Nitrogen (N) enrichment typically enhances plant aboveground biomass (AGB) by alleviating N limitation. However, sustained or excessive N inputs can disrupt nutrient balance, constrain phosphorus (P) acquisition, and enhance root uptake of divalent cations such as manganese (Mn) ion, leading to Mn-induced damage to chlorophyll integrity and photosystem II function. Whether these changes may ultimately suppress further increases in AGB remains unclear. We conducted a four-year field experiment across a gradient of N addition rates (0, 2, 4, 8, 16, 32 g N m⁻2 yr⁻1) in a Tibetan alpine meadow. We measured plant AGB, foliar stoichiometric characteristics of functional groups (i.e., grass, sedge, forb and legume), and soil physicochemical properties. AGB exhibited a nonlinear response to N addition gradients. This pattern reflected an initial increase in AGB due to N-limitation alleviation, followed by suppression under high N addition driven by P limitation (foliar N:P ratios exceeded 16) and excessive Mn accumulation in leaves (up to 250.75 mg kg⁻1), which caused toxicity. The greater sensitivity of forbs to Mn toxicity compared to grasses contributed to the overall AGB being dampened, with the biomass gain in grasses insufficient to compensate. P limitation and Mn toxicity dampen the increase in AGB at continuous high N addition. These findings suggest that management strategies should focus on nutrient balance, such as P supplementation or optimized N fertilization rates, to sustain long-term productivity in alpine meadows under intensifying N enrichment.

The stoichiometry and allometry of nitrogen (N) and phosphorus (P) reflect nutrient absorption and dynamic allocation by plants, and can be regulated by global change factors (e.g. nitrogen enrichment, climate warming and altered precipitation). Yet, how multiple global change factors act interactively to influence the stoichiometric characteristics of N and P and their scaling relationships in different plant organs remains poorly understood. In a field experiment with treatments of nitrogen addition (Nadd), warming (W) and reduced precipitation (Pr) in an alpine meadow, we examined how global change factors interact to alter N and P stoichiometric characteristics of leaves and seeds. An allometry model (i.e. N = beta P alpha) was employed to detect changes in the scaling of plant N to P under different treatments. Our results showed that nitrogen addition significantly increased leaf N concentration (+44.0%), seed N concentration (+16.9%) and leaf N:P ratios (+27.8%) under ambient temperatures and significantly increased leaf N concentration (+53.7%) and leaf N:P ratios (+46.4%) under ambient precipitation. Importantly, nitrogen addition and warming (or reduced precipitation) had synergistic effects on P concentration of leaves and seeds, and antagonistic effects on N:P ratios of leaves. Moreover, although none of the three global change factors individually altered the scaling of N to P, nitrogen addition interacted with warming or with reduced precipitation to decrease the scaling exponents in leaves and increase them in seeds. Our results suggest that multiple global change factors can alter the N and P allocation patterns and result in decoupling of N and P in different plant organs. These findings highlight the importance of considering interactions of multiple factors when predicting dynamic changes in plant stoichiometric characteristics and nutrient utilization strategies under global change scenarios.Read the free Plain Language Summary for this article on the Journal blog. (sic)(N),(sic)(P)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)((sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic))(sic)(sic)(sic).(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(Nadd),(sic)(sic)(W)(sic)(sic)(sic)(Pr)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)((sic)N = beta P alpha)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)(sic)(+44.0%),(sic)(sic)N(sic)(sic)(+16.9%)(sic)(sic)(sic)N:P(sic)(+27.8%);(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)(sic)(+53.7%)(sic)(sic)(sic)N:P(sic)(+46.4%).(sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)N:P(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)((sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic))(sic)(sic), (sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)N(sic)P(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Water erosion in sloping cropland poses a significant challenge in the Mollisol region of Northeast China, largely due to the clay-rich soils and the presence of a compacted plow layer. Therefore, enhancing the hydraulic characteristics of soils is crucial for preventing erosion and degradation in this area. This study investigated the effects of composite soil amendments, comprising super absorbent polymers, polyacrylamide, and organic fertilizer, on soil hydraulic characteristics at the runoff plot scale. The experiment was conducted with four application amounts: low (M1), medium (M2), high (M3), and ultra-high (M4). The infiltration capacity of soils was determined by the in situ infiltration method, the water-holding capacity of soils was measured with the constant head method, the soil structure was quantified by the Yoder wet sieve method and the sandbox method. The results showed that, compared with the control (CK), different amounts of composite soil amendments all increased the soil infiltration capacity (i.e., initial infiltration rate, steady-state infiltration rate, near-saturation and saturated hydraulic conductivity), among which the enhancement effect under the low suction at −0.5 hPa was significant. Soil water-holding capacity was also increased, in which the natural water content and maximum water-holding content were increased by 0.58–12.18 % and 5.53–18.73 %, respectively. Applying a medium amount of composite soil amendment (M2) best increased soil hydraulic characteristics. The mechanism is that the composite soil amendments enhance soil infiltration capacity by increasing macroporosity, while the enhancement of soil water-holding capacity is affected by the combined effect of macroporosity and the increase of large soil water-stable macroaggregates (>2 mm). Overall, the composite soil amendment effectively increased soil hydraulic characteristics and can be recommended in the Mollisol region of Northeast China.

