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131.
132.
室内空气污染净化研究进展 总被引:3,自引:0,他引:3
介绍了室内空气污染的现状、特点及其危害,指出了室内空气污染的主要污染源和污染物。综述了各种室内空气污染净化技术,并介绍了各种技术的优缺点。本文最后对室内空气污染净化的发展前景进行了展望。 相似文献
133.
青藏高原林地土壤的氮转化特征及其影响因素分析:以祁连山和藏东南地区为例 总被引:3,自引:2,他引:1
矿化和硝化过程是森林生态系统氮素循环的重要组成部分,对生态系统功能的维持与土壤环境质量有着重要影响.净矿化和净硝化速率是评价土壤氮素供应能力和氮损失风险的常用指标.为探究青藏高原林地土壤氮转化特征及其影响因素,以气候差异较大的祁连山和藏东南地区作为研究对象,采集了327个林地土壤样本,通过样本处理及室内培养试验,分析了土壤中无机氮含量、净矿化速率、净硝化速率及其与环境因子之间的相关关系.结果表明,藏东南地区林地土壤的无机氮含量、净矿化速率和净硝化速率[109.70 mg·kg-1、3.08 mg·(kg·d)-1和2.19 mg·(kg·d)-1]均显著高于祁连山地区[49.47 mg·kg-1、0.70 mg·(kg·d)-1和0.69 mg·(kg·d)-1];土壤的净矿化速率与年平均温度、年平均降水量、湿润指数及土壤有机质含量之间具有极显著的正相关关系(P<0.001).净硝化速率与年平均温度、年平均降水量之间无显著正相关关系,但与土壤净矿化速率呈极显著的正相关关系(P<0.001).这表明藏东南地区林地土壤具有比祁连山林地土壤更高的氮素供应水平,而水热条件可能是造成两地土壤净矿化速率差异的主要原因,净矿化速率是净硝化速率的限制因子,对青藏高原林地土壤的氮素损失有着重要影响.这些结果强调了水热条件等气候环境因子对青藏高原林地土壤净矿化和净硝化速率的重要影响,进一步加深了人们对青藏高原林地土壤氮素转化规律的认识. 相似文献
134.
分别以硝酸盐、亚硝酸盐、氧气为电子受体,采用3组SBR反应器培养除磷污泥,连续126d的稳定运行表明:以硝酸盐、亚硝酸盐、氧气为电子受体除磷污泥对TP平均去除率分别为84.8%, 78.7%, 87.4%,出水TP平均浓度分别为0.758, 0.931, 0.632mg/L.采用高通量测序技术对不同电子受体除磷污泥的相似性与菌群结构进行了研究,结果表明,以硝酸盐,亚硝酸盐为电子受体的反硝化除磷污泥具有近似的菌群结构,与好氧除磷污泥菌群结构差异较大.基于各样品主导OTUs序列的系统发育关系及其比例的分布,主导微生物主要可以分为5个簇.通过序列比对,在97%的序列相似度条件下,种泥中聚磷菌与聚糖菌序列比例为0.716%与0.368%,以硝酸盐、亚硝酸盐、氧气为电子受体除磷污泥中聚磷菌与聚糖菌序列比例分别为1.78%, 2.53%, 4.80%与1.44%, 1.32%, 30.9%,厌氧-缺氧条件有利于抑制聚糖菌.亚硝酸盐为反硝化除磷污泥电子受体时潜在公共卫生安全隐患. 相似文献
135.
化学工业园区重大环境风险源监控技术研究与应用 总被引:2,自引:2,他引:0
基于监控系统综合集成的思想,以重大环境污染事件风险源监控技术规范、重大危险源控制规章、污染源在线监测为基础,从监控指标体系、监控布点范围及监控技术筛选三方面建立化学工业园区中重大环境风险源监控技术体系. 结果表明:重大环境风险源监控指标体系主要从企业内部及企业周边敏感受体两方面进行构建;监控范围从重大环境风险源本体、缓冲区及环境敏感受体三方面确定;监控技术筛选时考虑了环境风险源的状态、监控技术方法的实用性和环境风险源/受体属性. 以上海闵行区化学工业园区为例,经调研统计,该化学工业园区共有重大风险源87个,其中罐区60个、排放口12个,其余分散在库房、生产场所等处. 根据化学工业园区企业内部风险设施及周围敏感受体的监控指标、监控范围及常用监控技术,制定了以罐区、排放口的特征风险物质为指标,以储罐的温度、压力、图像视频、液位及排放口特征风险物质浓度的传感器监控技术为主的监控方案. 相似文献
136.
