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排序方式: 共有599条查询结果,搜索用时 406 毫秒
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氮对镉胁迫下东南景天根系形态及镉积累的影响 总被引:3,自引:0,他引:3
通过水培试验,研究了供氮(尿素)对镉胁迫下两种生态型东南景天根系形态及镉积累的影响.实验结果表明,当供氮水平为4~16 mmol/L时,能明显促进东南景天的根系生长;当供氮水平为32~64 mmol/L时,与对照相比,东南景天的根系长度、根系表面积和根系体积等指标明显受到抑制.不同供氮水平对两种生态型东南景天0<D≤0.2 mm的根系生长影响最大,而对D>0.2 mm的根系影响较小.不同供氮水平下,两种生态型东南景天均以0<D≤0.4 mm的根系为主,其中根系长度、根系表面积和根系体积分别占总根系长度、总根系表面积和总根系体积的66.3%~81.2%、68.5%~80.3%和62.1%~79.8%.氮素对东南景天的镉积累有一定的促进作用,随着氮素用量的增加,镉积累逐渐升高,与根系形态不同的是,镉积累量在供氮水平为32 mmol/L 时达到最大.适当提高营养液氮素用量有利于提高东南景天的各项根系形态指标和镉积累量. 相似文献
594.
根据2005年水质监测结果,对水磨河无机氮的特征分布及相互之间的相关性进行了初步分析探讨,结果显示,水磨河无机氮中硝酸盐氮含量最高,亚硝酸盐氮含量最低,亚硝酸盐氮与氨氮之间有非常显著的线性关系.通过对1991-2005年的监测资料分析,表明水磨河各断面无机氮含量呈下降趋势,但水磨河自上而下无机营养盐N总体浓度升高,说明氮污染还在延续,形势不容乐观. 相似文献
595.
被动式吸收采样监测空气中二氧化硫、二氧化氮主要影响因素探讨 总被引:3,自引:0,他引:3
论述了关于被动式吸收采样法用于监测环境空气中的二氧化硫、二氧化氮的影响因素,包括风向、风速、温度、湿度、吸收液种类及浓度、吸收液加入方式等;提出在四季温差较大地区,监测结果的计算中需引入温度校正系数;建议采样时间以2~3周为宜。 相似文献
596.
The arsenate(As(V)) biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen(N) and phosphorus(P) has been studied under laboratory conditions. When 15 μg/L As(V) was added, N and P in the medium showed effective regulation on arsenic(As) metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration(4–20 mg/L) significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid(DMA), the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell.However, As(V) uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As(V) transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As(V) biotransformation processes. 相似文献
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598.
Xiang Zhang Yue Xuan Bin Wang Chuan Gao Shengli Niu Gaiju Zhao Dong Wang Junhua Li Chunmei Lu John C. Crittenden 《Frontiers of Environmental Science & Engineering》2022,16(7):88
599.
Research on biofuel production pathways from algae continues because among other potential advantages they avoid key consequential effects of terrestrial oil crops, such as competition for cropland. However, the economics, energetic balance, and climate change emissions from algal biofuels pathways do not always show great potential, due in part to high fertilizer demand. Nutrient recycling from algal biomass residue is likely to be essential for reducing the environmental impacts and cost associated with algae-derived fuels. After a review of available technologies, anaerobic digestion (AD) and hydrothermal liquefaction (HTL) were selected and compared on their nutrient recycling and energy recovery potential for lipid-extracted algal biomass using the microalgae strain Scenedesmus dimorphus. For 1 kg (dry weight) of algae cultivated in an open raceway pond, 40.7 g N and 3.8 g P can be recycled through AD, while 26.0 g N and 6.8 g P can be recycled through HTL. In terms of energy production, 2.49 MJ heat and 2.61 MJ electricity are generated from AD biogas combustion to meet production system demands, while 3.30 MJ heat and 0.95 MJ electricity from HTL products are generated and used within the production system.Assuming recycled nutrient products from AD or HTL technologies displace demand for synthetic fertilizers, and energy products displace natural gas and electricity, the life cycle greenhouse gas reduction achieved by adding AD to the simulated algal oil production system is between 622 and 808 g carbon dioxide equivalent (CO2e)/kg biomass depending on substitution assumptions, while the life cycle GHG reduction achieved by HTL is between 513 and 535 g CO2e/kg biomass depending on substitution assumptions. Based on the effectiveness of nutrient recycling and energy recovery, as well as technology maturity, AD appears to perform better than HTL as a nutrient and energy recycling technology in algae oil production systems. 相似文献