深圳再生水补水河流溶解N2O空间分布和产生机制

为了探究在再生水回补城市河流的条件下河流N₂O的微生物产生过程及其空间变化特征,以深圳市西乡河为研究对象,分析了河水中c（溶解性N₂O）、c（NH₄+-N）、c（NO₃--N）、δ15Nbulk-N₂O、δ18O-N₂O、同位素异位体位嗜值（site preference,SP）及其他环境因子,并基于端元混合模型和同位素分馏模型定量计算硝化和反硝化作用对河水中N₂O贡献百分比.结果表明:①随着流速降低,西乡河河水从上游的好氧环境逐渐发育成中下游的厌氧环境.②再生水进入西乡河后河水c（溶解性N₂O）从1.36 μmol/L沿程降至0.19 μmol/L;相关性分析表明,影响c（溶解性N₂O）的主要因素为ρ（DO）（R2=0.800,P < 0.01）和c（CH₄）（R2=-0.736,P < 0.01）.③硝化和反硝化作用对河水中N₂O贡献率分别为14.36%~80.53%和19.47%~85.64%;N₂O的来源在好氧河段中以硝化作用为主,在厌氧河段则以反硝化作用为主;N₂O还原成N₂的比例与ρ（DO）具有显著负相关关系（R2=-0.782,P < 0.01）.研究显示,再生水回补城市河流引入了较高质量浓度的N₂O和NO₃--N,而河道的厌氧环境促进河水中N₂O还原成N₂,下游河流成为N₂O的汇.      

江苏省典型铅酸蓄电池企业周围环境铅污染水平调查

目的调查江苏省典型铅酸蓄电池企业对周围环境的影响。方法按照国家相关标准和规范对该企业内、外的环境样品进行检测。结果下风向区土壤铅含量中位数均明显高于上风向区域(L相似文献   

固定化氨氧化细菌短程硝化特性研究

以高分子聚合物为载体,采用固定化细胞增殖技术固定氨氧化细菌,研究温度、pH、碱度和溶解氧等因素对短程硝化过程的影响.实验结果表明,最适宜的温度、pH分别是30℃和8.5;当碱度/NH4 -N(质量比)=6.75时,亚硝化率为87.5%;溶解氧浓度影响氨氧化速率,但对亚硝化率影响不大,溶解氧的适宜质量浓度为403 mg/L.     

Effects of doping amounts of potassium ferricyanide with titanium dioxide and calcination durations on visible-light degradation of pharmaceuticals

Acetaminophen (ACT) is one of the most frequently detected pharmaceuticals in aqueous environments, and treatment of ACT were generally carried out by photocatalytic degradations under high energy UV irradiation. In this study, potassium ferricyanide was utilized as a quadruple-elemental dopant in a TiO₂ photocatalyst in order to enhance its visible-light activity. Two critical parameters (amounts of dopants and durations of calcination) of the synthesis of the photocatalyst by a sol–gel method were systematically evaluated. Crystal structure of the doping TiO₂ was examined by X-ray diffraction while the effects of the two parameters on the photocatalytic activity were elucidated by various characterizations. Increasing the amount of dopant or the duration of calcination red-shifted the UV–vis DRS of the doped TiO₂. The estimated band gap energy of the doped TiO₂ decreased slightly as the amount of dopant increased, but it increased as the duration of calcination increased. The FT-IR yielded characteristic peaks that revealed the effects of the two parameters, whereas the SEM images revealed the morphological evolutions of each effect. The photocatalyst, synthesized at optimum conditions was able to remove 99.1 % acetaminophen with rate constant of 7.9 × 10⁻³ min⁻¹, which was 4.88 times greater than virgin TiO₂. In general, this study not only optimized synthetic conditions of the new visible-light active photocatalyst for ACT degradation but also presented characterizations conducted by SEM, XRD, UV–vis DRS, and FTIR to elucidate the relationship between modified structure and the photocatalytic activity.

Effects of doping amounts of K₃[Fe(CN)₆] and calcunation duration on visible light absorbance of TiO₂ photocatalysts

     

A Landscape Approach for Detecting and Evaluating Change in a Semi-Arid Environment

Vegetation change in the American West has been a subject of concern throughout the twentieth century. Although many of the changes have been recorded qualitatively through the use of comparative photography and historical reports, little quantitative information has been available on the regional or watershed scale. It is currently possible to measure change over large areas and determine trends in ecological and hydrological condition using advanced space-based technologies. Specifically, this process is being tested in a community-based watershed in southeast Arizona and northeast Sonora, Mexico using a system of landscape pattern measurements derived from satellite remote sensing, spatial statistics, process modeling, and geographic information systems technology. These technologies provide the basis for developing landscape composition and pattern indicators as sensitive measures of large-scale environmental change and thus may provide an effective and economical method for evaluating watershed condition related to disturbance from human and natural stresses. The project utilizes the database from the North American Landscape Characterization (NALC) project which incorporates triplicate Landsat Multi-Spectral Scanner (MSS) imagery from the early 1970s, mid 1980s, and the 1990s. Landscape composition and pattern metrics have been generated from digital land cover maps derived from the NALC images and compared across a nearly 20-year period. Results about changes in land cover for the study period indicate that extensive, highly connected grassland and desertscrub areas are the most vulnerable ecosystems to fragmentation and actual loss due to encroachment of xerophytic mesquite woodland. In the study period, grasslands and desertscrub not only decreased in extent but also became more fragmented. That is, the number of grassland and desertscrub patches increased and their average patch sizes decreased. In stark contrast, the mesquite woodland patches increased in size, number, and connectivity. These changes have important impact for the hydrology of the region, since the energy and water balance characteristics for these cover types are significantly different. The process demonstrates a simple procedure to document changes and determine ecosystem vulnerabilities through the use of change detection and indicator development, especially in regard to traditional degradation processes that have occurred throughout the western rangelands involving changes of vegetative cover and acceleration of water and wind erosion.     

