不同氮形态对铅胁迫下苏丹草根系形态及铅吸收富集特征的影响

为进一步研究富营养化水体中不同氮形态和重金属对修复植物的交互作用,通过水培试验研究了水体中不同形态氮培养对铅胁迫下苏丹草根系形态及其对铅吸收富集的影响。结果表明,水体Pb(0.5mmol/L)污染时,不同氮形态培养虽然对苏丹草根系形态有一定的影响,但没达到显著性差异,然而对苏丹草根系中丙二醛(MDA)含量及其各器官生物量的影响达显著差异(p<0.05),NH4—N营养液培养的苏丹草根系MDA含量比NO3—N,NO2—N营养液培养的分别高出了4.6和1.6倍;NO3—N营养液培养的苏丹草根、茎、叶生物量比NH4—N营养液培养的分别高出了28.7%,19.6%和23.9%,比NO2—N营养液培养的高出37.6%,30.9%和36.7%。水体Pb(0.5 mmol/L)污染时,NO3—N营养液培养的苏丹草根中Pb浓度明显比NH4—N营养液培养的高出2倍多,且其地下富集系数最大;NO2—N营养液培养的苏丹草茎中Pb浓度明显比NH4—N营养液培养的高出近8倍,且其对铅的转运能力影响作用最强。这表明受重金属污染的富营养化水体中如存在不同形态氮,在一定程度上还有利于削弱重金属对修复植物的毒性作用,增大水体对某些重金属的环境容量。     

泰国的流域环境管理

流域的概念在泰国沿用已久。之所以这么普及，是由于河流自上游地区流往下游地区这一概念容易被人理解接受。与小流域相关的问题主要包括以下几个方面：水资源利用及其有效性。环境退化问题等。针对现在的工作举几个例子。上下游冲突是个全球性的问题，其中水资源利用是个主要问题，还包括因为杀虫剂和其他废弃物造成的环境污染问题等。滥用土地，特别是在坡地上的过度开发，可能会导致洪灾和山崩。在某些矿区，某些重金属，诸如铅等，对人体健康和居民生活产生不良影响。有些情况无法解决，而人们却无法从其他地区获得帮助。令人高兴的是，在拯救河流方面已经出现了很好的合作范例．如Tha Chin地区的做法，就可以作为其他类似个案的范例。即使只有部分河流由于当地或周边地区的人为活动而造成污染，这些污染物最终也会流入大海。因此为环境法庭各案处理而成立环境争议仲裁中心以及绿席，被视为泰国环境界一个良好的进步。     

山东寿光不同农业利用方式下土壤铅的累积特征

采用田间实地调查、地统计学和ICP-MS等方法,研究了基于GIS分析的山东省寿光市农业土壤中铅的含量及其空间分布特征,并比较了农业利用方式的影响。结果表明,研究区域农田中铅的平均含量为（17.97±1.22）mg.kg-1,与1990年山东省土壤背景值比较,有8.59%的样本出现了累积趋势,而以国家土壤质量Ⅱ级标准（GB 15618—1995）为基础进行分析则尚未发现超标样本;研究区域内4种主要农业利用方式比较,小麦/玉米/棉花为主的传统种植模式下土壤的铅含量最高,达（19.83±5.34）mg.kg-1,其后依次为露天菜地、设施菜地和对照土壤;研究区域内土壤铅含量在空间分布上以东北部、西部和西南部较高,且有由东北和西南向中部逐渐降低的趋势。设施种植条件下,土壤铅含量有随设施年限增加而升高的趋势（P〈0.05）,年累积速率为0.40 mg.kg-1,导致这种结果的原因可能在一定程度上与含铅量较高的有机肥大量施用有关。总体来说,目前研究区域土壤中铅含量尚处于正常范围,但从长远看仍需要注意其累积问题。     

Enhancement of Lead Uptake by Fenugreek Using EDTA and Glomus mosseae

The influence of Glomus mosseae supplemented with ethylenediaminetetraacetic acid (EDTA) on lead (Pb) uptake by Fenugreek (Trigonella foenum-graecum) was studied under pot conditions in a 2?×?2?×?5 factorial design with two AM treatments (G. mosseae inoculated and uninoculated), two EDTA concentrations (without and with 2.5 mmol EDTA kg^?1), and five lead concentrations (0, 50, 100, 400, and 800 mg kg^?1). A negative interaction was found between increasing lead concentration and G. mosseae. The plant dry matter and chlorophyll content was enhanced by G. mosseae whereas G. mosseae with EDTA showed the greatest root and shoot phosphorus (P) content. Ethylenediaminetetraacetic acid significantly enhanced lead concentration in the plant; however, at the same time it resulted in a slight decrease in the dry matter. However, when EDTA was applied along with G. mosseae, the deleterious effect of EDTA was overcome by the G. mosseae by promoting mineral uptake and plant growth, and hence metal accumulation also increased.     

镉、铅、锌对红壤微生物生物量的影响

Nitrogen(N)losses from ammonium bicarbonate or urea applied to wheat and then followed immediately by irrigation were investigated.Ammonia volatilization was determined by a micrometeorological method (ammonia sampler),total N loss was estimated by the ^15N mass balance method ,and denitrification loss was measured by the diference method(calculated from the difference between the total N loss and ammonia loss) and a direct method (measuring the emission of (N2 N2O)-^15N).Total ammonia losses from ammonium bicarbonate and urea in 33 days were 8.7% and 0.9% of the applied nitrogen ,respectively.The corresponding total N losses were 21.6% and 29.5%,Apparent denitrification losses(by the difference method) were rather high,being 12.9% from ammonium bicarbonate and 28.6% from urea .However,no emission of (N2 N2O)-^15N was detected using the direct method.     

