Modeling of acute cadmium toxicity in solution to barley root elongation using biotic ligand model theory

Protons（H⁺）as well as different major and trace elements may inhibit cadmium（Cd）uptake in aquatic organisms and thus alleviate Cd toxicity.However,little is known about such interactions in soil organisms.In this study,the independent effects of the cations calcium(Ca²⁺),magnesium(Mg²⁺),potassium（K⁺）,H+and zinc(Zn²⁺)on Cd toxicity were investigated with 5-day long barley root elongation tests in nutrient solutions.The tested concentrations of selected cations and trace metal ions were based on the ranges that occur naturally in soil pore water.The toxicity of Cd decreased with increasing activity of Ca²⁺,Mg²⁺,H⁺and Zn²⁺,but not K⁺.Accordingly,conditional binding constants were obtained for the binding of Cd²⁺,Ca²⁺,Mg²⁺,H⁺,and Zn²⁺ with the binding ligand:log K_CdBL5.19,logK_CaBL2.87,logK_MgBL2.98,logK_HBL5.13 and logK_ZnBL5.42,respectively.Furthermore,it was calculated that on average 29% of the biotic ligand sites needed to be occupied by Cd to induce a 50% decrease in root elongation.Using the estimated constants,a biotic ligand model was successfully developed to predict the Cd toxicity to barley root elongation as a function of solution characteristics.The feasibility and accuracy of its application for predicting Cd toxicity in soils were discussed.     

New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals

The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2+and Zn2+in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients(above 0.99 for both metal ions) and insignificant lack of fit(p = 0.0838 and 0.0782 for Pb2+and Zn2+, respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation(between –NH2,-CN and metal ions) and ion-exchange(between –COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.     

基于UNMIX模型对大气降雨中水溶性离子来源解析

对洛杉矾2005年1月至2015年1月的降水数据进行了分析,并通过UNMIX模型对降水中的无机离子成分进行了来源解析.结果表明,洛杉矶降水的pH均值为4.84,表现为轻度污染的弱酸性水平;降水的污染来源主要有3个,分别是二次污染源(50％)、海洋传输源(43％)、燃煤源及生物质燃烧源(7％);降水中离子解析结果与洛杉矶地区细颗粒物污染来源解析结果有较好的一致性,表明在细颗粒物化学成分缺失的情况下,降水离子可在一定程度上反应污染来源解析.     

Biodegradation of high concentration phenol containing heavy metal ions by functional biofilm in bioelectro-reactor

Functional microorganisms to high concentration phenol containing Cr^6＋ and Pb^2＋ were cultured and biofilm was formed on polypropylene packings in bioelectro-reactor. It was found that the biodegradation capability of such biofilm to phenol changed with the applied voltage. Under the optimal electric field conditions （voltage of 3.0 V, electric field of strength 17.7 V/m and current density of 1.98 A/m2）, biodegradation efficiency of phenol aof concentration of 1200 mg/L increased 33% compared to the instance without applying electric field. However, voltage had inverse effect on biodegradation, as microorganisms were killed under strong electric field. Voltage had little effect on heavy ions elimination. Higher absorption rate of Cr^6＋ and Pb^2＋ was observed when changing pH fi＇om acidic to neutral. The experiment results indicated that, after treatment, 10 L phenol of 2400 mg/L was biodegraded completely within 55 h and concentrations of Cr^6＋ and Pb^2＋ dropped to less than 1 mg/L within 12 h and 6 h, fi＇om initial values of 50 mg/L and 30 mg/L, respectively.     

西安地区大气降水化学组成特征与物源分析

于2007年1月至2008年1月间,系统采集西安市区及咸阳郊区大气降水样品70个,对其主成分进行了分析,以期获得大气降水组成特征及其物质来源信息。研究结果显示,Ca2+是最主要的阳离子,分别占西安和咸阳降水中阳离子总量的77.4%和79.6%,其次是Na+。SO42-是最主要的阴离子,分别占西安和咸阳降水中阴离子总量的83.2%和81.4%,NO3-次之。两地降水中各组分含量年内变化趋势具同步性,均显示冬季远高于夏季的特征,且西安降水中各组分含量均高于咸阳。说明两地降水化学组成具同源性,咸阳大气污染物主要来自西安大气污染物的扩散。海相贡献比例计算结果显示,两地降水中SO42-和Ca2+海相输入比例很小,SO42-主要来自工业生产释放的SO2,而雨水中高浓度的Ca2+和Mg2+则是由于酸性物质对大气颗粒物的强化溶解造成。西安和咸阳雨水SO42-/NO3-值分别为12.89和11.11,属于燃煤型大气污染。     

基于GGE双标图和BLUP分析筛选镉砷同步低累积水稻品种

种植重金属低累积水稻品种是中国耕地重金属污染稻田安全生产的有效措施,为筛选镉砷同步低累积水稻品种,该研究通过测定盆栽、早稻季、晚稻季3个试验环境中18个水稻品种稻米镉砷含量,利用基因型主效加基因型——环境互作效应(GGE)双标图分析品种稻米镉砷低累积能力、稳定性、环境适应性,进一步通过最佳线性无偏预测(BLUP)法验证...     

