Second derivative spectroscopy for the determination of volatilized ammonia from urea-amended soil

A second derivative spectrometer custom fitted with a 1 m stainless steel White cell and maintained at 105°C is used to make real-time measurements of volatilized NH₃ from urea-amended soil. Comparison of the technique to impinger data shows a 5–16% discrepancy between the two techniques; however, other experiments presented suggests that this is not real. Sulfur dioxide and nitrous oxide interferences are discussed, though they were not found to be present in this study. Instrument response time is shown to be fast if 67% of the total response is achieved in less than 5 min. Fast response is achieved for ammonia if wall-adsorption effects are minimal and if ammonia mass flow is maintained at 0.2 μg min^-1.     

铁路运输业污水治理系统分析

研究了乌鲁木剂铁路局系统污水治理污染控制方法及途径，提出了主要污染物为石油类，其最佳治理对策是：确定重点污染单位、污染源、用最低的治理投入，选择斜板隔油气浮工艺治理重点污染和次重点污染部门，得到较好的治理效果，否定盲目追求“零排放”的高投入方案。     

Environmental monitoring of historical change in arsenic deposition with tree bark pockets

ICP-MS analysis recorded historical change (c. 1846 to 2002) in the arsenic concentration of bark included within the trunks (tree bark pockets) of two Japanese oak trees (Quercus crispula), collected at an elevated location approximately 10 km from the Ashio copper mine and smelter, Japan. The arsenic concentration of the bark pockets was 0.016 +/- 0.003 microg cm(-2) c. 1846 (n = 5) and rose 50-fold from c. 1875 to c. 1925, from approximately 0.01 to 0.5 microg cm(-2). The rise coincided with increased copper production in Ashio from local sulfide ores, from 46 tons per year in 1877 to 16,500 tons per year in 1929. Following a decline in arsenic concentration and copper production, in particular during the Second World War, a second peak was observed c. 1970, corresponding to high levels of production from both local (6,000 tons per year) and imported (30,000 tons per year) ores, smelted from 1954. Compared to the local ores, the contribution of arsenic from imported ores appeared relatively low. Arsenic concentrations declined from c. 1970 to the present following the closure of the mine in 1974 and smelter in 1989, recording 0.058 +/- 0.040 microg cm(-2) arsenic (n = 5) in surface bark collected in 2002. The coincident trends in arsenic concentration and copper production indicated that the bark pockets provided an effective record of historical change in atmospheric arsenic deposition.     

The application of HPLC-F and GC-MS to the analysis of selected hydroxy polycyclic hydrocarbons in two certified fish bile reference materials

Four selected hydroxy polycyclic aromatic hydrocarbons (OH-PAHs), 2-hydroxy-naphthalene (2-OH-NPH), 1-hydroxy-phenanthrene (1-OH-PHE), 1-hydroxy-pyrene (1-OH-PYR) and 3-hydroxy-benzo[a]pyrene (3-OH-BaP) have been analysed in two certified fish bile reference materials (CRMs) for exposure monitoring of PAHs in the aquatic environment. The two materials, BCR 720 and BCR 721, consist of bile from fish exposed to contaminated sediment and dispersed crude oil, respectively. Both bile samples have been analysed by two different analytical techniques, gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-fluorescence detection (HPLC-F), and the separation performance, detection limits, recoveries and reproducibility for the four target compounds were evaluated. HPLC-F requires a simple sample preparation and the separation capacity is adequate for quantification of 1-OH-PYR and 3-OH-BaP. Detection limits are excellent for 1-OH-PYR (6 pg injected) and 3-OH-BaP (3 pg injected) and generally improved with increasing molecular size. Recoveries ranged from 48 to 99% for the four selected compounds, depending on compound and concentration. Sample preparation prior to GC-MS analysis was more demanding, as reflected by the obtained recoveries for 2-OH-NPH, 1-OH-PHE and 1-OH-PYR (35 to 61%). The sensitivity improved with decreasing molecular size, 2-OH-NPH (1.2 pg injected), 1-OH-PHE (2.4 pg injected) and 1-OH-PYR (6 pg injected). Because of the superior separation power of GC and the extra selectivity of MS detection, GC-MS was the method of choice for the determination of 2-OH-NPH and 1-OH-PHE in both CRMs. In fish bile samples these two compounds are more likely to suffer from chromatographic overlap, and HPLC-F was not sufficiently selective. Determination of 1-OH-PYR was performed with success by both methods, but HPLC-F would be preferred because of the simpler and less time-consuming sample preparation. Detectable concentrations of 3-OH-BaP were present in BCR 720 and could only be determined by HPLC-F. The present work aims to present HPLC-F and GC-MS as complementary methods for the quantitative analysis of OH-PAHs in fish bile.     

