Fuel derived pollutants and boating activity patterns in the Sea of Galilee

MTBE (Methyl tert-Butyl Ether) is a fuel additive that replaced lead as an antiknock compound in internal combustion motors. Few years after its introduction, detectable levels of MTBE were found in various water bodies. MTBE has a very low taste and odor threshold and is a potential carcinogen. Another group of fuel derived toxic compounds that has been detected in water bodies is BTEX (Benzene, Toluene, Ethylbenzene and Xylene). Boating activity and allochthonous contributions from watersheds are the major sources of fuel derived pollutants in lakes. Their concentrations in lakes thus vary as a function of boating activity intensity, lake surface area and depth, weather and wind regime, land-use in the watershed, etc. The Sea of Galilee (Lake Kinneret) is the only recreational lake in Israel and an important freshwater source. In the current study, a sampling campaign was conducted in order to quantify MTBE and BTEX concentrations in Lake Kinneret, its marinas and its main contributing streams. In addition, a boating-use survey was performed in order to estimate MTBE and BTEX contribution of recreational boating. The sampling campaign revealed that, as expected, MTBE concentrations were higher than BTEX, and that near shore (i.e., marina) concentrations were higher than in-lake concentrations. Despite the clear contribution from boating, high MTBE concentrations were found following a major inflow event in winter, indicating the importance of the allochthonous contribution. The contribution from boating during summer, as measured indirectly by in-lake concentrations, is likely underestimated due to enhanced MTBE volatilization due to strong winds and high temperatures. May–September was found to be the main recreational boating season, with continued boating year round. On average, a single boat is active 23 d/y, with 84% of the watercrafts being active only during weekends and holidays. The survey further indicated that boats stay in the lake for 4.5 h on average, which conforms to the unique winds regime that limits afternoon activity due to high winds, and have an average fuel consumption of 14 L/h. The annual load of MTBE and BTEX from recreational boating in Lake Kinneret was estimated at 4430 and 6220 kg/y respectively.     

2021年春节期间陕西省烟花爆竹燃放对PM2.5的影响

通过对比2021年春节烟花爆竹集中燃放时段和前期非集中燃放时段的PM_2.5浓度及特征组分浓度,分析了烟花爆竹集中燃放对陕西省PM_2.5的影响情况。分析结果显示,2021年春节烟花爆竹集中燃放时段,关中和陕南地区PM_2.5浓度增幅大且高值持续时间长,陕北地区PM_2.5浓度增幅小且高值持续时间短。陕北和陕南地区PM_2.5小时浓度峰值出现在2月12日(初一)00:00前后,关中地区略晚。西安市PM_2.5特征组分中,K⁺、Cl^-、SO₄^2-、NO₃^-、Mg²⁺、Al³⁺、Cu²⁺、Si²⁺、Ba²⁺的浓度分别为6.61、7.20、12.83、23.96、1.36、2.91、0.23、0.27、0.86 μg/m³,明显高于非集中燃放时段。烟花爆竹燃放对陕南地区PM_2.5的贡献率和贡献量均高于关中和陕北地区;对郊县PM_2.5的贡献率高于城区,且对郊县的贡献率正值的出现时间早于城区。除榆林市外,陕西省其他城市的城区均受到了相关郊县烟花爆竹燃放的影响。     

河北南部城市臭氧和VOCs的污染特征及传输贡献

“十四五”时期是河北南部城市（石家庄、邢台和邯郸）退出空气质量综合指数排名后10位的关键阶段.基于2020年4~10月南部城市的15个国家环境质量监测站臭氧（O₃）逐时数据和3个挥发性有机物（VOCs）组分监测站的逐时数据及同期气象资料,采用时空演替、O₃生成潜势（OFP）、后向轨迹模式和空间统计模型进行分析.结果表明：①南部城市4~10月O₃变化呈倒"U"型分布,空间呈南高北低的格局,6月O₃污染最重,其ρ（O₃）依次为：邢台（233.8 μg ·m^-3）>邯郸（225.2 μg ·m^-3）>石家庄（224.8 μg ·m^-3）,O₃与温度和风速呈正相关、与湿度和VOCs呈反相关;②4~10月ρ（TVOC）依次为：邢台（274 μg ·m^-3）>石家庄（266 μg ·m^-3）>邯郸（218 μg ·m^-3）,烯烃和芳香烃的总OFP占比均超过一半;③南部城市O₃污染轨迹具有空间方向性和关联性,经过石家庄到邢台的轨迹ρ（O₃）均值（198.92 μg ·m^-3）最高,经过邯郸到达邢台的O₃污染轨迹频数最多;④南部城市传输贡献上,邢台对石家庄的O₃传输贡献率最高（27.39%）,邯郸对邢台的VOCs传输贡献率最高（32.76%）.     

