长江中游不同潜育化土壤诊断指标探讨

田间原位测定，室内分析和模拟试验的结果表明，长江中游垸田土壤潜育化过程中发生一系列物质变化，其中以活性还原物质量，Ａｌ２（ＳＯ４）３溶液提取的亚铁量和氧化还原电位三者变化最为显著。活性还原物质量和亚铁量与潜育化作用强度正相关，而氧化还原电位则呈负相关。     

膨润土、煤渣在稳定底泥中对上覆水体及底泥pH Eh COD的影响

采用静态模拟试验,选取膨润土、煤渣为帽封材料,研究两者覆盖于河水底泥表层后各体系上覆水体及底泥的pH、氧化还原电位（Eh）、有机含量指标在60 d的变化情况。结果表明：底泥表层覆盖膨润土或煤渣后,上覆水体中的pH约为7.5,Eh在80~110 mV波动,均未造成持久严重的影响;同时由于它们的吸附性能使得上覆水体CODCr在反应周期里有所减少。膨润土存在体系,其底泥pH在反应周期里呈下降趋势,Eh呈上升趋势,底泥有机质去除率在25%左右。而煤渣帽封于底泥上,其底泥pH、Eh在反应周期里均呈上升趋势,底泥有机质去除率约为19%     

典型城内过富营养湖泊沉积物和间隙水中各形态磷的相关性研究

研究了武汉市繁华市中心典型过富营养湖泊沉积物—间隙水体系磷形态的相关性。对沉积物—间隙水中磷形态的连续提取分析发现,自然粒度下,沉积物中有机质含量与沉积物中有机/细菌聚合磷存在很好的线性相关性,说明沉积物中有机质是有机/细菌聚合磷的源;沉积物中总磷决定间隙水中总溶解性磷和溶解性磷酸盐的含量,并且总磷与间隙水中总溶解性磷和溶解性磷酸盐存在很好的相关性;沉积物中Fe P和Al P分别与间隙水中的Eh和溶解性磷酸盐存在相关性,说明Eh的大小严重影响Fe P和Al P的含量,但是Fe P和Al P含量之和又主导着间隙水中溶解性磷酸盐的含量。对典型市内过富营养湖泊的沉积物－间隙水体系中形态磷的相关性研究,旨在为控制这种典型过富营养湖泊沉积物中磷向水体释放提供理论参考。     

Investigating options for attenuating methane emission from Indian rice fields

The development of methods and strategies to reduce the emission of methane from paddy fields is a central component of ongoing efforts to protect the Earth's atmosphere and to avert a possible climate change. It appears from this investigation that there can be more than one strategy to contain methane emission from paddy fields, which are thought to be a major source of methane emission in tropical Asia. Promising among the mitigating options may be water management, organic amendments, fertilizer application and selection of rice cultivars. It is always better to adopt multi-pronged strategies to contain CH4 efflux from rice wetlands. Use of fermented manures with low C/N ratio, application of sulfate-containing chemical fertilizers, selection of low CH4 emitting rice cultivars, and implementation of one or two short aeration periods before the heading stage can be effective options to minimize CH4 emission from paddy fields. Among these strategies, water management, which appears to be the best cost-effective and eco-friendly way for methane mitigation, is only possible when excess water is available for reflooding after short soil drying at the right timing and stage. However, in tropical Asia, rice fields are naturally flooded during the monsoonal rainy season and fully controlled drainage is often impossible. In such situation, water deficits during the vegetative and reproductive stage may drastically affect the rice yields. Thus, care must be taken to mitigate methane emission without affecting rice yields.     

