Analysis of the nitrifying bacterial community in BioCube sponge media using fluorescent in situ hybridization (FISH) and microelectrodes

There is growing interest in the development of more cost-effective and retrofit technologies for the upgrade and expansion of existing wastewater treatment plants with extreme space constraints. A free-floating sponge media (BioCube) process, using a 24L lab scale reactor, was operated to study the nitrification profiles and microbial community. The COD removal efficiencies were maintained, at an average of 95%, with the mixed liquor suspended solids (MLSS) inside the BioCube sponge media maintained at 12,688mg/L. The nitrification removal efficiencies were between 92% and 100%, with an average value of 99%. From the results of microelectrode measurements, the ammonium ion concentration was found to rapidly decrease from the surface of the BioCube sponge media to a depth of 2mm due to chemical reactions carried out by ammonia oxidizing bacteria (AOB) species. Multi-fluorescence in situ hybridization (FISH) has been used to investigate the spatial distributions of various microbial activities within reactors. Microbial communities were targeted using different oligonucleotide probes specific to AOB and nitrite oxidizing bacteria (NOB). There were a large number of AOB populations, but these were not uniformly distributed in the biofilm compared to the NOB populations.     

Particulates, not plants, dominate nitrogen processing in a septage-treating aerated pond system

In pond and wetland systems for wastewater treatment, plants are often thought to enhance the removal of ammonium and nitrogen through the activities of root-associated bacteria. In this study, we examined the role of plant roots in an aerated pond system with floating plants designed to treat high-strength septage wastewater. We performed both laboratory and full-scale experiments to test the effect of different plant root to septage ratios on nitrification and denitrification, and measured the abundances of nitrifying bacteria associated with roots and septage particulates. Root-associated nitrifying bacteria did not play a significant role in ammonium and total nitrogen removal. Investigations of nitrifier populations showed that only 10% were associated with water hyacinth [Eichhornia crassipes (Mart.) Solms] roots (at standard facility plant densities equivalent to 2.2 wet g roots L(-1) septage); instead, nitrifiers were found almost entirely (90%) associated with suspended septage particulates. The role of root-associated nitrifiers in nitrification was examined in laboratory batch experiments where high plant root concentrations (7.4 wet g L(-1), representing a 38% net increase in total nitrifier populations over plant-free controls) yielded a corresponding increase (55%) in the non-substrate-limited nitrification rate (V(max)). However, within the full-scale septage-treating pond system, nitrification and denitrification rates remained unchanged when plant root concentrations were increased to 7.1 g roots L(-1) (achieved by increasing the surface area available for plants while maintaining the same tank volume). Under normal facility operating conditions, nitrification was limited by ammonium concentration, not nitrifier availability. Maximizing plant root concentrations was found to be an inefficient mechanism for increasing nitrification in organic particulate-rich wastewaters such as septage.     

Identification and quantitative evaluation of nitrogen-converting organisms in a full-scale leachate treatment plant

The presence of ammonia nitrogen in landfill leachates poses a significant problem for treatment plant operators. The nitrification-denitrification process mostly carries out the nitrogen conversion in biological treatment systems. However, recent research shows that other processes by anaerobic ammonia-oxidizing bacteria (Anammox) and ammonia-oxidizing archaea (AOA) were also responsible for the removal of nitrogen in biological systems. In this study, the nitrogen-converting microorganisms in the Bursa Hamitler Leachate Treatment Plant were identified and monitored by using molecular tools. Fluorescent in situ hybridization (FISH) and slot-blot hybridization results showed that the Nitrosomonas and Nitrospira species were the dominant ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), respectively. Quantitative real-time PCR results indicated that AOB, NOB, AOA and Anammox bacteria exist in the leachate treatment plant. However, the removal of ammonia can be ascribed mainly to nitrification because AOB (1.5%) and NOB (11.3%) were predominant among all nitrogen-converting bacteria. The results of the phylogenetic analysis based on amoA and 16S rDNA gene revealed that the uncultured bacterium clone 4-24, Kuenenia stuttgartiensis genome fragment KUST_E and the uncultured Crenarchaeota clone NJYPZT-C1 belong to AOB, Anammox and AOA populations, respectively, and were the dominant species in their cluster.     

