镉胁迫下植物的应答和调控

镉对植物引起的氧化胁迫是Cd毒害的重要原因之一.本文综述了Cd诱导植物氧化胁迫效应的机理以及植物对Cd氧化胁迫的相应防御反应,如抗氧化物质、抗氧化保护酶系统等,并介绍了缓解Cd诱导的氧化胁迫的机理和途径.     

Topsoil and Housedust Metal Concentrations in the Vicinity of a Lead Battery Manufacturing Plant

The aim of the study was to determine the extent of heavy metal pollution in the vicinity of a lead battery manufacturing plant in the Czech Republic, both in the general environment and within homes. Topsoils (0–5 cm) were sampled from 100 sites along 4 transects which crossed the battery factory, the town centre and outlying rural areas. Housedust samples were collected from 15 plant-workers' homes and 15 non plant-workers' homes located at various distances from the factory. Samples were analysed for levels of Pb, Zn, Cd, Cu, As and Sb, using ICP-AES. Soil concentrations of Pb, Cd, As and Sb peaked at the perimeter fence of the battery factory with Pb levels of up to 12 650 g g> ^-1. Concentrations of these metals decreased exponentially within 500 m of the plant. Whilst the battery factory does appear to be a source of all the metals with the exception of Zn, emissions do not appear to be transported to any great extent over distances of more than 0.5 km. Topsoil and housedust concentrations of Pb, Zn, Cd, Cu, As and Sb in the general Mlada Boleslav area do not appear to be significantly different from those recorded in a large scale survey of urban soils in the United Kingdom. A comparison of housedust Pb concentrations in homes of plant workers and non-plant workers suggests that there may be a small input of Pb into the home environment by battery plant employees.     

醋糟生物炭对水体中Pb(Ⅱ)吸附的影响

以醋糟为原料在700℃绝氧条件下制得醋糟生物炭,对比研究了醋糟炭化前后对水体中Pb(Ⅱ)的吸附效果与特性。采用比表面分析仪、傅立叶红外光谱(FTIR)和扫描电镜(SEM)对吸附质进行表征,并通过吸附试验测定了吸附质对Pb(Ⅱ)的吸附性能。结果表明,在温度为298 K,p H为3~6的条件下,醋糟生物炭与醋糟对Pb(Ⅱ)达到吸附平衡的时间均为30 min,最佳投加量均为3.3 g/L。两种物质对Pb(Ⅱ)的吸附均高度拟合准二级动力学方程,吸附过程符合Langmuir模型,推测其主要为单分子层的化学吸附。与醋糟相比,醋糟生物炭具有更大的吸附容量,为68.027 mg/g,且在常温下即可表现出优异的吸附效果。由SEM和FTIR分析结果可知,醋糟生物炭孔隙结构较醋糟更为发达,且表面含有丰富的含氧官能团和芳香类化合物。     

污泥掺烧过程中Cl/S/P/矿物质的热交互作用对Cd迁移转化行为的影响

采用化学热力学平衡分析方法,应用污泥实测数据模拟计算了污泥掺烧过程中Cl/S/P与矿物质的交互作用,重点模拟研究了Cl/S/P/矿物质交互体系对Cd迁移转化的影响.研究结果表明,污泥掺烧过程含Cl、S及P逸出气体以HCl(g)、SO_2(g)及(P_2O_5)_2(g)形式排放.污泥掺烧含有CaO-SiO_2-Al_2O_3体系中,CaO可以抑制S以SO_2(g)释放,而SiO_2及Al_2O_3对SO_2(g)逸出有促进作用,同时CaO及Al_2O_3可以抑制P的挥发.污泥掺烧过程中SiO_2及Al_2O_3对Cd挥发都有一定抑制作用,但CaO及Fe_2O_3对Cd基本无影响;当Cl存在时,Ti O2和SiO_2对Cd吸附作用减弱,并使Al_2O_3吸附剂失效;当S存在时,可导致吸附剂对Cd中毒,而P可导致Al_2O_3吸附剂失效;Cl-S-P耦合体系中,单一矿物质对Cd迁移转化影响主要受Cl和S控制.SiO_2+CaO+Al_2O_3共存体系中,Cl的存在可导致固体吸附剂SiO_2和Al_2O_3失效;S、S+Cl、S+P、S+Cl+P的存在受控元素为S,并且可以抑制Cd的挥发;P、Cl+P的存在对Cd影响受控元素为Cl,可促进Cd挥发.     

