Microbial community diversity in the profile of an agricultural soil in northern China

The soil microorganisms at different depths play an important role in soil formation,ecosystem biogeochemistry,recycling of nutrients,and degradation of waste products.The aims of this study were to observe the microbial diversity in the profile of an agricultural soil in northern China,and to research the correlation between soil microbes and geochemistry.First,the soil geochemistry of the profile was investigated through 25 chemical elements.Secondly,the various physiological groups of microorganisms w...     

Mercury in soil, vegetable and human hair in a typical mining area in China: Implication for human exposure

Concentrations of total mercury(T-Hg) and methylmercury(MeHg) in soil, vegetables, and human hair were measured in a mercury mining area in central China. T-Hg and MeHg concentrations in soil ranged from 1.53 to 1054.97 mg/kg and 0.88 to 46.52 μg/kg, respectively.T-Hg concentrations was correlated with total organic carbon(TOC) content(R~2= 0.50, p0.01)and pH values(R~2= 0.21, p0.05). A significant linear relationship was observed between MeHg concentrations and the abundance of sulfate-reducing bacteria(SRB)(R~2= 0.39, p0.05) in soil.Soil incubation experiments amended with specific microbial stimulants and inhibitors showed that Hg methylation was derived from SRB activity. T-Hg and MeHg concentrations in vegetables were 24.79 – 781.02 μg/kg and 0.01 – 0.18 μg/kg, respectively; levels in the edible parts were significantly higher than in the roots(T-Hg: p0.05; MeHg: p0.01). Hg species concentrations in rhizosphere soil were positively correlated to those in vegetables(p0.01), indicating that soil was an important source of Hg in vegetables. Risk assessment indicated that the consumption of vegetables could result in higher probable daily intake(PDI) of T-Hg than the provisional tolerable daily intake(PTDI) for both adults and children. In contrast, the PDI of MeHg was lower than the reference dose. T-Hg and MeHg concentrations in hair samples ranged from 1.57 to 12.61 mg/kg and 0.04 to 0.94 mg/kg, respectively, and MeHg concentration in hair positively related to PDI of MeHg via vegetable consumption(R~2= 0.39, p0.05), suggesting that vegetable may pose health risk to local residents.     

基于OLCI数据的福建近海悬浮物浓度遥感反演

悬浮物（TSM）是评估水质的重要指标,也是水色遥感反演的核心参数之一.海陆色度仪（OLCI）是新一代海洋水色传感器,具有良好的光谱及时空分辨率.为有效监测福建近海悬浮物浓度的时空变化,本文结合OLCI遥感数据和现场实测悬浮物浓度数据,使用CatBoost、随机森林和多元回归方法,分别构建悬浮物浓度反演模型,最后使用验证集对比分析不同模型的反演精度.结果表明,CatBoost模型估算精度最高,均方根误差（RMSE）为2.76 mg·L^-1,平均绝对百分比误差（MAPE）为23.67%,决定系数R²为0.89.使用CatBoost模型对2017—2018年多时相OLCI影像进行TSM浓度遥感反演,结果发现,福建近海TSM浓度变化显著,但总体呈现近岸高于远岸、北部高于南部、江河入海口和港湾处高于周围其他海域、春季高于夏季的时空分布特征.本研究可为福建近海的悬浮物浓度监测提供一种有效的方法,也进一步证明了OLCI影像良好的水色反演能力,可作为水质监测的有效遥感数据源.     

废旧车用动力电池安全放电研究

在动力电池回收处理流程中,对于发生过进水、过火、碰撞等情况的危险性动力电池需要进行放电安全处理。此外,动力电池从电动汽车上退役时残余电压很高,动力电池单体带电拆解极易发生起火甚至爆炸,拆解前也需要进行放电处理。以退役车用锂离子动力电池单体为研究对象,对比物理放电和化学放电的安全性,考察放电的安全截止电压、戳穿安全阀、电解质浓度对化学放电的影响。结果表明,电池电压值高于1.0 V时,电池拆解会产生火星,极易起火,电压值不高于1.0 V可实现安全拆解。物理放电后电池电压会反弹,拆解时仍有安全风险;化学放电后电池电压不反弹,可实现安全拆解。化学放电时戳穿安全阀并添加5%的Na Cl可满足产业化放电要求,SOC=100%的动力电池放电至安全截止电压需要15.3 h。对于10 Ah以上的动力电池,戳入深度应控制在5 mm以内,10 Ah以内的动力电池不建议戳穿安全阀。     

Research on the anti-interference capability of the tourism environment system for the core stakeholders of semi-arid valley-type cities: analysis based on the multi-scenario and time series diversity perspectives

Environmental Science and Pollution Research - Given the relatively harsh natural environment in semi-arid valley areas, the attraction and radiation functions of semi-arid valley cities have...     

