纳米氧化锌、硫酸锌和AM真菌对玉米生长的影响

纳米氧化锌(Zn O)是应用最为广泛但具有一定生物毒性的金属型纳米颗粒(nanoparticles,NPs)之一,而丛枝菌根(arbuscular mycorrhizal,AM)真菌能改善宿主植物矿质营养和增强宿主植物抗逆性,但纳米Zn O和其他锌污染物之间的关系以及AM真菌对其生物效应的影响目前尚不清楚.通过温室盆栽试验,研究了单一或复合施加纳米Zn O、ZnSO_4(500mg·kg~(-1))时接种AM真菌Funneliformis mosseae BEG 167对玉米生长的影响.结果表明,纳米Zn O对AM真菌侵染和玉米植株生长有一定抑制作用,表现出植物毒性,且与同浓度(500 mg·kg~(-1))下的ZnSO_4作用类似.与非菌根对照相比,接种AM真菌降低了玉米植株的Zn含量或Zn吸收量,且在复合处理中对玉米生长表现出较好的促生作用.结果首次表明,纳米ZnO与ZnSO_4在生物毒性上存在复杂的交互作用,而接种AM真菌在二者复合污染时对玉米具有一定的保护作用.     

丛枝菌根影响纳米ZnO对玉米的生物效应

人工纳米颗粒(engineered nanoparticles,ENPs)能被植物吸收、积累,随食物链进入人体而引起健康风险.丛枝菌根(arbuscular mycorrhizal,AM)真菌可与陆地生态系统中绝大多数高等植物互惠共生,可能影响ENPs的生物效应.在温室土壤盆栽条件下研究了施加不同水平纳米ZnO(0、500、1000、2000、3000 mg·kg-1)和接种AM真菌Acaulospora mellea对玉米生长和营养状况的影响.结果表明,随土壤中纳米ZnO施加水平的增加,菌根侵染率和玉米生物量均呈降低趋势,根系总长、总表面积及总体积降低,植株体内Zn含量和吸收量逐渐增加,地上部分P、N、K、Fe、Cu吸收量逐渐降低.与对照相比,接种AM真菌均促进玉米的生长,改善P、N、K营养,根系总长、总表面积及总体积增加,并在施加纳米ZnO时增加Zn在玉米根系中的分配比例.本结果首次表明,土壤中纳米ZnO对丛枝菌根具有一定毒性,而接种AM真菌能够减轻其毒性,对宿主植物起到保护作用.     

基于植物重金属毒性的陆地生物配体模型(t-BLM)研究进展

陆地生物配体模型(t-BLM)是生物配体模型(BLM)理论在陆地生态系统中的应用,目的是通过量化土壤重金属形态、土壤基本性质以及生态毒理剂量-效应三者之间的关系,评价重金属对陆生生物的毒性。BLM已经成功地预测重金属对水生生物的毒性,但t-BLM的发展相对较为缓慢。基于植物重金属毒性综述了t-BLM近年来国内外的研究进展,介绍了t-BLM的原理、基于t-BLM的重金属(Cu、Ni、Zn、Cd等)的植物毒性及其影响因素,并且提出基于植物重金属毒性的t-BLM研究面临的主要挑战。     

Effects of Cadmium on Nutrient Uptake and Translocation by Indian Mustard

Plants that hyperaccumulate metals are ideal subjects for studying the mechanisms of metal and mineral nutrient uptake in the plant kingdom. Indian Mustard (Brassica juncea) has been shown to accumulate moderate levels of Cd, Pb, Cr, Ni, Zn, and Cu. In this experiment, 10 levels of Cd concentration treatments were imposed by adding 10–190 mg Cd kg^–1 to the soils as cadmium nitrate [Cd(NO₃)₂]. The effect of Cd on phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and the micronutrients iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in B. juncea was studied. Plant growth was affected negatively by Cd, root biomass decreased significantly at 170 mg Cd kg^–1 dry weight soils treatment. Cadmium accumulation both in shoots and roots increased with increasing soil Cd treatments. The highest concentration of Cd was up to 300 mg kg^–1 d.w. in the roots and 160 mg kg^–1 d.w. in the shoots. The nutrients mainly affected by Cd were P, K, Ca, Fe, and Zn in the roots, and P, K, Ca, and Cu in the shoots. K and P concentrations in roots increased significantly when Cd was added at 170 mg kg^–1, and this was almost the same level at which root growth was inhibited. Zn concentrations in roots decreased significantly when added Cd concentration was increased from 50 to 110 mg kg^–1, then remained constant with Cd treatments from 110 to 190 mg kg^–1. However, Zn concentrations in the shoots seemed less affected by Cd. It is possible that Zn uptake was affected by the Cd but not the translocation of Zn within the plant. Ca and Mg accumulation in roots and shoots showed similar trends. This result indicates that Ca and Mg uptake is a non-specific process.     

