大气污染联合治理分区视角下的中国PM2.5关联关系时空变异特征分析

联合治理分区下PM_2.5关联关系时空变异特征识别对中国大气污染防治意义重大.本文主要基于2000～2016年遥感反演的中国大陆334个地级市PM_2.5浓度数据,利用空间单元聚合策略与地理时空加权回归技术,系统分析了大气污染联合治理分区视角下的中国PM_2.5关联关系时空变异特征.结果表明:①以PM_2.5为首要污染物,综合考虑污染程度、地理位置、气象、地形和经济等因素可将中国大陆地区划分为10个大气污染联合治理区.②地理时空加权回归能够有效刻画PM_2.5与关联因素间的时空非平稳关系.同时,人口规模、第二产业生产总值、SO₂排放量、年平均气温、年降水量以及年平均相对湿度被识别出对PM_2.5浓度的变化影响存在显著时空差异.③人口规模对PM_2.5浓度的影响程度各年最大的地区均为京津冀蒙区域;川渝滇黔区域中第二产业生产总值对PM_2.5浓度影响程度变异度最大,在黑吉辽区域之外,SO₂...     

渤海和北黄海有色溶解有机物(CDOM)的分布特征和季节变化

采集了2016年的4、8、12月和2017年2月渤海和北黄海表、中、底海水样品,分析了海水中有色溶解有机物(CDOM)的紫外-可见光吸收光谱和三维荧光光谱,探讨了渤海和北黄海海域CDOM的分布特征、影响因素和季节变化.结果表明,不同季节CDOM分布相似,呈近岸高、远海低的分布特征.吸收系数a(355)和光谱斜率S275-295呈显著负相关,说明CDOM受到陆源输入的显著影响.垂直分布上,8月,受强烈的光降解作用影响,表层CDOM含量最低. 2月,底层CDOM含量最低,这可能与受光照影响的初级生产力在水下分布不均匀有关.从2016年4月～2017年2月,CDOM含量先上升后下降,12月含量最高,2月含量最低. CDOM的季节变化主要受陆源输入和浮游植物生物量的季节变化控制.以光谱斜率S275-295表征CDOM的平均分子量,2月由于陆源输入最少,CDOM平均分子量最小.夏季光降解强烈,将部分大分子量有机物降解成小分子量有机物,小分子量有机物增加,因此,8月CDOM的平均分子量小于4月和12月.     

A framework for investigating the air quality variation characteristics based on the monitoring data: Case study for Beijing during 2013–2016

In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollution periods and airflow directions), through a case study in Beijing from 2013 to 2016. The results showed that the annual mean concentrations(MC) of PM_(2.5), SO_2, NO_2 and CO had decreased with annual mean ratios of 7.5%, 28.6%, 4.6%and 15.5% from 2013 to 2016, respectively. Among seasons, the MC in winter contributed the largest fractions(25.8%～46.4%) to the annual MC, and the change of MC in summer contributed most to the inter-annual MC variation(IMCV) of PM_(2.5) and NO2. For different pollution periods, gradually increase of frequency of S-1(PM_(2.5), 0～ 75 μg/m~3) made S-1 become the largest contributor(28.8%) to the MC of PM_(2.5) in 2016, it had a negative contribution(-13.1%) to the IMCV of PM_(2.5); obvious decreases of frequencies of heavily polluted and severely polluted dominated(44.7% and 39.5%) the IMCV of PM_(2.5). For different airflow directions, the MC of pollutants under the south airflow had the most significant decrease(22.5%～62.5%), and those decrease contributed most to the IMCV of PM_(2.5)(143.3%),SO2(72.0%), NO_2(55.5%) and CO(190.3%); the west airflow had negative influences to the IMCV of PM_(2.5), NO_2 and CO. The framework is helpful for further analysis and utilization of the large amounts of monitoring data; and the analysis results can provide scientific supports for the formulation or adjustment of further air pollution mitigation policy.     

典型草原区土壤水分变化特征及影响因素分析

为了揭示典型草原区土壤水分时空变化规律,探讨主要影响因子,利用内蒙古两个站点近20年土壤水分观测资料和相应的气象资料,采用数理统计方法,分析了该区域土壤水分变化的基本事实和统计特征及影响因子,得出:年内土壤水分基本呈双峰曲线变化,春季化冻(04-08)到入冬前(10-18)的土壤水分平均相差5.3mm,大多数年份土壤水分年内可以达到平衡;年际变化有每隔7～8年走势发生改变的趋势;垂直向水分变化主要发生在60cm以上土层中,近几年深层变幅有增大的倾向;蒸降差与土壤水分变化呈相反趋势,生长季蒸降差对土壤水分的干扰最大.样本站0～50cm土层的最大容水量为85mm和135mm,多数时期土壤相对含水量平均在40%～60%以上,有较强的调蓄能力.     

南京市郊蔬菜地土壤中重金属含量的时空变化规律

测定了28份蔬菜地土壤样品中的铜、锌、铅、镉、汞的含量,从城市化的角度研究了南京市郊蔬菜地土壤重金属在“城区、郊区和农区”的水平空间变化和在层次间的纵向空间变化,并结合历史数据分析了蔬菜地土壤重金属的时间累积作用。结果表明,城市化影响重金属的水平空间变化,蔬菜地土壤重金属含量随着蔬菜地与城市距离的增加,在城区到郊区这一距离段呈下降趋势,在郊区到农区则基本不变;城市化影响重金属的纵向空间变化,蔬菜地各重金属元素表层减底层差值的均值,城区均为正值且绝对值较高,郊区和农区各值都在0浓度附近摆动且绝对值较小。由于受城市化的时间累积作用的影响,1999年土壤中重金属Pb和Zn含量显著高于1985年。     

