Cu2+对普通小球藻的光合毒性：初始藻密度的影响

为了研究Cu2+对普通小球藻的光合毒性以及初始藻密度对Cu2+光合毒性的影响,将初始密度为107mL-1的普通小球藻暴露于Cu2+的6个浓度(0、5、10、20、30和40μmol.L-1)中进行96 h的毒性暴露实验,在2、48和96 h分别利用叶绿素荧光仪(MAXI-Imaging-PAM)测定各项叶绿素荧光参数,同时,针对3个不同初始密度的普通小球藻(2×106、5×106和2×107mL-1),测定并比较了其暴露于0、20和40μmol.L-1的Cu2+12 h后,叶绿素荧光参数的变化。不同初始藻密度的毒性实验结果显示,初始藻密度为2×106mL-1时,20和40μmol.L-1Cu2+可完全抑制普通小球藻的光合作用;当初始藻密度增加到5×106和2×107mL-1时,40μmol.L-1Cu2+对普通小球藻的实际光合作用效率仅有约75%和25%的抑制。这表明初始藻密度越大,Cu2+的光合毒性越弱。但随着初始藻密度的增加,初始藻密度的变化对Cu2+光合毒性的影响减弱。初始藻密度为107mL-1时的毒性实验结果显示,暴露于20~40μmol.L-1Cu2+2 h后,普通小球藻的光合作用即受到抑制,且该抑制程度随Cu2+浓度的增加而增强,并随着暴露时间的延长有所缓解。随着Cu2+浓度的增加,最大量子产量(Fv/Fm)、实际量子产量(Yield)、相对电子传递速率(ETR)和光化学淬灭系数(qP)逐渐降低,非光化学淬灭系数(NPQ/4)逐渐上升。研究结果表明,Cu2+对普通小球藻的光合作用有一定的抑制作用,其机理可能为通过引起PSII系统反应中心的部分失活,导致PSII系统反应中心的开放比例减少,引起电子传递速率降低以及ATP和NADPH的合成减慢,从而使光合作用速率下降;初始藻密度对Cu2+的光合毒性大小有较大的影响,故在进行藻类的毒性实验时,也应关注初始藻密度的影响。     

强降雨在滑坡发育中的关键控制机理及典型实例分析

通过构建水动力作用模型,对降雨的激发控制作用进行分析,得出水动力控制机理的结论:强降雨控制滑坡发育,集中表现在改变土体的静水压力、动水压力与浮托力的作用三方面.选取重庆市黔江流水湾滑坡为典型实例,对强降雨的激发控制作用进行验证,强降雨的水动力作用过程分为坡体剪切、滑动开始、剧烈滑动三个不同阶段.最后,提出久旱过后强降雨...     

Reductive dechlorination of activated carbon-adsorbed trichloroethylene by zero-valent iron: carbon as electron shuttle

Sequestration of organic contaminants in carbonaceous materials can significantly affect contaminant fate and transport. We investigated the reductive dechlorination of granular-activated carbon (GAC)-adsorbed trichloroethylene (TCE) by nanoscale zero-valent iron (nZVI) to understand the effect of sequestration on abiotic reactivity of organic contaminants. Significant reduction of TCE sequestered in GAC micropores was observed, even though direct contact with nZVI was unlikely. Reduction of sequestered TCE by reactive Fe(II) species or molecular hydrogen was ruled out as the reaction mechanisms. We propose that GAC served as the conductor for the transfer of electrons or atomic hydrogen from nZVI to the micropores, wherein adsorbed TCE molecules were reduced. An important implication for environmental remediation is that carbonaceous adsorbents not only function as a superb sink for organic contaminants but also allow them to be slowly degraded while being trapped.     

基于PPC-AHP-DM法的辽宁省整治修复海岛开发潜力评价研究

本文选取辽宁省在《中华人民共和国海岛保护法》颁布以来实施的17个整治修复海岛开展开发潜力评价,建立6大类23个指标因子的评价指标分类体系,选取PPC-AHP-DM组合模型对各海岛开发潜力进行了横向静态分析与对比,确定了各海岛在整治修复工程实施前后开发潜力综合排名及自身开发潜力变化幅度。研究结果表明:整治修复工程实施前大笔架山岛相对于其他海岛排名较为靠前,张家山岛、杨家山岛排名较为靠后,整治修复工程实施后各海岛相对于自身开发潜力均有不同幅度提升,整治修复工程类型不同,其提升幅度各异,大笔架山岛、觉华岛、张家山岛、杨家山岛等开发潜力提升幅度较大。     

