辽河盘锦段与河口海域水体氮素分布特征及其与溶解氧的关系

选取辽河盘锦段至河口近岸海域区域进行研究水体中氨氮、硝酸盐氮和亚硝酸盐氮的分布特征及其与溶解氧的关系进行研究。结果表明水中氮素含量高于海水,且氨氮表现尤为突出,可能与水体中溶解氧含量和微生物环境、海水的稀释和迁移有很大关系;河水中氮素与溶解氧的呈显著负相关,而海水中氮素与溶解氧的关系不明显。这可能与海水的质化作用有关。     

环境样品保存过程中氮的转化规律

通过对环境样品保存过程中NH3-N、NO2-N、NO3-N及总氮的测定来研究水样中氮转化规律,找出三氯在一定条件下相互转化规律关系,提高环境样品中三个分析项目的分析准确性,正确反应环境样品中的真实情况。对于认识水体中氮的循环,防止水体污染,保护水域环境,充分利用开发水资源有着十分重要的意义。     

ICS-1500离子色谱仪在地下水检测中的应用

采用ICS-1500离子色谱仪与淋洗液自动发生器联用,等浓度淋洗,用AS40自动进样,同时测定地下水中氟化物、氯化物、硫酸盐和硝酸盐氮。该方法简便快捷,灵敏度高,极大提高了分析的效率,适用于地下水中四项阴离子的检测。     

Formation of secondary inorganic aerosol in a frigid urban atmosphere

•Harbin showed relatively high threshold RH (80%) for apparent increase of SOR. •The observed SOR were at the lower end of the ratios from Beijing’s winter. •Temperature-dependent increase of NOR was sharper than that of SOR. • NOR increased with stronger biomass burning impact but SOR was largely unchanged. Formation of secondary inorganic aerosol (SIA) was investigated during a six-month long heating season in Harbin, China. Enhanced sulfate formation was observed at high relative humidity (RH), with the same threshold RH (80%) for both colder and warmer measurement periods. Compared to wintertime results from Beijing, the threshold RH was considerably higher in Harbin, whereas the RH-dependent enhancement of sulfur oxidation ratio (SOR) was less significant. In addition, the high RH events were rarely encountered, and for other periods, the SOR were typically as low as ~0.1. Therefore, the sulfate formation was considered inefficient in this study. After excluding the several cases with high RH, both SOR and the nitrogen oxidation ratio (NOR) exhibited increasing trends as the temperature increased, with the increase of NOR being sharper. The nitrate to sulfate ratio tended to increase with increasing temperature as well. Based on a semi-quantitative approach, this trend was attributed primarily to the temperature-dependent variations of precursors including SO₂ and NO₂. The influence of biomass burning emissions on SIA formation was also evident. With stronger impact of biomass burning, an enhancement in NOR was observed whereas SOR was largely unchanged. The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.     

Distribution of phytoplankton community and its influence factors in an urban river network,East China

To reveal the distribution characteristics of phytoplankton and the main influence factors under different conditions in the urban rivers, the investigations were conducted during autumn and winter 2014 in Changzhou City, East China. 178 taxa of phytoplankton belonging to 28 functional assemblages were identified. In autumn, the phytoplankton community compositions have high similarity for enhanced hydrological connectivity. The chlorophytes and diatoms (prevailing functional groups C, F, J, P), together with euglenoids (W1), showed high proportions of biomass in the main rivers and connected rivers. It was related to the well mixed eutrophic conditions. The phytoplankton community exhibited spatiotemporal heterogeneity in winter. Affected by the low water level and temperature, the free-living phytoflagellates (X2) replaced groups F and J in the main rivers. Phytoplankton productivity was the highest in the Tongji River. Chlorophytes Dictyosphaerium ehrenbergianum and Chlamydobotrys stellata had an overwhelming superiority during the winter bloom. They were significantly correlated with ammonium, total phosphorus and biochemical oxygen demand. Affected by tail water supply, the diatoms (MP) and euglenoids (W1) dominated in a beheaded river. The multivariate analyses based on the phytoplankton functional groups helped to evaluate the relationships and variations between the urban rivers. The redundancy analysis (RDA) results showed that nitrate nitrogen, water temperature, total nitrogen and total suspended solids were the main influence factors on the phytoplankton community. Except MP, the prevailing groups all showed significant negative correlations with nitrate nitrogen. Availability and utilization of dissolved inorganic nitrogen and hydrodynamic conditions affected the phytoplankton distribution.

