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791.
多壁碳纳米管对水稻幼苗的植物毒性研究 总被引:1,自引:0,他引:1
考察了浓度为10、50和100 mg·L~(-1)的多壁碳纳米管(MWCNTs)的植物毒性,通过测量水稻生长指数、根系氧化应激反应、细胞膜损伤和生理功能的变化,探索了其具体的毒性机制。将水稻幼苗暴露于不同浓度的MWCNTs悬浮液中培养10 d后,高浓度处理组(100 mg·L~(-1))中水稻幼苗地上部分和根系鲜重分别降低至对照组的87.6%±1.1%和69.2%±7.8%。对根系深入研究发现氧化应激反应和细胞膜的损伤主要出现在高浓度处理组,此时过氧化氢酶(CAT)活性由对照组的(8.8±1.6)U·mg-1prot(protein,蛋白质)增加至(16.3±2.8)U·mg-1prot,丙二醛(MDA)含量由对照组的(8.0±0.3)μmol·g-1FW(fresh weight,鲜重)增加至(15.1±1.4)μmol·g-1FW。然而,水稻根系的生化酶活性在低浓度(10 mg·L~(-1))时就开始明显降低。通过透射电镜(TEM)观察发现,MWCNTs颗粒分布在水稻幼苗根系细胞内,从而证实了MWCNTs能被植物细胞吸收。 相似文献
792.
根据高阶振型对结构位移的贡献,提出基于多振型侧向力分布形式用于竖向不规则结构的静力非线性分析。通过静力非线性分析和动力时程分析结果的对比,验证了侧向力分布形式的准确性。为研究不规则程度对混合结构非线性行为和破坏模式的影响,改变混凝土框架的刚度和强度形成6个竖向不规则混合结构。通过对不规则混合结构层间能力系数的计算,初步判断混合结构刚度和强度的竖向不规则分布特征,评估可能存在的薄弱层和结构破坏模式。采用所提出的侧向力分布形式分别对结构模型进行静力非线性分析,得到混合结构模型的塑性铰开展特征和层间位移角分布,结果表明:混合结构刚度和强度的不规则程度直接影响结构非线性行为和破坏模式,较均匀的层间能力系数分布能够避免结构中出现明显的薄弱层,使结构破坏模式更加合理。 相似文献
793.
794.
High cadmium pollution risk on vegetable amaranth and a selection for pollution-safe cultivars to lower the risk 总被引:3,自引:0,他引:3
Yihui ZHOU Meng XUE Zhongyi YANG Yulian GONG Jiangang YUAN Chunyan ZHOU Baifei HUANG 《Frontiers of Environmental Science & Engineering》2013,7(2):219-230
A pot experiment was carried out by growing 29 different genotypes (Amaranthus spp.) of vegetable amaranth under low- (0.12 mg·kg-1) and middle- (0.40 mg·kg-1) cadmium (Cd) exposure. The result showed that amaranth was vulnerable to cadmium (Cd) contamination in soil. Variations of Cd concentrations in both roots and edible parts among genotypes were significant (P <0.001) in both treatments. Cd concentrations in edible parts of the tested genotypes grown under low- and middle-Cd levels were significantly correlated (p <0.01), implying that Cd-accumulating property of amaranth is genotype-dependent. Differences in Cd chemical forms between cv. Nanxingdayemashixian (cv. Nan), a selected typical pollution-safe cultivar (Cd-PSC), and cv. Pennongjianyexian (cv. Pen), a selected typical non-Cd-PSC, under different Cd exposure conditions were compared. It was found that the alternation of Cd in FNaCl (Cd form extracted by 1 mol·L-1 NaCl) may be a key factor in regulating Cd accumulation of different amaranth genotypes and that the protein-binding Cd is considered to be associated with Cd translocation. The results indicated that amaranth is capable of enduring high level of Cd pollution when grown as vegetable crop, and accordingly, consuming vegetable amaranth would bring high health risk. Therefore, adopting Cd-PSC strategy would help reducing the risk of Cd pollution in amaranth. In this study, cv. Nan was identified as a Cd-PSC and recommended to be applied production practice. 相似文献
795.
印染污泥特性及其掺煤焚烧处置的环境影响研究 总被引:1,自引:0,他引:1
对佛山6家印染厂污泥的基本性质和重金属污染进行了分析研究。结果表明:印染污泥有机质含量较高;对照农用污泥污染物限值和城镇污水处理污泥处置混合填埋用泥质标准,Cr、Ni、Cu、Zn不同程度超标,说明印染污泥既不能农用,也不能混合填埋。污泥浸出液中重金属浓度远低于危险废物浸出毒性限值和城镇污水处理厂污泥单独焚烧用泥质的污染物限值。污泥与煤掺混焚烧烟道气中二恶英浓度在0.0125~0.022 ngTEQ/Nm3,远低于GB 18485—2001《生活垃圾焚烧污染控制标准》限值和GB/T 24602—2009《城镇污水处理厂污泥处置单独焚烧用泥质》限值。 相似文献
796.
