模拟根系分泌物对土壤吸附菲的影响

采用批量平衡试验方法,研究了模拟根系分泌物(ARE)对黄棕壤、棕红壤和红壤吸附菲的影响.结果表明,3种土壤对菲的等温吸附曲线均为线性,加入ARE后,土壤吸附菲的分配系数(Kd)和有机碳标化的分配系数(Koc)显著降低,且降低量随着ARE浓度的增加而增大,表明ARE抑制了土壤对菲的吸附.土壤有机质含量越低,ARE对土壤吸附菲的抑制作用越明显.分析土样吸附菲的平衡溶液中水溶性有机质(DOM)浓度,发现加入ARE后土壤有机质含量略有降低(1.64%),而DOM浓度增大,DOM与菲的结合作用对土壤吸附菲的抑制作用增强,这可能是ARE抑制土壤吸附菲的主要原因.     

重金属（Hg，As，Pb）污染对蚕豆根尖细胞微核的诱变研究

采用蚕豆根尖细胞微核检测技术,分别探讨不同浓度的HgCl2、As2O3、Pb（NO3）2对蚕豆根尖细胞微核率的影响。以蒸馏水处理作为阴性对照实验。结果表明不同浓度的HgCl2可使蚕豆根尖细胞微核率明显上升,说明HgCl2对蚕豆根尖具有明显的毒性效应——诱发突变（微核）。不同浓度As2O3可使蚕豆根尖细胞微核率明显上升。说明三氧化二砷（As2O3）对蚕豆根尖具有明显的毒性效应——诱发突变（微核）。蚕豆根尖微核率在铅离子浓度0—25mg／L范围内,随着硝酸铅处理浓度的升高而升高,说明硝酸铅是一种较强的诱变剂。     

焦亚硫酸钠对大鼠背根节神经元L-型钙电流的影响

为了探讨二氧化硫(SO2)及其衍生物对背根节神经元的生理调节作用,应用全细胞膜片钳技术,研究了SO2衍生物焦亚硫酸钠(sodiummetabisulfite,SMB)对大鼠背根节神经元L-型钙电流(ICa,L)的影响.结果表明,SMB可增大ICa,L,且具有剂量依赖性和电压依赖性的特征.SMB可使ICa,L的激活和失活过程均向去极化方向移动,但对失活的影响要大于对激活的影响,从而可导致背根节神经元钙离子内流增大,引起细胞内钙离子浓度增加.这说明SO2及其衍生物对背根节神经元的生理功能有调节作用,当其浓度过高时也可能引起该神经元的病理生理改变.     

两种常用兽药对作物发芽的生态毒性效应

采用室内生长箱培养的试验方法,研究了2种常用兽药磺胺嘧啶钠、环丙沙星对小麦、白菜和番茄种子发芽、根伸长、芽伸长的影响,分析了兽药和作物生长之间的剂量.效应关系,比较分析了小麦,白菜和番茄对2种兽药胁迫的敏感性.结果表明,根长抑制率和芽长抑制率与兽药浓度显著相关(p<0.05);种子发芽抑制率与2种兽药浓度不相关(p>0.05).2种兽药对根伸长和芽伸长的抑制明显强于对种子发芽的抑制.3种作物对磺胺嘧啶钠胁迫的敏感性依次为小麦＞白菜＞番茄;对环丙沙星胁迫的敏感性依次为白菜＞番茄＞小麦;磺胺嘧啶钠对3种作物的毒性效应明显强于环丙沙星.     

Effects of maize root exudates and organic acids on the desorption of phenanthrene from soils

The effects of maize root exudates and low-molecular-weight-organic anions (LMWOAs) on the desorption of phenanthrene from eight artificially contaminated soils were evaluated. A significant negative correlation was observed between the amounts of phenanthrene desorbed and the soil organic carbon (SOC) contents (P<0.01), and the influences of soil pH and clay content on phenanthrene desorption were insignificant (P>0.1). Neither maize root exudates nor oxalate and citrate anions influenced desorption of phenanthrene with the addition of NAN3. A faster phenanthrene desorption occurred without the addition of NaN3 in the presence of maize root exudates than oxalate or citrate due to the enhanced degradation by root exudates. Without the addition of NaN3, oxalate or citrate at different concentrations could inhibit phenanthrene desorption to different extents and the inhibiting effect by citrate was more significant than by oxalate. This study leads to the conclusion that maize root exudates can not enhance the desorption under abiotic condition with the addition of NaN3 and can promote the desorption of phenanthrene in soils without the addition of NAN3.     

