Chromium transformation driven by iron redox cycling in basalt-derived paddy soil with high geological background values

The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recognized. The typical basalt-derived paddy soil was incubated under alternating redox conditions. The Cr fractions and the dynamics of Fe/N/S/C were examined. The HCl-extractable Cr increased under anaerobic condition and then decreased during aerobic stage. The UV-vis spectra of the supernatant showed that amounts of colloids were released under anaerobic condition, and then re-aggregated during aerobic phase. The scanning transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed that Fe oxides were reduced and became dispersed during anaerobic stage, whereas Fe(II) was oxidized and recrystallized under aerobic condition. Based on these results, a kinetic model was established to further distinguish the relationship between the transformation of Cr and Fe. During anaerobic phase, the reduction of Fe(III) oxides not only directly released the structurally bound Cr, but also enhanced the breakdown of soil aggregation and dissolution of organic matter causing indirect mobilization of Cr. During aerobic phase, the oxidation of Fe(II) and further recrystallization of newly formed Fe(III) oxides might induce the re-aggregation of soil colloids and further incorporation of Cr. In addition, the kinetic model of Cr and Fe transformation was further verified in the pot experiment. The model-based findings demonstrated that the Cr transformation in the basalt-derived paddy soil with high geological background values was highly driven by redox sensitive iron cycling.     

云南洱海沉积物--水界面铁、锰的分布和迁移特征

洱海是一永久性含氧湖泊。对洱海沉积物中铁、锰的分布特征进行了分析，说明洱海沉积物中铁的循环比锰微弱的多，铁氧化物的还原作用受到了溶解氧和锰氧化物的双重控制。输入沉积物中的铁大部分都保存于沉积物中。锰氧化物的还原虽然也受到溶解氧的制约，但其还原作用仍很激烈，所以锰对环境的敏感程度比铁高，沉积物中的铁具有环境记录意义，而锰不具有环境记录意义。     

干湿循环与垃圾渗滤液耦合作用下GCL防渗性能

开展膨胀指数和渗透系数测定试验,研究干湿循环与垃圾渗滤液渗透耦合作用下膨润土的膨胀性能和土工合成黏土衬垫（GCL）防渗性能变化规律.结果表明,干湿循环与垃圾渗滤液渗透耦合作用对膨润土的膨胀性能和GCL的防渗性能具有显著负面影响：在7次干湿循环后,垃圾渗滤液饱和的膨润土的膨胀指数从20mL/2g降低至7.5mL/2g,GCL的渗透系数从1.65×10^-11m/s增加到1.89×10^-7m/s.膨胀指数下降和渗透系数升高的根本原因是膨润土渗透膨胀性能的丧失.单纯的垃圾渗滤液渗透不会改变GCL的渗透系数.将有效应力从20kPa升高至150kPa,可以促使GCL的渗透系数降低4个数量级,满足填埋场防渗要求（< 5.0x10^-11m/s）.     

Ce-based catalysts used in advanced oxidation processes for organic wastewater treatment: A review

Refractory organic pollutants in water threaten human health and environmental safety, and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants. Catalysts play vital role in AOPs, and Ce-based catalysts have exhibited excellent performance. Recently, the development and application of Ce-based catalysts in various AOPs have been reported. Our study conducts the first review in this rapid growing field. This paper clarifies the variety and properties of Ce-based catalysts. Their applications in different AOP systems (catalytic ozonation, photodegradation, Fenton-like reactions, sulfate radical-based AOPs, and catalytic sonochemistry) are discussed. Different Ce-based catalysts suit different reaction systems and produce different active radicals. Finally, future research directions of Ce-based catalysts in AOP systems are suggested.     

不同处理水芹浮床对城市河道黑臭污水的脱氮效果及其机理研究

通过对冬季不同留茬高度水芹（Oenanthe Javanica）浮床对城市河道污水氮循环细菌数量和脱氮效果的影响研究,试图阐明浮床植物去除污染水体氮素的可能途径.研究结果表明：不同处理水芹浮床对城市河道黑臭污水硝氮和氨氮的去除效果分别达到了52.5%～69.8%和68.1%～76.7%,19cm留茬高度水芹浮床对脱氮效...     