重金属污染对典型湿润富铁土上钾素行为的影响

Difference of montmorillonite(Mt),illite(It) and kaolinite(Kt) in lead sorption characteristics and the effects of amorphous Fe and Al oxide coatings on the characteristics were experimentally sutdied with logistic model.The sorption curves had sigmoid feature due to use of acetate-type buffer solution.With the model the sorption process could be divided into four stages and the sorption characteristics at the stages were discussed.The results showed that,after Mt,It and Kt were coated by amorphous Fe oxide,their maximum sorption capacity(MSC) and percentage of high-SSC concentration scope(HCS) of Pb^2 increased markedly,but the specific sorption capacity(SSC) decreased.with regard to effects of amorphous Al oxide coating,except for It Al,the SSC of other samples showed a downtrend,despite that their MSC remained unchanged.Eventually,the gray correlation degrees to Pb^2 sorption for different physicochemical characteristics of the clay minerals were indicated to be higher for hydronium,zero point of surface charge and hydroxy,but lower for specific surface area.density of surface charge and amount of surface charges.     

新乡市生活污水中有效成分和重金属铅·汞含量的分析

对新乡市生活污水中有效营养成分及重金属铅、汞含量进行测定,并对生活污水用于农业灌溉的利弊加以分析。结果表明,新乡市生活污水中有效氮、磷养分含量极高,且重金属Pb、Hg含量较低,未超过《农田灌溉水质标准》(GB5084-92),可以用于农田灌溉。     

土壤-烟草系统中铅的迁移特征及形态分布

通过盆栽试验,以两烟草品种(云烟85和红花大金元)为对象,研究了重金属铅(Pb)在土壤-烟草系统中的迁移特征以及土壤与烟草各器官Pb化学形态分布特征。结果表明:与非根际土壤相比,根际土壤铁锰氧化物结合态Pb明显降低(降幅3.86%~22.33%),碳酸盐结合态、有机态和残渣态呈上升趋势。随着土壤Pb处理浓度的升高,两品种烟草生物量均显著降低,各器官Pb含量均显著上升,云烟85各器官Pb含量大小顺序为根叶茎,红花大金元为根茎叶。CK处理下两个品种烟草各器官Pb形态主要以氯化钠、醋酸和盐酸提取态为主(66.49%~72.40%),随着Pb处理浓度的升高,根部与叶部乙醇提取态Pb显著增加,这加剧了Pb的迁移性,红花大金元茎部Pb向盐酸提取态转化从而抑制Pb由茎部向叶部的转运。     

生物质炭对湘南矿区轻度Pb污染土壤性质及Pb的累积转运影响

为探讨生物质炭对湘南矿区附近轻度Pb污染土壤的改良效果,通过盆栽试验,研究不同施炭条件(0、0.5%、1.0%、2.0%)对水稻土壤性质及Pb在水稻中的累积转运影响。结果表明:施用玉米秸秆炭能使土壤pH值提高0.50~0.67个单位,有机质增加6.9%~25.1%,CEC升高24.7%~41.3%,土壤Pb的毒性浸出量降低4.4%~25.9%,且Pb的毒性浸出量与有机质、CEC分别呈极显著和显著性负相关;在相同施炭条件下,上述各指标在水稻生长的幼苗期和成熟期时存在差异,土壤pH值和有机质幼苗期高于成熟期,CEC和Pb的毒性浸出量幼苗期低于成熟期。水稻各部位中,根表铁膜对Pb的累积量最多,谷壳对Pb的转运能力最大,施用玉米秸秆炭能增加水稻根表铁膜及谷壳富集Pb的能力,降低水稻根系、茎叶及糙米中Pb含量,当施炭量≥1%时,糙米中Pb含量低于0.2 mg·kg~(-1),达到国家食品污染物限量标准。研究表明,生物质炭能够有效改良湘南矿区轻度Pb污染土壤,显著降低糙米中Pb的累积。     

根际pH调控下景天三七对铅积累及铅胁迫的生理响应

为探索不同根际pH下,景天三七对重金属铅的忍耐指数和植株各个部位铅含量的积累规律,并找到提高植株对Pb²⁺耐受性的pH值。在不同根际pH(5、6、7、8)条件下,采用水培试验,研究景天三七在不同铅浓度(0、20、60、100、140 mg·L^-1)下对铅积累与铅胁迫的生理响应。结果表明:1)在相同pH条件下,随着铅浓度的增加,景天三七根长、株高和干质量均逐渐减小,生长受到抑制,忍耐指数逐渐下降;叶绿素含量呈现先增加后降低的趋势,谷胱甘肽(GSH)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性逐渐降低,MDA含量逐渐增加;根、茎、叶中铅含量随着铅浓度的增加而逐渐增加,且铅积累量表现为根>茎>叶。2)在相同Pb²⁺浓度条件下,随着pH的增加,根长、株高和干质量表现为先增加后降低的趋势;当pH=6时,植株生长较好,忍耐指数最高;忍耐指数、叶绿素含量、GSH含量和SOD、POD、CAT活性均表现出先增加后降低的趋势,且pH=6时达最大值;MDA含量变化则相反,pH=6时达最小值;根、茎、叶的铅含量逐渐降低。综上,景天三七生长受pH及Pb²⁺浓度的影响,pH影响Pb²⁺的吸收,根际pH为6时能提高植物对铅的耐受性,且Pb²⁺为20 mg·L^-1时,对铅的耐受性最强。