广西西江流域土壤重金属背景值再研究

为深入探究广西西江流域土壤重金属背景值状况,在大规模系统采样的基础上,从2864件土壤样品中筛选出处于自然状态下的土壤样品.通过计算不同均值并分析比较后重新提出广西西江流域土壤重金属背景值.研究结果表明,西江流域各土壤重金属背景值为(mg·kg~(-1)):As17.04、Sb 5.08、Cd 0.56、Pb 50.72、Cu 20.79、Ni 26.47、Zn 67.34、Cr 82.66.与以前研究结果相比,本研究新提出的As、Cu、Ni、Zn、Cr背景值略有差异,差异在5%以内,而Cd、Pb背景值则分别为《土壤背景值研究方法及广西土壤背景值》研究结果的4.2、2.5倍,Sb则是全国土壤背景值的4.8倍.偏高的主要原因是西江流域上游地区的南丹县、金城江、环江县、都安县、大化县、宜州市处于地球化学异常区,该区域Cd、Pb、Sb含量十分异常,使得土壤中重金属含量整体偏高.重新提出的背景值可为该流域土壤环境研究提供参考,同时为制定土壤环境质量标准提供重要依据.     

砷污染土壤中不同基因型水稻根表铁膜的形成及其对砷吸收和转运影响

采用土壤盆栽试验法,研究6个不同基因型水稻品种根表铁膜形成及其对As吸收、转运的影响。结果表明,水稻形成根表铁膜在不同基因型品种之间差异显著（p<0.001）,其中品种94D-22形成铁膜量（以Fe含量计）是品种圭630的1.5~1.8倍,添加As处理对水稻根表铁膜形成影响不显著。低As含量的对照土壤中,水稻根表铁膜量与根系As含量存在着显著的正相关关系（r=0.657,n=24,p<0.01）,与As转移系数呈显著的负相关关系(r=-0.612,n=24,p<0.01）。土壤添加As后,水稻根表铁膜量与茎叶As含量存在显著的正相关关系（r=0.653-0.673,n=24,p<0.01）,与As转运之间无显著相关性。比较生长于As污染土壤的不同水稻品种,科优1360茎叶积累As较少,且其根系转运As能力也较差,而品种94D-22正好相反。研究结果表明,在As含量较低的土壤中,水稻根表铁膜的存在可成为根系As的障碍层,阻止As向地上部转运;但在As含量较高的土壤,根表铁膜的存在却促进了水稻茎叶对As的积累,其对As的转运没有显著影响。人们可通过作物品种筛选来防治土壤As污染危害、降低As对人体健康的威胁。     

南京城区与郊区秋季大气PM_(10)中水溶性离子的特征研究

对南京市城区与郊区秋季PM10中水溶性离子的浓度水平,变化规律及其相关性进行分析。结果表明:水溶性离子是南京市PM10的重要组成部分,占PM10总量的26.8%～49.5%;NO3-、SO24-为南京PM10中离子的主要成分同时SO24-与PM10的相关性高,在郊区与城区相关系数分别为0.97与0.98;土壤源对Mg2+的贡献多于海洋气溶胶。郊区与城区非海盐Mg2+和Ca2+的比值分别为0.0308～0.0557与0.0314～0.0558,与中国北方沙漠地区相异,说明观测期间南京大气PM10主要受局地源影响;南京城、郊NO3-/SO24-均值分别为0.74和0.80,说明南京市城郊PM10中NO3-与SO24-更多地来自于机动车尾气排放。     

镉对不同生态型水稻的毒性及其在水稻体内迁移转运

采用溶液培养方法研究镉(Cd)对两种不同生态型水稻的毒性影响以及Cd在水稻体内的转运.结果表明,粳稻品种杨辐粳7号比籼稻品种K优818对Cd毒害反应更敏感.两种生态型水稻品种的根系对Cd的吸收积累差异比较大,在10 μmol·L-1 Cd浓度下生长3～14 d,杨辐粳7号根系中Cd浓度比K优818高44.5％ ～ 99...     

长江上游植被覆盖的时空分异季节变化及其驱动因子研究

以GIMMS/NDVl为基础,结合气候与人类活动数据,研究了1982～2003年间长江上游植被覆盖季节变化的空间分布.结果表明,近22年来,长江上游春季、夏季植被覆盖呈增加趋势,以春季最显著;秋季、冬季植被覆盖呈降低趋势,以秋季降低最显著.春季、夏季降雨与气温的同步增加,致使植被覆盖增加;秋季降雨减少,以及气温的增加导致植被覆盖降低;另外,作物播种面积的增加是春季、夏季植被覆盖增加,秋季、冬季植被覆盖减少的重要原因.春季→夏季→秋季→冬季NDVI增加的区域在窄问上大致呈现低纬度向高纬度转移的趋势.春季、夏季所有植被类型的NDVI均有增加趋势;而秋季所有植被类型的NDVI均降低;冬季植被除针叶林的NDVI略有增长外,其余植被类型的NDVI均降低.     

