Effect of phosphorus on arsenic accumulation in As-hyperaccumulator Pteris vittata L. and its implication

Pot experiment was conducted to understand the effect of phosphorus on arsenic accumulation in As-hyperaccumulator Chinese brake (Pteris vittata L.). It is shown that arsenic concentrations in the fronds and rhizoids, the arsenic bioaccumulation factor, and the total arsenic in the fronds were not influenced significantly under low levels of phosphorus (≤400 mg/kg) and increased sharply under high levels of phosphorus (>400 mg/ kg). The discovery implies that the efficiency of arsenic removal in phytoremediation using the hyperaccumulating plant can be greatly elevated by the phosphorus addition at high rates. The interaction between the accumulation of phosphorus and that of arsenic in plant was stimulated mutually. The result represents that Chinese brake is a good material for plant physiologist to conduct comparative and mechanism studies on the uptake behaviors of phosphorus and arsenic, and phosphorus is also a potential accelerator for phytoremediation of arsenic-contaminated soils.     

Arsenic hyperaccumulator Pteris Vittata L. and its arsenic accumulation

An arsenic hyperaccumulator Pteris vittata L. (Chinese brake) was first discovered in China by means of field survey and greenhouse cultivation. Field survey showed that Chinese brake had large accumulating capacity to arsenic; the orders of arsenic content in different parts of the fern were as follows: leaves>leafstalks>roots, which is totally different from that of ordinary plants; bioaccumulation coefficients of the above ground parts of the fern decreased as a power function of soil arsenic contents. In the control of pot trials with normal unpolluted soil containing 9 mg/kg of arsenic, the bioaccumulation coefficients of the above ground parts and rhizoids of Chinese brake were as high as 71 and 80 respectively. Greenhouse cultivation in the contaminated soil from mining areas has shown that more than 1 times greater arsenic can be accumulated in the leaves of the fern than that of field samples with the largest content of 5070 mg/kg As on a dry matter basis. During greenhouse cultivation, arsenic content in the leaves of the fern increased linearly with time prolonging. Not only has Chinese brake extraordinary tolerance and accumulation to arsenic, but it grew rapidly with great biomass, wide distribution and easy adaptation to different environmental conditions as well. Therefore, it has great potential in future remediation of arsenic contamination. It also demonstrates important value for studies of arsenic physiology and biochemistry such as arsenic absorption, translocation and detoxification mechanisms in plants.     

Arsenic hyperaccumulator Pteris Vittata L. and its arsenic accumulation

An arsenic hyperaccumulator Pteris vittata L. (Chinese brake) was first discovered in China by means of field survey and greenhouse cultivation. Field survey showed that Chinese brake had large accumulating capacity to arsenic; the orders of arsenic content in different parts of the fern were as follows: leaves>leafstalks>roots, which is totally different from that of ordinary plants; bioaccumulation coefficients of the above ground parts of the fern decreased as a power function of soil arsenic contents. In the control of pot trials with normal unpolluted soil containing 9 mg/kg of arsenic, the bioaccumulation coefficients of the above ground parts and rhizoids of Chinese brake were as high as 71 and 80 respectively. Greenhouse cultivation in the contaminated soil from mining areas has shown that more than 1 times greater arsenic can be accumulated in the leaves of the fern than that of field samples with the largest content of 5070 mg/kg As on a dry matter basis. During greenhouse cultivation, arsenic content in the leaves of the fern increased linearly with time prolonging. Not only has Chinese brake extraordinary tolerance and accumulation to arsenic, but it grew rapidly with great biomass, wide distribution and easy adaptation to different environmental conditions as well. Therefore, it has great potential in future remediation of arsenic contamination. It also demonstrates important value for studies of arsenic physiology and biochemistry such as arsenic absorption, translocation and detoxification mechanisms in plants.     

黄葛树对土壤铅、镉污染耐受性的研究

以黄葛树为实验材料,通过盆栽实验研究梯度浓度土壤外源铅胁迫(0,250,500,900mg/kg)、外源镉胁迫(0,5,10,20,30mg/kg)对黄葛树形态生长、生理生化特征的影响,旨在综合评价黄葛树对土壤铅、镉污染的适应性,为黄葛树对土壤铅、镉污染的修复潜力研究提供基础.结果表明:250mg/kg铅污染胁迫与5mg/kg镉胁迫对黄葛树株高、地径净生长量、可溶性糖质量分数、SOD活性均无显著影响;250,500mg/kg铅污染与5,10mg/kg镉污染显著增加了黄葛树叶片叶绿素质量比;实验组MDA浓度均显著高于对照;实验设置污染浓度内,900mg/kg铅胁迫与30mg/kg镉胁迫对黄葛树生长的抑制作用最强.研究说明:土壤铅、镉污染对黄葛树生长的影响具有"低促高抑"的特点,500,10mg/kg是铅、镉胁迫对黄葛树生长产生抑制作用的临界质量比,此临界质量比与土壤污染标准相比较可得黄葛树对镉胁迫的耐受性更强.     

