Changes in quality of groundwater with seasonal fluctuations: an example from Ghor Safi area, southern Dead Sea coastal aquifers, Jordan

Introduction The alluvial fan along the eastern and southern m argins of the D ead Sea (hereafter denoted D S) consists of fine to coarse-grained siliclastic sand and pebble-size gravel w ith thin intercalations of lam inated m arl of H olocene age (Pow e…     

Vehicle emissions of primary air pollutants from 2009 to 2019 and projection for the 14th Five-Year Plan period in Beijing, China

Over the past decade, the emission standards and fuel standards in Beijing have been upgraded twice, and the vehicle structure has been improved by accelerating the elimination of 2.95 million old vehicles. Through the formulation and implementation of these policies, the emissions of carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxides (NO_x), and fine particulate matter (PM_2.5) in 2019 were 147.9, 25.3, 43.4, and 0.91 kton in Beijing, respectively. The emission factor method was adopted to better understand the emissions characteristics of primary air pollutants from combustion engine vehicles and to improve pollution control. In combination with the air quality improvement goals and the status of social and economic development during the 14th Five-Year Plan period in Beijing, different vehicle pollution control scenarios were established, and emissions reductions were projected. The results show that the emissions of four air pollutants (CO, VOCs, NO_x, and PM_2.5) from vehicles in Beijing decreased by an average of 68% in 2019, compared to their levels in 2009. The contribution of NO_x emissions from diesel vehicles increased from 35% in 2009 to 56% in 2019, which indicated that clean and energy-saving diesel vehicle fleets should be further improved. Electric vehicle adoption could be an important measure to reduce pollutant emissions. With the further upgrading of vehicle structure and the adoption of electric vehicles, it is expected that the total emissions of the four vehicle pollutants can be reduced by 20%-41% by the end of the 14th Five-Year Plan period.     

Seasonal variation and sources of derivatized phenols in atmospheric fine particulate matter in North China Plain

Qualitative and quantitative analyses of derivatized phenols in Beijing and in Xinglong were performed from 2016 to 2017 using gas chromatography-mass spectrometry.The results showed substantially more severe pollution in Beijing.Of the 14 compounds detected,the total average concentration was 100 ng/m~3 in Beijing,compared with 11.6 ng/m~3 in Xinglong.More specifically,concentration of nitro-aromatic compounds(NACs)(81.9 ng/m~3 in Beijing and 8.49 ng/m3 in Xinglong) was the highest,followed by aromatic acids(14.6 ng/m~3 in Beijing and 2.42 ng/m~3 in Xinglong) and aromatic aldehydes(3.62 ng/m~3 in Beijing and 0.681 ng/m~3 in Xinglong).In terms of seasonal variation,the highest concentrations were found for 4-nitrocatechol in winter in Beijing(79.1±63.9 ng/m~3) and 4-nitrophenol in winter in Xinglong(9.72±8.94 ng/m~3).The analysis also revealed diurnal variations across different seasons.Most compounds presented higher concentrations at night in winter because of the decreased boundary layer height and increased heating intensity.While some presented higher levels during the day,which attributed to the photo-oxidation process for summer and more biomass burning activities for autumn.Higher concentrations appeared in winter and autumn than in spring and summer,which resulted from more coal combustions and adverse meteorological conditions.The significant correlations among NACs indicated similar sources of pollution.Higher correlations presented within each subgroup than those between the subgroups.Good correlations between levoglucosan and nitrophenols,nitrocatechols,nitro salicylic acids,with correlation coefficients(r) of 0.66,0.69 and 0.69,respectively,indicating an important role of biomass burning among primary sources.     