Soil acidification often suppresses microbial growth and activities, resulting in a negative impact on soil organic carbon (C) decomposition. While the detrimental effects of acidification on soil and plant properties have been extensively studied, less attention has been paid on the shifts in soil microbial communities and their influences of the decomposition of organic C with different chemical complexities. Taking advantage of an acid addition experiment in a Tibetan alpine meadow, here we examined the response of soil microbial communities to soil acidification and microbial effect on the decomposition of organic C with different chemical complexities (i.e., glucose and lignin, representing labile and recalcitrant C respectively). We found that soil acidification had no impact on microbial respiration and microbial abundance even though it decreased bacterial diversity significantly. Soil acidification increased the relative abundance of some microbial taxa, like Alphaproteobacteria and Acidobacteriia in bacteria increased by 36 %, 284 %, and Eurotiomycetes, Sordariomycetes and Leotiomycetes in fungi increased by 145 %, 279 % and 12.7-fold, but decreased the relative abundance of Acidimicrobiia by 33 % in highest acid addition treatment. Changes in microbial communities (bacterial and fungal community composition, the diversity of bacterial community and the ratio of fungi to bacteria) are significantly related to the decomposition of glucose and lignin. More specifically, soil acidification decreased the decomposition of glucose but increased the decomposition of lignin, indicating a trade-off between the decomposition of labile and recalcitrant soil organic C under soil acidification. Overall, shifts in microbial communities under soil acidification might be accompanied by an increased ability to break down more recalcitrant C. This trade-off between the decomposition of labile and recalcitrant C may change soil C quality under future acid deposition scenarios.

[目的]研究人居环境适宜性在时空尺度上的变化和驱动性因素,为城市建设和人居环境改善提供理论依据.[方法]以江苏省为研究对象,构建由社会、经济、生态和建设环境4个维度组成的评价指标体系,采用熵值法、趋势分析法、地理探测器法等对2009,2013和2017年江苏省65个县域的人居环境适宜性进行定量评价研究.[结果]①江苏省人居环境适宜性空间分异显著,总体呈现出“局部连片”,自南至北逐渐递减的空间分布特征.空间变化上,人居环境适宜性自南至北递减的空间分层显著度降低,中高水平、中水平和低水平地区连片分布趋势减弱.②2009,2013和2017年的江苏省人居环境适宜性的平均得分和变异系数分别为0.432,0.475,0.494和0.179,0.192,0.165.研究末期95.38％县域的人居环境适宜性得分上升,人居环境县级区域性差异减小.研究期间内,苏南地区各县域人居环境适宜性排名较稳定,苏中和苏北地区波动性显著.③地理探测研究表明,经济环境是江苏省人居环境适宜性演变的主要驱动力,社会和建设环境是关键动力,生态环境是次要动力.[结论]未来江苏省应扩大经济规模,刺激消费水平,促进经济发展及均等化,并主要通过缓解老龄化危机,加强区域人口资源流动,降低工业污染物排放量,提高空气质量等方面加强人居环境建设.

