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31.
Numerous studies support that biodiversity predict most to ecosystem functioning, but whether other factors display a more significant direct impact on ecosystem functioning than biodiversity remains to be studied. We investigated 398 samples of the phytoplankton phosphorus resource use efficiency (RUEP = chlorophyll-a concentration/dissolved phosphate) across two seasons in nine plateau lakes in Yunnan Province, China. We identified the main contributors to phytoplankton RUEP and analyzed their potential influences on RUEP at different lake trophic states. The results showed that total nitrogen (TN) contributed the most to RUEP among the nine lakes, whereas community turnover (measured as community dissimilarity) explained the most to RUEP variation across the two seasons. Moreover, TN also influenced RUEP by affecting biodiversity. Species richness (SR), functional attribute diversity (FAD2), and dendrogram-based functional diversity (FDc) were positively correlated with RUEP in both seasons, while evenness was negatively correlated with RUEP at the end of the rainy season. We also found that the effects of biodiversity and turnover on RUEP depended on the lake trophic states. SR and FAD2 were positively correlated with RUEP in all three trophic states. Evenness showed a negative correlation with RUEP at the eutrophic and oligotrophic levels, but a positive correlation at the mesotrophic level. Turnover had a negative influence on RUEP at the eutrophic level, but a positive influence at the mesotrophic and oligotrophic levels. Overall, our results suggested that multiple factors and nutrient states need to be considered when the ecosystem functioning predictors and the biodiversity-ecosystem functioning relationships are investigated. 相似文献
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Zhe Feng Lin Zeng Qingle Zhang Shifeng Ge Xinyue Zhao Hongjun Lin Yiming He 《环境科学学报(英文版)》2020,32(1):149-162
A graphite carbon nitride(g-C_3N_4) modified Bi_4O_5I_2 composite was successfully prepared insitu via the thermal treatment of a g-C_3N_4/Bi OI precursor at 400°C for 3 hr.The as-prepared g-C_3N_4/Bi_4O_5I_2 showed high photocatalytic performance in Methyl Orange(MO) degradation under visible light.The best sample presented a degradation rate of 0.164 min~(-1),which is 3.2 and 82 times as high as that of Bi_4O_5I_2 and g-C_3N_4,respectively.The g-C_3N_4/Bi_4O_5I_2 was characterized by X-ray powder diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman,X-ray photoelectron spectroscopy(XPS),ultraviolet-visible diffuse reflectance spectra(DRS),electrochemical impedance spectroscopy(EIS) and transient photocurrent response in order to explain the enhanced photoactivity.Results indicated that the decoration with a small amount of g-C_3N_4 influenced the specific surface area only slightly.Nevertheless,the capability for absorbing visible light was improved measurably,which was beneficial to the MO degradation.On top of that,a strong interaction between g-C_3N_4 and Bi_4O_5I_2 was detected.This interplay promoted the formation of a favorable heterojunction structure and thereby enhanced the charge separation.Thus,the g-C_3N_4/Bi_4O_5I_2 composite presented greater charge separation efficiency and much better photocatalytic performance than Bi_4O_5I_2.Additionally,g-C_3N_4/Bi_4O_5I_2 also presented high stability.·O_2~-and holes were verified to be the main reactive species. 相似文献
34.
农业生态环境中的锰元素 总被引:14,自引:0,他引:14
论述了锰元素的地球化学特征和分布,农作物与锰元素的关系以及锰元素有效态含量的制约因素:土壤的含量、土壤的酸碱度、土壤的氧化还原环境、土壤的有机质含量。 相似文献
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Investigation on Cr( Ⅵ ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) canbe effectively reduced to Cr( Ⅲ ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr( Ⅵ ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of calls inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43. 76% and 28.86% respectively. The optimum pH for Cr( Ⅵ ) reduction was ?.0, with reduction efficiency of 61.71 % being achieved. With the increase of initial Cr(Ⅵ) concentration,the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr( Ⅵ ) reduction also increased. The mechanism of Cr( Ⅵ ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr (Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr( Ⅲ ) was not precipitated in the form of Cr(OH)3. 相似文献
37.
二段生物接触氧化法处理城市污水评析 总被引:1,自引:0,他引:1
介绍了二段生物接触氧化法的构成、特点、运行情况、脱氮除磷效果及生物填料的选择,并进行了技术经济分析,最后总结了该工艺在城市污水处理厂中的应用情况. 相似文献
38.
A mathematical model relating to the change in phytoplankton biomass in the period of growth and nutrient concentration in the media was proposed on the basis of the Monod equation and was testified by simulation experiments. Analysis of the experiment data showed that: the half-saturation constants for growth Kp (μmol/L) for Skeletonema, Chaetoceros and Prorocentrum were 5.52, 1.90 and 0.46, respectively; the balance between stimulation of nutrients and the inhibition of some other materials was found in the effect of domestic sewage on algal growth and the stimulation played a leading role; domestic sewage was more stimulative on dinoflag-ellate than on diatom and chlorophyte when the assemblage of the algae was cultured. The experiment suggested that mathematical model reasonably explained the characteristics of phytoplankton growth in different nutrient conditions and was worthy to be further improved for eutrophication prediction in off-shore water. 相似文献
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综观我国环保和世界各国环保对计算机的应用 ,环境保护计算机化的发展趋势 ,对环保的计算机化水平要求及前景提出了积极的见解。 相似文献