Matrix diffusion effects in the cleanup of heterogeneous aquifers

Simple mathematical models are developed to account for the rather slow mass transport of nonaqueous phase liquid (NAPL) into aqueous solution in groundwater during flushing operations. The models are based on the assumption that this bottleneck in the process is associated with diffusion in the aqueous phase in the porous medium from the location of the NAPL drops/ganglia in a region of relatively low permeability out into a region of substantially higher permeability, somewhat analogous to diffusion from a block of porous rock into a nearby fracture, where the fracture system overwhelmingly dominates the overall permeability. The models include batch flushing, flushing in a laboratory column, and a one-dimensional model for flushing by means of a single recovery well.     

无剩余污泥的多级活性生化处理工艺

介绍了多级活性生化处理 (MSABP)这项新的废水处理技术的原理、技术特点及两个实例运用。这是此项技术在国内的首次运用 ,其最大的优点是无剩余污泥产生 ,不需要沉淀池     

Application of PCR and probe hybridization techniques in detection of airborne fungal spores in environmental samples

Specific PCR amplification and probe hybridization techniques were applied to examine the compositions of airborne fungi in samples from three different environments. The results from microscopic and CFU counting were compared to those of the molecular-based detections. The detection sensitivity for PCR amplifications was 9 to 73 spores and 1.3 to 19.3 CFUs per PCR reaction. The hybridization detection limit was 2 to 4 spores and 0.2 to 1.2 CFU. The hybridization method was more sensitive than PCR amplification and showed less variation among samples. Using specific PCR primers and probes we identified the presence of several fungal groups and species in the air samples. Specific detections through probe hybridization to PCR products amplified with universal or group-specific fungal primers have promising applications in the examination of air samples for environmental monitoring.     

Optimizing the removal of small fish passage barriers

Removing small artificial barriers that hinder upstream migrations of fish is a major problem in riparian habitat restoration. Because of budgetary limitations, it is necessary to prioritize barrier removal and repair decisions. These have usually been based on scoring and ranking procedures, which, although simple to use, can be very inefficient in terms of increasing the amount of accessible instream habitat. We develop a novel decision-making approach, based on integer programming techniques, which optimizes repair and removal decisions. Results show based on real datasets of barrier culverts located in Washington State that scoring and ranking is over 25% below the optimum on average and a full 100% below in the worst case, producing no net habitat gain whatsoever. This is compared to a dynamic programming method that was able to find optimal solutions in less than a second, even for problems with up to several hundred variables, and a heuristic method, which found solutions with less than a 1% average optimality gap in even less time.     

Migration of pollutants in groundwater: I. reduction of numerical dispersion by conformal mapping

The partial differential equations governing the migration of adsorbable pollutants undergoing 2-dimensional flow in saturated aquifers are presented. The analytical solution of these equations is rarely possible, and the use of mesh or grid techniques for numerical integration leads to so-called numerical dispersion, excessive dispersion which is an artifact associated with the numerical method. We discuss here the use of conformal mapping techniques to develop coordinate systems in which numerical dispersion transverse to the direction of flow is eliminated. Some simple illustrations are presented.