IMPLEMENTATION OF BIORETENTION SYSTEMS: A WISCONSIN CASE STUDY1

ABSTRACT: The implementation of various bioretention systems was analyzed, including rain gardens, vegetated swales, trenches, and infiltration basins in the St. Francis subdivision, Cross Plains, Wisconsin. Through the examination of archival data and interviews with key participants, it was found that although regulatory and political pressures encouraged the inclusion of bioretention, current standards for storm water management prevailed. The developers had to meet both existing requirements and anticipated rules requiring infiltration. As a result, bioretention systems simply supplemented, rather than replaced, traditional storm water practices. The confusion surrounding dual standards contributed to substantial delays in the negotiations among relevant stakeholders in the watershed. It is concluded that the St. Francis subdivision serves as both a cautionary tale and a bioretention success story. As a caution, this situation demonstrates the need for careful review and refinement of existing storm water ordinances to incorporate water quality improvement technologies, such as bioretention. The demonstrated success of the St. Francis development, however, is that it became a positive prototype for best management storm water practices elsewhere in the region. In addition, the water quality monitoring data from the site has contributed to development of a new county ordinance, the first in Wisconsin to address both quantity and quality of storm water runoff.     

Functional clustering of varved lake sediment to reconstruct past seasonal climate

Annually laminated (varved) lake sediments constitutes excellent environmental archives, and have the potential to play an important role for understanding past seasonal climate with their inherent annual time resolution and within-year seasonal patterns. We propose to use functional data analysis methods to extract the relevant information with respect to climate reconstruction from the rich but complex information in the varves, including the shapes of the seasonal patterns, the varying varve thickness, and the non-linear sediment accumulation rates. In particular we analyze varved sediment from lake Kassjön in northern Sweden, covering the past 6400 years. The properties of each varve reflect to a large extent weather conditions and internal biological processes in the lake the year that the varve was deposited. Functional clustering is used to group the seasonal patterns into different types, that can be associated with different weather conditions. The seasonal patterns were described by penalized splines and clustered by the k-means algorithm, after alignment. The observed (within-year) variability in the data was used to determine the degree of smoothing for the penalized spline approximations. The resulting clusters and their time dynamics show great potential for seasonal climate interpretation, in particular for winter climate changes.     

Influence of the mineralogical composition on microbial activities in marine sediments: an experimental approach

We investigated the influence of the mineralogical composition of marine sediments on bacterial activity in experimental microcosms. Calcite and quartz were added to natural marine sediments and microbial response in terms of total bacterial abundance and biomass, β-D-glucosidase exo-enzymatic activity and bacterial incorporation of a radio-labelled (³H-leucine) substrate were investigated for a period of one month. We report here that after 15 days the mineralogical composition of the sediment (calcite vs. quartz) had an impact on bacterial abundance and activity (reduced for ca 15% and 56%, respectively). However, such impact was mitigated or even disappeared in high organic nutrient conditions.     

Landowner Satisfaction with the Wetlands Reserve Program in Wisconsin

We evaluated ecological monitoring data and landowner perceptions to the federally funded Wetlands Reserve Program (WRP) in a three-county region in Wisconsin. We surveyed landowner satisfaction, involvement, participation, and use of the WRP restoration sites. We found that landowners are satisfied with the overall program (mean, 3.6 ± 0.2 [SE], on a scale of 1–5, with 5 being completely satisfied). WRP restorations significantly increased the area of wetland within the sites surveyed, the increase was primarily of fresh meadow (736.32 ha after restoration). Satisfaction is related to landowner participation during restoration and to the economic incentives provided by the WRP, Landowner satisfaction and the number of plant communities after restoration are unrelated to each other or to restoration and easement costs per hectare. Survey participants recommended some changes to the WRP, including a reduction in the tax rate of land enrolled in the WRP, approval for permanent deer stands, and increased communication with WRP officials during the restoration. Monitoring information collected for WRP restoration sites does not allow assessment of whether WRP sites are functionally equivalent to natural sites. We suggest that the WRP require a more rigorous monitoring program, including guidelines for invasive species control. Managers should also encourage collaborations with external researchers and consider restorations within an experimental framework.     

Effect of tunnel inclination on digging energetics in the tuco-tuco, Ctenomys talarum (Rodentia: Ctenomyidae)

Burrows play an important role for many species, providing them with shelter and access to food resources. For subterranean rodents, living underground imposes constraints on morphology and physiology. The convergence in burrow architecture among subterranean rodents has been related to the energy demands imposed by the cost of constructing an entire system. The low frequency of tunnels with downward angles steeper than 40° appears to be a common feature in burrow design. In the subterranean habitat, movements through the soil are expensive and gravity can exert important restrictions on digging energetics when individuals push out the soil removed in steeper digging angles. The aim of this study was to determine the effect of digging angle on digging energetics in Ctenomys talarum. The mass of the removed soil and burrowing speed were similar while digging metabolic rate and net cost of transport were higher in individuals digging in tunnels with angles >40° than in those digging tunnels with angles <40°. The cost of constructing a burrow in the horizontal plane differed by 20% from others in which the natural representation of tunnels >40° was considered. Even given that tunnels >40° represented only 6% of the total burrow length, burrow architecture appears to be constrained by the high energetic cost of constructing in steeper angles.