Nutrient conversions by photosynthetic bacteria in a concentrated animal feeding operation lagoon system

A diurnal examination was conducted to determine the effect of photosynthetic bacteria on nutrient conversions in a two-stage concentrated animal feeding operation (CAFO) lagoon system in west-central Oklahoma. Changes in nutrients, microbial populations, and physical parameters were examined at three depths (0, 1.5, and 3.0 m) every 3 h over a 36-h period. The south lagoon (SL) was anaerobic (dissolved oxygen [DO] = 0.09 +/- 0.12 mg/L) while the north lagoon (NL) was facultative (DO ranged from 4.0-0.1 mg/L over 36-h period). Negative sulfide-sulfate (-0.85) and bacteriochlorophyll a (bchl a)-sulfate (-0.83) correlations, as well as positive bchl a-sulfide (0.87) and light intensity (I)-bchl a (0.89) correlations revealed that the SL was dominated by sulfur conversions driven by the photosynthetic purple sulfur bacteria (PSB). The correlation data was supported by diurnal trends for sulfate, sulfide, and bchl a. Both nitrogen and sulfur conversions played a role in the NL; however, nitrogen conversions appeared to dominate this system because of the activity of cyanobacteria. This was shown by positive chlorophyll a (chl a)-I (0.91) and chl a-nitrate (0.98) correlations and the negative correlation between ammonium and nitrite (-0.88). Correlation data was further supported by diurnal trends observed for chl a, DO, and ammonium. For both lagoons, the dominant photosynthetic microbial species determined which nutrient conversion processes were most important.     

Solids and nutrient removal from flushed swine manure using polyacrylamides

Most of the organic nutrient elements (nitrogen and phosphorus) and carbon compounds in liquid swine are contained in fine suspended particles. Flocculation treatment with polyacrylamide (PAM) followed by screening is one the best methods to separate the liquid fraction from the solid fraction in swine manure, and thus to eliminate nutrient elements associated with solids. In this study, the efficiency of a synthetic polyacrylamide to treat swine manure was evaluated. After polymer treatment samples were sieved and the filtrated liquid was analyzed. TSS, VSS and COD concentrations in the liquid fraction were 2.17, 1.93 and 16.42 g/L respectively, accounting for 94, 94 and 77% removal percentages for TSS, VSS and COD using 30 mg/L of PAM.     

S-TE剩余污泥溶解过程中VSS的变化研究

从土壤中筛选出1株能分泌胞外酶、促进污泥溶解的嗜热脂肪芽孢杆菌Bacillus stearothermophilusAT07-1,将AT07-1培养液接种到不同浓度（TSS约为7.5、14.5、20.5 g/L）的剩余污泥中,于65℃进行嗜热菌溶解试验,并与未接种试验进行对比。结果表明,接种嗜热菌AT07-1促进了污泥中悬浮固体的溶解。60h时接种试验VSS的溶解率分别为61.41%、53.79%、41.86%,比不接种试验同期分别提高了27.57%、25.24%、16.26%。试验条件下VSS溶解过程在初始阶段（t=3d）符合一级反应动力学模型,接种后溶解速率常数Kd显著提高,从0.12 d-1、0.08 d-1、0.09 d^-1分别增加到0.27 d^-1、0.24 d^-1、0.13 d^-1。     

Response of spinach and komatsuna to biogas effluent made from source-separated kitchen garbage

Recycling of kitchen garbage is an urgent task for reducing public spending and environmental burdens by incineration and/or landfill. There is an interesting regional effort in Ogawa, Saitama prefecture, Japan, in which source-separated kitchen garbage is anaerobically fermented with a biogas plant and the resultant effluent is used as a quick-release organic fertilizer by surrounding farmers. However, scientific assessments of fertilizer values and risks in the use of the effluent were lacking. Thus, a field experiment was conducted from 2003 to 2004 in Tohoku National Agricultural Research Center to grow spinach (Spinacia oleracea L.) and komatsuna (Brassica rapa var. perviridis L. H. Bailey) for evaluating the fertilizer value of the kitchen garbage effluent (KGE), nitrate, coliform group (CG), Escherichia coli, fecal streptococci (FS), and Vibrio parahaemolyticus concentrations of KGE and in the soil and the plant leaves. A cattle manure effluent (CME) and chemical fertilizers (NPK) were used as controls. Total nitrogen (N) and ammonium N concentrations of the KGE were 1.47 and 1.46 g kg(-1), respectively. The bacteria tested were detected in both biogas effluents in the order of 2 to 3 log CFU g(-1), but there was little evidence that the biogas effluents increased these bacteria in the soil and the plant leaves. At the rate of 22 g N m(-2), yield, total N uptake, apparent N recovery rate, and leaf nitrate ion concentration at harvest of spinach and komatsuna in the KGE plot were mostly comparable to those in the NPK and CME plots. We conclude that the KGE is a quick-release N fertilizer comparable to chemical fertilizers and does not cause contamination of CG, E. coli, FS, or V. parahaemolyticus in the soil and spinach and komatsuna leaves.     