为了探究3种不同粒径的污泥生物质炭(S1:大粒径＞0.165 mm;S2:中粒径为0.025 ～ 0.165 mm;S3:小粒径＜0.025 mm)对Zn的吸附效率和固化稳定的机理,以此为污泥生物质炭在水污染控制方面的应用提供科学依据.利用实验室模拟法,研究不同反应时间、溶液初始pH和重金属浓度对生物炭吸附效果的影响,并运用四步萃取法分析生物炭上Zn的吸附形态.结果表明:①生物炭在4h左右达到吸附平衡,吸附率呈先增加后平缓的趋势,最终吸附量S1＞S2＞S3;②溶液初始浓度为0～2 mmol·L-1时Zn2+的吸附量呈线性增长趋势,但随溶液浓度超过2 mmol· L-1时吸附量开始趋于饱和;③3种不同粒径生物炭的水溶性组分Zn分别占总萃取量的1.70％、5.02％和7.47％,可交换态组分分别占25.27％、32.35％和27.29％,酸溶性组分分别占35.06％、38.63％和27.90％,非生物利用组分分别占37.97％、24.00％和37.34％.④污泥生物质炭的动力学吸附特征更符合准二级动力学吸附模型,单位质量的污泥生物质炭粒径越小吸附量越大;⑤污泥生物质炭的等温吸附特征更符合Langmuir模型,小粒径的生物质炭最大吸附量最优;⑥在酸性条件下随着pH的上升污泥生物质炭的吸附率在逐渐增加,碱性条件下吸附率的增加可能是形成锌的络合物沉淀导致的;⑦Zn的吸附形态以酸溶性和非生物利用态为主,水溶性占比较小.污泥生物质炭对Zn的吸附以化学吸附为主,S1吸附的Zn酸溶性组分和非生物利用组分占比最大,吸附效果较为稳定.

利用水热浸渍法制备了生物炭基-Co3O4复合材料(Co-OB),采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换衰减全反射红外光谱仪(ATR-IR)等手段对Co-OB进行表征,并研究了其活化过一硫酸盐(PMS)降解阿特拉津(ATZ)的性能,探究了PMS投加量、腐殖酸(HA)和Cl-对ATZ降解的影响.结果表明,在Co-OB活化投加量0.025g/L,PMS浓度200μmol/L,ATZ浓度20Mmol/L,室温条件下10min内ATZ的去除率为86.3％,与生物炭(OB)和Co3O4相比,其去除率为后两者之和的2.2倍.随着PMS浓度增加,ATZ去除率显著提高.Cl-、HA的存在抑制了ATZ的降解,且随Cl-、HA浓度增加,抑制程度增大.自由基猝灭实验表明·OH和SO4?-是ATZ降解的主要活性物种.通过液相色谱-质谱联用仪(LC-MS)分析出6种中间产物,并推测出ATZ的降解途径.稳定性实验表明Co-OB具有重复使用性及低Co2+溶出.

[目的]了解江苏省农田生态系统近年来碳源碳汇的基本演变趋势,识别江苏省农业发展过程中的重要碳排放源,指导江苏农业低碳化发展.[方法]利用模型对农田碳排放量、碳吸收量及碳足迹进行测算,并对其动态变化进行分析.[结果]①江苏省农田生态系统碳排放总量总体趋向于增加,2001年江苏省碳排放量为4.44×106 t,2016年碳排放量为4.60×106 t,增幅为3.4％,化肥为碳排放的主要贡献因子.碳排放强度总体表现为下降趋势,各阶段碳排放强度均低于1 t/hm2.②碳吸收量总体呈现增加趋势,2001-2016年农作物总碳吸收量增加了3.57×107 t,年均复合增长率约为2.2％,单位面积碳吸收量呈整体增加趋势.园艺作物的碳吸收量明显高于粮食作物和经济作物.③农田生态系统碳足迹总体呈现降低趋势,存在较大的生态盈余.[结论]①2001-2016年江苏省农田生态系统的碳吸收量明显高于碳排放量,具有良好的固碳能力,农田生态系统呈现碳汇;②农业投入物品对碳排放的影响程度不同,化肥是影响农业碳排放的最关键因子.