车尔臣河流域土地利用变化及生态环境效应分析

借助ArcGIS与ERDAS软件,以1990年、2000年、2010年遥感影像Landsat TM/ETM为数据源,提取3期车尔臣河流域土地利用/覆盖利用图.在土地利用类型与区域生态风险之间的经验联系基础上,推求出土地利用类型生态风险指数,进而获得研究区域生态安全指数,建立了车尔臣河土地利用类型与生态环境之间的数量关系.同时,在空间尺度上将研究区分为若干特定研究单元,并对整体及局部地区进行生态环境质量动态分析.结果表明:1990—2010年间,车尔臣河流域总体生态环境指数呈逐步升高趋势,但生态环境质量的改善与恶化两种趋势并存,并在特定研究单元上出现明显的区域分异特征;盐碱地向耕地、林地及低覆盖度草地的转化,低覆盖度草地向林地的转化和未利用地向耕地的转化是环境改善的主导因素,林地与中覆盖度草地向盐碱地和未利用地的转化是环境恶化的主导因素.     

不同轮作和管理措施下根系呼吸对土壤呼吸的贡献

根系呼吸对土壤呼吸的贡献是研究土壤碳排放和土壤碳平衡的重点和难点.本研究采用根系排除法联合运用Li-8100土壤碳通量系统测定了华北平原冬小麦-夏玉米一年两熟传统管理体系(Con.W/M)、冬小麦-夏玉米一年两熟优化管理体系(Opt.W/M)、冬小麦-夏玉米(或夏大豆)-春玉米两年三熟优化管理体系(W/M-M、W/S-M)和春玉米一年一熟优化管理体系(M)作物根区土壤呼吸和非根区土壤呼吸,以根区和非根区土壤呼吸差异除以根区土壤呼吸计算根系呼吸的贡献.结果表明,根区土壤呼吸和非根区土壤呼吸具有明显的季节变化特征,二者具有显著的拟合关系.Con.W/M和Opt.W/M处理小麦季非根区土壤呼吸可分别解释根区土壤呼吸变异的65%和87%,玉米季非根区土壤呼吸的分别解释根区土壤呼吸变异的48%和65%.W/M-M、W/S-M和M处理春玉米非根区土壤呼吸可分别解释根区土壤呼吸变异的68%、76%和58%.Con.W/M处理小麦和玉米季根系呼吸对土壤呼吸贡献分别为25.0%和29.6%,Opt.W/M处理则分别为31.1%和35.0%.不同轮作和管理措施对春玉米根系呼吸的贡献无显著影响,W/M-M、W/S-M和M处理春玉米季根系呼吸贡献分别为23.7%、24.8%和24.9%.5 cm土壤温度对根区土壤呼吸的影响程度大于非根区土壤呼吸.     

贵州典型酸雨城市降尘中有毒重金属时空分布及来源分析

对2012年贵阳、遵义、安顺市区和背景点降尘样品进行逐月采集,并利用微波消解、ICP-MS对降尘中Cr、As、Cd、Hg、Pb的含量进行测定,分析其来源与贡献。结果表明,降尘五种重金属元素中,Pb含量最高,Hg含量最低。与土壤背景值相比,除Cr外,其它四种重金属元素含量总体明显升高;As、Cd、Hg含量季节性变化明显,Cr、Pb不明显。从降尘中五种重金属元素总量看,安顺夏季最高,市区点降尘总量均高于背景点,遵义和贵阳冬季最高,且在秋冬季背景点含量高于市区点。相关系数和主成分分析表明,贵阳、安顺、遵义降尘中重金属污染均受燃煤影响,其贡献率分别为61%、35%、75%。此外,安顺市交通尘贡献率为50%,遵义市风沙扬尘贡献率为21%。与其他城市相比,研究区城市降尘重金属元素除Cr外,As、Cd、Hg、Pb含量均较高。     