Management strategy impacts on ammonia volatilization from swine manure

Ammonia emitted from manure can have detrimental effects on health, environmental quality, and fertilizer value. The objective of this study was to measure the potential for reduction in ammonia volatilization from swine (Sus scrofa domestica) manure by temperature control, stirring, addition of nitrogen binder (Mohave yucca, Yucca schidigera Roezl ex Ortgies) or urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)], segregation of urine from feces, and pH modification. Swine manure [total solids (TS) = 7.6-11.2%, total Kjeldahl nitrogen (TKN) = 3.3-6.2 g/L, ammonium nitrogen NH(+)(4)-N = 1.0-3.3 g/L] was stored for 24, 48, 72, or 96 h in 2-L polyvinyl chloride vessels. The manure was analyzed to determine pre- and post-storage concentrations of TS and volatile solids (VS), TKN, and NH(+)(4)-N. The concentration of accumulated ammonia N in the vessel headspace (HSAN), post-storage, was measured using grab sample tubes. Headspace NH(3) concentrations were reduced 99.3% by segregation of urine from feces (P < 0.0001). Stirring and NBPT (152 microL/L) increased HSAN concentration (119 and 140%, respectively). Headspace NH(3) concentration increased by 2.7 mg/m(3) for every 1 degree C increase in temperature over 35 degrees C. Slurry NH(+)(4)-N concentrations were reduced by segregation (78.3%) and acidification to pH 5.3 (9.4%), and increased with stirring (4.8%) and increasing temperature (0.06 g/L per 1 degree C increase in temperature over 35 degrees C). Temperature control, urine-feces segregation, and acidification of swine manure are strategies with potential to reduce or slow NH(+)(4)-N formation and NH(3) volatilization.     

Nutrient transport in a restored riparian wetland

We determined the water quality effect of a restored forested riparian wetland adjacent to a manure application area and a heavily fertilized pasture in the Georgia Coastal Plain. The buffer system was managed based on USDA recommendations and averaged 38 m in width. Water quality and hydrology data were collected from 1991-1999. A nitrate plume in shallow ground water with concentrations exceeding 10 mg NO3-N L(-1) moved into the restored forested riparian wetland. Along most of the plume front, concentrations were less than 4 mg NO3-N L(-1) within 25 m. Two preferential flow paths associated with past hydrologic modifications to the site allowed the nitrate plume to progress further into the restored forested riparian wetland. Surface runoff total N, dissolved reactive phosphorus (DRP), and total P concentrations averaged 8.63 mg N L(-1), 1.37 mg P L(-1), and 1.48 mg P L(-1), respectively, at the field edge and were reduced to 4.18 mg N L(-1), 0.31 mg P L(-1), and 0.36 mg P L(-1), respectively, at the restored forested riparian wetland outlet. Water and nutrient mass balance showed that retention and removal rates for nitrogen species ranged from a high of 78% for nitrate to a low of 52% for ammonium. Retention rates for both DRP and total P were 66%. Most of the N retention and removal was accounted for by denitrification. Mean annual concentrations of total N and total P leaving the restored forested riparian wetland were 1.98 mg N L(-1) and 0.24 mg P L(-1), respectively.     