桂林市菜地土壤和蔬菜砷含量调查与健康风险评估

通过对桂林市蔬菜和菜地土壤中砷含量状况的调查,研究了蔬菜和菜地土壤中的砷含量、富集特征及对人体的健康风险,并筛选出抗砷污染能力强的蔬菜品种.本研究在桂林市13个县区蔬菜种植基地和蔬菜批发市场共采集71种566个蔬菜样品,160个相对应菜地的土壤样品和32个背景土壤样品.研究发现,与背景土壤相比,桂林市菜地土壤没有明显的砷积累(平均积累指数为0.839),砷含量范围、算术均值、几何均值分别为5.55~132、23.4、21.4 mg·kg-1.蔬菜(鲜重)总砷含量范围、中值和几何平均值分别为5.34~49.7、24.0、22.2 mg·kg-1,均未超标,且叶菜类蔬菜中的砷含量高于根茎类和瓜果类.根据蔬菜砷富集系数的高低用层级聚类法分析,结果表明,西红柿、油麦菜、胡萝卜、生菜等18种蔬菜的抗砷污染能力最强.桂林市居民通过消费蔬菜的人均总砷摄入量为2.54μg·d-1,蔬菜消费只占总砷摄入量的7.07%左右,因此,对于大多数居民而言不存在明显的健康风险.     

集合最优插值同化方法在珠三角空气质量模拟中的初步应用

本文旨在探讨集合最优插值(EnOI)同化方法对MM5-STEM空气质量模式污染物浓度预报场的修正能力,先从局地化尺度(L)及经验系数(α)的敏感性试验中获得NO2、SO2和PM10各自的"最优L和α组合",然后对此参数设置下的同化结果进行分析.研究结果显示,EnOI在NO2、SO2及PM10的同化试验中均取得较好的效果,检验站点均方根误差(RMSE)的平均下降比例分别可达33%、32%和42%,RMSE值下降的站点占检验站点总数的比例分别为86%、84%和91%.表明该方法能够有效地应用在珠三角空气质量模拟中,产生与实际更为接近的污染物浓度预报场.     

Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai

The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe （visibility 〈 2 km） and moderate （2 km 〈 visibility 〈 3 km） haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm3 in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1μm and 1-10 μm size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100 nm and 100-200 nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15 μm3/cm3 and 949, 649, 206 μm2/cm3, respectively. As haze events got more severe, the number concentration of particles smaller than 50 nm decreased, but the particles of 50-200 nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4, SO24- and NO3 increased great/y, followed by Na＋, IC, Ca2＋ and CI-. These ions were very different in size-resolved particles during haze and photochemical smog episodes.     

低剂量多次暴露焦性没食子酸的抑藻效果初步研究

目前实验室对化感物质抑藻效应的研究多在EC50水平上进行,而水生植物释放化感物质具有微量、持续性的特征。本研究试图探索在化感物质暴露总量相同的前提下,全剂量一次性暴露与低剂量多次暴露在抑藻效果上是否存在差异,以便为今后开展进一步研究提供依据。实验以能够诱导藻细胞产生活性氧进而引发氧化损伤的化感物质焦性没食子酸作为研究对象,以细胞密度、细胞内O2·ˉ、H2O2及OH·的产生水平和细胞膜损伤情况作为指标,比较了低剂量多次暴露(0.25 mg/L×4次×5 d,间隔4 h)与单次暴露(5 mg/L)对铜绿微囊藻的致毒效应。实验结果显示,就生长速度而言:单次暴露组<低剂量多次暴露组<对照组;而低剂量多次暴露下样品藻细胞内的O2·ˉ、H2O2及OH·水平则呈逐步升高趋势(P<0.01),且当累计暴露量仅为设计暴露总量的一半时就超过了单次暴露下的相应水平,到实验的第5天分别达到相应单次暴露组的1.10(O2·ˉ)和1.06(H2O2及OH·)倍;而膜损伤的情况,单次暴露与低剂量多次暴露均能造成藻细胞膜的损伤,且相对膜损伤水平(%)实验后期还维持在160%上下。从上述实验结果看出,低剂量多次暴露的方式很可能具有比单次暴露更强的持续抑藻能力,因而开展对低剂量多次暴露条件下化感抑藻效应的研究十分重要,其结果将更接近水生植物释放化感物质的低剂量、持续性特征。     

火灾事故中的环境污染控制研究

火灾对周围的环境造成水污染、大气污染、有毒气体的污染等,严重影响我们生活环境。人们对环境保护的意识在逐年提高,对于火灾造成的环境污染也开始努力控制。