氧化胁迫对沉水植物黑藻抗冷力的影响

以3种不同质量浓度的H2O2分别对沉水植物黑藻做3种不同程度的氧化胁迫预处理,再经冷胁迫后测定黑藻顶枝的膜脂过氧化程度(MDA含量)、细胞抗氧化酶(SOD,CAT)活性.结果发现低浓度氧化胁迫预处理(0.06mmol/L的H2O2浸泡4或6 h预处理组)的黑藻经冷胁迫处理后,成活率不降低,其膜脂过氧化程度和细胞抗氧化酶的活性还有提高;而经中、高浓度氧化胁迫预处理(0.60mmol/L的H2O2浸泡6和12 h预处理组或1.00mmol/L的H2O2浸泡4,6和12 h预处理组)后的黑藻在冷胁迫处理后的结果则相反.因此,沉水植物黑藻对氧化胁迫感知并做出反应的机制(氧化应激机制),在其对低温反应和适应过程中起着很重要的调节作用.建议早春时节在进行水生植物恢复过程中可采用适宜浓度的H2O2预处理植株,以提高植株的适应性和保持成活率,进一步提高水生植物恢复的效率和效果.     

镉胁迫下植物的应答和调控

镉对植物引起的氧化胁迫是Cd毒害的重要原因之一.本文综述了Cd诱导植物氧化胁迫效应的机理以及植物对Cd氧化胁迫的相应防御反应,如抗氧化物质、抗氧化保护酶系统等,并介绍了缓解Cd诱导的氧化胁迫的机理和途径.     

不同重金属在烤烟中的累积分配特征研究

研究了重金属Hg、As、Pb在烤烟中的累积分布。结果表明：烤烟对Hg、As、Pb的耐受力较强；Hg抑制K326根系的生长，Pb、As对K326的生长有一定的促进作用。随着重金属浓度的增加，各部位重金属含量和烟株累积总量多呈增加趋势。在不同的处理下，3种重金属的含量在根系中最高；在相同的处理下，重金属在烟叶各部位的含量按大小顺序均为下部叶〉中部叶〉上部叶。随着处理浓度的增加，分配在根系中的重金属元素的比例不断增加，而在叶片中的分配比例不断降低；按重金属元素在叶片中的分配比例排序为Hg〉As〉Pb。     

Determination of total arsenic by photo-decomposition of organoarsenic compounds and hydride generation electrothermal atomic absorption spectrometry

A method was developed for the determination of total arsenic concentration in less than ng/ml level by decomposition of organoarsenicals using photo -oxidation combined with in situ trapping of arsenic hydride on a palladium coated graphite tube with subsequent atomization and detection by AAS. The organoarsenicals include monomethylarsenic, dimethylarsenic, arsenobetaine, arsenocholine, o -aminobenzenarsenate and p -aminobenzenarsenate. The method is simple and sensitive. Detection limit was obtained from different arsenic compounds over the range from 0. 058 to 0.063 ng/ml as As (based on three times of the standard deviation of 10 blank measurements) and the relative standard deviations for ten replicate measurements were from 2.0 to 3.8%. The calibration curves of arsenic compounds including inorganic and organic arsenicals were linear over the range from 0.1 to 3.0 ng/ml as As. The recommended method has been applied to the determination of total arsenic in tap and lake water samples at ng/ml leve     

大型圆形储水池池壁竖向裂缝成因的探讨

大型圆形贮水池如不设变形缝则普遍存在着池壁竖向产生裂缝的现象 ,本文结合一实例分析池壁产生裂缝的原因 ,提出设计时应当注意的问题和可采取的相应措施。     

土壤含水量对三种阔叶树苗气体交换及生物量分配的影响

在温室内用盆栽法研究了土壤含水量对茶条槭、山梨和山桃的气体交换及生物量分配的影响,设置4种土壤水分处理(土壤相对含水量75．0％、61．1％、46．4％和35．4％)．结果表明：随土壤含水量降低，3树种苗木净光合速率、蒸腾速率和气孔导度均下降，土壤含水量最低时，茶条槭苗木各生理指标降低幅度最大，山梨和山桃次之．茶条槭和山梨水分利用效率(WUE)随土壤含水量的减少呈降低趋势，山桃WUE呈升高趋势．水分胁迫下，3树种苗木根分配生物量显著增加．茶条槭在水分胁迫下，根冠比增加幅度最大，山梨次之，山桃最小．此外，茶条槭叶形态可塑性强，随土壤含水量降低，茶条槭单叶叶面积和总叶面积显著减小，叶厚度增加．山梨和山桃在水分胁迫下单叶叶面积及总叶面积无显著变化．综合3树种苗木在水分胁迫下的生理和形态指标及生物量分配的变化，茶条槭和山桃对水分胁迫的适应能力强于山梨．表4参31     