Water and nitrogen management effects on water and nitrogen fluxes in Florida Flatwoods

The effects of water and fertilizer best management practices (BMPs) have not been quantified for groundwater nitrogen (N) beneath seepage irrigated vegetable fields with shallow water table environments. This effect was evaluated by a 3-yr study conducted in the Flatwoods of south Florida for watermelon ( cv. Mardi Gras and Tri-X 313) and tomato ( cv. BHN 586) using three treatments of water and inorganic fertilizer N (N) rates: (i) high fertilizer and water rates with seepage irrigation (HR), (ii) recommended fertilizer and water rates (BMP) with seepage irrigation (RR); and (iii) RR with subsurface drip irrigation (RR-SD). These treatments were implemented on six hydraulically isolated plots. The N rate treatments for high (HR) and recommended (RR and RR-SD) were based on a grower survey and BMP recommendations, respectively. Water applied, water table depth, and soil moisture content were regularly monitored for each treatment. Plant, soil, and groundwater N sampling and analyses were conducted for each season of the 3-yr study. The average water applied in HR (187 cm) was greater than RR (172 cm) and RR-SD (94 cm). Soil N maintained in crop beds for HR was significantly higher than RR and RR-SD. Soil solution analyses showed that N leached beneath HR (112 mg L) was greater ( = 0.053) than RR (76 mg L) and RR-SD (88 mg L). Shallow groundwater concentrations of dissolved inorganic nitrogen (NH-N + NO-N) were higher ( = 0.02) in HR (37 mg L) compared with RR (15 mg L) and RR-SD (19 mg L). Decreased N and water table levels can improve groundwater quality by reducing N leachate in shallow water table environments with seepage irrigated vegetable production systems.     

氮素和水分对贝加尔针茅草原土壤酶活性和微生物量碳氮的影响

在内蒙古贝加尔针茅草原,分别设对照（N0）、1.5 g·m^-2（N15）、3.0 g·m^-2（N30）、5.0 g·m^-2（N50）、10.0 g·m^-2（N100）、15.0 g·m^-2（N150）、20.0 g·m^-2（N200）和30 g·m^-2（N300）（不包括大气沉降的氮量）8个氮素（NH4NO3）梯度和模拟夏季增加降水100 mm的水分添加交互试验,研究氮素和水分添加对草原土壤养分、酶活性及微生物量碳氮的影响。结果表明：氮素和水分添加对草原土壤理化性质和生物学特性有显著影响。随施氮量的增加土壤总有机碳、全氮、硝态氮、铵态氮含量呈增加的趋势,相反,土壤pH值呈降低的趋势。土壤脲酶和过氧化氢酶的活性随施氮量的增加而升高,多酚氧化酶则随施氮量的增加呈下降的趋势。氮素和水分添加对草原土壤微生物量碳氮含量有显著影响,高氮处理（N150、N200和N300）显著降低了微生物碳含量,微生物氮含量随施氮量的增加呈上升趋势。水分添加能够减缓氮素添加对微生物的抑制作用,提高微生物量碳、微生物量氮含量。草原土壤养分、土壤酶活性及土壤微生物量碳氮含量间关系密切,过氧化氢酶与全氮、总有机碳、硝态氮呈显著正相关,多酚氧化酶与铵态氮、硝态氮、全氮呈显著负相关。微生物量氮含量与土壤全氮、铵态氮、硝态氮含量以及过氧化氢酶和磷酸酶活性呈显著正相关,与多酚氧化酶呈负相关;微生物量碳与过氧化氢酶呈负相关,与多酚氧化酶活性呈正相关。     

Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins

Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L and decreases in nitrate nitrogen (NO-N) from 2.7 mg L to <0.016 mg L, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0-7.8 mg L), resulting in NO-N of 1.3 to 3.3 mg L in shallow groundwater. Enrichment of δN and δO of NO combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO transport beneath the sandy basin. Soil-extractable NO-N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO impacts.     

