秸秆和肥料管理措施对太湖流域水稻种植氮流失的影响

稻田系统的氮流失是农业面源污染的重要组成部分. 当前,氮肥投入量已得到有效控制,针对不同秸秆和肥料管理措施的多途径（径流、侧渗、下渗）氮流失特征研究还较为缺乏. 对此,选取太湖流域种植时长超过20 a且持续秸秆还田超过5 a的稻田,研究秸秆和肥料管理措施对水稻全生育期不同途径氮流失的影响,并基于作物产量、氮利用效率及氮流失强度,对秸秆和肥料管理措施的生产适宜性和环境友好性进行研判. 结果表明,秸秆离田会提升水稻植株对施氮的敏感度. 稻季氮总流失量为9~17 kg·hm^-2,占氮肥施用量的5%~7%. 对秸秆管理而言,秸秆离田的泡田排水具有更高氮流失风险;秸秆还田可降低15%以上的下渗途径氮流失量,但是对侧渗途径的氮流失作用并不明确. 对肥料管理而言,有机肥的适宜替代可较同施氮梯度下的化肥施用减少16%的种植期径流氮流失、26%的下渗氮流失,以及37%的侧渗氮流失. 综合产量数据,实施秸秆还田和肥料类型优化能够有效降低生产单位重量稻米的氮流失量,切实实现对农业生产和环境友好的双向兼顾.     

热带海洋大气环境氯离子浓度立体化观测技术研究

目的 对热带海洋环境氯离子开展立体化观测,掌握热带海洋环境下大气氯离子浓度在空间上的分布规律,为海洋大气环境下装备产品和重大工程服役环境研究提供立体化观测数据支撑。方法 在观测海岸线附近科学选点,采用无人机搭载远程控制大气采样器开展大气氯离子浓度立体化观测,对不同空间高度氯离子浓度分布规律进行分析。结果 成功采集万宁某海岸线附近1 km×300 m×100 m区域1 a以上氯离子浓度数据,通过GIS技术分析并建立了氯离子浓度分布三维场,实现了氯离子浓度可视化,并随离海距离、离地高度剖切显示。结论 海南万宁某区域海岸线附近氯离子浓度在冬季最大,夏季最低,且在一定观测范围内,随观测高度增加而先增大、后降低,随离海距离增大而逐渐降低。     

Dual-reaction-center catalytic process continues Fenton’s story

• Dual-reaction-center (DRC) system breaks through bottleneck of Fenton reaction. • Utilization of intrinsic electrons of pollutants is realized in DRC system. • DRC catalytic process well continues Fenton’s story. Triggered by global water quality safety issues, the research on wastewater treatment and water purification technology has been greatly developed in recent years. The Fenton technology is particularly powerful due to the rapid attack on pollutants by the generated hydroxyl radicals (•OH). However, both heterogeneous and homogeneous Fenton/Fenton-like technologies follow the classical reaction mechanism, which depends on the oxidation and reduction of the transition metal ions at single sites. So even after a century of development, this reaction still suffers from its inherent bottlenecks in practical application. In recent years, our group has been focusing on studying a novel heterogeneous Fenton catalytic process, and we developed the dual-reaction-center (DRC) system for the first time. In the DRC system, H₂O₂ and O₂ can be efficiently reduced to reactive oxygen species (ROS) in electron-rich centers, while pollutants are captured and oxidized by the electron-deficient centers. The obtained electrons from pollutants are diverted to the electron-rich centers through bonding bridges. This process breaks through the classic Fenton mechanism, and improves the performance and efficiency of pollutant removal in a wide pH range. Here, we provide a brief overview of Fenton’s story and focus on combing the discovery and development of the DRC technology and mechanism in recent years. The construction of the DRC and its performance in the pollutant degradation and interfacial reaction process are described in detail. We look forward to bringing a new perspective to continue Fenton’s story through research and development of DRC technology.     

Shadow economy and air pollution in developing Asia: what is the role of fiscal policy?