A newly-discovered Cd-hyperaccumulator Solanum nigrum L.

Phytoremediation emerged in early the 1980s is animportant technology for remedying contaminated sites.One of the most promising phytoremediation technologiesis phytoextraction using hyperaccumulators to removeheavy metals from contaminated soils. The ter…     

植物修复重金属-有机物复合污染河道疏浚底泥的研究

针对目前国内普遍存在的排污河道污染问题,通过盆栽试验研究了玉米、印度芥菜、超积累油菜、紫花苜蓿在施用不同配比的排污河道疏浚底泥上对重金属-有机物复合污染的修复情况及超积累的机理.结果表明,随着底泥配比的增加,植物发芽率的抑止程度也增加;适应底泥中高浓度复合污染的植物,底泥施用能促进其生长,提高植物体内的叶绿素含量.植物体内积累的重金属Zn、Pb、Cd以生长在底泥与土壤比为2:1的印度芥菜为最大,分别为1 521 mg/kg、453 mg/kg和11.7 mg/kg;Cu、Ni积累量以生长于底泥中的玉米为最大,分别为128 mg/kg和89.1 mg/kg.在本实验条件下,底泥中有机物以种植玉米的底泥为最大,为76.89%.通过环境扫描电子显微镜及配套的能谱分析发现,重金属在植物体内的聚集存在;经X荧光光谱仪和X射线衍射仪分析,确证了配合体之间及重金属和配合体相互形成架桥而聚集成团,形成重金属结合物积累在植物体内,且在植物根部发现积累了Cu的有机氯化物.种植前后底泥的X射线衍射对比表明,种植后重金属的晶格结构和存在形态发生了变化.     

两种不同消解方法测定近海沉积物氮磷含量的比较

采用两种不同的消解方法—微波消解法和高压消解法,对近海沉积物中的总氮、总磷进行同时消解,并比较了测定结果.结果表明:高压消解条件下测定样品1和样品2总氮的相对标准偏差分别为7.7%和7.4%,总磷的标准偏差分别为3.9%和7.8%;微波消解条件下测定样品1和样品2总氮的相对标准偏差分别为9.4%和10.1%,总磷的相对标准偏差分别为6.9%和8.1%;两种消解条件下的总磷含量相差不大(样品1分别为0.460 mg/kg和0.454 mg/kg,样品2分别为0.449 mg/kg和0.439 mg/kg),但高压消解条件下的总氮含量(样品1为0.114 mg/kg,样品2为0.122 mg/kg)明显高于微波消解(样品1为0.088 mg/kg,样品2为0.092 mg/kg),且相对标准偏差较小.因此可以认为高压消解方法的精密度高于微波消解方法.     

水铁矿促进湿地植物净化含砷微污染水源水的试验研究

为了研究水铁矿促进湿地植物净化微污染水体中砷的效果及机理,选用美人蕉,添加不同比例水铁矿的石英砂构建微型垂直流人工湿地,考察含砷微污染水连续漫灌条件下美人蕉根表铁膜中铁含量及砷在湿地基质和植物茎叶中的分布规律。结果表明:湿地基质中水铁矿的添加剂量在200 mg/kg以内,湿地基质吸附截留砷的能力随水铁矿添加剂量的增加而提高;超过200 mg/kg以后,增加水铁矿对湿地基质截留砷的能力影响不明显。美人蕉根表铁膜中的铁含量随湿地基质中水铁矿添加剂量(在50~1 200 mg/kg范围内)的增加而增加;渍水状态下的美人蕉净化含砷的微污染水,根表铁膜中铁含量在100 mg/kg左右,最有利于砷的吸收和最终去除。     

