Fate of nitrogen during composting of chicken litter

Chicken litter (a mixture of chicken manure, wood shavings, waste feed, and feathers) was composted in forced-aeration piles to understand the changes and losses of nitrogen (N) during composting. During the composting process, the chemical [different N fractions, organic matter (OM), organic carbon (C), and C:N ratio], physical, and microbial properties of the chicken litter were examined. Cumulative losses and mass balances of N and organic matter were also quantified to determine actual losses during composting. The changes in total N concentration of the chicken litter piles were essentially equal to those of the organic N. The inorganic N concentrations were low, and that organic N was the major nitrogenous constituent. The ammonium (NH(4)(+))-N concentration decreased dramatically during first 35 days of composting. However, the rapid decrease in NH(4)(+)-N during composting did not coincide with a rapid increase in (NO(3)(-)+NO(2)(-))-N concentration. The concentration of (NO(3)(-)+NO(2)(-))-N was very low (<0.5 g kg(-1)) at day 0, and this level remained unchanged during the first 35 days of composting suggesting that N was lost during composting. Losses of N in this composting process were governed mainly by volatilization of ammonia (NH(3)) as the pile temperatures were high and the pH values were above 7. The narrow C:N ratio (<20:1) have also contributed to losses of N in the chicken litter. The OM and total organic C mass decreased with composting time. About 42 kg of the organic C was converted to CO(2). On the other hand, 18 kg was lost during composting. This loss was more than half (59%) of the initial N mass of the piles. Such a finding demonstrates that composting reduced the value of the chicken litter as N fertilizer. However, the composted chicken contained a more humified (stabilized) OM compared with the uncomposted chicken litter, which would enhance its value as a soil conditioner.     

Catalytic wet oxidation of ammonia: why is N2 formed preferentially against NO3 -?

The role of catalyst and the reason for the preferential formation of N(2) in the catalytic oxidation reaction of ammonia in water over a Ru (3wt.%)/TiO(2) catalyst were elucidated. It was verified that the catalyst in the reaction had no direct relevance to the selective formation of N(2), but was responsible only for the oxidation of aqueous ammonia, NH(3)(aq), finally giving a molecule of nitrous acid. The preferential production of N(2) was experimentally demonstrated due to the homogeneous aqueous phase reaction of the nitrous acid-dissociated NO(2)(-) with NH(4)(+) ions. Even under the highly oxidizing condition, NO(2)(-) was much more likely to react with NH(4)(+) to form N(2) than being oxidized over the catalyst to NO(3)(-) as long as NH(4)(+) was available in solution.     

Atmospheric nitrogen inputs to the Delaware Inland Bays: the role of ammonia

A previous assessment of nitrogen loading to the Delaware Inland Bays indicates that atmospheric deposition provides 15-25% of the total, annual N input to these estuaries. A large and increasing fraction of the atmospheric wet flux is NH(4)(+), which for most aquatic organisms represents the most readily assimilated form of this nutrient. Particularly noteworthy is a 60% increase in the precipitation NH(4)(+) concentration at Lewes, DE over the past 20 years, which parallels the increase in poultry production on the Delmarva Peninsula over this period (currently standing at nearly 585 million birds annually). To further examine the relationship between local NH(3) emissions and deposition, biweekly-integrated gaseous NH(3) concentrations were determined using Ogawa passive samplers deployed at 13 sampling sites throughout the Inland Bays watershed over a one-year period. Annual mean concentrations at the 13 sites ranged from <0.5 microg NH(3)m(-3) to >6 microg NH(3)m(-3), with a mean of 1.6+/-1.0 microg NH(3)m(-3). At most sites, highest NH(3) concentrations were evident during spring and summer, when fertilizer application and poultry house ventilation rates are greatest, and seasonally elevated temperatures induce increased rates of microbial activity and volatilization from soils and animal wastes. The observed north-to-south concentration gradient across the watershed is consistent with the spatial distribution of poultry houses, as revealed by a GIS analysis of aerial photographs. Based on the average measured NH(3) concentration and published NH(3) deposition rates to water surfaces (5-8 mm s(-1)), the direct atmospheric deposition of gaseous NH(3) to the Inland Bays is 3.0-4.8 kg ha(-1)yr(-1). This input, not accounted for in previous assessments of atmospheric loading to the Inland Bays, would effectively double the estimated direct dry deposition rate, and is on par with the NO(3)(-) and NH(4)(+) wet fluxes. A second component of this study examined spatial differences in NO(3)(-) and NH(4)(+) wet deposition within the Inland Bays watershed. In a pilot study, precipitation composition at the Lewes NADP-AIRMoN site (DE 02) was compared with that at a satellite site established at Riverdale on the Indian River Estuary, approximately 21 km southwest. While the volume-weighted mean precipitation NO(3)(-) concentrations did not differ significantly between sites, the NH(4)(+) concentration observed at Riverdale (26.3 micromoles L(-1)) was 73% greater than at Lewes (15.2 micromoles L(-1)). More recently, a NADP site was established at Trap Pond, DE (DE 99), which was intentionally located within the region of intense poultry production. A comparison of the initial two years (6/2001-5/2003) of precipitation chemistry data from Trap Pond with other nearby NADP-AIRMoN sites (Lewes and Smith Island) reveals fairly homogeneous NO(3)(-) wet deposition, but significant spatial differences ( approximately 60%) in the NH(4)(+) wet flux. Overall, these results suggest that local emissions and below-cloud scavenging provide a significant contribution to regional atmospheric N deposition.     

