马兰黄土对Cr(Ⅲ)吸附的试验研究

为获取马兰黄土对水溶液中Cr(Ⅲ)的吸附机制.深入完善马兰黄土除Cr(Ⅲ)的理论研究,设计了等温吸附、土柱吸附、形态提取和去方解石除Cr(Ⅲ)试验.通过对试验结果的对比分析得出,马兰黄土对水溶液中Cr(Ⅲ)的吸附作用主要为方解石水解所引起的Cr(Ⅲ)吸附沉淀反应和铁锰氧化物对Cr(Ⅲ)的表面络合反应,辅以多种矿物对Cr(Ⅲ)的阳离子交换作用;马兰黄土对水溶液中Cr(Ⅲ)的等温吸附方程较符合非线性Langmuir型等温吸附方程,其吸附动力学模型较符合抛物线扩散方程.     

活性污泥系统中自养菌浓度及生长动力学参数测定

利用批式呼吸计量法测定了实际污水处理厂厌氧/缺氧/好氧工艺和小试装置厌氧/好氧工艺好氧池内自养菌（X_A）的浓度及其最大比生长速率常数(μ_A)。结果表明,活性污泥系统中X_A与混合液挥发性悬浮固体的比例为1.60%～2.34%,μ_A实测值为0.69～0.76 d^-1,测定结果有较好的重现性,且与文献值非常接近,说明该方法具有较高的准确度和精密度。     

油田采油污泥的热解动力学及其热解效果研究

以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动力学方程,提高热解的升温速率,可使油泥的最大失重速率D_max、失重速率峰值温度θ_max、升温终点的最大失重率都随之增加,表现在动力学上,反映出表观活化能和碰撞频率因子的同时升高,即提高油泥热解转化率的同时也影响了热解效率。失水油泥用流化床热解,在热解温度600℃、反应时间3 min时,油泥回收率可达到87%。     

水泥旋窑并行处理城市污水厂污泥的污染物排放研究

通过重庆某水泥厂的工业试验,测定了水泥旋窑并行处理城市污水厂污泥的烟气参数及污染物排放指标,分析了并行处理污泥对旋窑烟气的影响程度及各项指标之间的相关性。结果表明：①在污泥添加速率增大时,烟气流速、排气量、含氧量、空气过剩系数、HF和SO₂等排放浓度均随之增加,粉尘、NO_x排放浓度基本保持不变,HCl排放浓度下降,CO排放浓度先剧增后缓慢下降,而总烃排放浓度无明显规律;②污泥添加速率与SO₂排放浓度、烟气流速与排气量、含氧量与空气过剩系数、总烃浓度与SO₂排放浓度、烟气流速与总烃浓度呈显著正相关,污泥添加速率与HCl浓度、SO₂浓度与HCl浓度、NO_x与总烃浓度呈显著负相关;③烟气排放的污染物主要来自煤的燃烧,各指标之间的相关性主要表现为煤耗量增加而引起的连锁效应,但污泥本身在高温条件下燃烧产生的污染物较少,由污泥燃烧产生的污染物之间的相关性较小;④污泥添加速率达到2.4 t/h时,水泥旋窑并行处理城市污水处理厂污泥过程中所有指标均满足国家及相应的控制标准,但其参数优化及污染物控制极为复杂,该方法处理污泥需要进行深入研究才能在工业上应用。     

Altitude dependence of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in surface soil from Tibetan Plateau, China

Remote mountain areas besides high latitude regions are beginning to receive increased attention in studying the transport and behavior of persistent organic pollutants (POPs). In the present work, surface soil samples were collected from the Tibetan Plateau, the highest plateau in the world which includes the northern slope of Mt. Qomolangma, to investigate the levels and trends of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) along the altitudinal gradient. The average PCB and PBDE concentrations were 185.6 ng kg⁻¹ dry weight (dw) (range 47.1–422.6 ng kg⁻¹ dw) and 11.1 ng kg⁻¹ dw (range 4.3–34.9 ng kg⁻¹ dw), respectively. Regression analysis between the log-transformed TOC-normalized concentrations and the altitudes of the sampling sites showed two opposite trends with regard to altitude dependence: negative relationship with altitude below about 4500 m followed by a positive altitude dependence above this point. Considering minimum anthropogenic activities and very sparse precipitation in the north of Himalayas, the trends above 4500 m imply that the significant altitude dependence of these two groups of POPs were irrespective of pollution sources, but could be predicted by the global distillation effect involving cold condensation in high altitude mountain areas. Increasing levels of heavier congeners were found in higher altitude sites, although the lighter congeners were the main contributors to the total amount, suggesting that less volatile congeners seem to become enriched easier than those more volatile at higher altitudes in this region.     