SBR法处理垃圾渗滤液及其同时硝化反硝化生物脱氮研究

采用SBR系统处理城市垃圾渗滤液，研究了不同C／N、130和MLSS对同时硝化反硝化脱氮效率的影响。结果表明：总氮去除率随着C／N、MLSS升高而上升；DO越低，总氮去除率越高；当进水CODCr与NH3-N浓度分别为420mg／L和112mg／L,DO和MLSS分别为1．5mg／L和5016mg／L时，CODCr、NH3-N及TN去除率分别为81．54％、96．57％和46．66％。根据试验结果，对同时硝化反硝化一个代表周期作了分析。     

NUTRIENT CONCENTRATIONS IN WASTEWATER TREATMENT PLANT EFFLUENTS,SOUTH PLATTE RWER BASIN1

ABSTRACT: Accurate data about nutrient concentrations in wastewater treatment plant effluents are needed for river basin water-quality studies. As part of the U.S. Geological Survey's National Water-Quality Assessment Program in the South Platte River Basin, nutrient data were requested from 31 wastewater-treatment plants located in the basin. This article describes the types of nutrient data available from the plants, examines the variability of effluent nutrient concentrations, and discusses methods for estimation of nutrient concentrations where data are lacking. Ammonia was monitored at 88 percent of the plants, nitrite plus nitrate was monitored at 40 percent of the plants, and organic nitrogen and phosphorus were monitored at less than 25 percent of the plants. Median total nitrogen concentrations and median total phosphorus concentrations were small compared to typical literature estimates for wastewater-treatment plants with secondary treatment. Nutrient concentrations in effluent from wastewater-treatment plants varied widely between and within plants. For example, ammonia concentrations varied as much as 5 mg/L during a day, as much as 10 mg/L from day to day, and as much as 30 mg/L from summer to winter within a plant. In the South Platte River Basin, estimates of median annual ammonia and nitrite plus nitrate concentrations can be improved based on plant processes; and nitrite plus nitrate and organic nitrogen concentrations can be estimated based on ammonia concentrations. However, to avoid large estimation errors, more complete nutrient data from wastewater-treatment plants are needed for integration into river basin water quality studies. The paucity of data hinders attempts to evaluate the relative importance of point source and nonpoint source nutrient loadings to rivers.     

NUTRIENT CONCENTRATIONS AND YIELDS IN UNDEVELOPED STREAM BASINS OF THE UNITED STATES1

ABSTRACT: Data from 85 sites across the United States were used to estimate concentrations and yields of selected nutrients in streams draining relatively undeveloped basins. Flow‐weighted concentrations during 1990–1995 were generally low with median basin concentrations of 0.020, 0.087, 0.26, 0.010, and 0.022 milligrams per liter (mg/L) for ammonia as N, nitrate as N, total nitrogen, orthophosphate as P, and total phosphorus, respectively. The flow‐weighted concentration of nitrate exceeded 0.6 mg/L in only three basins. Total nitrogen exceeded 1 mg/L in only four basins, and total phosphorus exceeded 0.1 mg/L in only four basins. The median annual basin yield of ammonia as N, nitrate as N, total nitrogen, orthophosphate as P, and total phosphorus was 8.1, 26, 86, 2.8, and 8.5 kilograms per square kilometer, respectively. Concentrations and yields of nitrate tended to be highest in northeastern and mid‐Atlantic coastal states and correlated well with areas of high atmospheric nitrogen deposition. Concentrations and yields of total nitrogen were highest in the southeastern part of the nation and in parts of the upper Midwest. In the northeast, nitrate was generally the predominant form of nitrogen, and in the southeast and parts of the upper Midwest, organic nitrogen was the dominant form. Concentrations of total phosphorus were generally highest in the Rocky Mountain and Central Plain states.     

硫酸盐生物还原的限制性生态因子的影响研究

利用厌氧颗粒污泥对烟气中SO2吸收生成的硫酸盐或亚硫酸盐废水进行处理,考察起始SO4^2-质量浓度、初始COD／SO4^2-、初始pH、接种污泥质量、亚铁离子等限制性生态因子对硫酸盐还原的影响。结果表明：在起始SO4^2-质量浓度800mg／L,初始COD／SO4^2-为3．0,pH值为7．0,接种污泥质量为31．10gVSS／L,添加亚铁离子的条件下,进行半连续试验,硫酸根去除率可迭70％。表明在COD／SO4^2-较低的条件下,各生态因子综合作用下,硫酸盐还原可得较好效果。     