Environmental Economics and Policy Studies - Asian developing countries face challenges of serious air pollution and large shadow economy. Fiscal policy is anticipated as a solution to cope with...     

Enhanced nitrogen removal in filled-and-drained vertical flow constructed wetlands: microbial responses to aeration mode and carbon source

Environmental Science and Pollution Research - For the purpose of enhancing the removal rate of nitrogen (N) and organic matters, intermittent aeration and carbon source were used in...     

利用有效微生物菌群控制蓝藻水华研究

蓝藻水华污染在我国和世界都呈现迅猛的发展趋势,如何治理是环境科学研究领域的热点。2008年7～8月在北京市延庆县妫水湖的现场围隔水体中,通过投加筛选和培养土著有效微生物菌群(EM菌),对控制蓝藻水华污染形成的效果进行研究。结果表明,与对照相比,投加EM菌不仅可以控制蓝藻水华的暴发,使蓝藻生物量降低70%以上,而且可以快速降低水体中的氮和磷浓度,因此,明显控制了蓝藻水华的形成,在治理湖泊蓝藻水华污染方面具有重要的应用前景。     

城市污水厂污泥替代营养盐培养海水小球藻的研究

为了城市污水厂污泥的资源化利用,对污泥替代F/2培养基培养海水小球藻(Chlorella pacifica)进行了研究。首先采用研磨-离心法制备污泥抽提液,将其与F/2培养基按体积比7∶3混合,接种微藻并在优化的条件下培养6 d,逐日测定混合液中无机氮、磷的浓度,培养结束后测定微藻生物量以及干藻中蛋白质、氨基酸和重金属含量。结果表明,将微藻在最佳条件下培养6 d后,混合液中PO34--P、NO2--N、NH4+-N和NO3--N的吸收率分别达到97.32%、96.72%、97.55%和78.13%;与F/2培养基对照组相比,混合液中微藻的生物量增加11.5%;蛋白质、必需氨基酸和非必需氨基酸的含量变化不大。另外,干藻中的重金属含量符合饲料行业标准的要求。     

自来水污泥堆肥化研究

研究了自来水污泥脱水防粘预处理技术、高温好氧堆肥技术及其应用于园林种植效果。机械组成测定和电镜扫描结果表明,调理剂QS可以显著改善自来水污泥的粘结性及脱水性能;堆肥实验结果表明,预处理的自来水污泥与枯枝落叶按体积比3∶7混匀,加入尿素调节碳氮比,27 d后,可达腐熟,EM菌可以加快堆肥物料腐熟,19 d后,即可达腐熟要求;桉树盆栽实验结果表明,自来水污泥经堆肥化处理后,保水性提高,促进桉树生长,而且堆肥过程中添加EM菌可以进一步促进桉树生长。     

鱼虾贝类立体生态养殖对水质净化作用研究

2009年在山东无棣的滨州市水产研究所养殖基地,进行了鱼虾贝类立体生态养殖对水质净化作用的试验,结果表明:鱼虾贝类立体生态养殖与单纯贝类生态养殖对水质的净化作用相比较,鱼虾贝类立体混养对CODMn、BOD5、无机氮、活性磷酸盐、硫化物、挥发酚的去除率明显高于贝类单独养殖的去除率,总磷的去除率二者相差不大,唯单纯贝类养殖对总氮的去除率高于鱼虾贝类立体养殖。     

生物法降解养殖场臭气中H2S的反应器启动

畜禽养殖场臭气成分复杂,完全去除较为困难。生物法是目前应用较广泛的脱臭方法,其中能否将生物膜附着在填料上是影响生物法去除恶臭气体效率的重要因素。本实验采用定时定量投加Na2S的方式驯化活性污泥,并选用MLSS浓度和SO42-浓度增量变化2个指标作为污泥驯化成熟的指标,比传统的以MLSS作为污泥驯化成熟的指标更准确。采用循环污泥的挂膜方式,运行2 d后,通入新鲜的空气和H2S气体,2周后反应器启动成功。