Study on the aerosol optical properties and their relationship with aerosol chemical compositions over three regional background stations in China

The special and temporal characteristics of aerosol optical depth (AOD) and Angstrom wavelength exponent (Alpha) and their relationship with aerosol chemical compositions were analyzed by using the data of CE318 sun-photometer and aerosol sampling instruments at Lin'an, Shangdianzi and Longfengshan regional atmospheric background stations. Having the highest AOD among the three stations, Lin'an shows two peaks in a year. The AOD at Shangdianzi station shows a single annual peak with an obvious seasonal variation. The AOD at Longfengshan station has obvious seasonal variation which peaks in spring. The Alpha analysis suggests that the aerosol sizes in Lin'an, Longfengshan and Shangdianzi change from fine to coarse categories. The relationship between the aerosol optical depths of the Lin'an and Longfengshan stations and their chemical compositions is not significant, which suggests that there is not a simple linear relationship between column aerosol optical depth and the near surface chemical compositions of atmospheric aerosols. The aerosol optical depth may be affected by the chemical composition, the particle size and the shape of aerosol as well as the water vapor in the atmosphere.     

Experimental and Ecological Implications of Evening Bird Surveys in Stream-Riparian Ecosystems

Stream-riparian ecosystems are dynamic and complex entities that can support high levels of bird assemblage abundance and diversity. The myriad patches (e.g., aquatic, floodplain, riparian) found in the riverscape habitat mosaic attract a unique mixture of aquatic, semiaquatic, riparian, and upland birds, each uniquely utilizing the river corridor. Whereas standard morning bird surveys are widely used across ecosystems, the variety of bird guilds and the temporal habitat partitioning that likely occur in stream-riparian ecosystems argue for the inclusion of evening surveys. At 41 stream reaches in Vermont and Idaho, USA, we surveyed bird assemblages using a combination of morning and evening fixed-width transect counts. Student’s paired t-tests showed that while bird abundance was not significantly different between morning and evening surveys, bird assemblage diversity (as measured by species richness, Shannon-Weiner’s index, and Simpson’s index) was significantly higher in the morning than in the evening. NMS ordinations of bird species and time (i.e., morning, evening) indicated that the structure of morning bird assemblages was different from that of evening assemblages. NMS further showed that a set of species was only found in evening surveys. The inclusion of evening counts in surveying bird assemblages in stream-riparian ecosystems has important experimental and ecological implications. Experimentally, the sole use of morning bird surveys may significantly underestimate the diversity and misrepresent the community composition of bird assemblages in these ecosystems. Ecologically, many of the birds detected in evening surveys were water-associated species that occupy high trophic levels and aerial insectivores that represent unique aquatic-terrestrial energy transfers.     

时间因素在安全评价中的作用

安全评价的主要作用是为生产经营单位和监管部门准确反映系统的安全状态,为安全生产管理和监管提供决策依据,但目前的评价结果只能反映某一特定时刻的系统情况,而对未来一段时间系统安全状况的变化情况不能做出预判,如果能有效考虑时间因素,安全评价的结果将更加完善.     

Remediation aspect of microbial changes of plant rhizosphere in mercury contaminated soil

Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation, may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed. The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil with moderate mercury contamination as well as the basis for plant selection.     

A GIS-based Study for Optimizing the Total Emission Control Strategy in Lanzhou City

A geographic information system (GIS)-based approach with spatial analysis advantages was developed to optimize the total emission control scheme on air pollution in Lanzhou, combined with Models-3 modeling system and a linear programming model. GIS system is mainly used for establishing a multifactor assessment model to quantitatively divide environmental functional zone, and also used for selecting control sites in linear programming model. The results show that most of the urban area belongs to the second type of function, which is 122.8 km² occupying about 76.5% and the third type of about 32.9 km² occupying 20.5%. To reach the air quality up to the national standard in the entire control area, some large-emission factories need to cut emissions from 19% to 27%. For small but low-emission height sources, the cut may be as high 40%. The improvement of the ecological environment is urgently needed for controlling the background particle pollution in Lanzhou city.