2种基因型菜心根系解剖结构差异及其对DEHP吸收累积的影响

在前期筛选出油青60 d菜心和特青60 d菜心分别为PAEs高/低吸收累积基因型菜心的基础上,对其进行邻苯二甲酸二(2-乙基己基)酯(DEHP)不同污染水平(20 mg.L-1、50 mg.L-1)的溶液培养试验,对比研究2种基因型菜心根系解剖结构的差异性,初步探讨其与菜心吸收累积DEHP的关系.结果表明,油青60 d菜心和特青60 d菜心的根系解剖结构及其对DEHP污染处理下的响应均存在显著差异.油青60 d菜心根系和茎叶中DEHP含量均主要受主根形成层外围厚度和须根中柱直径控制,决定系数分别为0.900和0.809.特青60 d菜心根系中DEHP含量主要受主根形成层外围厚度和须根皮层厚度控制,决定系数为0.757;茎叶中DEHP含量主要受主根形成层外围厚度控制,决定系数为0.856.油青60 d菜心根系木射线细胞形状以排列规则的长方形为主,主根木栓层厚度和须根皮层厚度较小,须根中柱直径、导管数和导管直径较大,表明油青60 d菜心根系比特青60 d菜心更有利于对DEHP的吸收累积.     

当前环境问题的根本原因及其客观必然性分析

本文在简要介绍生态环境问题的基础上,分析了工业革命以来生态环境问题产生的根本原因与客观必然性。以及生态环境问题的解决途径。     

应用根去除法对内蒙古温带半干旱草原根系呼吸与土壤总呼吸的区分研究

2005年生长季分别对内蒙古锡林河流域温带半干旱草原中的羊草自由放牧草原、大针茅自由放牧草原和羊草退化草原中的土壤总呼吸速率和去根土壤的呼吸速率进行了野外测定,初步探讨了在草地群落应用根去除法间接进行根系呼吸测定的可能性,并应用该方法对草地群落根系呼吸占土壤总呼吸的比例进行了估测. 结果表明,应用根去除法在不同草地群落进行根系呼吸占土壤总呼吸比例的估测是切实可行的,其比值范围介于25%～45%之间,平均值为3566%,与国内外相关研究比较,大大提高了其比值的估测精度,在草地碳循环研究中具有较高的应用价值.     

紫云英还田配施石灰对水稻镉吸收转运的影响

采用田间小区试验,研究了紫云英(CMV)与石灰(L)单施及两者配施(CMVL)对土壤Cd有效性、水稻根表胶膜及Cd吸收转运的影响.结果表明:L与CMVL处理土壤pH值分别显著提高2.11～2.43和1.68～2.48个单位、二乙烯三胺五乙酸提取态(DTPA-Cd)含量分别显著降低18.88％～40.53％和20.74％...     

Estimating Root Zone Soil Moisture at Continental Scale Using Neural Networks

This study investigates the feasibility of artificial neural networks (ANNs) to retrieve root zone soil moisture (RZSM) at the depths of 20 cm (SM20) and 50 cm (SM50) at a continental scale, using surface information. To train the ANNs to capture interactions between land surface and various climatic patterns, data of 557 stations over the continental United States were collected. A sensitivity analysis revealed that the ANNs were able to identify input variables that directly affect the water and energy balance in root zone. The data important for RZSM retrieval in a large area included soil texture, surface soil moisture, and the cumulative values of air temperature, surface soil temperature, rainfall, and snowfall. The results showed that the ANNs had high skill in retrieving SM20 with a correlation coefficient above 0.7 in most cases, but were less effective at estimating SM50. The comparison of the ANNs showed that using soil texture data improved the model performance, especially for the estimation of SM50. It was demonstrated that the ANNs had high flexibility for applications in different climatic regions. The method was used to generate RZSM in North America using Soil Moisture and Ocean Salinity (SMOS) soil moisture data, and achieved a spatial soil moisture pattern comparable to that of Global Land Data Assimilation System Noah model with comparable performance to the SMOS surface soil moisture retrievals. The models can be efficient alternatives to assimilate remote sensing soil moisture data for shallow RZSM retrieval.