Fe3+负载凹凸棒土(Fe/ATP)结构表征及其稳定化修复镉(Cd)机制研究

以凹凸棒土(凹土,ATP)为原料,采用浸渍法制备Fe3+负载凹土(Fe/ATP),表征了其结构与形貌,研究了凹土和Fe/ATP对土壤中镉(Cd)的吸附效果,以浸出浓度作为稳定化评价指标,通过吸附前后凹土和Fe/ATP形貌等特征的变化探讨了稳定化修复Cd机制.结果表明,加入质量比20%的凹土和Fe/ATP,Cd的浸出浓度分别降低了45%和91%,说明Fe/ATP对土壤中Cd有显著的稳定化作用.形貌表征分析表明,凹土主要通过结构中的水、—OH基团和晶格缺陷来稳定Cd,而Fe/ATP对土壤中Cd稳定化作用可能主要来自—OH基团以及Fe—O中桥氧的贡献.凹土与氧化铁均为土壤中天然矿物,廉价易得且环境友好,制备方法简单易实现,该复合材料用于Cd污染土壤的稳定化修复具有较好的应用前景.     

Effect of Coal Mine Soil Contamination on the Elemental Uptake and Distribution in Two Edible Amaranthus Species,A. dubius and A. hybridus

The impact of coal mine dump contaminated soil on the elemental uptake by two edible plants, namely, Amaranthus dubius (red herbs) and Amaranthus hybridus (green herbs), was studied by investigating their response and ability to tolerate and accumulate varying levels of elements in their roots and shoots. The vegetation was grown on varying amounts of contaminated soil, viz. 0%, 5%, 15%, 25% w/w using coal mine dump soil. The soil was analyzed for soil pH, cation exchange capacity (CEC), soil organic matter (SOM), moisture content, and selected heavy metals. The distribution of six metals, namely, Pb, Cd, Hg, Ni, Mn, and Fe, in roots, stem, and leaves of the plants was determined in two stages of growth after 5 weeks and 10 weeks. All soil and plant samples were microwave digested and subjected to heavy metal analysis using the ICP-OES, GFAAS, and CVAAS. The pH of the coal mine dump contaminated soil decreased with an increase in contamination. Both the SOM and CEC values decreased, which increases the availability of elements, by providing more binding sites in the soil. Relatively, the red herbs had higher elemental concentrations than the green herbs. Both plants recorded high manganese accumulation. No mercury was detected in the soils or plants.     

河道型水库支流库湾营养盐动态补给过程

河道型水库支流库湾营养盐季节变化直接决定支流藻类群落结构的演替及初级生产力变化过程.为分析三峡水库支流香溪河库湾主要营养盐来源对营养盐季节性变化的影响,基于2010~2011年香溪河库湾野外监测数据,选取干、支流差异显著(P0.01)的常量离子Cl-和Na+作为水团混合示踪离子,采用二元线性混合模型计算不同时期营养盐各来源的贡献率.结果表明,在枯水运行期(11月~次年2月)和汛后蓄水期(9~10月)时,长江干流对支流库湾营养盐贡献率超过75%,干流倒灌为库湾营养盐主要来源;在汛前泄水期(3~5月)和汛期(6~8月)时,干流倒灌和上游来水的贡献率差异缩小,库湾营养盐来源需考虑两者共同的影响,但干流倒灌仍占据优势.上游来水磷营养浓度相对较高,而长江干流氮、硅营养盐浓度较高,不同时期香溪河库湾分层异重流模式不同,库湾营养盐各来源的贡献率也随之改变,因此库湾营养盐在水库不同运行时期呈现出规律性变化.     

磁场强化铁碳微电解降解甲基橙的研究

铁碳微电解技术因其操作简单、生态环保和经济高效等优势,常被用于印染废水的治理研究,但该技术存在COD去除率低和适用p H范围窄的问题。为了克服以上问题,引入磁场强化技术。通过批试验,系统考察了初始p H、初始甲基橙浓度、转速和温度等对磁场强化铁碳微电解去除甲基橙过程的影响。研究结果表明:磁场能够显著提升铁碳微电解去除甲基橙和COD的效率,且拓宽了p H的适用范围。结合SEM、XRD和电化学技术表征,阐明了磁场强化铁碳微电解去除甲基橙的机理是磁场能够加速铁碳微电解的腐蚀,产生大量二价铁,从而强化还原去除甲基橙。本研究提出了一种新的强化铁碳微电解高效去除污染物方法。