磷铝胁迫对马尾松苗期生长的影响及评价

为明晰磷铝胁迫下马尾松(Pinus massoniana Lamb.)苗期的生长变异规律，筛选出耐低磷酸铝型优良家系，本文以马尾松二代种子园54个优良家系幼苗为研究对象，对磷铝胁迫下其株高、地径、主根长和干重等生长指标进行测定并计算其耐低磷酸铝胁迫系数，将各指标的耐胁迫系数作为耐胁迫评价指标，运用相关性分析和因子分析将7个耐胁迫指标降维归纳为3个综合指标，并使用隶属函数法加权计算出综合评价值——D值，综合评价不同家系马尾松幼苗的耐低磷酸铝特性，并利用系统聚类分析进行分等定级。结果表明：低磷酸铝胁迫下，不同家系马尾松幼苗的生长均受到抑制，株高、主根长和地下部干重积累受抑制最严重；除株高与根冠比、地上部干重与根冠比呈负相关外，其他各指标之间呈正相关。家系间D值为0.155-0.919,17号家系耐低磷酸铝特性最好，25号家系最差。综上，低磷酸铝胁迫下，马尾松的长势特征为体矮径细，其干物质的积累受抑制、分配方式发生改变，使得其根冠比大幅度减少。     

土壤加砷对魔芋砷的含量、吸收与分布的影响

为了认识土壤砷污染与植物砷含量的关系,进行土壤加砷盆栽魔芋试验.结果表明,本实验条件下,魔芋球茎和茎叶的砷含量范围分别为2.12～14.98和1.23～21.23μg g-1,均与土壤加砷量呈极显著的线性相关.在对照下,球茎砷含量高于茎叶,在土壤加砷下,茎叶的砷含量高于球茎.魔芋的富砷量与土壤加砷量呈极显著的线性相关,在低土壤砷水平下,魔芋球茎富砷量大于茎叶,高土壤砷水平下,魔芋茎叶的富砷量大于球茎.同对照相比,土壤加砷降低了魔芋球茎富砷量所占比例,增加了魔芋茎叶富砷量所占比例,低土壤砷水平下,球茎富砷量所占比例高于茎叶,高土壤砷水平下,茎叶富砷量所占比例高于球茎.魔芋对土壤加砷的利用量与土壤加砷量呈极显著的线性相关,魔芋对土壤加砷的利用率只有0.25‰～0.84‰.魔芋球茎和茎叶对砷的富集系数分别为0.03～0.13和0.07～0.13,同对照相比,土壤加砷降低了球茎的富集系数,增加了茎叶的富集系数,在对照下,球茎的富集系数高于茎叶,在土壤加砷下,茎叶富集系数高于球茎.总之,土壤加砷不仅显著增加了魔芋球茎和茎叶的砷含量,也改变砷在魔芋体内的分布格局,魔芋是吸收利用土壤砷能力弱的植物,魔芋通过将所吸收的砷转移到地上部分以适应砷污染土壤环境.     

Chelators effect on soil Cu extractability and uptake by Elsholtzia splendens

Phytoremediation is emerging as a potential cost-effective solution for remediation of contaminated soils, and bioavailability of metal in the soil for plant uptake is an important factor for successful phytoremediation.This study aimedat investigating the ability of EDTA and citric acid for enhancing soil bioavailability of Cu and phytoremediation by E1sholtzia splendens in two types of soils contaminated with heavy metals [i.e. mined soil from copper mining area (MS), and paddy soil (PS) polluted by copper refining].The results showed that addition of 2.5 mmol/kg EDTA significantly increased the H2O extractable Cu concentration from 1.20 to 15.78mg/kg in MS and from 0.26 to 15.72mg/kg in PS,and that shoot Cu concentration increased 4-fold and 8-fold as compared to the control.There was no significant difference between the treatment with 5.0mmol/kg EDTA and that with 2.5mmol/kg EDTA, probably because that 2.5mmol/kg EDTA was enough for elevating Cu bioavailability to the maximum level.As compared with the control, citric acid had no marked effect on both soil extractable Cu and shoot Cu concentration or accumulation. The results indicated that EDTA addition can increase the potential and efficiency of Cu phytoextraction by E.splendens in polluted soils.     

紫花苜蓿对土壤中铜的富集效应及其生理响应

依据我国土壤环境质量标准设置10个铜污染指标(1~400mg.kg-1),采用盆栽试验研究了铜污染对紫花苜蓿的生物量、铜积累、叶绿素和游离脯氨酸含量等的影响,探讨叶绿素和游离脯氨酸含量与紫花苜蓿铜积累之间的相互关系.结果表明叶绿素和游离脯氨酸的含量变化分别与紫花苜蓿的生物量和铜积累量的变化趋势一致.随土壤中铜含量的增加,叶绿素含量先增加后减小.游离脯氨酸含量在外源添加铜含量高于10mg.kg-1时与对照组相比增加显著(P<0.05).紫花苜蓿根系的铜积累显著高于地上部分.铜含量为400mg.kg-1时紫花苜蓿铜的总积累量达每盆617μg,是对照组的12倍左右,表明紫花苜蓿对铜污染土壤具有潜在的...     

