污泥处置方式对污水处理系统可持续性的影响

脱水污泥的污染问题影响了城市污水处理厂的生存和发展,不同的中水处置方式对经济和环境的影响也不一样.将污水处理、脱水污泥和中水处置结合起来构建污水处理生态系统有利于研究污水处理的综合效益、探索促进污水处理事业可持续发展的途径.在考虑废物处理处置和排放的影响基础上,提出了针对污水处理生态系统的改进的能值分析方法和指标体系,即能值产出率(WEYR)、环境负载率(WELR) 和可持续发展指标(WESI), 指标反映了资源消耗和废物排放对系统可持续性的影响.以明镜滩污水处理生态系统作为案例,评价了"污水处理系统 污泥填埋系统 中水排放"(方案1)、"污水处理系统 陶粒生产系统 中水排放"(方案2)、"污水处理系统 聚合材料生产系统 中水排放"(方案3)和"污水处理系统 好氧堆肥生产系统 中水排放"(方案4)等4种方案的可持续性.方案1、2、3和4的WEYR分别为1.65、3.84、3.95和3.63, WELR分别为5.19、5.41、7.69和4.24,WESI分别为0.32、0.71、0.51和0.86.方案1由于未对污泥进行资源化利用,其能值产出率远远低于其他3个方案,故可持续性最低;其他三个方案的能值产出率比较接近,但方案4的环境负载率远远低于其他2个方案,故方案4的可持续性最高.结果表明,污泥利用可提高污水处理生态系统的可持续性,而不同废物利用方式由于对不可更新资源的消耗不同对污水处理生态系统的可持续性影响不一样;改进的能值分析方法适合于评价污水处理生态系统的可持续性.     

聚丙烯酰胺对紫色土中磷素吸附特征的影响

通过等温吸附实验分别研究了特定磷质量浓度下系列PAM用量和系列磷质量浓度下特定PAM用量对磷素在土壤中吸附特征的影响.试验表明,土壤经过PAM处理后其对磷素的吸附性能发生了明显改变.施用PAM使紫色土磷的吸附量降低,PAM用量较低时,吸附量随PAM用量的增加而减少,并且在0.1%～0.5%PAM内两者之间达到极显著负相关.紫色土磷最大吸附量为277.8 靏穏-1 ,0.1%、0.2%、0.4%PAM处理后紫色土对磷的最大吸附量均降低,分别为263.28 靏穏-1、227.38 靏穏-1、212.88 靏穏-1,但吸附强度却没减弱,甚至得到加强.PAM通过改变土壤集结状态和表面性质对土壤磷慢速吸附阶段产生了显著影响,但对快吸附阶段无明显影响.     

Enhanced debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) by zero-valent zinc with ascorbic acid

• Highly efficient debromination of BDE-47 was achieved in the ZVZ/AA system. • BDE-47 debromination by the ZVZ/AA can be applied to a wide range of pH. • AA inhibits the formation of (hydr)oxide and accelerates the corrosion of ZVZ. • Reduction mechanism of BDE-47 debromination by the ZVZ/AA system was proposed. A new technique of zero-valent zinc coupled with ascorbic acid (ZVZ/AA) was developed and applied to debrominate the 2,2′,4,4′-Tetrabromodiphenyl ether (BDE-47), which achieved high conversion and rapid debromination of BDE-47 to less- or non-toxic forms. The reaction conditions were optimized by the addition of 100 mg/L ZVZ particles and 3 mmol/L AA at original solution pH= 4.00 using the solvent of methanol/H₂O (v:v= 4:6), which could convert approximately 94% of 5 mg/L BDE-47 into lower-brominated diphenyl ethers within a 90 min at the ZVZ/AA system. The high debromination of BDE-47 was mainly attributed to the effect of AA that inhibits the formation of Zn(II)(hydr)oxide passivation layers and promotes the corrosion of ZVZ, which leads to increase the reactivity of ZVZ. Additionally, ion chromatography and gas chromatography mass spectrometry analyses revealed that bromine ion and lower-debromination diphenyl ethers formed during the reduction of BDE-47. Furthermore, based on the generation of the intermediates products, and its concentration changes over time, it was proposed that the dominant pathway for conversion of BDE-47 was sequential debromination and the final products were diphenyl ethers. These results suggested that the ZVZ/AA system has the potential for highly efficient debromination of BDE-47 from wastewater.     

Species and distribution of rare earth elements in the Baotou section of the Yellow River in China

This paper analyses the contents and species distributions of rare earth elements (REEs) in the water-suspended particulate-sediment system of the Baotou section of the Yellow River, China, with known anthropogenic REE input from industrial discharges. The major forms of REEs were suspended and dissolved in the mainstream and the tributaries of the Baotou section, respectively. The concentrations of the dissolved and suspended REEs had the same trends in the overlying water along the mainstream, which increased from the Seqi section (site A) to the mouth of the Sidaosha River (site D), reaching a maximum value at site D, and tending to decrease thereafter. The contents of REEs in sediment cores showed enrichment with light rare earth elements (LREEs). The bound to carbonates and to Fe–Mn oxides are the major forms of REE in the secondary phase and the REE exhibited LREE enrichment pattern and moderate Eu depletion in suspended particulates and surface sediments. The contents and species distributions of REEs in the water-suspended particulate-sediment system of the Baotou section suggest that the anthropogenic source of REEs from Baotou city have enhanced REE accumulation to the Baotou section. This information is important for predicting possible pollution resulting from anthropogenic REE input into rivers.     

