o-Coumaric acid from invasive Eupatorium adenophorum is a potent phytotoxin

A phytochemical study of the invasive Eupatorium adenophorum indicated that the plant was rich in a phenolic compound o-coumaric acid (or 2-hydroxycoumaric acid). Biological investigations with the model plant Arabidopsis thaliana and crop plants showed that o-coumaric acid strongly inhibited seed germination, plant growth and root elongation, reduced the photosynthesis in old leaves, and induced the root cell death and the expression of genes related to senescence, oxidative stress, and systemic acquired resistance. The phytotoxic effects of o-coumaric acid exhibit selectivity between under- and above-ground parts of test plants and between E. adenophorum and other plants. These results indicate that o-coumaric acid is a potent toxin that might play an important role in the competition of E. adenophorum with its neighboring plants during its invasion and establishment.     

海洋放射性污染生态风险评价研究进展

近年来,随着我国核电事业迅猛发展,海洋放射性污染的风险激增,放射物质的事故性污染将成为海洋环境一个重要问题。目前,海洋环境放射性污染风险评估的研究仍然较为薄弱,开展海洋放射性污染生态风险评价有助于了解事故对海洋生态的危害程度,为海洋与海岸带环境管理提供科学决策依据,维护海洋生态系统的健康与安全。梳理总结当前国内外海洋放射性污染生态风险评价的相关研究进展,结果表明:目前国内外对海洋放射性污染生态风险评价尚未做出科学的定义;现有海洋放射性污染生态风险评价的技术路线大体可归纳为基于经典风险评估框架和基于迭代的生态风险评价框架2种类型;ERICA Tool模型以及RESRAD-BIOTA模型是目前放射性风险评价中应用最多的方法,但存在海洋放射性污染标准限值少的问题;现有的研究主要集中于评估事故中后期均衡条件下的长期慢性暴露评价,对事故初期的高剂量、短期急性暴露的风险影响研究较少;我国海洋放射性污染的生态风险评价与环境影响评价的概念混淆,至今没有明确的海洋放射性污染生态风险评价的概念及技术框架。     

Estimating national-scale ground-level PM25 concentration in China using geographically weighted regression based on MODIS and MISR AOD

Taking advantage of the continuous spatial coverage, satellite-derived aerosol optical depth (AOD) products have been widely used to assess the spatial and temporal characteristics of fine particulate matter (PM2.5) on the ground and their effects on human health. However, the national-scale ground-level PM2.5 estimation is still very limited because the lack of ground PM2.5 measurements to calibrate the model in China. In this study, a national-scale geographically weighted regression (GWR) model was developed to estimate ground-level PM2.5 concentration based on satellite AODs, newly released national-wide hourly PM2.5 concentrations, and meteorological parameters. The results showed good agreements between satellite-retrieved and ground-observed PM2.5 concentration at 943 stations in China. The overall cross-validation (CV) R ² is 0.76 and root mean squared prediction error (RMSE) is 22.26 μg/m³ for MODIS-derived AOD. The MISR-derived AOD also exhibits comparable performance with a CV R ² and RMSE are 0.81 and 27.46 μg/m³, respectively. Annual PM2.5 concentrations retrieved either by MODIS or MISR AOD indicated that most of the residential community areas exceeded the new annual Chinese PM2.5 National Standard level 2. These results suggest that this approach is useful for estimating large-scale ground-level PM2.5 distributions especially for the regions without PMs monitoring sites.     

富铁环境中甲烷氧化菌群落结构与甲烷氧化特性

近年来湿地潜在甲烷排放备受关注,牟尼沟草海富铁湿地具有十分重要的生态地位,而目前有关该区域甲烷氧化菌群落结构与氧化特性的研究相对较少。通过第二代高通量测序技术探究了草海富铁湿地中甲烷氧化菌的群落结构及功能并从中筛选出一株优势甲烷氧化菌在富铁溶液中进行实验探究。测序结果表明,优势甲烷氧化菌为Type Ⅰ型的甲基杆菌(Methylobacter)和甲基单胞菌(Methylomonas),RDA分析结果表明,pH和ORP是影响甲烷氧化菌群落的关键环境驱动因素。结果表明,反应过程中菌株会分泌腐殖质等产物将胞内电子转移到胞外,使溶液中的Fe(Ⅲ)作为电子受体。并且在富铁溶液中甲烷氧化效率提高了10.8%左右,7 d内菌株能够完全氧化瓶内的甲烷气体。以上结果以期为湿地甲烷减排提供理论参考依据。     

河床原位修复对城市河流微生物群落的影响

采用分子生物学检测方法对实施了河床原位修复的河段进行全面的微生物群落分析。结果表明:河床生态修复后微生物群落结构及多样性发生了明显的变化。从微生物多样性指数来看,河床修复段的下游大于上游;从微生物群落结构来看,上游断面中ε-变形菌纲为最主要的细菌类型,多为致病病原菌,与该采样点周边人口密集而水质 经其他处理有关。经河床原位修复后,下游断面ε-变形菌纲丰度减少,α-变形菌纲和β-变形菌纲成为最优势的类群,其他细菌比例也相对均衡,NH₃-N和其他理化指标有所好转,说明微生物载体原位修复措施对城市景观河流黑臭的改善有一定的效果。     

溢油事故造成的海湾生态系统服务损失的货币化评估

海湾是人类活动的密集地带,它以其特有的生态系统为人类的生产和生活提供了物质和精神方面的多种服务。从海湾生态系统服务的分类入手,在分析溢油事故可能给海湾生态系统的供给、调节、文化和支持服务带来的各种负面影响的基础上,运用市场价值法、替代市场法、调查评价法和成果参照法,构建了海湾生态系统服务（子服务）损失货币化评估的相应计量模型。     

棕色碳气溶胶来源、性质、测量与排放估算

随着对碳气溶胶吸光性认识的提高,近年来吸光有机碳——BrC(brown carbon,棕色碳)的吸光问题成为继BC(black carbon,黑碳)之后国际大气环境领域的新热点. 基于已有的研究报道,将BrC大体分为焦油类物质、类腐殖质(HULIS)和其他吸光性有机气溶胶三大类,其来源包括一次排放和二次生成2种. 由于BrC缺少BC所具有的类石墨烯结构,致使颗粒间较为分散,加之含氧官能团比重较高,因而在水及有机溶剂中均有较强的可溶性. BrC的光学性质通常借助AAE(ngstrm吸收波长指数)、MAE(质量吸收效率)、RI(折射率)及SSA(单次散射反照率)来表示,其中由于BrC分子结构中缺少sp2杂化成分,形成了区别于BC的典型特征,即AAE>1(而对于BC,其AAE=1)). 虽然已有借助于光学法、热光法、化学法和质谱法进行BrC测定的报道,但目前没有公认的标准测定方法和参考物质,测定结果实际依赖于选定的测定方式. 在排放估算研究方面,BrC远落后于BC,致使有些排放估算方法多以相伴的BC排放量作为参照. 建议今后对BrC研究应主要面向气候影响、生成机理、测定方法、排放因子与控制策略等领域来展开.