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341.
Jingjing Jiang Jiaying Gao Shu Niu Xingyue Wang Tianren Li Shengda Liu Yanhong Lin Tengfeng Xie Shuangshi Dong 《环境科学学报(英文版)》2021,33(8):147-160
The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH. The obtained Bi2WO6/CuFe2O4 exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H2O2, thereby generating abundant ?OH for pollutant oxidation. Various environmental factors including H2O2 concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that ?O2? and ?OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation. 相似文献
342.
343.
The highly e cient inorganic polymer flocculants (IPFs) of the ferric-silica system is a new and promising coagulant. Interactions
between ferric species and silica play a large part in the coagulation of suspensions. These e ects are quite distinct from those associated
with polymeric or colloid silica. However, although these species are key to coagulation e ciency, they have not been comprehensively
discussed. A new type of coagulant, poly-silica-ferric-chloride (PFSC), was synthesized by co-polymerization and characterized by
time complexation spectroscopy and photon correlation spectroscopy. Compared with traditional ferric salt, the results indicated that
PFSC had a higher molecular weight, lesser positive charge, lower Feb and higher Fec. The higher the Si/Fe ratio, the higher the silica
and lower the silicac found. The PFSC with appropriate polysilica acid not only obtained better coagulation/flocculation e ciency in
turbidity removal, enhanced the flocculation index (FI) and provided less residual ferric, it also lowered water treatment costs compared
to traditional ferric salt. Results showed that PFSC could remove colloid particles in water by charge neutralization and sweeping,
adsorption bridging mechanism. 相似文献
344.
以北京油松(Pinus tabuliformis)人工林为研究对象,采用独立样本T检验、冗余分析等方法,分析重度火烧1年后林下植被(灌木层和草本层)的物种多样性、叶功能性状及其与土壤因子的关系.结果显示:(1)与对照样地相比,重度火烧后灌木层物种丰富度指数极显著降低(P <0.01),但Shannon指数、Simpson指数以及Pielou指数虽呈下降趋势但未达显著水平(P> 0.05);草本层除Pielou指数外,各物种多样性指数均显著增加(P <0.05).(2)重度火烧样地灌木层和草本层的叶厚度(LT)、叶干物质含量(LDMC)、叶碳含量(LCC)、叶磷含量(LPC)均高于对照样地,而比叶面积(SLA)、叶氮含量(LNC)、叶片氮磷比(N:P)、叶绿素含量(CHL)低于对照样地,除灌木层LPC和N:P及草本层SLA、LCC和LPC外,其他各叶功能性状在火烧与对照间差异均达显著水平.对于不同生活型而言,对照样地的LDMC、LNC、LCC、CHL存在显著差异,而在重度火烧后差异不显著;LT、SLA在重度火烧和对照样地上均呈现显著差异;而LPC、N:P在重度火烧与对照样地上均无显著差异.(3)重度火烧后1年,灌木层和草本层的叶功能性状均仅与土壤含水率、容重和非毛管孔隙度密切相关.本研究表明在油松人工林重度火烧后1年,灌木层物种多样性降低,而草本层物种多样性增加,灌草层的各叶功能性状主要受土壤物理性质的影响呈现不同的变化规律.(图4参45) 相似文献
345.
The spread of invasive species is a major ecological and economic problem. Dynamic spread modelling is a potentially valuable tool to assist regional and central government authorities to monitor and control invasive species. To date a lack of suitable data has meant that most broad scale dispersal models have not been validated with independent datasets, and so their predictive ability and reliability has remained unscrutinised. A dynamic, stochastic dispersal model of the widely invasive plant Buddleja davidii was calibrated on European spread data and then used to project the temporal progression of B. davidii's distribution in New Zealand, starting from several different historical distributions. To assess the model's performance, we constructed an occupancy map based on the average number of simulation realisations that have a population present. The application of Receiver Operating Characteristic (ROC) curves to occupancy maps is introduced, but with specificity substituted by the proportion of available area used in a realisation. A derivative measure, the partial area under these curves when assessed through time (pAUC), is introduced and used to assess overall performance of the spread model. The model was able to attain a high level of model sensitivity, encompassing all of the known locations within the occupancy envelope. However, attempting to simulate the spread of this invasive species beyond a decade had very low model specificity. This is due to several factors, including the exponential process of spread (the further a population spreads the more sites exist from which it can spread stochastically), and the Markovian chain property of the stochastic system whereby differences between realisations compound through time. These features are seen in many reports of spread models, without being explicitly acknowledged. Our measure of pAUC through time allows a model's temporal performance and its specificity to be simultaneously assessed. While the rapid deterioration in model performance limits the utility of this type of modelling for forecasting long-term broad-scale strategic management of biological invasions, it does not necessarily limit its attractiveness for informing smaller scale and shorter term invasion management activities such as surveillance, containment and local eradication. 相似文献
346.
