原广州氮肥厂地块地下水环境质量评价

对原广州氮肥厂遗留地块浅层地下水环境质量进行调查与评价。结果表明,其整个地块浅层地下水被污染,特别是硫酸车间和造气车间为地下水污染最重区域。主要污染项目为Mn、NH3-N、亚硝酸盐、Fe、总硬度、IMn、SO2-、F-。提出,在作土壤开挖、修复和新建工程项目过程中,工程施工排水应处理后方可排放,以减少对周围环境水体的影响;建筑工人应避免直接接触地下水,施工时佩带手套,做好保护措施,减少皮肤暴露。     

污染源排气自动监测氮氧化物的不确定度分析

使用烟气排放连续监测系统自动监测仪器测定污染源排气中氮氧化物,按照最新的《测量不确定度评定与表示》(JJF1059.1—2012)的要求,测量不确定度评定的要求,首次对其氮氧化物自动监测的不确定度进行分析,得出不确定度报告。     

Low cost measurements of nitrogen and sulphur dry deposition velocities at a semi-alpine site: gradient measurements and a comparison with deposition model estimates

The conditional time averaged gradient method was used to measure air-surface exchange of nitrogen and sulphur compounds at a semi-alpine site in Southern Norway. Dry deposition velocities were then obtained from the bi-weekly concentration gradient measurements. Annual deposition velocities were found to be 1.4, 11.8 and 4.0 mm s(-1) for NH3, HNO3 and SO2, respectively, if all data were included, and to be 10.8, 11.8 and 13.0 mm s(-1), respectively, if only positive values were included. Measured deposition velocities were compared to two sets of values estimated from a big-leaf dry deposition module applying to two different land types (short grass and forbs, and tundra), driven by measured micrometeorological parameters. The deposition module gives reasonable values for this site throughout the year, but does not reproduce the large variability as shown in the measured data. No apparent seasonal variations were found from either measurements or module estimates due to the very low productivity of the studied area.     

Evaluation of ogawa passive sampling devices as an alternative measurement method for the nitrogen dioxide annual standard in El Paso, Texas

Nitrogen Dioxide (NO₂) is a common urban air pollutant that results from the combustion of fossil fuels. It causes serious human health effects, is a precursor to the formation of ground level ozone, another serious air pollutant, and is one of the six criteria air pollutants established by the United States (U.S.) Clean Air Act (CAA). Ogawa Passive Sampling Devices (PSDs) for NO₂ were collocated and operated at six NO₂ Federal Reference Method (FRM) monitor locations in the El Paso, Texas area for the 2004 calendar year. Passive samples were taken at 2-week, 3-week, and 4-week intervals and compared against the continuously operating FRM monitors. Results showed that the collective NO₂ annual arithmetic mean for all passive monitors was identical to the NO₂ mean for all FRM monitors. Of the individual locations, three passive annual NO₂ means were identical to their corresponding FRM means, and three passive annual NO₂ means differed from their corresponding FRM means by only one part per billion (ppb). Linear correlation analysis between all readings of the individual NO₂ PSDs and FRM values showed an average absolute difference of 1.2 ppb with an r ² of 0.95. Paired comparison between high and low concentration annual NO₂ sites, seasonal considerations, and interlab quality control comparisons all showed excellent results. The ease of deployment, reliability, and the cost-savings that can be realized with NO₂ PSDs could make them an attractive alternative to FRM monitors for screening purposes, and even possibly an equivalent method for annual NO₂ monitoring. More tests of the Ogawa NO₂ PSD are recommended for different ecosystem and climate regimes.     

Trends in snowpack chemistry and comparison to National Atmospheric Deposition Program results for the Rocky Mountains, US, 1993–2004

Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993–2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions. Seasonal Kendall tests were used to evaluate trends at individual sites.Significant trends occurred during the period in wetfall and snowpack concentrations and deposition, and in precipitation. For the comparison, trends in concentrations of ammonium, nitrate, and sulfate for the two networks were in fair agreement. In several cases, increases in ammonium and nitrate concentrations, and decreases in sulfate concentrations for both wetfall and snowpack were consistent in the three subregions. However, deposition patterns between wetfall and snowpack more often were opposite, particularly for ammonium and nitrate. Decreases in ammonium and nitrate deposition in wetfall in the central and southern rockies subregions mostly were moderately significant (p<0.11) in constrast to highly significant increases in snowpack (p<0.02). These opposite trends likely are explained by different rates of declining precipitation during the recent drought (1999–2004) and increasing concentration. Furthermore, dry deposition was an important factor in total deposition of nitrogen in the region. Sulfate deposition decreased with moderate to high significance in all three subregions in both wetfall and snowpack. Precipitation trends consistently were downward and significant for wetfall, snowpack, and snow-telemetry data for the central and southern rockies subregions (p<0.03), while no trends were noted for the Northern Rockies subregion.     

Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem

Elevated CO2 can stimulate wetland carbon(C) and nitrogen(N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant–water–soil system. The results showed:(1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively.(2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0–15 cm layer, and22.7% and 26.0% in the 15–30 cm soil layer.(3) Averaged across the rice growing period,elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%,respectively.(4) The TOC/TN ratio and natural δ15N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns.     

Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process

Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al₂O₃/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO₂ selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O₃ and highest CO₂ selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.     

Short- and medium-term effects of experimental nitrogen fertilization on arthropods associated with Calluna vulgaris heathlands in north-west Spain

We studied the short- and medium-term effects of experimental nitrogen fertilization (3 and 15 months after the treatment) on the arthropods of Calluna vulgaris heathlands in NW Spain. Three heathland sites were selected with two permanent plots per site: control and fertilized. Ammonium nitrate fertilizer (56 kg N ha(-1) yr(-1)) was applied monthly and insects were caught using pitfall traps. We found mainly species-level responses to nitrogen addition. Seven species (e.g. Lochmaea suturalis) showed a consistent trend (benefited or harmed) in both periods and were proposed as possible reliable indicators of the effects of nitrogen deposition in these ecosystems. We also found variable arthropod trophic-group responses: (a) herbivores (leaf beetles, true bugs) increased in abundance on a short-term scale; (b) predators (carabid beetles, true bugs) showed opposite and less clear responses in both periods. Further long-term studies are needed to determine the mechanisms underlying the observed arthropod responses.     

碳氮磷比失调对污水生物脱氮除磷的影响

我国南方城市污水普遍存在低碳相对高氮磷特征，本文介绍了同时生物脱氮除磷的机理、对碳源的需求与竞争，以及一些针对此类污水生物脱氮除磷的改进工艺及其在实际运用中的效果，并对此类污水的处理方向进行了展望。