Uranium Accumulation of Crop Plants Enhanced by Citric Acid

Citric acid was applied to soil to enhance U accumulation in four crop plants. While the highest enhanced U accumulation of aboveground tissues (a.c. 2000 mg kg⁻¹ dry weight) occurred in the leaves of Indian mustard (Brassica juncea), the highest enhanced U accumulation of roots (a.c. 3500 mg kg⁻¹ dry weight) occurred in canola (Brassica napus var. napus). Uranium translocation among tissues of test plants is in the relation of roots>shoots ≅ leaves. The flowers of sunflower (Helianthus annuus) contained similar or higher U concentrations than those found in shoots, but concentrations in seeds are close to zero. In conclusion, Indian mustard is recommended as a potential species for phytoextraction for U-contaminated soil due to its high U accumulation of aboveground biomass (a.c. 2200 μg per plant). There is no evidence that two types of soils cause a significant difference of the enhanced U accumulation (p<0.05). Results, however, indicate that additional citric acid may result in downward U migration that may contaminate groundwater. Speciation of U that is taken up by plants is also discussed in the end.     

Blooms of the dinoflagellate Gyrodinium aureolum in a Long Island estuary:

A dense dinoflagellate bloom of Gyrodinium aureolum Hulburt in a shallow temperate zone estuary was monitored during the summers of 1982 and 1983. The bloom was typically extremely localized, its densest part exceeding 1000g chlorophyll a liter^-1 (2x10⁴ cells ml^-1). The bloom began at temperatures between 24.5° and 27°C, existed at as high as 30°C and terminated when water temperature dropped to between 19° and 22°C. The highest specific growth rate measured was 0.90d^-1 (1.3 divisions d^-1) and near the termination of the bloom decreased to 0.28d^-1 (0.4 divisions d^-1). A diel vertical migration of the bloom was observed. A box model analysis, based on division rates, vertical migration and water circulation patterns, indicated that the bloom must move downward at the estuary mouth to maintain itself in the estuary, either by means of a convergence system or by downward swimming. High growth rate, low grazing pressure, and a stratified water column are proposed to stimulate bloom formation. Decreasing growth rate appeared to reduce the intensity of the bloom and finally allowed its disappearance by estuarine flushing and mixing.Communicated by J. M. Shick, Orono     

纳米颗粒与植物相互作用的研究热点和演变趋势分析——基于CiteSpace和VOSviewer的知识图谱方法

纳米颗粒(nanoparticles, NPs)具有独特的表面效应、小尺寸效应、量子效应和宏观量子隧穿效应,对于促进农业科学、食品科学、纳米科技和生物医学等领域的发展具有重要意义。因此,亟待对国内外近20年来的有关NPs与植物相互作用的研究进行总结和梳理,为植物生产和纳米科技的协同发展提供理论依据。本研究以Web of Science (WOS)核心合集数据库和中国知网(CNKI)全文数据库为数据检索源,借助CiteSpace和VOSviewer文献计量工具,对2000—2022年NPs与植物相互作用领域的相关文献进行知识图谱的可视化分析。结果表明,在2000—2022年间,国内外对NPs与植物相互作用方面的研究呈J型增长,目前处于快速增长阶段,且英文文献的发文量和年增长率均显著高于中文文献(P<0.05)。国际对该领域的关注度和研究要早于国内,并且我国在NPs与植物相互作用领域的研究对全球贡献较大(排名第二),但有影响力的研究较为缺乏,亟待进一步提高。在NPs种类上,国内外关注较多的是纳米银、纳米金、纳米氧化锌和纳米氧化铜;在植物种类上,玉米和水稻的研究较多。由国际合作关系比较可知,国内学者大部分为独立作者,合作关系较为松散。关键词提取和时空突现分析表明,未来的研究热点主要集中在以下3个方面：(1)NPs对植物的负面效应及其生态环境安全的风险评估;(2)NPs对植物的正面效应及纳米颗粒毒性的降低,使之更好地用于农业生产活动中;(3)植物介导NPs的绿色合成,从而促进纳米技术的发展。     

利用生物标记物综合指数评价煤矿区水体沉积物污染及其因果关系分析

煤矿区废水渗漏是下游沉积物中重金属的主要来源之一,持久影响着周边水生态健康。本研究以重庆市某煤矿区周边水系为研究区域,利用内梅罗综合污染指数(P_综合)和污染负荷指数(PLI)分析沉积物中重金属污染程度及其主要污染因子。以当地大量养殖的美国青蛙(Rana grylio)蝌蚪为试验动物,通过筛选生物标记物,利用生物标记物综合指数(IBRv2)指示沉积物重金属复合污染程度及其生态毒性效应,并分析其因果关系。结果显示,该煤矿废水渗漏导致周边水域沉积物中Zn、Cu、Cr、Ni、Mn含量显著提高,且以Cu、Zn为主。与对照组比较,3个样地沉积物重金属污染对蝌蚪超氧化物歧化酶活性、总抗氧化能力、丙二醛和谷胱甘肽含量、微核率影响显著(P<0.05),IBRv2与P_综合和PLI显著相关。结果表明,IBRv2法能够很好地反映出煤矿区下游沉积物重金属综合污染程度及其对受试生物的生态毒性效应,且明确了二者之间具有直接的因果关系,导致综合生物效应的主要化学污染因子为Cu、Zn、Cr。同时,表明了该煤矿区主要污染来源于洗煤厂区域的废水排放。本研究可为煤矿区水环境污染的生物监测技术开发与生物标记物优选提供数据支持。     

铁聚合反应速率研究

研究了聚合硫酸铁絮凝剂制备中亚铁的氧化反应速率.证明该速率对Fe2+,为零级.对NO2(g)为一级,因此提高气相中NO2的分压可大大缩短制备时间,     

A simple approach to modeling microbial biomass in the rhizosphere

Microorganisms make an important contribution to the degradation of contaminants in bioremediation as well as in phytoremediation. An accurate estimation of microbial concentrations in the soil would be valuable in predicting contaminant dissipation during various bioremediation processes. A simple modeling approach to quantify the microbial biomass in the rhizosphere was developed in this study. Experiments were conducted using field column lysimeters planted with Eastern gamagrass. The microbial biomass concentrations from the rhizosphere soil, bulk soil, and unplanted soil were monitored for six months using an incubation–fumigation method. The proposed model was applied to the field microbial biomass data and good correlation between simulated and experimental data was achieved. The results indicate that plants increase microbial concentrations in the soil by providing root exudates as growth substrates for microorganisms. Since plant roots are initially small and do not produce large quantities of exudates when first seeded, the addition of exogenous substrates may be needed to increase initial microbial concentrations at the start of phytoremediation projects.     

硅酸钙-壳聚糖聚合物制备及其对重金属废水的吸附特性

使用溶液共混法制备出硅酸钙-壳聚糖聚合物,同时采用FT-IR、XRD等方法对制备的硅酸钙-壳聚糖聚合物进行表征,并分别对壳聚糖、硅酸钙、硅酸钙-壳聚糖聚合物吸附去除重金属废水的特性进行了初步研究.结果表明,硅酸钙-壳聚糖聚合物在制备过程中晶型发生变化,结晶度降低;硅酸钙-壳聚糖聚合物对各重金属离子的吸附能力最强,其对Ni2+、Cu2+、Pb2+、Zn2+、Cr3+的最大吸附量分别为167.01、192.30、232.47、174.71、162.33 mg·g-1;重要的是,硅酸钙-壳聚糖聚合物可在酸性环境下更有效吸附去除废水中重金属离子.