Environmentally stratified sampling design for the development of Great Lakes environmental indicators

Understanding the relationship between human disturbance and ecological response is essential to the process of indicator development. For large-scale observational studies, sites should be selected across gradients of anthropogenic stress, but such gradients are often unknown for a population of sites prior to site selection. Stress data available from public sources can be used in a geographic information system (GIS) to partially characterize environmental conditions for large geographic areas without visiting the sites. We divided the U.S. Great Lakes coastal region into 762 units consisting of a shoreline reach and drainage-shed and then summarized over 200 environmental variables in seven categories for the units using a GIS. Redundancy within the categories of environmental variables was reduced using principal components analysis. Environmental strata were generated from cluster analysis using principal component scores as input. To protect against site selection bias, sites were selected in random order from clusters. The site selection process allowed us to exclude sites that were inaccessible and was shown to successfully distribute sites across the range of environmental variation in our GIS data. This design has broad applicability when the goal is to develop ecological indicators using observational data from large-scale surveys.     

Metal Levels in Raccoon Tissues: Differences On and Off the Department of Energy's Savannah River Site in South Carolina

Levels of arsenic, cadmium, chromium, copper, lead, manganese, selenium, and strontium⁸⁸ were examined in heart, kidney, muscle, spleen and liver of raccoons (Procyon lotor) from four areas on the Department of Energy's Savannah River Site (SRS), including near a former reactor cooling reservoir and a coal ash basin, and from public hunting areas within 15 km of the site. Mercury is mentioned briefly because it is discussed more fully in another paper. We test the hypotheses that there are no differences in metal levels between raccoons on SRS and off the SRS (off-site), and among different locations on the SRS. Although raccoons collected off-site had significantly lower levels of mercury and selenium in both the liver and kidney, there were few consistencies otherwise. There were significantly higher levels of cadmium in liver of on-site compared to off-site raccoons, and significantly higher levels of chromium and strontium⁸⁸ in kidney of on-site compared to off-site raccoons. Copper and manganese were highest in the liver; cadmium, lead, mercury and selenium were highest in the liver and kidney; chromium was highest in the spleen and muscle; arsenic was highest in the heart, and strontium⁸⁸ was slightly higher in the kidney than other organs. Where there were significant differences on site, chromium, manganese were highest in raccoon tissues from Steel Creek; arsenic, lead and selenium were highest in the Ash Basin; cadmium was highest at Upper Three Runs; and strontium⁸⁸ was highest at Upper Three Runs and Steel Creek. The patterns were far from consistent.     

Impact of Pollution Caused by Uranium Production on Soil Macrofauna

Thirty years of mining and milling activities of the Priargunsky Mining-Chemical Production Company (South-Eastern Siberia, Russia) have resulted in an enrichment of uranium in adjacent steppe soils by a factor of up to 600. A number of attendant pollutants (thorium, arsenic and heavy metals) also have high concentrations in the soil. To estimate the effects of this pollution on soil-living macroinvertebrates, pitfall trapping and core sampling were applied. The element composition of four beetle species was analysed. Soil macroinvertebrates had 3–37 times lower abundance and biodiversity at the contaminated sites compared with the control. Ground beetle communities at the contaminated sites were reduced compared to the control site. The concentrations of uranium and arsenic in beetles collected at the contaminated sites were 2–41 and 2–26 times higher, respectively, than at the control site. There is strong evidence that the contamination caused by uranium production has severe negative biological effects on important groups of the soil food web.     

加热砷锑钼蓝杂多酸光度法测定水中痕量砷

本文采用单纯形最优化法探讨了加热显色砷锑钼蓝杂多酸的最佳条件，砷锑钼蓝杂多酸的最大吸收波长位于６９０ｎｍ，砷在０～５μｇ／２５ｍｌ范围内符合比耳定祁。方法灵敏、准确与简便，应用于水样痕量测的测定，结果满意．