中亚热带针阔混交林土壤-大气界面释汞通量研究

为了揭示不同气候条件下森林与大气间汞交换的规律,应用动力学通量箱与Lumex RA 915+测汞仪联用技术,选择重庆缙云山国家级自然保护区为研究地点,于2011年4月~2012年3月对针阔混交林土/气界面释汞通量进行了为期1 a的连续监测,并考察了各环境因子对土壤释汞通量的影响.结果表明,缙云山针阔混交林林地土壤年平均释汞通量值为(16.82±6.70)ng·(m2·h)-1,明显高于欧美国家自然背景区;受光照、温度、相对湿度等气象因素以及亚热带地区森林植被生长变化规律影响,缙云山地区林地土壤释汞通量存在显著的季节性差异,暖季林地土壤释汞通量[(22.23±13.19)ng·(m2·h)-1]明显高于冷季[(6.01±4.05)ng·(m2·h)-1];通径分析结果表明林地土壤释汞通量的日变化特征和1 d中光照强度变化有密切关系,土温、气温和相对湿度与土壤释汞通量之间的显著相关关系可能是光照强度与土壤释汞通量相关关系的表象.     

长江流域污染物输出对河口水质的影响

基于EFDC模型建立长江口及邻近海域三维水质模型,模拟2004—2007年不同水期的ρ(COD_Mn)、ρ(DIN)、ρ(PO₄3--P)状况,分析水质分布的变化特征,研究流域污染物输出对河口水质分布的影响. 根据GB 3097—1997《海水水质标准》,长江口门以上ρ(COD_Mn)为Ⅱ类水质,ρ(DIN)、ρ(PO₄3--P)为劣Ⅳ类,并且有明显的分层现象. 枯水期各指标等值线均向东北方向延伸,丰水期和平水期向东南延伸,丰水期流域污染物输出对河口水质的影响最大,不同类别水体的分布形态和水体面积年际变化不明显. 按不同时期ρ(COD_Mn)、ρ(DIN)、ρ(PO₄3--P)分布面积进行统计,长江口ρ(COD_Mn)、ρ(DIN)、ρ(PO₄3--P)分布与流域污染物输出之间有显著关系,河口水质分布面积与流域污染物输出之间存在定量的压力-响应关系.ρ(COD_Mn)、ρ(DIN)、ρ(PO₄3--P)达Ⅳ类以上水体面积(y)与流域污染物输出通量(x)的关系分别为:y_CODMn=2 061.4 ln x_CODMn-15 357.0,y_DIN=1 386.8 ln x_DIN-6 546.1,y_PO43--P=2 219.3 ln x_PO43--P-6 166.1.      

长江流域污染负荷核算及来源分析

为研究长江流域污染物输出的时空变化特征和来源,将长江流域划分为114个排污单元,195个纳污河段,应用污染物“产生-排放-入河-消减-输出”模型,结合长江流域2004—2007年的社会经济、水文监测资料,利用朱坨、寸滩、宜昌、大通4个监测断面2004—2007年逐月的水量和水质数据,通过连续演算核算长江流域各河段的污染物输出过程,进行区间污染物输出平衡分析,估算出姚港断面污染物输出过程. 结果表明,各断面计算数据与实测数据相对误差不超过20%,模型及参数组合的可靠性较好. 点源对COD_Mn输出贡献较大,占56.4%;非点源对TN、TP的贡献大,分别占74.3%和92.1%. 从污染物输出分布来看,江西、四川、湖南、湖北四省占流域污染物输出总量的60%以上,贡献率较大,是流域污染物输出的重要区域.      

广东东江流域多氯萘的大气沉降研究

为考察多氯萘(PCNs)通过大气沉降作用对东江流域的影响,利用通用型大气沉降采样器,在东江流域广东省境内代表性地段布设11个采样点,于2010年冬季(1、2月)和夏季(7、8月)分别采集和分析了沉降样品中PCNs的通量及组成.结果表明,东江流域总PCNs日均沉降通量为828 pg.(m2.d)-1,对应毒性当量(TEQ)为0.14 pg.(m2.d)-1,由此估算东江流域广东境内PCNs年沉降总量为8.5 kg,相应TEQ年沉降总量为1.3 g.地域上,广州和东莞地区沉降通量明显高于惠州,同时城镇采样点的沉降通量显著高于农村;季节上,各采样点总体呈现夏季高于冬季的特点;组成上,三氯萘(tri-CNs)是主要的污染物,占总量的50%以上,但广州、东莞的5～8氯萘含量比惠州高.来源分析表明,东江流域PCNs的大气沉降可能受燃烧源与非燃烧源的共同影响;东莞大气沉降中PCNs多来自燃烧源,广州点大气沉降的PCNs以非燃烧源为主.     