Sedum alfredii H: A new Zn hyperaccumulating plant first found in China

Field survey and greenhouse experiments were carried out to identify and characterize zinc (Zn) uptake and accumulation by a new Zn hyperaccumulating plant species (Sedum alfredii Hance) native to China. Zinc concentration in the shoots of Sedum alfredii Hance grown on an ancient mined area ranged from 4134 to 5000 mg/kg, with a mean of 4515 mg/kg. It suggests that Sedum alfredii could not only grow on heavily Pb/Zn contaminated soils, but also could accumulate extraordinarily high concentration of Zn. Under nutrient solution culture conditions, Sedum alfredii Hance grew healthy at Zn supplying levels from 0.006 to 240 mg@L-1. Zinc concentration in the shoots increased with external Zn levels increasing. The Zn concentration and accumulation in the shoots reached the highest at Zn supply level of 80 mg/L, with 19.67 g/kg and 19.83 mg/plant, respectively. All the results showed that Sedum alfredii Hance is a new Zn hyperaccumulating plant. This provides a new plant material to explore mechanism of plant to hyperaccumulate Zn, and a potent new plant species to phytoremediate Zn contaminated soils.     

木芙蓉对土壤铅离子的耐性及转移富集特性研究

为了解木芙蓉对土壤铅污染的修复潜力,以木芙蓉扦插幼苗为材料,通过盆栽试验研究不同程度土壤铅污染对木芙蓉幼苗生长、生理生化指标及铅离子转移富集特性的影响.结果表明:轻度(300 mg/kg)、中度(800 mg/kg)铅污染对木芙蓉幼苗生物量的影响不显著,植株生长正常;重度(1 300 mg/kg)铅污染对木芙蓉光合系统、抗氧化系统造成严重伤害,显著抑制了木芙蓉幼苗根长、根粗和生物量的增长.随着铅污染质量分数升高,幼苗根系铅含量显著上升,在重度铅污染时达到最大值,为1 610.106 mg/kg;地上地下部转移率在中度铅污染时达到最大值,为0.093;地下部富集系数在重度铅污染下大于1,与对照差异明显.说明木芙蓉根系对铅离子有较强富集能力,向茎叶转移较少,可作为修复轻度、中度铅污染的树种之一.     

江西省稻米中总砷和无机砷含量的测定与分析

选取江西省10个县市的100份新收获稻米为实验材料,分别采用电感耦合等离子体质谱法和高效液相色谱-电感耦合等离子体质谱法,测定了稻米中的总砷和无机砷含量。测定结果表明,该方法线性方程和相关系数良好,稻米粉标准物质测定结果良好。100份稻米中的总砷含量变化为0.045~0.382mg/kg,均值为 0.170mg/kg;无机砷含量变化为0.000~0.180mg/kg,均值为 0.067mg/kg;单因素方差分析结果显示,江西省10个县市稻米中的总砷和无机砷含量之间均存在不同程度的差异性,其中无机砷含量的差异性最为显著。实验结果证实,稻米无机砷中三价As³⁺含量较高,约占无机砷含量的90%。美国环境保护署健康风险评估结果表明,江西省稻米中无机砷含量的暴露对人体健康没有风险。     

Synergistic defensive mechanism of phytochelatins and antioxidative enzymes in <Emphasis Type="Italic">Brassica chinensis</Emphasis> L. against Cd stress

Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins （PCs）, and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.     

马缨丹对镉的耐性及Glomus intraradices对镉吸收转运的影响

为探讨马缨丹（Lantana camara L.）应用于植物修复的可行性，通过盆栽试验，研究了马缨丹对土壤中重金属镉（Cd）的耐性，以及不同施Cd水平下丛枝菌根真菌（Arbuscular Mycorrhizal Fungi，AMF）Glomus intraradices（GI）对马缨丹吸收和转运Cd的影响. 结果显示:当土壤Cd含量为50 mg/kg时，马缨丹的生长受到明显的抑制作用；当土壤Cd含量为10 mg/kg时，马缨丹地上部具有较高的Cd积累量. GI表现出对Cd较强的耐性，能较好地侵染马缨丹根系. 与对照相比，接种GI能缓解Cd对马缨丹的生物毒性效应，显著提高马缨丹的生物量（P＜0.05）；接种GI对马缨丹转运Cd没有显著影响（P＞0.05），但当土壤Cd含量为100 mg/kg时,接种GI会抑制马缨丹对Cd的富集. 结果表明马缨丹对Cd具有较强的耐受性，在低Cd污染土壤中具有较高的提取效率；接种GI显著提高了马缨丹对Cd的耐性和地上部Cd的提取量（P＜0.05），表明马缨丹在修复Cd污染土壤方面具有应用潜力.     