分光光度法测定硝酸盐氮中的干扰因素

对酚二磺酸分光光度法测定水样中硝酸盐氮的标准方法进行研究,在不同浓度的氯化物、氨氮和亚硝酸盐氮中加入不同浓度的硝酸盐氮标准溶液进行干扰试验。结果表明:在最佳的试验条件控制下,氯离子对低浓度硝酸盐氮测定产生的负干扰明显大于对高浓度硝酸盐氮产生的负干扰;随着加入的氨氮和氯化物浓度的增加,硝酸盐氮含量的测定结果低于实际值,且逐渐减小;在试验浓度范围内亚硝酸盐氮浓度对硝酸盐氮的测定几乎无影响。     

Influence of alternative and conventional farming practices on subsurface drainage and water quality

Agricultural runoff contributes nutrients to nonpoint-source pollution of surface waters. This study was conducted to investigate the potential use of alternative farming practices to improve water quality. The study examined the effects of both alternative and conventional farming practices on subsurface drainage and nitrogen and phosphorus loss through subsurface drainage from glacial till soils (i.e., Calciaquolls, Endoaquolls, Eutrudepts, Hapludolls) in southwest Minnesota. Alternative farming practices included organic management practices, species biodiversity, and/or practices that include reduced inputs of synthetic fertilizer and pesticides. Conventional farming practices include corn-soybean (Zea mays L.-Glycine max L., respectively) rotations and their associated recommended fertilizer rates as well as pesticide usage. Precipitation was highly variable during the 3-yr study period including a below-average year (2003), an average year (2002), and an above-average year (2004). Results indicate that alternative farming practices reduced subsurface drainage discharge by 41% compared with conventional practices. Flow-weighted mean nitrate-nitrogen (nitrate N) concentrations during tile flow were 8.2 and 17.2 mg L(-1) under alternative and conventional farming practices, respectively. Alternative farming practices reduced nitrate N losses by between 59 and 62% in 2002 and 2004 compared with conventional practices. Ammonium-nitrogen (ammonium N), orthophosphorus, and total phosphorus losses in subsurface drainage were very low and did not pose a substantial risk of pollution. Results suggest that alternative farming practices have the potential to reduce agricultural impacts on water quality.     

Upgrading of distillery effluent by Nitrosococcus oceanus for its use as a low-cost fertilizer

Distillery effluent can be converted into biogas and the residue can be utilized as a fertilizer if it is detoxified. Several nitrifying bacteria were screened for detoxification of distillery effluent rich in chloride, nitrogen compounds, free ammonia and monovalent cations. Nitrosococcus oceanus collected from a brackish water lake (Chilka, Orrisa) was noticed to be a potential candidate for detoxification of distillery effluent. The detoxified distillery effluent was used in rice plant culture. The growth and development of rice plants was examined in terms of DCPIP—Hill activity, total carbohydrate, total protein and biomass of rice plants. The detoxified effluent-treated rice plants showed better growth and development as compared with control plant grown in full nutrient solution (Hoagland solution).     

Atmospheric nitrogen deposition and its long-term dynamics in a southeast China coastal area

Measurements were conducted during 2004-2005 and 2009-2010 to characterize atmospheric nitrogen (N) deposition to the Jiulong River Estuary - Xiamen Bay area in southeast China. Isotopic analysis and long-term data (1990-2009) for inorganic N extracted from the national acid deposition dataset were used to determine the dominant source of atmospheric nitrate and N component dynamics. The results showed that the mean dissolved total N concentration in rain water for the three coastal area sites was 2.71 ± 1.58 mg N L(-1) (n = 141) in 2004. The mean dissolved inorganic N at the Xiamen site was 1.62 ± 1.19 mg N L(-1) (n = 46) in 2004-2005 and 1.56 ± 1.39 mg N L(-1) (n = 36) in 2009-2010, although the difference is not significant, nitrate turnover dominates the N component in the latter period. Total deposition flux over Xiamen was 30 kg N ha(-1) yr(-1), of which dry and wet deposition contributed 16% and 84%, respectively. Nitrate in wet deposition with low isotopic value (between -3.05 and -7.48‰) was likely to have mostly originated from combustion NO(x) from vehicle exhausts. The inorganic N in acid deposition exhibited a significant increase (mainly for nitrate) since the mid-1990s, which is consistent with the increased gaseous concentrations of NO(x) and expanding number of automobiles in the coastal city (Xiamen). The time series of nitrate anions and ammonium cations as well as pH values during the period 1990-2009 reflected an increasing trend of N emission with potential implication for N-induced acidification.