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161.
Changes of organic acid exudation and rhizosphere pH in rice plants under chromium stress. 总被引:1,自引:0,他引:1
Fanrong Zeng Song Chen Ying Miao Feibo Wu Guoping Zhang 《Environmental pollution (Barking, Essex : 1987)》2008,155(2):284-289
The effect of chromium (Cr) stress on the changes of rhizosphere pH, organic acid exudation, and Cr accumulation in plants was studied using two rice genotypes differing in grain Cr accumulation. The results showed that rhizosphere pH increased with increasing level of Cr in the culture solution and with an extended time of Cr exposure. Among the six organic acids examined in this experiment, oxalic and malic acid contents were relatively higher, and had a significant positive correlation with the rhizosphere pH, indicating that they play an important role in changing rhizosphere pH. The Cr content in roots was significantly higher than that in stems and leaves. Cr accumulation in plants was significantly and positively correlated with rhizosphere pH, and the exudation of oxalic, malic and citric acids, suggesting that an increase in rhizosphere pH, and exudation of oxalic, malic and citric acid enhances Cr accumulation in rice plants. 相似文献
162.
Marcos A. dos Santos Cynthia F. Illanes Adalgiza Fornaro Jairo J. Pedrotti 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):85-92
During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown São Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, $ \rm NH^{ + }_{4} During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown
S?o Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as
well as major ions (Na+, , K+, Ca2+, Mg2+, Cl−, , ) and carboxylic acids (acetic, formic and oxalic) using ion chromatography. The volume weighted mean, VWM, of the anions
, and Cl− was, respectively, 20.3, 12.1 and 10.7 μmol l−1. Rainwater in S?o Paulo was acidic, with 55% of the samples exhibiting a pH below 5.6. The VWM of the free H+ was 6.27 μmol l−1), corresponding to a pH of 5.20. Ammonia (NH3), determined as (VWM = 32.8 μmol l−1), was the main acidity neutralizing agent. Considering that the H+ ion is the only counter ion produced from the non-sea-salt fraction of the dissociated anions, the contribution of each anion
to the free acidity potential has the following profile: (31.1%), (26.0%), CH3COO− (22.0%), Cl− (13.7%), HCOO− (5.4%) and (1.8%). The precipitation chemistry showed seasonal differences, with higher concentrations of ammonium and calcium during
autumn and winter (dry period). The marine contribution was not significant, while the direct vehicular emission showed to
be relevant in the ionic composition of precipitation. 相似文献
163.
Demirak A 《Environmental monitoring and assessment》2007,129(1-3):189-196
In this study, the chemical composition of the rainwater in Yatağan, which is a region surrounding a coal power plant was
investigated from February to April 2002. Rainwater samples were obtained from Yatağan, located northwest of Muğla City in
Turkey. pH values and concentrations of major ions (Ca2+, Na+, K+, , , ) in the rainwater samples were analyzed. The pH varied from 5.1 to 7.9 with an average of 6.7 which was in alkaline range
considering 5.6 as the neutral pH of cloud water in equilibrium with atmospheric CO2. In the total of 30 rain events, only three events were observed with water in the acidic range (<5.6), which occurred after
continuous rains. The equivalent concentration of components followed the order: Ca2+ > > Na+ > > > K+ > H+. The anion and cation concentrations in the rainwater samples showed a high sulphate concentration (131 μEq/l), as well as
high sodium (40 μEq/l) and calcium (298 μEq/l) concentrations. These values indicate that one probable source of the high
sodium concentration is fly ash, after the coal burning process and the power plant can be effective on level concentrations in rainwater. In addition, the dust-rich local and surrounding limestone environment might have caused the
high concentration of Ca2+ in rainwater of the Yatağan Basin. Due to a large contribution of these cations to the sulphate neutralization action, the
rainwater of this region displays only a moderate acidity, which does not cause significant environmental impact. 相似文献
164.
负载型固体超强酸催化剂上的烷基化反应 总被引:3,自引:0,他引:3
本文利用Pt/SO^2-4/ZrO2,Pt/WO3/ZrO2负载于大比表面Al2O3固体强酸催化剂,进行异丁烷和丁烯的烷基化反应。 相似文献
165.
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168.
小麦在与水杨酸诱导的应答过程中PGIP的积累 总被引:7,自引:1,他引:6
以SW89-2589小麦品系为材料,利用自制的小麦抗PGIP血清和dot-immunobinding assay,并结合PGIP粗提液对endo-PG的抑制实验,研究了小麦内源多聚半乳糖醛酸酶抑制蛋白(PGIP)水平与水杨酸之间的应答关系。发现用水杨酸处理过的PGIP粗提液在NC膜上的显色斑点颜色均较H2O处理的PGIP粗提液深,而且对en-do-PG的抑制程度也高于未用水杨酸处理的PGIP粗提液 相似文献
169.
在湖北农村 10个地点 ,利用澳大利亚集雨器自 1996年 1月至 1998年 6月 ,按季度采集大气降水样品测定SO2 - 4浓度 ,并对数据进行统计分析。研究结果表明 ,各地 1997年降水中SO2 - 4浓度年均值比 1996年显著升高 ;大多数地点 1996、1997、1998年 1季度和 2季度降水中SO2 - 4浓度呈逐年升高趋势 ;大多数地点每年 1、4季度降水中SO2 - 4浓度高 ,2、3季度降水中SO2 - 4浓度低 ,说明湖北农村降水中的硫对秋冬作物影响比对春夏作物影响大 ;湖北农村降水中SO2 - 4浓度近两年不仅有时间变化规律 ,而且同一季度内的地区差异也很明显 ,在 1996年和 1997年 8个季度 10个点的降水SO2 - 4浓度最大值中 ,有 4个最大值出现在襄樊 ,它是目前湖北继宜昌市区、恩施市区之后又一个酸雨发展较快的地区 相似文献
170.
丁基黄原酸是水质监测的重要项目之一。水中丁基黄原酸的测定,在样品采集保存、前处理及仪器分析各阶段都存在一定的技术难点。实际分析时很容易出现测定结果不理想,甚至定性定量错误等问题。结合实验对丁基黄原酸测定中容易出现的问题及注意事项进行探讨,正确区分丁基黄原酸及其盐,有效保存样品,采用低损失的前处理方法以及选择性好的分析仪器,有利于提高丁基黄原酸测定的准确性。众多丁基黄原酸测定方法中,液相色谱质谱法、离子色谱法以及液相色谱法在选择性和灵敏度方面更具优势,也可用于其他方法检出丁基黄原酸时对测定进行确认。 相似文献