河道沉积物中重金属的生态修复及根际细菌的原位检测

调查分析了哈尔滨某排污河道化工区段表层沉积物中的重金属（Pb、Zn、Cr、As、Ni、Cu和Cd）含量,通过盆栽试验研究了4种当地具有金属耐性的植物（玉米、酸模叶蓼、龙葵和酸模）对受污染的河道沉积物中重金属的修复效果,进而调查了这4种植物对重金属赋值形态的影响、富集能力及重金属的转运能力.结果显示,排污河道沉积物受到多种重金属的复合污染.表层沉积物中重金属经过两季植物修复后,7种重金属的残渣态均有不同程度的减少,并且金属形态逐渐向铁锰氧化态及可交换态转化,结果说明供试植物能够调节沉积物中重金属的生物有效性.重金属在沉积物中与在植物体内具有相同的总含量趋势：Zn＞Pb＞Ni＞Cr＞Cu＞As＞Cd,该趋势也反映出4种供试植物的生物监测潜能.植物对重金属表现出不同的吸收特性,4种植物对Zn和Ni的富集量相对较大,而Cu在植物地上部分的含量普遍较低,Zn和Ni在植物组织中的含量范围分别为108.4~543.92 mg/kg和36.8~246.91 mg/kg.总体来说,这4种植物主要将金属元素积累在根部,而非地上部分,表现出对重金属的耐受性.酸模叶蓼、酸模和龙葵这3种植物的地上部分分别积累了高浓度的Pb、Zn和Cd,并且具有较高的转运系数（TF>1）,反映出这3种植物对相应的重金属具有植物提取的潜力.采用荧光原位杂交（fluorescence in situ hybridization, FISH）技术,分析对照和经过栽培试验后根际沉积物中真细菌的数量和空间分布,结果表明植物对沉积物中的细菌有明显的活化作用.     

Effects of dietary nickel on detoxification enzyme activities in the midgut of <Emphasis Type="Italic">Spodoptera litura</Emphasis> Fabricius larvae

Nickel accumulated in midugt of Spodoptera litura Fabricius could induce the expression of metallothionein, one of the most important detoxification proteins in organisms. In the present study, the effects of dietary nickel on the activities of detoxification enzymes, such as carboxylesterase （CarE） and giutathione S-transferase （GST） in the midgut of S. litura larvae have been studied to get an understanding of the detoxification mechanisms of S. litura larvae to excessive nickel. Results showed that CarE activities in the midgut of the 5th instar larvae decreased at lower levels of nickel （≤5 mg/kg）, while increased with increasing nickel doses at higher levels of nickel （≥10 mg/kg） exposure in successive 3 generations. CarE activities of the 6th instar larvae were also characterized as inhibited at low levels of nickel exposure, and improved at higher levels in the 1st generation. CarE activities of 6th instar larvae in the 2nd and 3rd generations were all lower than that in control. However, GST activities in the midgut of the 5th and 6th instar larvae all increased with increasing nickel doses （1 --20 mg/kg） in diets.     

Endangered plants persist under phosphorus limitation

Nitrogen enrichment is widely thought to be responsible for the loss of plant species from temperate terrestrial ecosystems. This view is based on field surveys and controlled experiments showing that species richness correlates negatively with high productivity and nitrogen enrichment. However, as the type of nutrient limitation has never been examined on a large geographical scale the causality of these relationships is uncertain. We investigated species richness in herbaceous terrestrial ecosystems, sampled along a transect through temperate Eurasia that represented a gradient of declining levels of atmospheric nitrogen deposition--from approximately 50 kg ha(-1) yr(-1) in western Europe to natural background values of less than 5 kg ha(-1) yr(-1) in Siberia. Here we show that many more endangered plant species persist under phosphorus-limited than under nitrogen-limited conditions, and we conclude that enhanced phosphorus is more likely to be the cause of species loss than nitrogen enrichment. Our results highlight the need for a better understanding of the mechanisms of phosphorus enrichment, and for a stronger focus on conservation management to reduce phosphorus availability.