2016~2017年长荡湖流域河湖系统营养盐时空分布机制分析

以江苏省常州市长荡湖流域河湖系统为研究对象,基于野外监测与室内分析,探讨了水体氮、磷等营养盐的时空分布特征及其影响因素.结果表明,2016~2017年长荡湖流域河湖系统氮、磷污染突出,河流TN、NO₃^--N、NH₄⁺-N、TP和Chla平均质量浓度和高锰酸盐指数分别为（3.70±0.76）mg ·L^-1、（1.81±0.42）mg ·L^-1、（1.03±0.61）mg ·L^-1、（0.38±0.31）mg ·L^-1、（25.74±37.00）μg ·L^-1和（6.35±0.81）mg ·L^-1.河流总氮污染季节差异明显,表现为冬、春季劣于夏、秋季,河流总磷污染表现为秋、冬季劣于春、夏季,空间差异表现为北 > 西北 > 南 > 东部,河流处于中~高度富营养化状态.湖区TN、NO₃^--N、NH₄⁺-N、TP和Chla平均质量浓度和高锰酸盐指数分别为（2.25±0.94）mg ·L^-1、（0.98±0.47）mg ·L^-1、（0.19±0.14）mg ·L^-1、（0.11±0.03）mg ·L^-1、（18.71±8.76）μg ·L^-1和（4.59±1.09）mg ·L^-1,氮、磷质量浓度均超过Ⅲ类水标准,在空间上表现为从西部向东、南部降低的趋势,湖区处于轻~中度富营养状态.丹金溧漕河、通济河与薛埠河等河流是长荡湖流域河湖水系的主要污染物输送通道,丹金溧漕河干流输送氮、磷年通量最大,约为通济河和薛埠河年通量总和的10~12倍.长荡湖流域河流氮、磷污染同时受到农业面源污染物流失与城镇污水排放的影响.土地利用方式转变和大气沉降是导致长荡湖流域河湖系统氮、磷污染加剧的重要驱动因素.     

2005—2015年中国及境内典型城市群甲醛柱浓度时空变化及影响因子分析

基于2005—2015年OMI反演的甲醛柱浓度月均数据,对中国及境内典型城市群甲醛柱浓度时空变化及影响因子进行了分析.结果发现,甲醛柱浓度高值区集中在京津冀中南部、山东西部、河南北部、江浙沪、珠三角、湖北东部、湖南东部、广西、四川与重庆交界.2005—2015年中国甲醛柱浓度总体呈上升趋势,其中,京津冀地区增长趋势最明显,江浙沪地区呈略微下降趋势.中国、京津冀及江浙沪地区夏季甲醛柱浓度明显高于其余3个季节,呈明显的周期性变化;2005—2015年中国4个季节甲醛柱浓度均呈增加趋势,京津冀地区除夏季外其余3个季节也呈增加趋势,江浙沪和珠三角地区各季节甲醛柱浓度变化趋势不一致.近11年,中国、京津冀和江浙沪地区7月甲醛柱浓度最高,珠三角地区9月甲醛柱浓度最高.京津冀和江浙沪地区甲醛柱浓度月最高值和月最低值之间的差异大于珠三角地区.中国、京津冀、江浙沪和珠三角地区近11年秸秆焚烧与相应甲醛柱浓度呈明显正相关,相关系数为0.84~1.00,表明秸秆焚烧是影响近11年甲醛柱浓度变化的重要因子.尽管有些区域季节温度与相应甲醛柱浓度呈负相关,但温度总体也是影响中国及这3个典型城市群甲醛柱浓度变化的另一个重要因子,京津冀地区尤其明显.月平均温度与相应甲醛柱浓度的相关系数为0.52~0.85.人口、民用汽车保有量和国内生产总值与中国、京津冀、江浙沪和珠三角地区相应甲醛柱浓度相关系数均低于0.60.影响因子分析结果暗示控制秸秆焚烧和减少温室效应是降低我国甲醛柱浓度的重要途径.     

浙北地区PM2.5中多环芳烃特征

为了研究浙北地区PM_2.5中多环芳烃（PAHs）的季节性变化和它们的来源,于2014年11月~2015年11月收集了杭州和宁波2个城市中4个采样点的PM_2.5样品,利用气-质联用仪测定了17种PAHs浓度.结果表明,∑PAHs年平均浓度范围为24.1~51.9ng/m³,平均值为（35.5 ±12.3） ng/m³.2~3环PAHs在PM_2.5中的浓度较低（<1ng/m³）,而4~6环PAHs占总PAHs的77.0%.∑PAHs的浓度与PM_2.5呈相似的季节性变化特征,冬季浓度最高而夏季最低.惹烯作为软木燃烧的示踪物,冬季的浓度是夏季的4倍,表明在冬季软木燃烧的排放和对PM_2.5的贡献都有所增加.除了夏季的2个城区站点,其它季节和站点∑PAHs浓度和PM_2.5呈现一定的正相关性.特征PAHs比值显示,浙北地区气溶胶相关的多环芳烃主要来自燃烧和热解排放,如生物质燃烧和煤燃烧,而交通排放和石油挥发源的影响不大.     