淳安县工业结构发展研究

基于《国民经济行业分类》及环境统计调查数据,淳安县的经济贡献率、污染贡献率、资源消耗贡献率、相对环境绩效及相对资源绩效在各行业之间差异比较明显,且聚集性较强。从产业竞争力来看,根据区位商评价,饮料制造业、纺织业、金属制品业具有较强的竞争力。应用聚类分析方法对淳安县11个行业进行分类,结合当地实际情况得出以下结论:环境绩效水平高且经济贡献率高,及环境绩效水平高且经济贡献率低的行业应作为该县重点鼓励发展的行业,其余两类行业应重点控制或逐步限制其发展。淳安县应进一步运用各种绿色经济政策,充分利用当地的生态优势大力发展生态工业,打造生态工业体系,同时还要加大对中小企业的扶持和服务力度。     

基于铅同位素解析技术的土壤铅污染来源研究

通过分析耕层土壤铅污染的程度,分析耕层土壤铅污染的来源,解析各污染源对土壤铅污染的相对贡献率.以陕西某工业区为研究区域,采集大气降尘、耕层土壤(0 ～ 20 cm)和背景土壤样品,用ICP-MS测定铅元素质量比及同位素比率(206pb/207 pb和208pb/206pb),分析耕层土壤铅污染的来源,结合二元混合模型计算各污染源对耕层土壤铅的贡献率.结果表明,耕层土壤铅质量比范围为21.8 ～ 40.0mg/kg,平均值为27.1 mg/kg;背景土壤铅质量比范围为19.1 ～22.1mg/kg,平均值为21.4 mg/kg;大气降尘铅质量比范围为570.2 ～2 221.7 mg/kg,平均值为1 062.36 mg/kg.该区域铅锌冶炼活动对耕层土壤铅的贡献率约为18.43％,焦化厂燃煤对耕层土壤铅的贡献率约为9.36％,热电厂燃煤对耕层土壤铅的贡献率约为19.71％,背景土壤对耕层土壤的贡献率约为52.5％.背景土壤是耕层土壤铅污染的主要来源.     

不同生育期Cd胁迫对水稻生长及镉累积的影响

采用水培试验方法,从水稻移栽至某特定生育期之间添加外源镉(Cd),通过递推减法,研究了湘晚籼13号水稻不同生育期Cd胁迫对其生长和不同部位中Cd含量的影响.结果表明,50μg·L~(-1)外源Cd胁迫不会影响水稻的正常生长发育,糙米中的Cd主要来源于水稻分蘖期吸收的Cd在后期的迁移、灌浆期吸收的Cd和成熟期吸收的Cd,这3个关键生育期对糙米中最终Cd含量的贡献率分别为36.4%、18.2%和16.4%.因此,与灌浆期和成熟期相比,在水稻分蘖期采用一些植物阻隔技术可能对水稻籽粒中Cd含量的削减更为重要.     

Response surface modeling-based source contribution analysis and VOC emission control policy assessment in a typical ozone-polluted urban Shunde, China

To develop a sound ozone (O₃) pollution control strategy, it is important to well understand and characterize the source contribution due to the complex chemical and physical formation processes of O₃. Using the “Shunde” city as a pilot summer case study, we apply an innovative response surface modeling (RSM) methodology based on the Community Multi-Scale Air Quality (CMAQ) modeling simulations to identify the O₃ regime and provide dynamic analysis of the precursor contributions to effectively assess the O₃ impacts of volatile organic compound (VOC) control strategy. Our results show that Shunde is a typical VOC-limited urban O₃ polluted city. The “Jiangmen” city, as the main upper wind area during July 2014, its VOCs and nitrogen oxides (NO_x) emissions make up the largest contribution (9.06%). On the contrary, the contribution from local (Shunde) emission is lowest (6.35%) among the seven neighbor regions. The local VOCs industrial source emission has the largest contribution comparing to other precursor emission sectors in Shunde. The results of dynamic source contribution analysis further show that the local NO_x control could slightly increase the ground O₃ under low (10.00%) and medium (40.00%) reduction ratios, while it could start to turn positive to decrease ground O₃ under the high NO_x abatement ratio (75.00%). The real-time assessment of O₃ impacts from VOCs control strategies in Pearl River Delta (PRD) shows that the joint regional VOCs emission control policy will effectively reduce the ground O₃ concentration in Shunde.