically from day 5 to day 35, and then remained stable, while C-2 was not biodegraded. The changes in the F-max values of the fluorescence components reflected the biodegradation of lignin and/or embedded cellulose by rumen microorganisms. The changes in the Stokes shift of the fluorescence peak were readily explained by the variation in the hydrophobic/hydrophilic fraction distribution. The humidification index (HIX) and A : T ratio of the DOM decreased after 5 d and then increased gradually. Compared with the McKnight fluorescence index (MFI), the Y fluorescence index (YFI) was better able to track the evolution of the DOM. Correlation analysis of the different fluorescence indices (intensities) and absorbance indices was also carried out. The EEM-PARAFAC individual components, HIX and A : T ratio were conveniently used to characterize the degree of anaerobic conversion of the organic matter, and the peak at the Stokes shift of similar to 1.0 mu m(-1) was used as one of the indicators showing the stabilization of anaerobic digestion. These findings may assist in developing fluorescence technology for monitoring the anaerobic digestion of crop straw.