Fe3O4/C纳米粒子的制备及其对水中罗丹明B的去除 总被引:1,自引:0,他引:1
采用溶剂热-水热法合成了碳覆盖的Fe3O4纳米粒子Fe3O4/C,利用扫描电镜(SEM)与红外光谱(FT-IR)对其进行了表征,并研究了其对水中罗丹明B的吸附性能.系统考察了吸附动力学、吸附等温线、吸附剂用量对吸附性能的影响.Fe3O4/C对罗丹明B的吸附在3 h内即可达到平衡,最大吸附量可达13.23 mg.g-1.分别用Langmuir和Freundlich吸附模型解释了Fe3O4/C对罗丹明B的作用机理,吸附反应过程符合准二级动力学方程.结果表明,该吸附剂具有良好的磁效应和吸附性能,可快速去除罗丹明B,去除率高达90%以上;吸附剂可重复利用,成本低,具有环境友好的优势. 相似文献
137.
The mid-Holocene decline of Tsuga canadensis (hereafter Tsuga) populations across eastern North America is widely perceived as a synchronous event, driven by pests/pathogens, rapid climate change, or both. Pattern identification and causal attribution are hampered by low stratigraphic density of pollen-sampling and radiometric dates at most sites, and by absence of highly resolved, paired pollen and paleoclimate records from single sediment cores, where chronological order of climatic and vegetational changes can be assessed. We present an intensely sampled (contiguous 1-cm intervals) record of pollen and water table depth (inferred from testate amoebae) from a single core spanning the Tsuga decline at Irwin Smith Bog in Lower Michigan, with high-precision chronology. We also present an intensively sampled pollen record from Tower Lake in Upper Michigan. Both sites show high-magnitude fluctuations in Tsuga pollen percentages during the pre-decline maximum. The terminal decline is dated at both sites ca. 5000 cal yr BP, some 400 years later than estimates from other sites and data compilations. The terminal Tsuga decline was evidently heterochronous across its range. A transient decline ca. 5350 cal yr BP at both sites may correspond to the terminal decline at other sites in eastern North America. At Irwin Smith Bog, the terminal Tsuga decline preceded an abrupt and persistent decline in water table depths by approximately 200 years, suggesting the decline was not directly driven by abrupt climate change. The Tsuga decline may best be viewed as comprising at least three phases: a long-duration pre-decline maximum with high-magnitude and high-frequency fluctuations, followed by a terminal decline at individual sites, followed in turn by two millennia of persistently low Tsuga populations. These phases may not be causally linked, and may represent dynamics taking place at multiple temporal and spatial scales. Further progress toward understanding the phenomenon requires an expanded network of high-resolution pollen and paleoclimate chronologies. 相似文献
138.
Soil C and N changes with afforestation of grasslands across gradients of precipitation and plantation age 总被引:3,自引:0,他引:3
Afforestation, the conversion of unforested lands to forests, is a tool for sequestering anthropogenic carbon dioxide into plant biomass. However, in addition to altering biomass, afforestation can have substantial effects on soil organic carbon (SOC) pools, some of which have much longer turnover times than plant biomass. An increasing body of evidence suggests that the effect of afforestation on SOC may depend on mean annual precipitation (MAP). The goal of this study was to test how labile and bulk pools of SOC and total soil nitrogen (TN) change with afforestation across a rainfall gradient of 600-1500 mm in the Rio de la Plata grasslands of Argentina and Uruguay. The sites were all former grasslands planted with Eucalyptus spp. Overall, we found that afforestation increased (up to 1012 kg C x ha(-1) x yr(-1)) or decreased (as much as 1294 kg C x ha(-1) x yr(-1)) SOC pools in this region and that these changes were significantly related to MAP. Drier sites gained, and wetter sites lost, SOC and TN (r2 = 0.59, P = 0.003; and r2 = 0.57, P = 0.004, respectively). Labile C and N in microbial biomass and extractable soil pools followed similar patterns to bulk SOC and TN. Interestingly, drier sites gained more SOC and TN as plantations aged, while losses reversed as plantations aged in wet sites, suggesting that plantation age in addition to precipitation is a critical driver of changes in soil organic matter with afforestation. This new evidence implies that longer intervals between harvests for plantations could improve SOC storage, ameliorating the negative trends found in humid sites. Our results suggest that the value of afforestation as a carbon sequestration tool should be considered in the context of precipitation and age of the forest stand. 相似文献
139.
140.