1979-2014年中国地面风速的长期变化趋势

基于中国国家级地面气象站均一化风速月值数据集,采用线性回归等方法分析了1979-2014年中国2268个台站地面风速演变的时空特征。结果表明：中国地面风速总体呈显著下降趋势,年平均风速变化速率为-0.142 m/s/10 a;四个季节中春季平均风速下降趋势（-0.18 m/s/10 a）明显大于其他三个季节,其次依次为冬季（-0.135 m/s/10 a）、夏季（-0.13 m/s/10 a）及秋季（-0.129 m/s/10 a）;研究选取的台站中约82%的台站风速呈现下降趋势;划分的七个区域中,高原区和东北区风速下降趋势最明显,华北区下降趋势最小,但都通过了0.05显著性检验;中国地面风速在1980s下降趋势最显著（-0.235 m/s/10 a）,1990s下降趋势减缓（-0.112 m/s/10 a）,2000-2014年下降趋势最小,为-0.099 m/s/10 a;研究期间地面风速与地面气温呈显著负相关,表明近期中国气温变暖可能导致风速减弱。     

长江三角洲地区耕地数量变化及保护对策——以吴江市为例

长江三角洲是我国经济最发达的地区之一 ,但在经济发展的同时 ,耕地资源却日益减少 ,这将严重影响到我国未来的粮食安全问题。吴江市位于长江三角洲中心位置 ,强大的经济基础和有利的区位条件使土地资源得以高速地开发利用 ,它是长江三角洲地区在耕地数量变化上一个较典型的地区 ,在土地整理方面也进行了成功的尝试。以吴江市为例 ,定性和定量地对耕地数量变化的人文驱动力进行分析 ,得出影响本地耕地数量变化的主要驱动因素为 :工业发展 ,固定资产投资规模扩大和农业产业结构调整。随着经济的发展 ,在这些驱动因素的影响下 ,必然会造成耕地数量的进一步减少。如何保护长江三角洲地区现有的有限的耕地资源 ,实现国家新的《土地管理法》中所要求的耕地总量动态平衡是本地区面临的一个严峻问题。在进行保护对策研究时 ,除了采用通常各地已采取的一些措施外 ,还做了进一步的思考 ,对本地区在实施耕地总量动态平衡过程中、农业产业结构调整存在的问题及本地区如何面对WTO的挑战提出建议     

北京市大气中多氯联苯的污染水平和分布特征

利用XAD树脂被动采样技术和同位素稀释高分辨气相色谱/高分辨质谱联用法(HRGC/HRMS)研究了2012年11月至2014年1月北京地区大气中多氯联苯(PCBs)的污染现状、区域分布特征及季节性变化规律.结果表明,北京大气中19种PCBs总浓度为8.42—45.2 pg·m-3(平均值23.1 pg·m-3),各采样点全年平均毒性当量范围为0.33—3.33 fg WHO-TEQ m-3(平均值1.85 fg WHO-TEQ m-3).PCB-11浓度范围为27.9—136pg·m-3,平均值为78.2 pg·m-3.大气中的PCBs以低氯代(2—5氯代)PCBs为主.季节变化规律呈现出夏/秋季节PCBs浓度高于冬/春季节的规律;区域分布特征呈现出人口密集的城区大于背景区、工业区大于城区的规律.     

Temporal variations of concentrations of currently used pesticides in the atmosphere of Strasbourg, France

Atmospheric samples have been collected in Strasbourg between April 18 and May 29, 2007 and were analyzed for 71 current-use pesticides, of which 38 were detected. Average concentrations ranged from 0.09 ng m⁻³ for Fenarimol to 110.42 ng  m⁻³ for Dimethachlor, which was slightly higher than the concentrations reported from other, comparable agricultural regions.Significant temporal variations were observed for 30 pesticides, and for most of them it could be shown that these were linked to time, temperature or atmospheric pressure. In several cases this helped to identify pesticide application just before or at the beginning of the sampling period, or ongoing treatment. Humidity, in contrast to previous reports, could not be linked to these variations. For the other 8 pesticides, only very little temporal variations were observed. Generally, these concentrations were low (less than 1 ng m⁻³), and it was assumed that they are not in use in Alsace at present.     

Hydrogeochemical and Geophysical Investigation of the Istanbul Tuzla–Icmeler Spring Area for Environmental and Land Use Planning Purposes

The spring waters of Tuzla–Icmeler are on the Marmara Sea coast in Tuzla town of Istanbul city. The springs discharge a natural sodium chloride mineral water that consumed for ages for therapeutic purposes attributed to their chemical properties. Development of springs commenced during the Ottoman times and a surface collection structure was built at the discharge point of the main spring. Two deep wells were drilled to tap mineral water within the past decades. The bottled water of these springs is also sold for a couple of years and its consumption as a beverage is increasing. The geochemical properties of these springs were investigated by several researchers in the past. This study comprises geochemical and geophysical measurements performed between July 2001 and July 2002 in order to construct a conceptual hydrogeological model for environmental and land use planning purposes. The seasonal evaluation of Tuzla–Icmeler (mineral spring) shows that the chemical properties fluctuate from the beginning of summer until the beginning of winter. This indicates that the overdraft of water during the summer season causes the movement and mix of normal groundwater with the mineralized groundwater. As a result, mixing of less mineralized groundwater decreases the salinity of mineralized groundwater. Using the site-specific hydrogeological, geochemical and geophysical data, zones of protection areas were delineated in order to prevent a possible pollution access to the springs and surroundings from nearby dockyards, dwellings and vehicle traffic. For this purpose, a new land use plan was proposed using the existing settlement sustainability plans.