珠江流域土壤中碳库的存量与通量

通过对珠江流域各主要环境介质中不同形态碳含量的分析和计算,得出该流域0~1.0m范围内土壤碳库的存量为1.36×1013kg,占中国陆地碳库总量的9.51%,全球碳库总量的0.907%;流域净碳输入量为4.141×1010kg/a,碳通量912.74kg/(hm2·a),初步计算表明珠江流域可能是陆地生态系统的一个碳汇区。另一方面,人类活动造成流域内有机碳的大量流失,其中,水土流失损失的碳8.01×109kg/a,植物收割及森林砍伐从土壤-植物系统中携带出的有机碳高达6.26×1011kg/a,这将造成土壤有机质含量的降低,因此促进陆地生态系统有机碳存储是提高本流域土地质量的关键。     

Polycyclic aromatic hydrocarbons in the bulk precipitation and surface waters of Northern Greece

Bulk (wet and dry) precipitation and surface water sampling was undertaken in the main plain of central Macedonia in Northern Greece. Fourteen polycyclic aromatic hydrocarbons (PAHs) included in the US EPA's priority pollutant list were analysed. The concentrations determined in bulk precipitation were in general within the range of values worldwide reported. Concentrations were highest in the cold months. Deposition fluxes of PAHs were of the same order of magnitude as reported data. The greatest values were found when high concentrations of PAHs in precipitation coincided with large precipitation amounts. The concentrations of PAHs in surface waters (main rivers, tributaries, ditches, etc) were in general lower than those in bulk precipitation, and among the lowest reported for European rivers, excepting Np and Ph. Bulk deposition and domestic effluents are suggested as being the main PAH sources into surface waters.     

北太平洋地区春季粉尘的空间分布特征——观测及模拟

通过对2001年4月的一次中亚强沙尘暴过程的观测事实分析和数值模拟,结果表明,源自中亚的强沙尘暴扬起的粉尘,通过西风急流远程传输到韩国、日本、北太平洋、北美大陆.北太平洋地区的沙尘沉积通量空间分布将主要取决于3个方面:沙尘沉积通量随传输距离的增加呈指数衰减;传输路径上粉尘有较高的沉降通量;沙尘过境时的降水空间格局将在很大程度上决定粉尘的沉降空间格局.     

Chemical fluxes in time through forest ecosystems in the UK - Soil response to pollution recovery

Long term trend analysis of bulk precipitation, throughfall and soil solution elemental fluxes from 12 years monitoring at 10 ICP Level II forest sites in the UK reveal coherent national chemical trends indicating recovery from sulphur deposition and acidification. Soil solution pH increased and sulphate and aluminium decreased at most sites. Trends in nitrogen were variable and dependant on its form. Dissolved organic nitrogen increased in bulk precipitation, throughfall and soil solution at most sites. Nitrate in soil solution declined at sites receiving high nitrogen deposition. Increase in soil dissolved organic carbon was detected - a response to pollution recovery, changes in soil temperature and/or increased microbial activity. An increase of sodium and chloride was evident - a possible result of more frequent storm events at exposed sites. The intensive and integrated nature of monitoring enables the relationships between climate/pollutant exposure and chemical/biological response in forestry to be explored.     

NUTRIENT LOADS TO WISCONSIN LAKES: PART I. NITROGEN AND PHOSPHORUS EXPORT COEFFICIENTS1

ABSTRACT: Export coefficients (kg/km²/yr) for dissolved ortho-phosphate (OP), total phosphorus (TP), total inorganic nitrogen (TIN), and total nitrogen (TN) were derived for watersheds in Wisconsin using data bases available for 17 basins from the U.S. Environmental Protection Agency — National Eutrophication Survey, U.S. Geological Survey, and the Wisconsin Department of Natural Resources. Three general land use categories, representative of most regions in Wisconsin, were established: forest, mixed, and agricultural. Data for the 17 basins indicated greater exports of OP. TP, TIN, and TN as the percentage of forest decreased and agriculture increased. These region-specific coefficients are compared to the values reported in the literature representing much broader areas of the U.S.     

AN EXAMINATION OF LAND USE - NUTRIENT EXPORT RELATIONSHIPS1

ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed