无机硅叶面肥及土壤调理剂对水稻铅、镉吸收的影响

喷施叶面阻控剂和施用土壤调理剂是目前污染稻田治理的主要措施,针对不同污染类型、污染程度稻田研发效果较好的叶面阻控剂及土壤调理剂是研究重点。文章通过2019年的田间试验研究无机硅叶面肥及土壤调理剂对中重度铅镉复合污染稻田水稻铅镉阻控效果。共设3个处理:常规施肥处理(CK)、常规施肥+喷施无机硅叶面肥处理(L-Si)、常规施肥+施用无机硅土壤调理剂处理(S-Si)。结果表明:L-Si处理土壤中铅质量分数较对照(116.00±4.35)mg·kg-1高18.97%;S-Si处理较对照(5.51±0.06)能够显著提高稻田土壤pH值0.73,土壤中铅和镉分别较对照(116.00±4.35)、(1.89±0.03)mg·kg-1高12.07%和14.81%。L-Si处理下铅在根、叶片、稻米中富集较对照分别减少11.69%、12.40%和38.46%;镉在叶片、稻壳、稻米中较对照显著减少了18.10%、5.84%和40.84%。而S-Si处理中铅在根、茎、叶、稻壳、稻米中富集量较对照显著减少11.69%、36.93%、15.16%、23.47%和51.28%;镉在根、茎、叶、稻壳、稻米中富集量显著降低12.93%、42.28%、61.75%、59.85%和49.21%。L-Si及S-Si处理水稻产量较对照(7052.27±95.07)kg·hm^-2分别提高3.24%和4.09%。综上所述,无机硅经叶面吸收后,在减少叶片中铅富集的同时减少了根系对土壤铅的吸收,将经根系吸收的铅富集于茎和稻壳中;而在减少叶片中镉富集的同时并未减少根系对镉吸收,将经根系吸收的镉富集于根和茎中。无机硅土壤调理剂在将土壤中铅和镉固定于土壤中的同时阻隔了水稻根系对铅和镉下吸收,因此水稻根、茎、叶、稻壳、稻米中铅和镉的含量均显著降低。     

添加羟基磷灰石对土壤铅吸附与解吸特性的影响

采用羟基磷灰石对四种不同类型的土壤进行铅的吸附-解吸试验.结果表明:四种土壤对铅的吸附均可用Langmuir和Freundlich方程进行描述,土壤中加入羟基磷灰石明显增加了土壤对铅的吸附量和吸附亲和力,同时降低了土壤中铅的解吸百分数,在偏酸性的红壤上表现更为明显,其最大吸附量增加28%.羟基磷灰石对铅吸附的反应机理可能与磷灰石溶解后与铅形成磷酸盐沉淀及其对铅的表面吸附作用有关.土壤对铅的吸附量及吸附亲和力与土壤的有机质、阳离子交换量及粘粒含量有显著正相关,而与土壤砂粒的含量呈负相关.     

沉水植物龙须眼子菜(Potamogeton pectinatus)对镉、铅的吸附特性

采用龙须眼子菜(Potamogeton pectinatus)干样为实验材料,研究了龙须眼子菜对溶液中镉、铅吸附的基本特征。相同浓度不同时间条件下的吸附实验结果显示,龙须眼子菜对溶液中镉、铅离子的吸附速度很快,大约20min就能达到平衡,吸附的限速过程是小孔扩散过程,随着时间的延长,吸附的动力学特征可用假二次方程描述。相同时间不同浓度条件下的吸附实验结果显示,龙须眼子菜对镉、铅的最大吸附量分别能达到32368和24776mg·kg-1,吸附的浓度动力学特征符合Langmuir曲线方程。所有结果都表明,龙须眼子菜能有效地从溶液中去除镉和铅,可以用于水体镉、铅污染的植物修复,也可把龙须眼子菜干样作为一种新的吸附剂用于去除工业废水中的镉和铅。     

温度、pH值及盐度对龙须眼子菜吸附镉、铅的影响

以龙须眼子菜(Potamogeton pectinatus)干样为材料,研究了不同温度、pH值和盐度对龙须眼子菜吸附镉、铅离子的影响.结果表明,不同温度及不同pH值下龙须眼子菜对镉吸附符合Langmuir模型,对铅的吸附符合Freundlich模型.与5 ℃、10 ℃、30 ℃处理相比,20 ℃时龙须眼子菜对镉、铅的吸附能力较强.当其它条件不变时,在pH值为3～7的范围内,龙须眼子菜对镉的吸附随pH值升高而增加,对铅的吸附随pH值升高而减少.在0.5～10 g·L-1的盐度范围内,随着溶液盐度的增加龙须眼子菜对镉吸附减少,但对铅的吸附却增加.龙须眼子菜是一种对镉、铅有很强的吸附能力的沉水植物,对温度、酸碱度、盐度适应范围也很广,因而可作为生物吸附剂用于含镉、含铅废水的处理.     

土壤性质对水稻土中外源镉与铅生物有效性的影响

为定量了解土壤理化性质对进入土壤中的外源镉和铅生物有效性的影响,采集了性质相差较大的16个水稻土,通过添加Cd(或Pb)培养和老化处理(Cd的加入量为0、0.2、0.5、1、2和5 mg·kg-1;Pb加入量为0、20、50、100、200和500 mg·kg-1,培养时间为1年),研究了不同土壤中Cd(或Pb)负荷与土壤中水溶态和交换态Cd(或Pb)的关系.结果表明,随着Cd(或Pb)污染水平的提高,土壤中水溶态和交换态Cd(或Pb)均显著增加,但不同土壤中水溶态和交换态Cd(或Pb)随土壤Cd(或Pb)积累的增加幅度有很大的差异.相关分析表明,水稻土中水溶性Cd(或Pb)主要与土壤Cd(或Pb)污染水平和pH值有关;而交换态Cd(或Pb)主要与土壤Cd(或Pb)污染水平、pH值、CEC及质地等有关.数据显示,pH值较高、质地较黏的土壤可大大减缓因污染引起的CA和Pb生物有效性的提高.     

土壤盐化过程中阳离子对镉的形态分布影响

以硝酸盐为例,实验分析了无机盐阳离子对碱性盐化土壤中镉形态分布的影响。结果表明,随着Na＋、K＋、Ca2＋、Mg2＋等阳离子进入土壤,土壤中镉的有效态含量增加,对镉有明显的活化作用;随着Na＋、K＋、Ca2＋、Mg2＋浓度的增加,有效态镉的含量进一步增加,镉有效态的增加幅度可达到55.46%～68.39%;土壤镉的其它各形态含量都随着Na＋、K＋、Ca2＋、Mg2＋等的加入而减少,其中碳酸盐态的减少量为23.61%～63.14%,铁锰氧化态的减少量为10.77%～25.66%,有机态的减少量为18.11%～54.68%,残渣态的减少量为2.14%～12.78%。不同种类阳离子对土壤中镉形态变化的影响程度有差异,钙离子对土壤中镉的吸附竞争能力最强,镁离子次之,而钠离子和钾离子对镉的吸附竞争能力相似。     

等毒性配比法研究镉、铬和铅对淡水发光细菌的联合毒性

当待测生物暴露在混合污染物中时,由于混合物中各组分相互影响,会产生联合毒性作用,表现为加和作用、协同作用和拮抗作用。为了深入了解重金属混合物的联合毒性对发光细菌的作用,利用淡水发光细菌——青海弧菌Q67(Vibrio qinghaiensis sp.nov-Q67)发光值的测定方法,采用联合毒性单位法,在测定了硝酸镉、重铬酸钾和硝酸铅单一毒性EC50的基础上,对硝酸镉 重铬酸钾、硝酸镉 硝酸铅、硝酸铅 重铬酸钾3种重金属二元混合物的联合毒性进行了评价。结果表明,硝酸镉 重铬酸钾、硝酸铅 重铬酸钾是拮抗作用,硝酸铅 硝酸镉是协同作用。     

污染土壤中Sn、Hg、Sb、Bi解吸动力学特性的研究

土壤中重金属的解吸直接影响重金属在环境中的形态转化和植物有效性.文章以我国东北地区草甸棕壤作为研究对象,通过对Sn、Hg、Sb、Bi单一及复合污染土壤中Sn、Hg、Sb、Bi的解吸动力学行为的研究,探索污染土壤中重金属Sn、Hg、Sb、Bi的解吸特性与规律.结果表明,不同污染类型的污染土壤中Sn、Hg、Sb、Bi这几种重金属的解吸量随着振荡时间的延长而不断增加.重金属Sn、Hg、Sb、Bi的解吸过程可分为快速反应阶段和慢速反应阶段.描述土壤Sn、Hg、Sb、Bi解吸动力学过程的最优模型为Elovich方程,其次为双常数方程,而一级动力学方程拟合效果不佳.此外,污染土壤中重金属Sn、Hg、Sb、Bi的解吸过程受共存重金属元素的影响.     