四川水力资源开发和长江上游水土保持的思考

四川具有丰富的水力资源，在西部大开发的形势下，将大力进行开发。根据四川境内的四大河流流域的水土流失及河道泥沙资料，经初步分析，认为水土流失与河道泥沙的关系非常密切，二者成正相关态势。然后，进一步探讨了长江上游水利工程在阻挡流失水土进入长江主河道过程中的地位和作用，探讨表明，这些水利工程有效地阻拦了流失水土进入长江河道；与此同时，水利工程，如电站，水库等的库容却大大减少,降低了工程效益发挥，缩短了使用年限。在此基础上，还探讨了控制水土流失，大力开发四川水力资源和进行长江上游生态屏蔽建设的措施。在四川水力资源开发过程中，对四川，对整个长江流域，必须工程效益和生态效益并重，故应当加强水土保持生态环境建设，而生物工程植物治沙措施在这一问题中具有特殊意义。     

三峡库区不同退耕还林模式水土流失特征及其影响因子

三峡库区为国家水土保持重点防治区,土地利用/覆盖变化（LUCC）与水土流失的关系已成为水土流失治理研究的关注重点之一,退耕还林工程的水土保持效益对于库区生态环境的建设具有重要意义。通过对库区典型退耕还林模式的水土流失的监测,分析其不同降雨条件下水土流失特征及影响因子,结果标明：（1）退耕还林后库区的水土流失问题得到了有效控制,退耕还林后各土地利用类型的年地表径流量下降了70%~95%,泥沙流失量则比农田降低了97%以上,其中乔木林和竹林对水土保持的效果最为理想;（2）退耕还林后各土地利用类型年地表径流量与降雨量呈较好的指数关系,随着降雨量的增加而增加。除农田和板栗林外,各土地利用类型年地表径流量与雨强关系不显著;（3）泥沙流失量与降雨量和降雨强度的关系均不显著;（4）各土地利用类型地表径流的80%以上,泥沙流失量的95%以上都是发生在暴雨条件下,暴雨事件成为库区水土流失的主要气候影响因素;（5）凋落物层盖度是控制退耕还林各模式地表径流的主要因素,各土地利用类型的年地表径流量均随着凋落物层盖度的增加而显著降低     

太湖水体中悬浮物研究

为了全面了解太湖水中悬浮物的物质组成、变化规律,选取了太湖站近10年来各测点的连续观测资料及2次定点观测资料,分析了太湖水体中悬浮物的无机和有机颗粒成份、时空分布、垂直变化、与风速、风向的关系以及与重要光 学参数的关系。研究结果表明：太湖悬浮物中有机物大概占30%;浓度大小的湖区分布大致是：湖心区＞河口区、梅梁湖、贡湖、五里湖＞东太湖;悬浮物浓度的季节变化是：湖心区冬季、春季＞秋季＞夏季,东太湖冬季＞春季、夏季、秋季,其他湖区则没有明显季节变化;垂直分布是：深层＞表层并且底泥悬浮的临界风速在5~6.5 m/s之间;悬浮物浓度的增加是引起湖水透明度降低和光学衰减系数增大的主要原因。     

三峡工程蓄水后荆江河段河势变化及生态护岸研究

三峡工程蓄水以来,进入长江中下游河道的水沙过程发生明显改变,从而导致中下游河道尤其是荆江河段冲刷、崩塌,局部河段河势调整较为剧烈,并导致主流顶冲部位发生变化,可能会引起新的崩岸发生。分析了荆江河段河势变化特点,列举了各种传统护岸方法,分析了传统护岸的特点和适用性,针对传统护岸工程的不足,提出生态护岸理念,在满足整体性、稳定性、适应变形等要求下,采取工程措施与植物措施共同护岸,并为河道与河岸之间水分交换提供条件,建立了水生生态系统和陆地生态系统之间的联系,实现了河流原本完整的结构和作为生态廊道的功能,进而保证整个生态系统的稳定,有利于生态环境的保护和水土保持,实现生态理念,满足生态需要,达到人与自然和谐发展。     