Increasingly intensive strategies to maintain biodiversity and ecosystem function are being deployed in response to global anthropogenic threats, including intentionally introducing and eradicating species via assisted migration, rewilding, biological control, invasive species eradications, and gene drives. These actions are highly contentious because of their potential for unintended consequences. We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. To evaluate conservation outcomes, we developed a community assessment framework for systematically mapping the range of possible interaction types for 111 case studies. Applying this tool, we quantified the number of interaction types considered in each study and documented the nature and strength of intended and unintended outcomes. Intended outcomes were reported in 51% of cases, a combination of intended outcomes and unintended outcomes in 26%, and strictly unintended outcomes in 10%. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs. unintended effects), some unintended effects were fairly innocuous relative to the conservation objective, whereas others resulted in serious unintended consequences in recipient communities. Studies that assessed a greater number of community interactions with the target species reported unintended outcomes more often, suggesting that unintended consequences may be underreported due to insufficient vetting. Most reported unintended outcomes arose from direct effects (68%) or simple density-mediated or indirect effects (25%) linked to the target species. Only a few documented cases arose from more complex interaction pathways (7%). Therefore, most unintended outcomes involved simple interactions that could be predicted and mitigated through more formal vetting. Our community assessment framework provides a tool for screening future conservation actions by mapping the recipient community interaction web to identify and mitigate unintended outcomes from intentional species introductions and eradications for conservation. 相似文献
347.
To protect the ecosystem of barren mountains, massive Cupressus funebris plantations were allowed in hilly areas of the central Sichuan Basin in the late 1980s. In recent years, Cupressus funebris plantations have faced problems such as biodiversity decline and soil erosion. To study the effects of different forest densities on understory species diversity and soil anti-scourability of Cupressus funebris plantations in Yunding Mountain, a typical sampling method was used to investigate the five different forest densities (1 100, 950, 800, 650, and 500 trees/hm2) and to analyze the correlation between the species diversity index, soil anti-scourability, and root index. In total, 176 species from 128 genera and 69 families were recorded in this area. The number of species in the herb layer was higher than that in the shrub layer. The species diversity index of the shrub layer first increased and then decreased with the decrease in stand density; and the species richness index D and Shannon–Wiener diversity index H showed peak values at a density of 650 trees/hm2. The species richness index D, Shannon–Wiener diversity index H, and Simpson dominance index H’ in the herb layer showed a bimodal trend of increasing, then decreasing, increasing again, and finally decreasing with the decrease in stand density; and the peak values were found at the densities of 650 and 950 trees/hm2. When soil anti-scourability decreased with stand density, it showed a trend of increasing and then decreasing, reaching a peak at a density of 650 trees/hm2. The positive correlation between the species richness index and soil anti-scourability was evident. Thus, 650 trees/hm2 is relatively more conducive to the stability of species diversity and soil anti-scourability in cypress plantations. © 2022 Authors. All rights reserved. 相似文献
348.
Hasti Daraei Kimia Toolabian Ian Thompson Guanglei Qiu 《Frontiers of Environmental Science & Engineering》2022,16(2):19
349.
Shengqi Zhang Chengsong Ye Wenjun Zhao Lili An Xin Yu Lei Zhang Hongjie Sun Mingbao Feng 《Frontiers of Environmental Science & Engineering》2022,16(7):93
350.
2015年8月,对秦山岛周边的10个站位进行大型底栖动物定量调查。采用生物多样性指数法和丰度生物量比较法对大型底栖动物群落健康状况进行评价。结果显示,共鉴定大型底栖动物7大类31种,其中软体动物、环节动物各10种,节肢动物5种,脊索动物和棘皮动物各2种,纽虫类和腔肠动物各1种;密度优势类群为软体动物,占总密度的35.00%,生物量优势类群为脊索动物,占总生物量的49.35%;优势种分别为红狼牙虾虎鱼(Odontamblyopus rubicundus)、棘刺锚参(Protankyra bidentata)、内卷原盒螺(Eocylichna involuta)和微角齿口螺(Odostomia subangulata)。大型底栖动物密度为站位St.6最大,为115 ind./m2,St.2最小,为20 ind./m2,平均值为70 ind./m2;生物量St.3最大,为197.25 g/m2,St.9最小,为2.56 g/m2,平均值为54.04 g/m2。秦山岛受污染压力、人为活动干扰和生境限制能因素影响,多样性偏低,优势种为耐污的软体动物、脊索动物和棘皮动物,但其主要为K对策种类,大型底栖动物群落受到了轻度干扰,但群落结构仍较为稳定。 相似文献