锅炉协同处置危险废物过程中Pb和Cd的挥发特性

为研究危险废物在锅炉协同处置过程中Pb和Cd的挥发特性,通过共燃烧和消解试验,研究了不同化合物形态下Pb、Cd的挥发率(α)、残留率(r)和表观活化能(E). 结果表明:以硫化物、氯化物、硫酸盐和氧化物存在的Pb、Cd的挥发率与温度(T)和停留时间(t)均呈正相关. 当温度低于950 ℃、停留时间为52 min时,不同化合物形态的Pb、Cd挥发率相差较大,PbCl₂在800 ℃下挥发率接近64%,而PbO仅为17%;温度高于1 250 ℃、停留时间为52 min时,不同化合物形态下的Pb、Cd挥发率均大于95%,接近于完全挥发;1 400 ℃时,不同化合物形态的Pb、Cd在燃烧残渣中的残留率均低于0.3%. 结合化学反应动力学理论,对Pb、Cd在锅炉协同处置过程中的挥发特性进行动力学模拟,得到PbS、PbCl₂、PbSO₄、PbO 中Pb的表观活化能分别为23.64、18.44、65.79、61.35 kJ/mol,CdS、CdCl₂、CdSO₄、CdO中Cd的表观活化能分别为53.22、20.87、42.42、28.75 kJ/mol. 由表观活化能数据可以得出不同形态化合物的Pb、Cd挥发率随温度和停留时间变化的动力学方程α=f(T,t),并可预测锅炉协同处置危险废物过程中Pb和Cd的挥发率,确定适合锅炉协同处置的危险废物类别.      

能源植物修复土壤镉污染过程中细菌群落分析

选取油脂类能源植物大豆和碳水化合物类能源植物玉米,采用高通量测序方法研究大豆、玉米修复Cd污染土壤过程中根际土壤细菌群落组成.结果表明,100 mg·kg-1Cd的添加会抑制玉米、大豆生长,其中,大豆生物量降低比玉米高.不同组织中根部Cd积累量最高,转移系数TF分别为0.56(玉米)和0.14(大豆).基于Mi Seq的群落分析表明,大豆、玉米根际土壤细菌主要包括Proteobacteria(变形菌门)、Acidobacteria(酸杆菌门)、Gemmatimonadetes(芽单胞菌门)、Actinobacteria(放线菌门)、Bacteroidetes(拟杆菌门)等33个门.细菌群落的PCo A和UPGMA分析表明,Cd的添加和能源植物种植均能对细菌群落结构产生影响,其中,Cd的添加影响最大.Gemmatimonas、Flavisolibacter、Flexibacter、Ramlibacter、Ohtaekwangia、Flavitalea等细菌在Cd胁迫条件或大豆、玉米种植条件下相对丰度有所变化,分析其可能在大豆、玉米耐受Cd污染中起作用.     

纳米铁炭复合材料的制备及对水中镉(Cd)污染的修复

为提高纳米零价铁对水体中镉污染的修复效果,通过液相化学还原法制备纳米零价铁颗粒,并用活性炭包覆,制备纳米铁炭复合材料。设计单因素和正交实验,探讨材料制备中的3个主要因素对材料降解水体中镉(Cd(II))的影响。结果表明:在炭铁比为0.2,硼氢化钠加料速率为32 m L/min,搅拌强度为1 000 r/min的条件下,材料对水体中Cd(II)的降解效果最好;实验表明纳米铁炭复合材料对Cd(II)的去除以纳米零价铁的化学还原过程为主,活性炭的物理吸附为辅。     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

原子吸收法测定土壤中铜锌铅镉

通过对几种消解体系的对比 ,选择出铅、镉最佳的消解方法为硝酸 氢氟酸 双氧水体系 ;铜锌最佳的消解方法为硝酸 氢氟酸 高氯酸体系。不同方法既能达到全量分析的要求 ,又能使基体干扰降到最小。通过对标准样品的多次测定 ,测定值均在其保证值范围内 ,铅镉相对标准偏差为 2 2 %～ 7 2 % ,加标回收率在 83%～ 116 %之间 ;铜锌相对标准偏差为 2 6 %～ 4 5 % ,加标回收率在 92 %～ 10 3%之间。     

土壤-植物系统中模拟酸雨与Cd复合污染的短期环境效应--黄豆盆栽试验

通过盆栽实验,研究了在黄豆(Glycne max)的一个生长周期内,模拟酸雨与Cd复合污染对土壤基本性质的影响,模拟酸雨作用下土壤-植物系统中Cd的迁移转化规律以及模拟酸雨与Cd复合污染对黄豆生长与生理特性的影响,探讨了土壤-植物系统中这种复合污染的短期环境效应.结果表明,短期内模拟酸雨和Cd污染对土壤-植物系统都有致害作用,但Cd污染的效应大于模拟酸雨的效应,模拟酸雨与Cd复合污染环境效应大于这2种污染物的单因素效应,且表现出明显的协同作用.在本试验条件下,pH值为3.5的模拟酸雨和20 mg·kg-1Cd的处理组合对土壤-植物系统的危害最严重.尽管在短期内,协同作用仅在土壤交换态Cd含量、黄豆茎和根中的Cd含量这3项指标上得到一定程度的体现,但这种复合污染的化学机制和环境效应值得关注,这2种污染物长时期共同作用对土壤-植物系统的影响也值得深入研究.