Dynamics of major air pollutants from crop residue burning in mainland China, 2000–2014

Based on satellite image data and China's Statistical Yearbooks(2000 to 2014), we estimated the total mass of crop residue burned, and the proportion of residue burned in the field vs.indoors as domestic fuel. The total emissions of various pollutants from the burning of crop residue were estimated for 2000-2014 using the emission factor method. The results indicate that the total amount of crop residue and average burned mass were 8690.9 Tg and4914.6 Tg, respectively. The total amount of emitted pollutants including CO_2, CO, NOx,VOCs, PM_(2.5), OC(organic carbon), EC(element carbon) and TC(total carbon) were 4212.4–8440.9 Tg, 192.8–579.4 Tg, 4.8–19.4 Tg, 18.6–61.3 Tg, 18.8–49.7 Tg, 6.7–31.3 Tg, 2.3–4.7 Tg, and8.5–34.1 Tg, respectively. The emissions of pollutants released from crop residue burning were found to be spatially variable, with the burning of crop residue mainly occurring in Northeast, North and South China. In addition, pollutant emissions per unit area(10 km ×10 km) were mostly concentrated in the central and eastern regions of China. Emissions of CO_2, NOx, VOCs, OC and TC were mainly from rice straw burning, while burning of corn and wheat residues contributed most to emissions of CO, PM_(2.5) and EC. The increased ratio of PM_(2.5) emissions from crop residue burning to the total emitted from industry during the study period is attributed to the implementation of strict emissions management policies in Chinese industry. This study also provides baseline data for assessment of the regional atmospheric environment.     

淀山湖总氮和总磷的时空模拟分布

为了解氮磷在淀山湖的时空分布特征及变化规律,运用ELCOM-CAEDYM耦合模块分析了2008年淀山湖总氮和总磷浓度的时空变异。研究表明:模型较好地模拟了淀山湖上覆水中的总氮、总磷的时空分布,总氮、总磷质量浓度总体变化趋势与实测值相一致。淀山湖春冬季总氮的质量浓度要明显高于夏秋季,3月份是淀山湖总氮质量浓度最高的时候,千墩港是淀山湖总氮质量浓度最高的区域。淀山湖总磷的分布并未表现出季节上的规律性,空间分布整体呈现北高南低的趋势。     

京津冀晋鲁区域气溶胶光学厚度的时空特征

利用2000年3月至2013年12月MODIS Level 3遥感反演大气气溶胶光学厚度(AOD)产品数据,分析近年来京津冀晋鲁区域AOD的时空分布和变化特征.结果表明:1从时变特征来看,近14年来全区年平均AOD值在0.428~0.550之间变化,年际间变化浮动大,因此多年平均增长率并不高,仅呈微弱增长趋势;以2008年为界可将近14年的AOD变化分为呈明显上升趋势的第一阶段(2000—2007年,增长率为1.349%)以及呈明显下降趋势的第二阶段(2008—2013年,增长率为-1.483%);全区四季AOD多年变化除夏季呈微弱下降趋势,其它3季均为上升趋势,冬季增长率最大;夏季AOD最高,但有回落的趋势,冬季AOD最低,但有上升的趋势.2从空间分布特征来看,全区多年AOD空间分布大体上呈南高北低的格局,河北和山东的西南部为高值区(AOD为0.72),河北和山西的北边为低值区(AOD为0.23),北京和天津则处于中上水平(AOD为0.58);全区四季AOD空间分布呈现出强烈的季节变化,春季较高,夏季最高,进入秋季显著降低,冬季则最低,冬季到来年春季呈跳跃性增高.这些结果有助于京津冀晋鲁区域的气候变化和环境研究.     

2000～2010年贵州省植被净初级生产力时空变化研究

为了探明贵州省植被净初级生产力(NPP)在2000~2010年的变化状况,以2000~2010年植被NPP数据为基础,运用ArcG IS和SPSS进行综合分析。结果表明:近11年间,草地、城镇用地、阔叶林、针叶林和湿地等面积呈增加趋势,而灌木林和农田则持续减少,其中农田面积变化尤为明显;2000~2010年贵州省植被NPP变化较大,NPP变化范围为778~889 g/(m2·a),平均值为828.1 g/(m2·a),NPP缓慢上升趋势;全省NPP分布有明显地域性差异,铜仁和六盘水为显著增加(P0.05),其余地州市增加缓慢(P0.05)。黔东南年均NPP最高((927±111)g/(m 2·a)),毕节最低((725±107)g/(m2·a))。NPP变化趋势为东南向西北方向递减,而往西北方向NPP波动程度明显;阔叶林和灌木林缓慢下降,而针叶林和针阔混交林则上升。NPP表现为针阔混交林阔叶林针叶林灌木林。