Arsenic uptake, accumulation and phytofiltration by duckweed （Spirodela polyrhiza L.）

This study investigates arsenic (As) accumulation and tolerance of duckweed Spirodela polyrhiza L: and its potential for As phytofiltration. S. polyrhiza was able to survive in high concentration of As(V) solution: The EC50 values ( SE) based on the external As(V) were (181.66 20.12) mol/L. It accumulated (999 95) mg As/kg dw when exposed in 320 mol/L As(V) solution for one week, and was able to take up appropriately 400 mg As/kg dw in tissues without a significant biomass loss. The EC50 values (the e ective concentration of As(V) in the nutrient solution that caused a 50% inhibition on biomass production) was (866 68) mg/kg dw for the tissues, indicating that S. polyrhiza had a high capability of As accumulation and tolerance. The uptake kinetic parameters Vmax was (55.33 2.24) nmol/(g dw min) and Km was (0.144 0.011) mmol/L. Within 72 hr, S. polyrhiza decreased As concentration in the solution from 190 to 113 ng/mL with a removal rate of 41%. The study suggested that this floating aquatic plant has some potential for As phytofiltration in contaminated water bodies or paddy soils.     

Production and contribution of hydroxyl radicals between the DSA anode and water interface

Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and e ect of hydroxyl radicals on the interface between DSA anode and water was investigated by examining the quenching e ect of iso-propanol on Orange II decolorization. We observed that with an increase in electrode potential from 4 to 12 V across electrodes at pH 7.0, the contribution percentage of hydroxyl radicals increased dramatically. More OH radicals were produced in acidic and alkaline conditions than at neutral conditions. At electrode potential of 4 V, the contribution percentage of hydroxyl radicals was obviously higher at near neutral pH conditions, while removal e ciency of Orange II achieved was the lowest concurrently. Finally, for photocatalytic oxidation, electrochemical oxidation, and photoelectrochemical oxidation using the same DSA electrode, the e ect of hydroxyl radicals proved to be dominant in photocatalytic oxidation but the contribution of hydroxyl radicals was not dominant in electrochemical oxidation, which implies the necessity of UV irradiation for electrochemical oxidation during water treatment.     

Characterization of soil heavy metal contamination and potential health risk in metropolitan region of northern China

Soil in metropolitan region suffers great contamination risk due to the rapid urbanization especially in developing countries. Beijing and Tianjin, together with their surrounding regions, form a mega-metropolitan region in northern China. To assess the soil environmental quality, a total of 458 surface soil samples were collected from this area. Concentrations of Cr, Cu, Pb, Zn, As, Cd, and Hg were analyzed and compared to the Chinese environmental quality standards for soil. Multivariate analysis was carried out to identify the possible sources and Geographic Information Systems techniques were applied to visualize the spatial data. It was found that the primary inputs of As were due to pedogenic sources, whereas Hg was mainly of anthropogenic source. Other elements including Cr, Cu, Pb, Zn, and Cd were from both lithogenic and anthropogenic origins. Health risk assessment based on the maximum heavy metal concentration indicated that As derived from sewage irrigation area can result in carcinogenic lifetime risk due to ingestion and/or dermal contact of soil. The potential non-carcinogenic risk for children is significant for Pb and the cumulative effect of multiple metals is of concern for children in the vicinity of mining site. The results increased our knowledge for understanding natural and anthropogenic sources as well as health risk for metals in metropolitan soil.     

登陆中国台风灾害损失预评估模型研究

整理了2000-2008年登陆中国且灾情记录完整的34个台风案例,建立案例集;基于模糊数学法建立了台风灾害损失预评估模型。选择8项影响因子作为模型输入指标,利用层次分析法确定影响因子权重,计算案例集中每个台风的综合评价指数;通过对综合评价指数与受灾人口、农作物受灾面积及直接经济损失等典型灾情指标进行拟合;通过适当调整影响因子权重,拟合得出最优幂函数回归方程,从而实现对台风灾情的定量预评估。     

根表铁膜对水稻铅吸收转运的影响

通过温室土壤盆栽试验研究不同生育期水稻根表铁膜形成对水稻吸收和转运Pb的影响。结果表明,两种水稻根表铁膜形成量(以DCB-Fe含量计)及铁膜中吸附的Pb量均随着生育期的延长而减少。水稻根表铁膜Fe含量与铁膜吸附的Pb量呈显著的正相关关系(r=0.798,p0.01)。水稻根系和茎叶吸收积累Pb随着不同品种和不同生育期而变化。品种NK57籽粒Pb含量显著高于品种YD6,前者为后者的1.9倍。从富集系数和分配比率来看,Pb主要富集在水稻的铁膜和根系中,而积累在茎叶和籽粒中的比率较少。Pb从水稻根表铁膜、根系和茎叶向籽粒中的转运系数在两个水稻品种间差异均不显著。水稻分蘖期和孕穗期根表铁膜量与根系Pb含量均呈显著的正相关关系(p0.05),但是成熟期水稻根表铁膜量与根系、茎叶和籽粒中Pb含量相关性均不显著,说明根表铁膜形成对水稻分蘖期和孕穗期吸收积累Pb有一定影响,但对水稻成熟期根系、茎叶和籽粒吸收积累Pb影响不大。