三峡水库消落带优势草本植物残体淹水后温室气体排放特征

三峡水库消落带淹水后植物腐烂分解，向水体释放碳、氮养分，可能导致二氧化碳（CO₂）、甲烷（CH ₄）和氧化亚氮（N₂O）等温室气体（GHGs）排放，消落带可能成为大气GHGs的排放源，但目前植物淹水腐解导致的GHGs排放还缺乏定量研究。选择三峡水库消落带优势草本植物狗牙根（Cynodon dactylon (Linn.) Pers.）、水蓼（Polygonum hydropiper）、鬼针草（Bidens bipinnata Linn.）和苍耳（Xanthium sibiricum Patrin ex Widder.）的茎叶，开展为期120 d的室内浸泡模拟淹水实验，测定植物残体干重、上覆水的水化学指标和养分浓度并监测其动态变化，同时测定水-气界面GHGs排放速率，旨在查明消落带植物残体淹水后的GHGs排放过程和通量及其植物种间差异。结果表明:植物残体淹水初期（前15 d）干重下降较快，随后下降变缓，其中苍耳干重损失最大，狗牙根干重损失最小；植物残体淹水初期（前15 d）水-气界面的GHGs快速排放，淹水第4~7 d达到峰值，中后期（第30 d起）平稳排放，鬼针草和苍耳淹水后水-气界面GHGs排放速率显著高于狗牙根和水蓼（P<0.05），鬼针草和苍耳淹水后CO ₂和CH₄累积排放量显著高于狗牙根和水蓼，苍耳、鬼针草和水蓼淹水后N₂O累积排放量显著高于狗牙根，总体而言，狗牙根淹水后GHGs排放量最低；消落带优势草本植物残体淹水后的CO₂和CH ₄排放速率随上覆水的DOC浓度升高而增加， N₂O排放速率与上覆水的NO^-₃-N浓度具有正相关关系，受NO^-₃-N浓度驱动。同时，植物形态和其碳氮含量影响植物淹水分解速率、进而影响养分释放和GHGs排放。     

三峡库区172 m蓄水位实现后干流水体溶解态重金属含量变化特征

从2008年至2010年连续两年,对三峡库区涪陵至巴东段水体溶解态重金属含量进行监测,分析三峡水库自2008年首次以172 m高水位试验性蓄水以来水体溶解态重金属含量变化特征及其影响因素。结果表明：水体溶解态重金属含量在丰水期低水位时含量较高,而在平水期和枯水期高水位蓄水时,水体重金属含量较低,丰水期时水体溶解态重金属含量虽然相对较高,但仍然达到《地表水环境质量标准》(GB 3838 2002)Ⅰ类水域标准。重金属在水体与沉积物和消落带土壤中含量并无明显相关性,沉积物和消落带土壤重金属对水体溶解态重金属含量分布影响较小。库区水环境因素在丰水期和平水期、枯水期呈现出明显差异特征,特别是汛后水体悬浮物SS含量远低于丰水期。三峡水库水环境因素的变化对重金属的分配有着重要作用,丰水期过后三峡库区水体pH值和DO升高,水温和Eh降低,SS含量显著下降,水环境因素、气象条件、水位调度等因素的变化致使水体溶解态重金属含量降低     

不同麦秸还田方式对周年稻麦轮作农田碳足迹的影响

为明确麦秸不同还田方式对稻麦轮作农田碳足迹的影响,该研究通过开展两年的大田试验,设计了3种麦秸还田方式（麦秸旋耕还田、麦秸翻耕还田和麦秸沟埋还田）,并以麦秸不还田为对照,采用静态箱-气相色谱法连续两年对农田温室气体排放进行监测,并对不同麦秸还田方式的生产资料投入和生产过程碳排放及温室气体排放进行全面分析。结果表明：(1）与不还田相比,麦秸还田显著增加了稻季日均CH4排放,稻麦周年全球增温潜势95%来自稻田CH4排放;（2）在水稻季,农田CH4排放占碳足迹总量比例最大,3种麦秸还田方式中,麦秸沟埋还田处理下碳足迹最小,且能比麦秸旋耕还田处理减少4.9%;(3）在小麦季,化肥投入造成的碳足迹所占比例最大,为64.5%~77.4%,其次是土壤N2O的排放;（4）从整个稻麦周年轮作系统来看,与麦秸旋耕还田和麦秸翻耕还田处理相比,麦秸沟埋还田处理能分别减少4.6%和3.6%的周年碳足迹及8.7%和4.9%的周年单位产量的碳足迹。因此,对于稻麦轮作地区,采用麦秸沟埋还田能在一定程度上降低农业生产过程中的碳足迹。     