Effect of organic acid on Cd toxicityin tomato and bean growth

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Phytotoxicity and persistence of metribuzin residues in black soil

A bioassay procedure based on the root and shoot growth of cucumber and sorghum were used to study the phytotoxicity, as affected by varying the concentration of metribuzin, and persistence of metribuzin residues in soil. Sorghum and cucumber were found to be very susceptible test plant species to metribuzin. It was found that the persistence and phytotoxicity increased with increasing rate of application of metribuzin, and the relationship between herbicide concentration and phytotoxicity was best described by a quadratic equation. Sorghum and cucumber plants emerged as very sensitive new bioassay plants for metribuzin and could detect residues even at 0.010 and 0.046?ppm in the post harvest soil of potato crop.     

全氟辛烷磺酸短期暴露对不同作物苗期生长的影响

全氟辛烷磺酸(PFOS)作为一种新型持久性有机污染物,目前国内外对其生态毒性研究主要集中在水环境领域,而高等植物的生态毒性数据尚不完善。因此,本研究采用内培养方式,选取小麦、大麦、小白菜、三叶草、绿豆作为供试植物,利用根伸长、芽伸长、地上部分生物量等评价指标,研究了PFOS短期暴露对不同供试作物苗期生长的影响,建立了PFOS和作物苗期生长的剂量-效应关系,并对不同的评价指标进行相关性分析,筛选出表征PFOS生态毒性的敏感植物。结果表明,不同供试作物培育3 d后,PFOS对其于不同毒性终点的最小EC₅₀值为：小麦352 mg·kg^-1(根伸长)、大麦434 mg·kg^-1(根伸长)、三叶草794 mg·kg^-1(地上部分生物量鲜重)、小白菜829 mg·kg^-1(地上部分生物量鲜重)、绿豆>1 000 mg·kg^-1,因此敏感程度依次为：小麦>大麦>三叶草>小白菜>绿豆。须根系作物小麦、大麦较直根系作物三叶草、小白菜和绿豆敏感,而须根系作物各评价指标的敏感程度依次为：根伸长>地上部分生物量鲜重>芽伸长>地上部分生物量干重,可见小麦的根伸长对PFOS污染最为敏感。各评价指标间均呈正相关关系,表明PFOS对同种植物的不同评价指标影响趋势一致。     

酚类化合物短期暴露对小麦和大麦苗期根伸长的影响

采用小麦和大麦为受试作物,以其在受试化合物污染的土壤中培育3 d后获得的根伸长的半数抑制浓度(IC50)评价了12种酚类化合物的毒性效应。结果表明,在所设浓度范围内,酚类对作物根伸长均存在剂量-效应关系。小麦对受试酚类的IC50范围为:12.92~231.76 mg·kg-1,其中邻苯二酚只在最高浓度500 mg·kg-1时对小麦的毒性效应显著。大麦对受试化合物的IC50范围为:7.15~478.31 mg·kg-1。小麦对3-甲基酚、双酚A、2-萘酚和壬基酚相对敏感,而其它8种化合物则是大麦相对更敏感。酚类化合物对小麦和大麦的毒性强度整体趋势一致。     

Bioconcentration and Phytotoxicity of Cd in Eichhornia crassipes

Plants of Eichhornia crassipes grown at various levels of cadmium ranging from 0.1 to 100 μg ml⁻¹ accumulated Cd in a concentration and duration dependent manner. At all levels, Cd accumulation by various plant tissues followed the order roots shoot leaves. Approximately 80% of total Cd was accumulated by plant at highest concentration (100 μg ml⁻¹) used in the experiment. Cadmium induced phytotoxicity appears at 25.0 μg ml⁻¹ resulting into reduced levels of chlorophyll, protein and in vivo nitrate reductase activity of the plant. However, a slight induction of these physiological variables was obtained at lowest Cd (0.1 μg ml⁻¹) concentration. In contrast, carotenoid content increased at highest Cd concentration i.e., 100 μg ml⁻¹. Similar effects at low and high levels of Cd was obtained with respect to mitotic index and micronuclei in root meristem of the plant. It could be inferred that Cd toxicity in plant is differential depending upon the low and high concentration of Cd in the medium.     

Biogeochemical characteristics of natural and technogenic ecosystems of the southern Baikal region

The distribution of chemical elements in plants was studied in natural and technogenic ecosystems of the southern Baikal region. Basic statistical parameters characterizing the contents of a wide range of elements in different soil horizons and plants of the region and the “world land” (average for all the continents) were compared. On the basis of data on the distribution of chemical elements in the soil-plant system, groups of elements differing in the coeffient of biological absorption (C _b) were distinguished. Evidence of antagonism between the main biophilous elements and heavy metals accumulating in plants was obtained. Interrelations of K and Na, which play an important role in the regulation of osmotic processes in plants, were analyzed. The phenomenon of potassium replacement by sodium in plants of technogenic ecosystems may serve as a criterion for assessing the phytotoxicity and environmental quality.