Improved speciation of dissolved organic nitrogen in natural waters: amide hydrolysis with fluorescence derivatization

The objective of this study was to improve primary-amine nitrogen (1°-N) quantification in dissolved organic matter (DOM) originating from natural waters where inorganic forms of N, which may cause analytical interference, are commonly encountered. Efforts were targeted at elucidating organic-N structural criteria influencing the response of organic amines to known colorimetric and fluorescent reagents and exploring the use of divalent metal-assisted amide hydrolysis in combination with fluorescence analyse...     

Nutrient retention in tile-fed and non-tile reconstructed oxbows in north central Iowa

Nutrient export from the agricultural Midwest threatens the Gulf of Mexico and new conservation practices are needed to reduce the loss of nutrient from subsurface tile drainage systems. Oxbows are natural waterbodies formed when a river cuts off a meander loop and water quality benefits of reconstructed oxbows are being increasingly recognized. In this study, we monitored four reconstructed oxbow sites (two tile-fed, two non-tile) over a 2-year period in north-central Iowa and assessed their capacity for NO₃-N and dissolved reactive phosphorus (DRP) reductions. Water flow and quality monitoring of tiles, shallow groundwater, oxbow and receiving streams documented that the oxbows were dominated by tile drainage inputs. NO₃-N concentrations were highest in the drainage tiles flowing into the tile-fed oxbows (mean 8–10 mg/L) and much lower in floodplain groundwater (<1–2 mg/L). Annual NO₃-N loads into the tile-fed oxbows were substantially larger than input loads into the non-tiled oxbows. For the two tile-fed oxbows, the 2-year NO₃-N retention efficiencies were very similar (0.76–0.77) and on a monthly basis, greater retention efficiencies were measured in summer and fall. DRP concentrations and loads into the tile-fed oxbows were too low to allow for meaningful estimates of retention. Reconstructing oxbows to receive tile drainage water should be considered a sustainable conservation practice for tile drainage treatment in agricultural areas.     

河流水质1号模型探讨

介绍了河流水质模型70年来的发展历程和目前存在的不足之处,论述了河流水质1号模型(RwQM1)的研究成果.河流水质1号模型从活性污泥模型ASM中发展而来,并推出了建立模型的决策化方法,其对生化反应模型的完善而成为河流水质模型发展的一个标准平台.本文重点介绍了其在生化反应模型方面的进展,并和QUAL2E做了比较.     

鸭绿江口的溶解无机氮

本文讨论了１９９６年５月鸭绿江溶解无机氮的含量和分布变化特征，并同其他一些河口作了比较，鸭绿江口ＮＯ３－Ｎ，ＮＯ２－Ｎ，ＮＨ４－Ｎ的平均含量分别为５０．３．０．４５和３．０５μｍｏｌ／Ｌ，而丹东上游鸭绿江支流瑗河下降的溶解无机氮浓度很高，达２０３．４μｍｏｌ／Ｌ，主要由农业施用氮肥大量从耕用地中流失所致。     

北京动物园水禽湖溶解氧动态与喷泉增氧效果分析

对北京动物园水禽湖的溶解氧动态规律进行了分析研究 ,根据得出的结果及动物园特殊的环境特征 ,提出了采用喷泉增氧的方式来改善水禽湖的溶解氧状况 ,同时对喷泉的增氧效果作了分析     

Factors affecting simultaneous nitrification and denitrification in an SBBR treating domestic wastewater

An aerobic sequencing batch biofilm reactor (SBBR) packed with Bauer rings was used to treat real domestic wastewater for simultaneous nitrification and denitrification. The SBBR is advantageous for creating an anoxic condition, and the biofilm can absorb and store carbon for good nitrification and denitrification. An average concentration of oxygen ranging from 0.8 to 4.0 mg/L was proved very efficient for nitrification and denitrification. Volumetric loads of TN dropped dramatically and effluent TN concentration increased quickly when the concentration of average dissolved oxygen was more than 4.0 mg/L. The efficiency of simultaneous nitrification and denitrification (SND) increased with increasing thickness of the biofilm. The influent concentration hardly affected the TN removal efficiency, but the effluent TN increased with increasing influent concentration. It is suggested that a subsequence for denitrification be added or influent amount be decreased to meet effluent quality requirements. At optimum operating parameters, the TN removal efficiency of 74%–82% could be achieved. Translated from Acta Scientiae Circumstantiae, 2006, 26(5): 728–733 [译自: 环境科学学报]     

大亚湾海域海水中各种形态磷的研究

根据 1999年 5月 (春季 )的调查 ,统计了大亚湾海域海水微表层、次表层、表层和底层水中各种形态P的含量 ,计算了各种形态P分别占总磷 (TP)和总溶解磷 (TDP)的百分比 ,讨论了各种形态P之间的相互关系 ,分析了影响颗粒磷 (PP)和溶解磷 (TDP)分布的环境因素。结果表明 ,大多数站位微表层对各种形态P产生了富集 ,但是富集概率有所差别 ;大亚湾海域水中P ,除微表层主要以PP形态存在外 ,其余水层均主要以TDP形态存在 ,TDP在所有水层中均以DOP为主要存在形态 ;各个水层中PP是影响TP分布变化的主要因素 :影响PP在微表层、次表层和表层分布变化的主要环境因素为COD ,在底层则为叶绿素a与COD的叠加 ;影响TDP在微表层和底层分布变化的主要环境因素为盐度 ,在次表层和表层则为COD。     

物化-厌氧-好氧-溶气吸附工艺在毛条废水治理中的应用

介绍了应用物化 厌氧 好氧 溶气吸附工艺治理毛条废水（ＣＯＤＣｒ浓度１３８０００～１５６００ｍｇ／Ｌ）的工程实例。一年多的运行情况表明ＣＯＤＣｒ去除率达９９３％。     

Urea Fluctuations in Stream Baseflow across Land Cover Gradients and Seasons in a Coastal Plain River System

Urea‐N is a component of bioavailable dissolved organic nitrogen (DON) that contributes to coastal eutrophication. In this study, we assessed urea‐N in baseflow across land cover gradients and seasons in the Manokin River Basin on the Delmarva Peninsula. From March 2010 to June 2011, we conducted monthly sampling of 11 streams (4 tidal and 7 nontidal), 2 wastewater treatment plants, an agricultural drainage ditch, and groundwater underlying a cropped field. At each site, we measured urea‐N, DON, dissolved organic carbon (DOC), total dissolved nitrogen (TDN), NO₃^?‐N, and NH₄⁺‐N. In general, urea‐N comprised between 1% and 6% of TDN, with the highest urea‐N levels in drainage ditches (0.054 mg N/L) and wetland‐dominated streams (0.035–0.045 mg N/L). While urea‐N did not vary seasonally in tidal rivers, nontidal streams saw distinct urea‐N peaks in summer (0.038 mg N/L) that occurred several months after cropland fertilization in spring. Notably, the proportion of wetlands explained 78% of the variance in baseflow urea‐N levels across the Manokin watershed. In wetland‐dominated basins, we found urea‐N was positively related to water temperature and negatively related to DOC:DON ratios, indicating short‐term urea‐N dynamics at baseflow were more likely influenced by instream and wetland‐driven processes than by recent agricultural urea‐N inputs. Findings demonstrate important controls of wetlands on baseflow urea‐N concentrations in mixed land‐use basins.