Green roofs can improve urban ecological conditions by mitigating the heat island effect and absorbing harmful gases. Soil additives can improve roof soil properties and promote the stability of the urban ecosystem. As soil additives, biochar and sludge are widely used in the ground, but their application on roofs is still scarce. This study examined the carbon storage potential of green roofs amended with sludge and biochar. The roof soil was composed of soil and varying proportions of the additives (0%, 5%, 10%, 15%, and 20%, v/v); Sedum lineare was then planted. The carbon contents of the soils and plants were measured for one year. The influence of biochar or sludge on the carbon content of the roof soil and the factors affecting the roof carbon storage potential were analyzed. The results showed that the carbon storage potential of a biochar green roof (9.3 kg C m−2) was significantly higher than that of a sludge green roof (7.9 kg C m−2). Biochar increased the carbon content of the green roof by improving the physical properties of the roof soil and promoting plant growth, whereas sludge increased the carbon content of the green roof by improving the chemical properties of the roof soil. Moreover, biochar could not only store large amounts of stable carbon, but also reduce the weight of the green roof, improve soil moisture, and provide a resourceful utilization of municipal sludge. Thus, biochar can be considered a material for promoting carbon storage on green roofs.

[目的]以江苏省镇江市新区大港片区某固体废物处理厂为研究对象,对地下水污染情况进行模拟研究,为同类建设项目及企业的地下水污染预测和防治提供参考.[方法]通过系统分析该固体废物处理厂野外水位和水质观测数据以及水文地质条件等资料,利用Visual Modflow软件构建了地下水水流和溶质运移模型.[结果]对厂区污水处理站防渗破损后特征污染物CODMn和氨氮运移情况以及地表硬化污染控制措施对污染物的阻隔效果进行预测评价,数值模拟预测污染物的影响范围、超标范围和最大运移距离.预测时间20 a后,污染物影响范围最大,运移距离最远,且CODMn影响范围较氨氮大,运移距离较远;地表硬化后,20 a后污染羽未超出评价范围.[结论]污染物主要沿水流方向迁移,对水环境的影响随时间逐渐增大,污染物浓度随着迁移距离的增加而减小,不同污染物在地下水含水层中的溶质运移范围和迁移距离不同.地表硬化措施能有效控制污染物扩散.

Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10–15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9–89.6% and 54.0–54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates.

Background Insect-proof nets are commonly used in crop production and scientific research because of their environmental, economic, and agronomic benefits. However, insect-proof nets can unintentionally alter the microclimate inside the screenhouse and therefore greatly affect plant growth and yield. To examine the microclimate and agronomic performance of pesticide-free rice under insect-proof nets, two-year field experiments were carried out in 2011 and 2012. Methods In the present study, the experiment was conducted by using a split-plot design considering the cultivation environment (open field cultivation (OFC) and insect-proof nets cultivation (IPNC)) as the main plot and the varieties as the subplot (Suxiangjing3 and Nanjing44). Results IPNC significantly reduced the air speed and solar radiation, and slightly increased the daytime soil temperature, daytime air temperature, and nighttime relative humidity. By contrast, the nighttime soil temperature, nighttime air temperature, and daytime relative humidity were relatively unaffected. The grain yield of both rice cultivars decreased significantly under IPNC, which was largely attributed to the reduced panicle number. The reduced panicle number was largely associated with the decreased maximum tiller number, which was positively correlated with the tillering rate, time of tillering onset, and tillering cessation for both rice cultivars under IPNC. In addition, dry matter accumulation significantly decreased for both rice cultivars under IPNC, which was mainly caused by the decreased leaf area duration resulting from the reduced leaf area index. By contrast, the mean net assimilation rate was relatively unaffected by IPNC. Discussion Insect-proof nets altered the microclimate in comparison with OFC by reducing the air speed and changing the radiation regime, which significantly affected dry matter production and yield of both japonica rice cultivars. Our results indicated that cultivation measures that could increase the tillering rate and the maximum tiller number under IPNC would lead to a significant increase in panicle number, ultimately increasing grain yield. In addition, maintaining a high leaf area duration by increasing the leaf area index would be important to compensate for the dry matter accumulation losses under IPNC. These findings are critical to provide a theoretical basis for improving agronomic performance of pesticide-free rice under IPNC.