长江中下游滨岸带水体温室气体释放的时空分布特征

内陆河流生态系统作为大气中温室气体通量交换的热点区域,对全球的碳循环有重要影响。分别于平水期(2017年5月)和丰水期(2018年7月)对长江中下游滨岸带水体两种温室气体(CH_4和CO_2)释放通量进行了调查研究。结果表明:平水期时,CH_4和CO_2的释放通量分别为0.39～9 668.83 nmol·m~(-2)·h~(-1)和0.25～3 229.41μmol·m~(-2)·h~(-1),平均值为298.24±1 308.65 nmol·m~(-2)·h~(-1)和290.75±645.99μmol·m~(-2)·h~(-1);丰水期时,二者的释放通量为-22.80～329.76 nmol·m~(-2)·h~(-1)和-110.21～16.39μmol·m~(-2)·h~(-1),平均值为21.51±49.56 nmol·m~(-2)·h~(-1)和-3.63±13.25μmol·m~(-2)·h~(-1)。水体温度、pH、溶解性总磷浓度、溶解性有机碳和溶解性有机氮比值是影响CH_4和CO_2通量的重要因素。CH_4和CO_2释放通量还受到通江湖泊的缓冲和入江河流输入的影响,表现为河口水系高,湖口水系低的特点。由于外源污染和滨岸带土地利用的差异,城市岸带的CH_4和CO_2排放量最高,其次为自然岸带,湿地岸带和河口较低,通量最低的为化工园岸带。估算表明,长江全年碳排放以CO_2为主,年释放量约为1.93×10~7 t(C),CH_4年释放量约为2.28×10~(4 )t(C),低于世界上一些其他大型河流。     

Environmental geochemistry and pollution studies of Aliaga metal industry district

The Aliaga metal industry district located 50 km northwest of Izmir City, in Turkey, includes many metal factories. The geology of the area is represented by Mesozoic flysch deposits and Cenozoic volcano sedimentary rocks. Tectonic elements are NE-SW and NW-SE trending faults and a W-NW trending fault direction that is important for water supply. Rock, soil, stream sediment, and water samples taken at various distances from the industrial area were analyzed for Fe, Ti, Mn, Cr, Pb, Cu, Ni, Zn, and Mo. According to the results, the elements in rocks are reasonable for the range of "Clarke" values, but in the soils and stream sediment, they comprise higher values than are acceptable for agricultural activities. Toxicity analyses were carried out in the drinking artesian water of Cakmakli village and wastewater samples of the factories and river water both of which are used for irrigation of the agricultural areas in and around the investigated area. The people should, however be made aware that this waste and river water is unacceptable for agriculture. Additionally, the contamination of seawater in Nemrut Bay is probably caused by contaminated river and underground water running to the sea. The chemical and toxicity analysis of drinking water samples show that they are above accepted standards and harmful. Previous air pollution studies (funnel gas emission analyses) also show that gas emission contains high amount of dust particles with high Fe, Zn, Pb, and Cu concentrations. As a result, all elements analyzed are of great importance relative to problems concerning contamination of the soil, stream sediment, ground surface water, and air by individual metals from uncontrolled processing of some metal factories.     

农田固碳措施对温室气体减排影响的研究进展

农田是CO2,CH4和N2O三种温室气体的重要排放源,在全球范围内农业生产活动贡献了约14%的人为温室气体排放量,以及58%的人为非CO2排放,不合理的农田管理措施强化了农田温室气体排放源特征,弱化了农田固碳作用。土壤碳库作为地球生态系统中最活跃的碳库之一,同时也是温室气体的重要源/汇。研究表明通过采取合理的农田管理措施,既可起到增加土壤碳库、减少温室气体排放的目的,又能提高土壤质量。农田土壤碳库除受温度、降水和植被类型的影响外,还在很大程度上受施肥量、肥料类型、秸秆还田量、耕作措施和灌溉等农田管理措施的影响。本文通过总结保护性耕作/免耕,秸秆还田,氮肥管理,水分管理,农学及土地利用变化等农田管理措施,探寻增强农田土壤固碳作用,减少农田温室气体排放的合理途径。农田碳库的稳定/增加,对于保证全球粮食安全与缓解气候变化趋势具有双重的积极意义。在我国许多有关土壤固碳与温室气体排放的研究尚不系统或仅限于短期研究,这也为正确评价各种固碳措施对温室气体排放的影响增加了不确定性。     

