Phosphorus utilization and microbial community in response to lead/iron addition to a waterlogged soil

Constructed wetlands have emerged as a viable option for helping to solve a wide range of water quality problems. However, heavy metals adsorbed by substrates would decrease the growth of plants, impair the functions of wetlands and eventually result in a failure of contaminant removal. Typha latifolia L., tolerant to heavy metals, has been widely used for phytoremediation of Pb/Zn mine tailings under waterlogged conditions. This study examined e ects of iron as ferrous sulfate (100 and 500 mg/kg) and lead as lead nitrate (0, 100, 500 and 1000 mg/kg) on phosphorus utilization and microbial community structure in a constructed wetland. Wetland plants (T. latifolia) were grown for 8 weeks in rhizobags filled with a paddy soil under waterlogged conditions. The results showed that both the amount of iron plaque on the roots and phosphorus adsorbed on the plaque decreased with the amount of lead addition. When the ratio of added iron to lead was 1:1, phosphorus utilized by plants was the maximum. Total amount of phospholipids fatty acids (PLFAs) was 23%–59% higher in the rhizosphere soil than in bulk soil. The relative abundance of Gram-negative bacteria, aerobic bacteria, and methane oxidizing bacteria was also higher in the rhizosphere soil than in bulk soil, but opposite was observed for other bacteria and fungi. Based on cluster analysis, microbial communities were mostly controlled by the addition of ferrous sulfate and lead nitrate in rhizosphere and bulk soil, respectively.     

低浓度下4个取代苯污染物与硝酸铅的混合对发光菌的联合毒性

多种污染物混合特别是低浓度下的混合对生物的联合毒性是生态毒理学研究的热点之一。选择了3类污染物苯酚、间甲基苯酚、苯胺、对硝基苯胺、硝酸铅,采用美国微板光度计测定了它们对发光菌青海弧菌-Q67(Vibrio-qinghaiensis sp.-Q67)的单一及联合毒性。应用非线性拟合技术模拟了这5种物质及其混合物的剂量-效应曲线,硝酸铅可用Logit模型模拟,其它4个物质能用Weibull模型准确描述,所有拟合相关系数在0.98以上,均方根误差在0.02以下。根据纯物质的EC50值,获得这5个物质的毒性强弱顺序:硝酸铅〉对硝基苯胺间甲基苯酚苯酚苯胺。混合实验设计了各物质在EC50、EC1、无观察效应浓度(no observed effect concentration,NOEC)比例的混合。用浓度加和(dose addition,DA)和独立作用模型(independent action,IA)对混合物毒性进行预测。IA基本准确预测了这5个物质在各自EC50混合的毒性。DA与IA模型都稍微过高地预测了以EC1及NOEC浓度比例混合的联合毒性,但都在毒理学实验容许的范围之内。这5个物质以NOEC混合时对测试生物Q67没有产生明显毒性,但是还不能判定这些物质在此浓度下混合是安全的。污染物在各自的NOEC浓度下混合是否对其它生物有潜在的威胁还需更多毒理学实验支持。     

Effect of lead on survival, locomotion and sperm morphology of Asian earthworm, Pheretima guillelmi

To provide basic toxicity data for formulating risk characterization benchmarks, the effects of lead on survival, locomotion, and sperm morphology were investigated in the Asian earthworm Pheretima guillelmi. The LC50 of P. guillelmi for 7 and 14 d were 4285±339 mg/kg and 3207±248 mg/kg, which shows P. guillelmi can tolerate a higher concentration of lead nitrate. The average weight of the surviving earthworms decreased at concentration of 2800 mg Pb/kg soil, and the locomotor ability of earthworms exposed ...     