Qinghai-Tibetan Plateau is the most sensitive region to global warming on Earth. Qinghai Lake, the largest lake on the plateau, has experienced evident area variation during the past several decades. To quantify the area changes of Qinghai Lake, a satellite-based survey based on Landsat images from the 1980s to 2010s has been performed. In addition, meteorological data from all the seven available stations on Qinghai-Tibetan Plateau has been analyzed. Area of Qinghai Lake shrank ~2% during 1987–2005, and then increased ~3% from 2005–2016. Meanwhile, the average annual temperature increased 0.319 °C/10 y in the past 50 years, where the value is 0.415 °C/10 y from 2005–2016. The structural equation modeling (SEM) shows that precipitation is the primary factor influencing the area of Qinghai Lake. Moreover, temperature might be tightly correlated with precipitation, snow line, and evaporation, thereby indirectly causes alternations of the lake area. This study elucidated the significant area variation of water body on the Qinghai-Tibetan Plateau under global warming since 1980s.

The Land Surface Temperature (LST) of a park is lower than the surrounding environment, and thus the parkland forms a Park Cool Island (PCI). However, more case studies are needed to reveal the relationship between park composition, vegetation characteristic and PCI development. The LST and Land Use/Land Cover (LULC) of 18 different sized parks in Changzhou, China were obtained from Landsat-8 and Mapworld Changzhou data. Then, a sample investigation method was used to calculate vegetation characteristics of these parks by an i-Tree Eco model. In order to reduce the impact from the external environment on PCI, the Temperature Drop Amplitude (TDA) and Temperature Drop Range (TR) inside the parks were analyzed by ArcGIS 9.3. Impact factors were tested by Pearson correlation analysis and curve fit to reveal the relationship between these factors and PCI formation. The result shows that a park area threshold of 1.34 to 17 hectares provides the best PCI effect, that park shape (perimeter/area), Leaf Area Index (LAI), density, tree cover, water cover, and impervious surface cover have significant correlation with PCI development, vegetation health and global climate change affect the PCI development. Advice is proposed to improve and maintain PCI effects.

[Objective] The gray water footprint was considered to evaluate the situation and trend of sustainable utilization of water resources in Jiangsu Province,and to provide scientific basis and policy support to some extent for the determination of reasonable water sustainable utilization strategies,and to give some innovative advices for water resources management.[Methods] The study calculated water footprint and its characteristics in Jiangsu Province from 2005 to 2015 by applying the water footprint theory,and analyzed the situation of sustainable utilization of water resource in terms of water footprint structure,social benefit,economic benefit and ecological security.In addition,GM(1,1) was used to predict the development trend in the next five years.[Results] ① The water footprint of Jiangsu Province showed an inverted U-shaped curve in the study periods got the highest(1.22×1010 m3) in 2011,and showed a fast declining trend.② Jiangsu Province can self-supply (average water self-supplication is 88.10％) in supply water resources.It is in a high level of economic and social benefit,but still be in a state of serious water shortage.③ According to the "Inertia development" situation,the water footprint in 2020 will have a 0.92％ decline as compared with that in 2015.[Conclusion] As the strictest water resources control system was applied,water use efficiency has been improved,and the water resources utilization of Jiangsu Province presents a trend of sustainable development.

[Objectives]The aim of this study was to analyze the stability of soil colloid and its ability to adsorb tetracycline from farmland soil under different fertilizations which aims to provide a theoretical basis for clarifying the colloid facilated-migration of tetracycline in soil.[Methods] The soil particles were divided into three fractions:0.053-2 mm,0.002-0.053 mm and ＜0.002 mm(soil colloid),respectively.The soil fertilization treatments were without fertilization (CK),chemical fertilizers only (NPK)and organic manure (OF).The dispersion stability of different soil colloids was analyzed by combination of static sedimentation method and dynamic light scattering technique.The kinetics of soil colloid under different electrolyte conditions was investigated.The effect of different electrolyte solutions on the surface potential of soil colloid was determined by zeta potential analyzer.Finally,the adsorption capacity,kinetics and isotherm of tetracycline on soil with different particle size were analyzed by batch adsorption method.[Results] The application of organic manure could significantly increase the content of large aggregates in soil and decrease the release of colloid.The released colloid content was highest in CK.The colloid in CK was easier to deposit and possessed the lowest stability.The critical coagulation concentration of soil colloid was in the order of OF,NPK and CK,indicating that the application of organic fertilizer will increase the soil colloid in the water.The addition of electrolyte could reduce the absolute value of zeta potential for the soil colloid,and then promote the soil colloid coagulation.The adsorption capacity of tetracycline in the soil in OF treatment was higher than other treatments.Among various particle sizes,soil colloid had the highest adsorption capacity towards tetracycline.[Conclusions] The application of chemical fertilizers and organic fertilizers could reduce the release of soil colloid.However,the application of organic manure was more favorable for the formation of large aggregates.For the soil colloid from OF treatment,the particle size was smaller,the zeta potential was higher,and the adsorption capacity of tetracycline was stronger compared to soil colloids in other treatments.Therefore,the application of organic fertilizer can effectively reduce the release of colloid in soil.However,it can also improve the stability of colloid in water and the adsorption capacity for tetracycline,thus affecting the distribution and migration of pollutant tetracycline in soil structure.