Contamination status of arsenic,lead, and cadmium of different wetland waters

The present investigation was conducted to determine the contamination status of arsenic (As), cadmium (Cd), and lead (Pb) in the wetland waters of Bhaluka in Bangladesh. Water samples were collected from 15 selected wetlands of Bhaluka region and analyzed using an atomic absorption spectrophotometer. Estimated results of three metals detected were As (7–80?µg?L^?1), Pb (0–86?µg?L^?1) and Cd (0–70?µg?L^?1) in water samples in all wetlands. The level of As in all investigated wetlands (93%) was higher than that of WHO recommended permissible limit of drinking water except Alanga wetland. However, As levels were higher than that recommended for livestock water quality levels. Eighty-seven percent of the investigated wetlands showed lower content of Pb than WHO recommended permissible limit of drinking water, but two wetland waters (Dohuria-1 and Chowdhuri) were polluted with higher Pb levels. Sixty-seven percent of the investigated wetlands displayed higher levels of Cd than WHO recommended permissible limit in drinking water. Dissolved organic material showed no significant difference among the 15 investigated wetlands water, but total dissolved solids was significantly greater. The condition of the water of all wetlands was basic pH. All water samples were applied to linear regression equation and correlation coefficients where values showed no significant differences. Data demonstrate that the estimated high metal concentrations of these ponds may contribute to bioaccumulation within plants, food grains and shrimp.     

Impact of cadmium and lead on Catharanthus roseus--a phytoremediation study

The Madagascar Periwinkle, Catharanthus roseus (L.) G. Don (a valued medicinal plant) was exposed to different concentrations ofheavymetals like, CdCl, and PbCl, with a view to observe their bioaccumulation efficiency. Germination was inhibited by both the heavy metals in the seeds previously imbibed in GA, and KNO, for 24 hr. EC50 (the effective concentration which inhibits root length by 50%) was recorded as 180 microM for CdCl2, and 50 microM for PbCl2. Both alpha-amylase and protease activity were reduced substantially on treatment of seeds with increasing concentrations of CdCl2, and PbCl2. Malondialdehyde (MDA) a product of lipoxigenase (LOX) activity also increased due to the treatment of both CdCl, and PbCl2. When two-months-old plants grown in normal soil were transferred to soils containing increasing amounts of these two heavy metals, senescence of lower leaves and extensive chlorosis were noticed after four days of transfer However, plants gradually acclimatized and after 20 days the chlorophyll content was almost comparable to normal. Plants receiving CdCl2 treatment (250 microg g(-1) and less) became acclimatized after two weeks and started normal growth. But PbCl2 of 432 microg g(-1) and less could not affect the plant growth throughout, after a preliminary shock was erased. In case of CdCl2 treatment, a stunted growth with reduced leaf area, reduced biomass and sterility were recorded after six months, while plants show normal growth and flowering in case of PbCl2 treatment. Total alkaloid was also found to be decreased in the roots of CdCl2 treated plants. No change was observed in case of PbCl2. GA3 treatments to the CdCl2 treated plants show internode elongation and increase in leaf area with relatively elongated leaves and thinning of stem diameter AAS analyses of leaves of treated plants exhibited 5-10% accumulation of cadmium, but there was no accumulation of lead at all.     

滇白前(Silene viscidula)对铅、锌、镉的共超富集特征

为了寻找新的重金属超富集植物特别是多金属共超富集植物,调查测定了云南兰坪铅锌矿区北厂矿段生长的8种植物及其根区土壤的重金属质量分数,以及土壤基本理化性质.结果表明:研究区土壤中磷和钾质量分数较低,总氮、总磷、总钾、铵态氮、硝态氮、速效磷分别占土壤干质量的0.2%、0.03%、0.52%、0.0029%、0.000 12%、0.00068%;有机质质量分数平均为4.81%,pH值平均为6.79,电导率变化范围为11.4～140-3μs·cm-1.该矿区土壤中锌(Zn)、铅(Pb)、镉(Cd)、铜(Cu)的质量分数平均值分别为(38 178±23 870)、(18 671±10 143)、(438±345)、(159±:82)mg·kg>-1,除Cu外均超过国家土壤环境质量(GB 15618-1995)三级标准.8种植物地上部Zn、Pb、Cd、Cu质量分数范围分别为271～17 986、51～5 430、1～617、2～26mg·kg-1,尤以滇白前(Silene viscidula Franch)地上部Zn、Pb、Cd质量分数为最高.进一步采集38个滇白前样本对其重金属富集特征进行深人调查,表明其地上部中含zn、Pb和Cd平均为(11 043±3 537)、(1 546±1 044)和(391±196)mg·kg-1,富集系数(地上部和土壤金属质量分数之比)分别为0.35、0.08和1.05,转运系数(地上部和根中金属质量分数之比)均超过1,均值分别为8.21、3.90和8.36.野外调查数据表明,滇白前是一种Pb/Zn/Cd共超富集植物.滇白前对Zn、Pb富集系数小于1,主要是由于其对应土壤中Zn、Pb质量分数太高(平均分别为(45 778±32 819)、(22 512±13 613)mg·kg-1)所致.     