Modeling the population dynamics of cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) over a wide area in northern China

The cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is one of the most serious crop pests in northern China, calling for accurate prediction of pest outbreaks and strategies for pest control. A computer model is developed to simulate the population dynamics of H. armigera over a wide area in northern China. The area considered covers 12 provinces where serious outbreaks of H. armigera have been observed. In this model, pest development is driven by local ambient temperature, and adults migrate long distances between regions and select preferred hosts for oviposition within a region. Six types of host including cotton, wheat, corn, peanut, soybean and a single category composed of all other minor hosts are considered in this model. Survival rates of eggs and larvae are based on life-table data, and simulated as a function of host type, host phenology and temperature. The incidence of diapause depends on temperature and photoperiod experienced during the larval stage. Survival rate of non-diapause pupae is a nonlinear function of rainfall, and overwinter survival rate is a nonlinear function of temperature. Insecticide is applied when population density exceeds the economic threshold on a host crop within a region. Comparisons of model output with light-trap data indicate that our model reflects the pest population dynamics over a wide area, and could potentially be used for testing novel pest control strategies in northern China.     

Removal of chelated copper from wastewaters by Fe<Superscript>2+</Superscript>-based replacement–precipitation

We studied the removal mechanism and affecting factors of Fe²⁺-based replacement–precipitation process for treating CuEDTA-containing wastewaters. Since Fe²⁺ was easily oxidized to Fe³⁺ in the presence of oxygen, the chelated copper was removed by the synergetic effect of Fe³⁺ replacement and NaOH precipitation. Our experiments showed that the copper removal efficiency was considerably dependant on pH conditions of the solution and molar ratio of Fe²⁺/Cu²⁺.     

Arkadolith土壤改良剂对内蒙沙区常见牧草生长状况的影响

通过盆栽试验,对土壤采用添加25%土壤改良剂、以及添加12.5%改良剂和12.5%腐殖质的2种处理方式,研究Arkadolith土壤改良剂对冰草（Agropyron desertorum）、沙打旺（Astragalus huangheensis）和准格尔苜蓿（Medicago sativa cv ＂Zhonggeer＂）3种沙生牧草的生长特性的影响。结果表明,3种牧草中,植株高度、生长力、发芽力以及产量都较土壤改良前有所增强,沙打旺和准格尔苜蓿的生长状况要明显好于冰草。含有多种矿物成分的Arkadolith土壤改良剂不仅可以改良贫瘠土壤,提高土壤肥力,促进牧草的增产,而且还可以减少化学肥料的施用,降低成本,做到绿色环保,因此其具有广泛的推广意义。     

Species phylogenetic relatedness, priority effects, and ecosystem functioning

Species immigration history can structure ecological communities through priority effects, which are often mediated by competition. As competition tends to be stronger between species with more similar niches, we hypothesize that species phylogenetic relatedness, under niche conservatism, may be a reasonable surrogate of niche similarity between species, and thus influence the strength of priority effects. We tested this hypothesis using a laboratory microcosm experiment in which we established bacterial species pools with different levels of phylogenetic relatedness and manipulated the immigration history of species from each pool into microcosms. Our results showed that strong priority effects, and hence multiple community states, only emerged for the species pool with the greatest phylogenetic relatedness. Community assembly also resulted in a significant positive relationship between bacterial phylogenetic diversity and ecosystem functions. Interestingly, these results emerged despite a lack of phylogenetic conservatism for most of the bacterial functional traits considered. Our results highlight the utility of phylogenetic information for understanding the structure and functioning of ecological communities, even when phylogenetically conserved functional traits are not identified or measured.     

采空区热环境对深部倾斜厚煤层自燃区域影响研究

为探究热场对深部倾斜采空区煤自燃区域划分的影响,通过对采场空隙结构和耗氧速率进行分析,利用Fluent软件模拟不同通风方式下热环境对采空区流场及自燃带影响.结果表明:受倾角工作面、采空区空隙率及地温梯度综合影响,下行冷风与受采空区浮升力作用的热风在工作面中下部汇合并涌向工作面,使工作面局部温度升高;上行通风方式采空区蓄...     

电动单梁起重机吊具冲顶引发起升电机坠落事故分析

针对一起电动单梁起重机吊具冲顶并引发起升电机坠落的起重作业事故,分析了事故起重机电气控制系统和现场紧急处置中存在的问题,指出了导致事故发生的直接原因和主要原因;并从完善起重机电气控制系统本质安全性和加强起重机械使用安全管理的角度提出了相应建议和意见,对预防类似事故的发生具有借鉴作用.