Zhaoxing HAN Zhenyao SHEN Yongwei GONG Qian HONG 《Frontiers of Environmental Science & Engineering》2011,5(1):119-129
Emission trading is one of the most effective alternatives to controlling water pollution. Water environmental functional zone (WEFZ) is used to determine the water quality standard and identify the zone boundary for each river or reach. In this study, a new emission trading scheme was addressed based on WEFZ, accounting for both the temporal dimension and water quality control. A temporal factor of emission trading was proposed based on variations in the environmental capacity within a year by dividing the year into three periods, including high, normal, and low periods of environmental capacity. During each period, emission trading was implemented exclusively. A water quality-control scheme was suggested based on the water quality requirement in the water functional zone, in which the water quality at the downstream boundary of the zone was required to meet the water standard following auto-purification in the stream. Two methods of calculating water quality control are addressed for point-source pollution and non-point-source pollution. The calculated temporal dimension and water quality control were located in Dongxi River of the Daning Watershed in the Three Gorges Watershed. The high period was during June, July, and August, the normal period was during April, May, September, and October, and the low period was during January, February, March, November, and December. The results from the water quality calculation demonstrated that the discharge of point-source and non-point-source pollutions led to an excess of common contaminants at the downstream boundary of WEFZ. The temporal and spatial factors above should be incorporated into the emission trading scheme based on WEFZ. 相似文献
797.
798.
Relationships between distributions of longevous population and trace elements in the agricultural ecosystem of Rugao County,Jiangsu, China 总被引:1,自引:0,他引:1
Huang B Zhao Y Sun W Yang R Gong Z Zou Z Ding F Su J 《Environmental geochemistry and health》2009,31(3):379-390
Soil, plant, and water, as well as trace elements they contain, can influence human health through the food chain. A survey
was conducted on distributions of trace elements in soils, plants, and drinking water in Rugao County, Jiangsu Province, China,
an agricultural area with a high level of centenarians and nonagenarians. The ratio of people over 90 years old per 100,000
inhabitants (90-rate) based on village (about 4,000 residents in 4 km2) was correlated with trace elements in soil, drinking water, and rice by means of correlation analysis and/or principal component
analysis. Although the average 90-rate in the whole area was as high as 277, the rates were not uniform across the entire
region. The 90-rate in the area of loamy and strongly-developed Anthrosols and Cambosols was about 330, significantly higher
than the 255 in the areas of sandy and strongly-developed Cambosols and of clayey and weakly-developed Cambosols. The concentrations
of available Se, B, Ni, and Mo in soils of the area with the high 90-rate were markedly greater than those in the area with
the low 90-rate. This was demonstrated by highly positive correlations between the 90-rate and available Se (r = 0.33), B (r = 0.21), Ni (r = 0.17) and Mo (r = 0.17) at the p < 0.01 level and high loadings of available Se (0.851), B (0.535), Ni (0.594) and Mo (0.394) in the longevous factor. Similar
relationships between the available elements in soils and elements in water and rice were found. These results suggest that:
(1) the available forms of elements in soil were more crucial to elemental bio-availability in the ecosystem and human health
than total elements in soil; and (2) the element association above might have affected the 90-rate positively and could be
an important environmental geochemical factor influencing the longevity of humans. 相似文献
799.
800.
为了解全氟辛烷磺酸盐(PFOS)对海洋贝类抗氧化防御系统的毒性效应及致毒机理,在实验室条件下研究了PFOS对翡翠贻贝的96h急性毒性,同时探讨PFOS胁迫和净水恢复过程中翡翠贻贝外套膜和内脏团组织中抗氧化指标(SOD活性、GSH和MDA含量)的变化。结果显示,PFOS对翡翠贻贝的96h半致死浓度(LC50)为68.3mg·L-1,安全浓度为6.83mg·L-1。在PFOS胁迫阶段,1mg·L-1浓度组外套膜SOD活性显著性升高(p<0.05),内脏团SOD酶活性显著降低(p<0.05);而PFOS浓度高于1mg·L-1时,外套膜SOD活性显著性降低(p<0.05),内脏团SOD活性显著升高(p<0.05)。PFOS胁迫对翡翠贻贝外套膜和内脏团中GSH含量均有显著的诱导作用(p<0.05),PFOS胁迫15d后各浓度组GSH含量均受到显著的抑制(p<0.05)。翡翠贻贝外套膜MDA含量受PFOS胁迫后显著升高(p<0.05),内脏团MDA含量的变化呈先降低、后升高的规律。净水释放阶段,翡翠贻贝两组织中SOD活性在释放7d后均恢复至对照组水平,GSH含量和MDA含量呈显著升高的趋势(p<0.05)。研究结果表明,PFOS暴露能够引起翡翠贻贝外套膜和内脏团氧化胁迫,但这种损伤的效果不明显,释放短时间后即可自我恢复。 相似文献