Exploring the fate,transport and risk of Perfluorooctane Sulfonate (PFOS) in a coastal region of China using a multimedia model

Perfluorooctane Sulfonate (PFOS) and related substances have been widely applied in both industrial processes and domestic products in China. Exploring the environmental fate and transport of PFOS using modeling methods provides an important link between emission and multimedia diffusion which forms a vital part in the human health risk assessment and chemical management for these substances. In this study, the gridded fugacity based BETR model was modified to make it more suitable to model transfer processes of PFOS in a coastal region, including changes to PFOS partition coefficients to reflect the influence of water salinity on its sorption behavior. The fate and transport of PFOS in the Bohai coastal region of China were simulated under steady state with the modified version of the model. Spatially distributed emissions of PFOS and related substances in 2010 were estimated and used in these simulations. Four different emission scenarios were investigated, in which a range of half-lives for PFOS related substances were considered. Concentrations of PFOS in air, vegetation, soil, fresh water, fresh water sediment and coastal water were derived from the model under the steady-state assumption. The median modeled PFOS concentrations in fresh water, fresh water sediment and soil were 7.20 ng/L, 0.39 ng/g and 0.21 ng/g, respectively, under Emission Scenario 2 (which assumed all PFOS related substances immediately degrade to PFOS) for the whole region, while the maximum concentrations were 47.10 ng/L, 4.98 ng/g and 2.49 ng/g, respectively. Measured concentration data for PFOS in the Bohai coastal region around the year of 2010 were collected from the literature. The reliability of the model results was evaluated by comparing the range of modeled concentrations with the measured data, which generally matched well for the main compartments. Fate and transfer fluxes were derived from the model based on the calculated inventory within the compartments, transfer fluxes between compartments and advection fluxes between sub-regions. It showed that soil and costal water were likely to be the most important sinks of PFOS in the Bohai costal region, in which more than 90% of PFOS was stored. Flows of fresh water were the driving force for spatial transport of PFOS in this region. Influences of the seasonal change of fresh water fluxes on the model results were also analyzed. When only seasonal changes of the fresh water flow rates were considered, concentrations of PFOS in winter and spring were predicted to be higher than that under annual average conditions, while the concentrations in summer and autumn were lower. For PFOS fluxes entering the sea, opposite conclusions were drawn compared to the concentrations. Environmental risks from the presence of PFOS in fresh water were assessed for this region through comparison with available water quality criteria values. The predicted concentrations of PFOS in the Bohai coastal region provided by the model were lower than the water quality criteria published by the United States Environmental Protection Agency and Chinese researchers, while the concentrations in more than 80% of the sampling locations exceeded the European Union Water Framework Directive Environmental Quality Standards values. Seasonal variations of flow rate might cause a significant increase in environmental risks.     

A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events

The factors affecting the release and bioavailability of contaminants present in sediments during natural and anthropogenic disturbance events are discussed and our current state of understanding of these processes reviewed. Published data are focused on the distribution of contaminants within undisturbed sediment, their affinities to the various solid-phase fractions of sediment and the interaction of contaminants between sediment and pore water. Sediment disturbance can lead to changes in the chemical properties of sediment that stimulate the mobilisation of contaminants. Research shows that changes in both redox potential (Eh) and pH can accelerate desorption, partitioning, bacterial degradation and the oxidation of organic contaminants. However, these processes are both sediment- and compound-specific. By affecting the affinity of contaminants to sediments, disturbance events in turn can have a significant effect on their bioavailability. Few studies have examined this phenomenon, and it is clear from the data available that there are gaps in our understanding in a number of key areas when assessing the release of contaminants from sediments: the fate of contaminants in undisturbed sediments and those that are not subjected to major disturbances, the kinetic processes that regulate metal release during changes in redox potential, the release of organometallic compounds from sediments during resuspension, the bioavailability of organic and organometallic compounds and the processes affecting contaminant release.     