土壤中镉的吸附解吸研究进展

首先概述了国内外关于土壤对镉的吸附解吸的基本研究方法与实验条件。用于吸附解吸实验的土样以通过20目筛为宜，而不同形式的支持电解质及其离子浓度的选择对实验结果有很大影响，应由实验的具体目的和要求确定合适的实验条件。位于土壤颗粒表面的各吸附点位与镉的结合能的能量高低不一，可将土壤对镉的吸附作用区分为专性吸附和非专性吸附。可用传统的或融入新参数的吸附等温线表达土壤对镉的吸附过程，土壤对镉的吸附性能可用综合因子来形容，如吸附势、吸持率、平均分配系数、Langmuir方程的常数k和Freundlich方程的系数k等表达方式，同时寻找这些综合因子与土壤基本理化性质之间的关系。文章最后讨论了影响吸附过程的主要环境因子，并就土壤pH和水分条件的影响机制进行了分析。     

Biosorption of lead and cadmium using marine algae

The use of algae (Ulva fasciata, green and Sargassum sp., brown) to reduce lead and cadmium levels from mono-metal solutions was investigated. The brown algae showed higher efficiency for the accumulation of lead (～1.5 times) and cadmium (～2 times) than green algae. The optimum pH value is found to be between 4 and 5.5. Regarding biomass concentration, an increase in metals percentage removal and a decrease in metal uptake capacity coincided with the increase in biomass concentration. All light metals (Ca, Mg and Na) showed a suppressive effect on biosorption capacity. The enhancement of biosorption in the case of NaOH was obvious. The biosorption process (65–90%) occurred within 3?min. Experimental data were in high agreement with the pseudo-second-order kinetic model and Freundlich model for lead and cadmium biosorption using different biosorbents. In the desorption study, 0.2?mol?L^?1 HCl recorded the best concentration for the elution of metals from the biomass. The biosorption capacity decreased over the four operational cycles for both lead and cadmium. Infrared analysis showed that amino, hydroxyl and carboxyl functional groups provide the major biosorption sites for metal binding. Use of the above-mentioned algae for cheap metal absorbance is considered as one water treatment criterion.     

Contribution to the ecotoxicological study of cadmium,lead, copper and zinc in the mussel Mytilus edulis

The understanding of natural fluctuations of metal concentrations in mussels used as bio-indicators is indispensable for a good assessment of the disturbances due to pollution. We have studied thoroughly the factors which condition bioaccumulation by using controlled populations of mussels, Mytilus edulis L., sampled monthly over more than two years (March 1982–May 1984) in the Bay of Bourgneuf, France. Seasonal changes in metal levels have been recognized, maximum values being observed in winter and early spring and minimum in later spring and summer. Depending on metal and size group, the ratios between these maximum and minimum values varied between 1.56 and 3.43. The fluctuations in soft-tissue weight appear to be the main explanatory factor of seasonal variations in metal concentrations in mussels. Fluctuations in metal levels related to size of mussels were observed. Except for cadmium in mussels with a mean dry weight of soft tissues >0.2 g, a slight decrease in metal concentrations was observed for growing individuals: the regression coefficient b was -0.10, -0.11, -0.13 and -0.27 for Cd, Cu, Zn and Pb, respectively. The metals examined were rather uniformly distributed among the different groups of organs (visceral mass, gills and palps, remainder) and, consequently, several analyses of metals in different organs do not provide much more information than one analysis on the whole soft tissues. It is concluded that fluctuations related to size or season are reflected by only moderate differences in the maximum and minimum concentrations of metals in the mussels, but that they are nevertheless sufficient to conceal low chronic or short-term pollution, except at those sites where the normal environmental conditions are well-documented.