喀斯特坡地土壤硫同位素变化指示的土壤硫循环

用土壤硫形态连续提取方法分离测定了喀斯特坡地土壤总硫、有机硫、SO24-和FeS2的硫同位素组成及其含量.总体来看,土壤剖面表层各形态硫δ34S值FeS2最低,介于-6.86‰~-4.22‰,其次为SO24-(-2.64‰~-1.34‰),第三为总硫(-3.25‰~-1.03‰),最高为有机硫(-1.63‰~0.50‰),随土壤剖面加深各形态硫δ34S值均有增大的趋势.SO24-和FeS2的δ34S值深度分布具有共变性,这与SO24-异化还原有关;而总硫和有机硫的δ34S值随剖面加深而平行增大,则与有机硫循环有关.硫同位素组成可鉴别土壤硫源,同时SO24-异化还原和有机硫矿化有明显的硫同位素分馏,而硫化物氧化及SO24-同化基本不产生同位素分馏,则土壤各形态硫的硫同位素组成的垂直变化可以很好地记录与深度相关的硫循环过程.并且,通过对比各形态硫含量及其硫同位素组成的深度分布特征,也可以很好地判别土壤内部的SO24-和有机硫组分的迁移过程.     

黄土丘陵沟壑区坡地土壤有机碳变化及碳循环初步研究

在利用长期定位试验的实测土壤有机碳(SOC)数据,验证DNDC(脱氮-分解作用)模型在黄土丘陵沟壑区应用的可行性基础上,应用DNDC模型来研究黄土丘陵沟壑区坡耕地农田土壤碳库储量动态变化及碳循环特征。结果表明:施肥可提高作物残体与根系分泌物的外源C携入量,也能提高土壤异氧呼吸对内源C的消耗,且施用有机肥后提高效果显著。总体上,单施有机肥、有机肥配施氮肥均能显著提高0~30 cm土层SOC含量,40年后各处理SOC分别比初始值提高了90.29%、86.46%。不施肥和单施氮肥,SOC含量总体都呈现下降趋势,40年后各处理SOC分别比初始值降低了3.52%、0.38%。依据DNDC模型模拟结果,在黄土丘陵沟壑区坡地上,为保持和提高土壤肥力,增加碳库储量,以施用有机肥为主,配合施用一定量的氮肥将是非常有效的措施。     

Chemical composition of rivers and streams in the forest and savanna zones of Nigeria

The aim of this study is to investigate the differences in the chemical conditions of lotic waterbodies in the two major ecosystems in Nigeria, the forest and savanna zones. The forest waters were slightly acidic (mean±SD pH = 6.72±0.58) while the savanna waters were slightly alkaline (pH = 7.11±0.33). The cationic order of dominance in the forest waters was Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ in contrast to Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ in savanna waters. The forest waters were chlorided (typical of coastal and/or marine waters) whereas the savanna waters were carbonated in nature, typical of the worldwide freshwater. Organic carbon was significantly higher in forest waters than in the savanna waters (p < 0.05) while nutrient compounds were significantly higher in savanna waters than in forest waters. The seasonal variation of the chemical parameters was generally more evident in savanna than in forest waters. The differences in water quality between the two major vegetation zones reflect the differences in the biogeochemical processes and nutrient cycling that characterise forest and savanna ecosystems.     

大力发展循环经济促进碳循环和碳汇产业发展

介绍了碳循环与碳汇产业的科学内涵及其在我国的发展现状与目标,提出“十二五”期间应大力推广的几种碳循环与碳汇产业的成功模式,以及促进碳循环和碳汇产业发展的对策建议。     

红壤区土壤有机碳的循环和平衡及有机资源利用

根据野外采样分析,调查及田间试验结果,讨论了红壤区土壤有机质含量的变异规律及影响因素,分析了红壤有机碳的循环和平衡状况,初步探讨了红壤有机质含量变化及其与土壤肥力退化的关系,并根据红壤有机物质资源特点提出合理利用的途径和措施。红壤区农田土壤有机质的平均含量低于东北黑土平原区,长江中下游平原区和珠江三角洲平原区,而高于黄淮海平原区以及黄土高原区,包括自然因素和人为因素所造成输入土壤的有机物质量的差异