Effects of soil properties on production and bioaccumulation of methylmercury in rice paddies at a mercury mining area, China

Rice paddy soil is recognized as the hotspot of mercury(Hg) methylation, which is mainly a biotic process mediated by many abiotic factors. In this study, effects of key soil properties on the production and bioaccumulation of Hg and methylmercury(MeHg) in Hg-contaminated rice paddies were investigated. Rice and soil samples were collected from the active Hg smelting site and abandoned Hg mining sites(a total of 124 paddy fields) in the Wanshan Mercury Mine, China. Total Hg(THg) and MeHg in soils and rice grains, together with sulfur(S),selenium(Se), organic matter(OM), nitrogen(N), phosphorus(P), mineral compositions(e.g., SiO_2, Al_2O_3 and Fe_2O_3) and pH in soils were quantified. The results showed that long-term Hg mining activities had resulted in THg and MeHg contaminations in soil-rice system. The newly-deposited atmospheric Hg was more readily methylated relative to the native Hg already in soils, which could be responsible for the elevated MeHg levels in soils and rice grains around the active artificial Hg smelting site. The MeHg concentrations in soils and rice grains showed a significantly negative relationship with soil N/Hg, S/Hg and OM/Hg ratio possibly due to the formation of low-bioavailability Hg–S(N)–OM complexes in rhizosphere. The Hg–Se antagonism undoubtedly occurred in soil-rice system, while its role in bioaccumulation of MeHg in the MeHg-contaminated rice paddies was minor. However, other soil properties showed less influence on the production and bioaccumulation of MeHg in rice paddies located at the Wanshan Mercury Mine zone.     

集约化畜禽养殖对环境的污染及防治研究

治理集约化畜禽养殖废弃物污染,开展废弃物的资源化利用,是解决中国畜牧业环境污染问题的主要路径。文章详述了中国畜禽养殖业污染问题的产生及对环境可能造成的影响,分析了畜禽废弃物处理措施与资源化利用的主要方式及其效果和存在的问题,并提出了控制畜禽粪污染物的对策和环境管理建议,将有助于推动中国畜禽养殖业的可持续发展,改善农业生态环境及农村人居环境。     

Ancient paddy soils from the Neolithic age in China’s Yangtze River Delta

Identifying prehistoric irrigated rice fields and characterizing the beginning of paddy soil development are important for a better understanding of human development and agricultural history. In 2003, paddy soils and irrigated rice fields buried at a depth of 100–130 cm were excavated at Chuo-dun-shan in the Yangtze River Delta, close to Suzhou, China. The fields of sizes between 1.4 and 16 m² were surrounded with ridges that were connected to ditches/ponds via outlets to control the water level within the fields. Many carbonized and partly carbonized rice grains with an age of 3,903 B.C.(measured ¹⁴C age 5,129±45 a BP) were recovered. The surface layers of these buried paddy fields showed a high content of soil organic matter and a considerable high density of rice opals. The latter were identified to derive from Oryza spp. Solid-state ¹³C nuclear magnetic resonance spectroscopy revealed aromatic carbon (C) as the predominant organic C form in the fossil surface layer. This is expected, if the major source represents burnt rice and straw. In summary, our data are in agreement with new evidences indicating that in China, paddy soils and irrigated rice cultivation were initiated and developed more than 6,000 years ago.     

南京市可吸入颗粒物（PM10）来源及防治对策

通过分析南京市可吸入颗粒物（PM10）来源分布特征,以及源贡献值和分担率的时空分布特征,提出南京市大气颗粒物污染防治对策;加强防治扬尘污染,巩固煤烟尘的治理成果,机动车尾气尘污染防治,提高环境监测能力和加强科学研究等措施。     

吸附法除氟技术的原理与方法

在水处理中应用的除氟的方法主要有：沉淀法、吸附法、电凝聚法、电渗析法、反渗透法和离子交换法等,其中吸附法是处理高含氟水的重要方法。本文重点介绍了几种常用的及新型的氟吸附剂的特点及应用概况,其中包括：铝盐吸附剂、铁盐吸附剂、稀土类吸附剂、生物类吸附剂以及其他类型的吸附剂;介绍了几种常用的及新型的氟吸附剂的除氟作用机理,并对今后的除氟研究进行了展望。     

乡村转型发展影响因素及其作用效应的空间分异——以陕西省为例

以陕西省为例,围绕人口、土地、产业等乡村社会经济发展要素构建乡村转型发展评价指标体系,借助ArcGIS平台分析陕西省乡村转型发展时空格局演化特征;利用逐步回归、地理加权回归模型（GWR模型）对陕西省乡村转型发展影响因素及作用效应的空间分异进行探究,以期为陕西省乡村高质量发展路径设计与政策制订提供参考依据。研究结论如下：（1）2005—2017年间,陕西省乡村转型发展程度呈现持续上升趋势,在空间上整体呈现西安及其周边以及榆林北部能源区发展程度高,其余地区发展程度低的特点,且乡村转型发展经历了低度转型主导到较低、中度转型主导的发展过程。（2）地均固定资产投入、加权路网密度、人均生产总值、规模以上工业企业个数和人均耕地资源量是陕西省乡村转型发展的主要影响因素。（3）影响因素中除人均耕地资源量对乡村转型发展整体呈现负向影响外,其余因素均呈现正向影响,且对不同县域影响程度不同,影响效应的空间分异明显。研究对因地制宜地制定陕西省乡村转型发展的差异化政策措施具有重要的参考意义。     

浅议现代企业安全管理需要法治

简述了现代企业安全管理必须加强法制建设。只有逐步形成以法治为保障的安全管理模式,企业才能不断自我完善和发展。     

基础工程施工中的事故隐患与整改

基础施工是基础设施建设中的首要环节,是整个工程建设赖以进行的基础工作,因而国家颁布了一系列标准与规程,用以确保施工质量与安全。本文就基础工程施工中事故隐患的整改谈谈个人看法。     

高含硫天然气井测试施工安全对策分析

本文阐述了作者在罗家寨等高含硫气田多口井的完井放喷测试施工中加强安全管理的具体做法,即施工现场安全组织、入场施工安全控制以及安全培训与演练,尤其是对放喷测试施工中危险点（源）的辨识及正确采取削减措施。     

植草沟在城市面源污染控制系统的应用

暴雨径流造成的城市面源污染已引起广泛重视,为控制和削减进入受纳水体的径流污染负荷,各种技术措施得到发展,植草沟便是其中之一.植草沟是景观型地表沟渠排水系统,从植草沟定义、类型、设计计算、参数确定、运行维护及应用实例方面作了较详细介绍.植草沟在条件合适时可代替传统的雨水管道,具有很好的推广应用前景.