低浓度下4个取代苯污染物与硝酸铅的混合对发光菌的联合毒性

多种污染物混合特别是低浓度下的混合对生物的联合毒性是生态毒理学研究的热点之一。选择了3类污染物苯酚、间甲基苯酚、苯胺、对硝基苯胺、硝酸铅，采用美国微板光度计测定了它们对发光菌青海弧菌．Q67（Vibrio-qinghaiensissp-Q67）的单一及联合毒性。应用非线性拟合技术模拟了这5种物质及其混合物的剂量．效应曲线，硝酸铅可用Logit模型模拟，其它4个物质能用Weibull模型准确描述，所有拟合相关系数在0．98以上，均方根误差在O．02以下。根据纯物质的EC50值，获得这5个物质的毒性强弱顺序：硝酸铅〉对硝基苯胺〉间甲基苯酚〉苯酚〉苯胺。混合实验设计了各物质在EC50、EC1、无观察效应浓度（noobserved effectcon centration，NOEC）比例的混合。用浓度加和（doseaddition，DA）和独立作用模型（independentaction，IA）对混合物毒性进行预测。IA基本准确预测了这5个物质在各自EC50混合的毒性。DA与队模型都稍微过高地预测了以EC。及NOEC浓度比例混合的联合毒性，但都在毒理学实验容许的范围之内。这5个物质以NOEC混合时对测试生物Q67没有产生明显毒性，但是还不能判定这些物质在此浓度下混合是安全的。污染物在各自的NOEC浓度下混合是否对其它生物有潜在的威胁还需更多毒理学实验支持。     

碱解法综合利用铅渣制硝酸铅

1.概述三盐基硫酸铅(简称三盐)和二盐基亚磷酸铅(简称二盐)是最重要和产量最大的铅盐塑料稳定剂。在其生产过程中,因除尘、冲洗设备、地面以及反应不完全等原因,产生一定数量的铅渣,约占总产量的1—1.5％。由于这些铅渣中含有大量机械杂     

不同环境因素下太湖中四环素的自然消减

四环素已经广泛应用于兽药生产和疾病治疗中,并通过禽畜粪便等途径进入环境中,基于四环素残留物的危害性,采用了模拟自然环境状态的实验方法,研究了四环素在不同环境状态(光照、底泥、重金属)下的自然消减过程.结果表明,四环素在自然光照下的消减不明显;未杀菌底泥水体中,四环素的消减速率大于杀菌底泥水体;实验初期,含硝酸铅水体中四环素消减缓慢,随着时间延长,消减速率加快,而在硝酸镉水体中四环素短时间内消减趋势已经十分明显,且消减速率大于硝酸铅水体;以0.08 mmol·L-1四环素为例,四环素在光照下各环境因素中的消减速率依次为:未杀菌底泥(87.2%)>杀菌底泥(70.37%)>硝酸镉水体(64.2%)>硝酸铅水体(32.3%)>空白组(6.6%),各环境因素均促进了四环素的消减.避光时,各环境因素中四环素的消减趋势与光照组相同,但消减速率较光照组小,表明光照对四环素的自然消减具有一定的促进作用.     

紫外光照下盐酸环丙沙星的光解性能

本研究重点考察了盐酸环丙沙星初始浓度、硝酸铅、硝酸镉、氯化铅、氯化镉等重金属盐对盐酸环丙沙星光降解性能影响.结果表明,黑暗条件下环丙沙星无降解;紫外光照可以有效去除环丙沙星,且环丙沙星的光降解速率随其初始浓度的增大而降低;硝酸铅和硝酸镉(除0.006 mmol·L~(-1)体系外)可以促进环丙沙星的光降解,且随摩尔比的增大(即硝酸盐浓度的降低),环丙沙星的半衰期逐渐增大;随着摩尔比的增大(即氯化盐浓度的降低),氯化铅和氯化镉先促进后抑制环丙沙星的光降解.     

化学稳定剂对矿渣胶凝材料固化Pb~(2+)的影响研究

针对化学药剂的添加对矿渣胶凝材料固化稳定化Pb~(2+)效果的影响进行了研究。首先分别采用硫化钠、硫脲、磷酸二氢钠、磷酸钠、硫酸铁、硫酸亚铁、有机重金属螯合剂对Pb~(2+)进行化学稳定化,再进行矿渣胶凝材料固化。其中单一矿渣胶凝材料固化作为对比样,通过抗压强度测定、TCLP浸出、XRD、连续化学萃取、电子探针对各固化体的水化产物,Pb的化学形态迁移以及分布特征进行对比分析。结果表明:硫化物的掺入使Pb和S在水化产物中发生了聚集,铁酸盐的掺入促进了水化进程,提高了强度,螯合剂的掺入使Pb化学形态由不稳定态向稳定态发生迁移。