丹江流域水沙变化特征分析

丹江流域是南水北调中线工程重要水源地,近年来受多种因素影响,径流泥沙情况发生了很大变化,准确把握其变化趋势对水资源管理及水土保持工作意义重大。该文基于荆紫关水文站1958～2015年径流和悬移质输沙量资料,运用Mann-Kendall 检验法、距平累积法、滑动t检验法以及双累积曲线法,阐明了丹江流域近60年径流量和悬移质输沙量变化特征,定量分析了各影响因素在径流泥沙变化中的作用。结果表明：丹江流域径流量与悬移质输沙量年际变化大,呈显著下降趋势,1958～1972、1982～1989年为丰水丰沙期,1972～1981年与1990～2015年处于枯水枯沙期,径流量和悬移质输沙量分别在1983年与1989年发生突变。人为因素和降水的贡献率分别为58.8%和41.2%,说明人为因素特别是水利水土保持工程是引起丹江流域输沙变化的主要因素。     

长江宜昌水文站流量、含沙量和悬移质粒度关系

以长江宜昌水文观测站实测资料为基础，基于长江上游河道特点，用回归分析的方法研究了宜昌站流量、含沙量与悬移质泥沙粒度的复杂关系。通过对流量、含沙量多年年内变化的正相关特性的分析，建立了流量与含沙量之间相应的回归模型；通过对流量与悬移质粒度复杂关系的研究，揭示了二者明显的双值关系以及水流挟沙力的控制性影响。对水文数据年际变化的研究表明由于短时间尺度内长江上游流量没有阶段性变化，流量与含沙量之间相关性不是很好，丰水年不一定是丰沙年；悬移质粒度与流量变化基本上不存在周期性变化。     

基于底泥再悬浮试验的太湖水质模拟

为探索浅水湖泊水动力扰动作用对底泥再悬浮影响的规律,在室内矩形水槽内模拟了各种水动力条件下太湖底泥的起动规律,得到了太湖底泥在3种不同起动标准下的起动流速,通过考察上覆水中悬浮物浓度的变化,建立了底泥沉积物再悬浮通量与水体流速的定量化关系。结果表明:太湖底泥在个别动、少量动、普遍动3种标准下的起动流速分别为15、30和40 cm/s,且底泥沉积物再悬浮通量与流速呈现线性正相关关系,再悬浮通量随流速增大而增大,且相关性较好。将该试验结果应用于太湖的水量水质数学模型中,并和太湖实测资料进行了对比,取得了比较满意的效果。该模拟装置能够在室内可控条件下较好地反映太湖沉积物再悬浮特征,对太湖的富营养化治理具有重要意义。     

长江源区草地植被退化对土壤持水能力影响

选择长江源区的格尔木市唐古拉山镇作为研究区,通过野外实地采样与室内测试分析相结合,在分析草地植被不同退化阶段和不同土层深度下土壤持水能力特征的基础上,探讨了草地植被退化对土壤持水能力影响。结果表明：（1）在相同草地植被退化阶段,毛管持水量、饱和含水量和田间持水量随土层深度变化的特征基本一致;在相同土层深度上,毛管持水量、饱和含水量和田间持水量随草地植被退化的特征也大体相同。（2）在相同草地植被退化阶段,土壤持水量总体上随土层深度增加而减少,特别是在未退化阶段,10~20 cm土层的毛管持水量、饱和含水量和田间持水量比0~10 cm土层分别减少了12.38%、33.73%和7.64%。（3）在相同土层深度上,土壤持水量总体上随草地植被退化而减少,特别是在0~10 cm土层,轻度退化阶段的毛管持水量、饱和含水量和田间持水量比未退化阶段分别减少了41.52%、59.95%和27.03%。（4）土壤持水量与土壤容重、总碳、有机质和总氮显著相关,它在草地植被不同退化阶段和不同土层深度下的变化可能与地表覆被状况、植物根系数量和分布特征所引起的土壤容重、有机质等变化有关。研究可深化对草地植被退化与土壤持水能力相互关系的理解和认识,并为长江源区生态环境和水资源状况研究提供参考依据。 关键词： 土壤持水能力;草地植被退化;长江源区;影响