[Objective] The paper aims to further reduce pollutant concentration and improve the reclamation rate of wastewater in iron and steel enterprises.[Methods] We adopted two sets of horizontal subsurface flow constructed wetlands for the treatment of discharged coking wastewater in iron and steel enterprises,and investigated the impacts of wetland vegetation with and without organic mulches on the treatment of discharged coking wastewater by constructed wetland in winter through the monitoring and analyzing the turbidity,chemical oxygen demand(COD),total nitrogen(TN),and total phosphorus(TP) concentrations in influent and effluent.[Results] In low-temperature season,the hydraulic retention time was 5 days,the average removal rates of turbidity,COD,TN,and TP was 68.55％,14.94％,14.20％ and 71.26％ in constructed wetland without organic mulches while the average removal rates of those in constructed wetland with organic mulches was 72.54％,21.62％,20.50％ and 71.88％,respectively.The removal rates of COD and TN increased by 44.68％ and 44.45％,respectively.[Conclusion] Organic mulches could be used as insulating material to help increase the purification rate of constructed wetland under the low-temperature condition.

[Objective] A scientific and systematic assessment of the feasibility and ecological value of urban roof greening construction is the prerequisite for a safe and sustainable exploitation of the idle roof resources in cities. It also profits urban ecological environment and assists city planners and managers in their decision-making regarding green roof development.[Method] This study selects the center area of Xinbei District, Changzhou City as a target and aims to build an index system for the feasibility and ecological value assessment of urban roof greening. Remote sensing image technology is employed to collect data for the index system, combined with raster image overlay and reclass methods in ArcMap software for construction feasibility evaluation. [Result]These methods reveal that in the total roof area of ap-proximately 150500 m2 , 72600 m2 proves suitable for roof greening, among which 19600 m2 is fit for intensive green-ing, 40000 m2 for semi-intensive greening and 13000 m2 for extensive greening. After feasibility assessment, market value method is then applied to analyze the ecological value of roof greening in the center of Xinbei District from four as-pects, namely, air quality promotion, carbon fixation and oxygen release, energy conservation, and rainwater adjustment. The ecological value is found to be 16.87 Yuan ( RMB) / (m2·a).[Conclusion]The study comprehensively analyze the feasibility and sustainability of roof greening construction in the study area, and help to improve the efficien-cy of the use of urban building roof.

[Objective] Applying low altitude remote sensing to the acceptance of soil and water conservation facilities so as to extract vegetation information based on visible spectrum from remote sensing image,and to propose an accurate and objective method to calculate the coverage rate which is an indicator of the soil and water conservation facilities evaluation in the hope of reducing workload and improving effectiveness.[Methods] The spectral characteristics of low-altitude remote sensing images containing only visible spectral information were analyzed by five vegetation indices as RGRI (ration vegetation index),EXG (excess green),VDVI (visible-band difference vegetation index),NGBDI (normalized green-blue difference index)and NRGRDI (normalized green-red difference index).And the threshold of each vegetation index was determined by the maximum entropy method or bimodal histogram method.Furthermore,with the help of ENVI,the vegetation information was extracted and the vegetation coverage were then calculated and compared with references.[Results] The accuracy of vegetation information extracted from the visible-band difference vegetation index (VDVI) was as high as 95.32％,and the vegetation coverage was 54.43％,which was the closest to the actual value.[Conclusion] It is feasible to calculate vegetation coverage from remote sensing image based on visible band.The method can provide real-time data as supporting information for the acceptance assessment of soil and water conservation facilities with its advantage of few artificial intervention and high accuracy.