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垃圾渗滤液脱氮新方法综述

有效去除垃圾渗滤液中的氮是一项艰巨的任务,传统的先硝化后反硝化处理方法存在的主要问题是反硝化阶段碳源不足和总氮去除效率过低。研究中研究人员提出了好氧反硝化、厌氧氨氧化和短程硝化反硝化等新方法。好氧反硝化菌可以利用硝化过程中充足的碳源进行反硝化;厌氧氨氧化是在缺氧条件下,以NO-2为电子受体,直接把氨氧化成N2;短程硝化反硝化将脱氮过程控制在亚硝化阶段,不但节省了反硝化过程中的碳源,而且减少了能量的消耗。本文对这些方法及其在实践的应用进行了论述。     

Assessment of sources and transformation of nitrate in the alluvial-pluvial fan region of north China using a multi-isotope approach

A multi-isotope approach and mixing model were combined to identify spatial and seasonal variations of sources,and their proportional contribution to nitrate in the Hutuo River alluvial-pluvial fan region.The results showed that the NO_3~- concentration was significantly higher in the Hutuo River valley plain(178.7 mg/L) region than that in the upper and central pluvial fans of the Hutuo River(82.1 mg/L and 71.0 mg/L,respectively)and in the river(17.0 mg/L).Different land use types had no significant effect on the groundwater nitrate concentration.Based on a multi-isotope approach,we confirmed that the main sources of groundwater nitrate in different land use areas were domestic sewage and manure,followed by soil nitrogen,ammonia fertilizer,nitrate fertilizer and rainwater,and there were no significant spatial or seasonal variations.Combining δ~(15)N-NO_3,δ~(18)O-NO_3~- and δ~(37)Cl results can increase the accuracy of traceability.Nitrification could be the most important nitrogen migration and transformation process,and denitrification did not significantly affected the isotopic composition of the nitrate.The SIAR model outputs revealed that the main nitrate pollution sources in groundwater and river water were domestic sewage and manure,accounting for 55.9%-61.0% and 22.6%(dry season),50.3%-60.4% and 34.1%(transition season),42.7%-47.6% and 35.6%(wet season 2016) and 45.9%-46.7% and 38.4%(wet season 2017),respectively.This work suggests that the random discharge and disposal of domestic sewage and manure should be the first target for control in order to prevent further nitrate contamination of the water environment.     

硝酸盐浓度及投加方式对反硝化除磷的影响

采用SBR反应器，详细研究了硝酸盐浓度及其投加方式对反硝化除磷过程的影响。结果表明，缺氧环境下的反硝化吸磷速率与作为电子受体的硝酸盐浓度有很大的关系，硝酸盐浓度越高．吸磷速率越快。当硝酸盐浓度较低．不足以氧化反硝化聚磷菌细胞内的PHB从而导致体系反硝化除磷效率的下降。相同浓度的硝酸盐，采用流加的方式可以获得比一次性投加更高的反硝化吸磷速率。缺氧环境下，反硝化脱氮量与磷的吸收量成良好的线性关系．借助于反硝化聚磷菌，反硝化脱氮与除磷可在一种环境中完成，有效解决了废水中COD不足的问题．同时达到了节省能源和降低污泥产量的目的。     

Determination of Water-soluble Atmospheric Aerosols Using Ion Chromatography

A field study was established to investigate the chemical composition of atmospheric aerosols in Chicago, IL. One goal of this study was to determine the influence of precursor trace gases and local meteorology on concentrations of secondary aerosol ionic species. This paper describes the method details, shows the method is analytically valid, and reports overall as well as some specific results found during the field study. Two particulate air samples were collected per day onto quartz fiber filters at the Loyola University Chicago Air Station during the summer months in 2002–2004. In parallel, mixing ratios of ozone and nitrogen oxides were monitored and weather parameters were recorded. Particulates were extracted from the filter substrates and the subsequent solutions were analyzed by ion chromatography for anions, including low molecular weight organic acids, and cations. A washing procedure was implemented to reduce the high background values of the quartz fiber filters. Method validation showed that the collection method was efficient for all ions with exception of nitrate, whose efficiency of 70% indicated losses caused by volatilization. The extraction method also proved efficient for both field and laboratory samples, and the repeatability of the method was high with relative standard deviations less than 10% for all ions. Reproducibility of the results was determined by comparison of sulfate to sulfur analyzed by total reflection X-ray fluorescence spectrometry and proved to be high as well. Concentrations differed significantly between the three summer studies due to varying levels of precursor species as a consequence of distinct temperatures and wind direction profiles.     

含氮杂环化合物吡啶缺氧降解过程中硝酸还原酶活性研究

在实验室中，采用摇床试验，在保证缺氧的条件下。研究了含氮杂环化合物吡啶缺氧反硝化降解过程中，硝酸还原酶的适宜作用条件、吡啶降解过程中硝酸还原酶活性变化情况及吡啶和硝态氮等的降解情况。结果表明，C／N对吡啶缺氧反硝化降解具有重要意义，pH和温度均对硝黧还原酶活性具有一定影响。硝酸还原酶的适宜作用条件为：温度25—30℃，pH7．5。吡啶降解过程中，硝酸还原酶活性由低到高逐渐提高，最后达到一个相对稳定的数值。在适宜的碳氮比条件下，吡啶起始浓度越高，硝酸还原酶最后稳定活性越高。