北京雾霾现象与机动车尾气排放关系分析

北京雾霾天气的成因存在争议。政府公布的结论是,20-30％的污染是来源于汽车尾气排放,但这是与事实相冲突的。本文主要讨论机动车尾气排放在雾霾成因中的实际比例,及可能解决的方案。     

The risks of sulfur addition on cadmium accumulation in paddy rice under different water-management conditions

Recently, the application of sulfur (S) has been recommended to control the accumulation of cadmium (Cd) in rice in contaminated paddy soil. However, the effects of exogenous S on Cd transfer in paddy rice systems under different water-management practices have not been systematically investigated. Pot experiments were performed to monitor the composition of soil pore water and the Cd accumulation in iron plaque and rice tissue were compared under different S (0 and 200 mg/kg Na₂SO₄) and water (continuous and discontinuous flooding) treatments. Sulfur application significantly increased Cd concentrations in soil pore water under discontinuous flooding conditions, but slightly reduced them under continuous flooding. Moreover, the oxidation/reduction potential (Eh) was the most critical factor that affected the Cd levels. When the Eh exceeded −42.5 mV, S became the second critical factor, and excessive S application promoted Cd dissolution. In addition, S addition elevated the Cd levels in iron plaque and reduced the Cd transfer from the iron plaque to rice roots. In rice, S addition inhibited Cd transfer from the rice roots to the straw; thus, more Cd was stored in the rice roots. Nevertheless, additional S application increased the Cd content in the rice grains by 72% under discontinuous flooding, although this effect was mitigated by continued flooding. Under simulated practical water management conditions, S addition increased the risk of Cd contamination in rice, suggesting that S application should be reconsidered as a paddy fertilization strategy.     

矿用风筒的现状与发展

分析了国内矿用风筒的现状,并指出矿用风筒应当向高安全性、高强度、多品种、多功能等方向发展.     

潜流人工湿地去除效果研究

在连续运行条件下,采用水平潜流人工湿地净化低浓度的生活污水,考察了其净化效果。结果表明,该系统能够有效的降低生活污水中的COD、TN、TP,适合于城镇生活污水的处理。在0.1、0.2 m3/(m2.d)的水力负荷条件下,系统较容易出现死水区;当0.3 m3/(m2·d)的水力负荷条件下,水流呈推流状态,有效容积和水力效率得到提高,去除率分别为90.3%、86.6%和96.7%。试验表明,适当增加水力负荷,有利于污染物的去除。     

哈尔滨大气中PAHs污染特征

多环芳烃(PAHs)是大气中广泛存在的一种有毒污染物,因其具有"三致"毒性,已成为关注的焦点。本文通过在哈尔滨市区设置大气采样点,利用大流量主动采样器进行为期一年的大气样品采集,对大气中PAHs的浓度、污染特征进行了研究,并深入探讨了PAHs的污染源和贡献率,结果表明,哈尔滨大气中∑16PAHs浓度范围为6.3～340 ng/m3,平均浓度为100±94 ng/m3,主要以低分子量的PAHs为主。与国内外的研究相比,哈尔滨大气中PAHs的污染处于中等污染水平。PAHs具有明显的季节差异,低温气象条件和排放源的增强是导致冬季PAHs污染加重的主要原因。     

A land use regression model incorporating data on industrial point source pollution

Advancing the understanding of the spatial aspects of air pollution in the city regional environment is an area where improved methods can be of great benefit to exposure assessment and policy support. We created land use regression (LUR) models for SO₂, NO₂ and PM₁₀ for Tianjin, China. Traffic volumes, road networks, land use data, population density, meteorological conditions, physical conditions and satellite-derived greenness, brightness and wetness were used for predicting SO₂, NO₂ and PM₁₀ concentrations. We incorporated data on industrial point sources to improve LUR model performance. In order to consider the impact of different sources, we calculated the PSIndex, LSIndex and area of different land use types (agricultural land, industrial land, commercial land, residential land, green space and water area) within different buffer radii (1 to 20 km). This method makes up for the lack of consideration of source impact based on the LUR model. Remote sensing-derived variables were significantly correlated with gaseous pollutant concentrations such as SO₂ and NO₂. R² values of the multiple linear regression equations for SO₂, NO₂ and PM₁₀ were 0.78, 0.89 and 0.84, respectively, and the RMSE values were 0.32, 0.18 and 0.21, respectively. Model predictions at validation monitoring sites went well with predictions generally within 15% of measured values. Compared to the relationship between dependent variables and simple variables (such as traffic variables or meteorological condition variables), the relationship between dependent variables and integrated variables was more consistent with a linear relationship. Such integration has a discernable influence on both the overall model prediction and health effects assessment on the spatial distribution of air pollution in the city region.