土霉素残留对猪粪堆肥过程中理化性质的影响

为探讨土霉素残留对猪粪堆肥过程的影响,以猪粪和锯末为原料,设置土霉素初始残留质量浓度分别为0、10、50、100、150 mg/kg的5个处理,进行为期30 d的好氧堆肥,研究土霉素对堆肥过程中温度、含水率、水溶性NH4+-N、水溶性NO3- -N、水溶性有机碳(DOC)的变化影响.结果表明:(1)土霉素残留加速了温度的下降,不利于温度的上升.(2)土霉素初始残留质量浓度为100、150 mg/kg不利于堆肥过程中水分的散失,并且会造成堆肥结束后堆体的高含水率.(3)土霉素抑制了堆肥过程中微生物对有机氮的分解及硝化细菌的硝化作用,其中150mg/kg处理的土霉素抑制作用最显著.(4)堆肥结束后,0、10、50、100、150 mg/kg处理的DOC分别为3 815.65、3 461.88、3 429.28、3 231.18、2 782.09mg/kg.0 mg/kg处理的DOC高于其他4个处理,且与150 mg/kg处理之间差异显著,表明土霉素抑制了堆肥过程中微生物对有机碳的利用,其中150 mg/kg处理的土霉素抑制作用最显著.     

Simulation modeling for nitrogen removal and experimental estimation of mass fractions of microbial groups in single-sludge system

Nitrification-denitrification in a single-sludge nitrogen removal system (SSNRS; with a sufficient carbon source for denitrification) was performed. With an increase in the mixed liquor recycle ratio (R(m)) from 1 to 2, the total nitrogen (TN) removal efficiency at a lower volumetric loading rate (VLR=0.21 NH(4)(+)-N m(-3) d(-1)) increased, but the TN removal efficiency at a higher VLR (0.35 kg NH(4)(+)-N m(-3) d(-1)) decreased. A kinetic model that accounts for the mass fractions of Nitrosomonas, Nitrobacter, nitrate reducer and nitrite reducer (f(n1), f(n2), f(dn1), and f(dn2)) in the SSNRS and an experimental approach for the estimation of the mass fractions of nitrogen-related microbial groups are also proposed. The estimated f(dn1) plus f(dn2) (0.65-0.83) was significantly larger than the f(n1) plus f(n2) (0.28-0.32); the f(n1) (0.21-0.26) was larger than the f(n2) (0.05-0.07); and the f(dn1) (0.32-0.45) varied slightly with the f(dn2) (0.33-0.38). At the lower VLR, the f(dn1) plus f(dn2) increased with increasing R(m); however at the higher VLR, the f(dn1) plus f(dn2) did not increase with increasing R(m). By using the kinetic model, the calculated residual NH(4)(+)-N and NO(2)(-)-N in the anoxic reactor and NO(2)(-)-N and NO(3)(-)-N in the aerobic reactor were in fairly good agreement with the experimental data; the calculated NO(3)(-)-N in the anoxic reactor was over-estimated and the calculated NH(4)(+)-N in the aerobic reactor was under-estimated.     

Deposition of nitrogen-containing compounds to an extensively managed grassland in central Switzerland

During four intensive observation periods in 1992 and 1993, dry deposition of nitrogen dioxide (NO(2)) and ammonia (NH(3)), and wet deposition of nitrogen (N) were determined. The measurements were carried out in a small, extensively managed litter meadow surrounded by intensively managed agricultural land. Dry deposition of NH(3) was estimated by the gradient method, whereas eddy correlation was used for NO(2). Rates of dry deposition of total nitrate (= nitric acid (HNO(3)) + nitrate (NO(3)(-))), total nitrite (= nitrous acid (HONO) + nitrite (NO(2)(-))) and aerosol-bound ammonium (NH(4)(+)) were estimated using deposition velocities from the literature and measured concentrations. Both wet N deposition and the vertical NH(3) gradient were measured on a weekly basis during one year. Dry deposition was between 15 and 25 kg N ha(-1) y(-1), and net wet deposition was about 9.0 kg N ha(-1) y(-1). Daily average NO(2) deposition velocity varied from 0.11 to 0.24 cm s(-1). Deposition velocity of NH(3), was between 0.13 and 1.4 cm s(-1), and a compensation point between 3 and 6 ppbV NH(3) (ppb = 10(-9)) was found. Between 60 and 70% of dry deposition originated from NH(3) emitted by farms in the neighbourhood. It is concluded that total N deposition is exceeding the critical load for litter meadows, is highly correlated to local NH(3) emissions, and that NH(3) is of utmost importance with respect to possible strategies to reduce N deposition in rural regions.     

Dry deposition of nitrogen and sulfur to Ponderosa and Jeffrey pine in the San Bernardino national forest in Southern California

Little is known about the concentrations, deposition rates, and effects of nitrogenous and sulfurous compounds in photochemical smog in the San Bernardino National Forest (SBNF) in southern California. Dry deposition of NO(3)(-) and NH(4)(+) to foliage of ponderosa pine (Pinus ponderosa Laws.) and Jeffrey pine (Pinus jeffreyi Grev. & Balf.) was correlated (R = 0.83-0.88) with historical average hourly O(3) concentations at 10 sites across an O(3) gradient in the SBNF. Mean deposition fluxes of NO(3)(-) to ponderosa and Jeffrey pine branches were 0.82 nmol M(-2)s(-1) at Camp Paivika (CP), a high-pollution site, and 0.19 nmol m(-2) s(-1) at Camp Osceola (CAO), a low-pollution site. Deposition fluxes of NH(4)(+) were 0.32 nmol m(-2) s(-1) at CP and 0.17 nmol m(-2) s(-1) at CAO, while mean values for SO(4)(2-) were 0.03 at CP and 0.02 nmol m(-2) s(-1) at CAO. Deposition fluxes to paper and nylon filters were higher in most cases than fluxes to pine branches at the same site. The results of this study suggest that an atmospheric concentration and deposition gradient of N and S compounds occurs along with the west-east O(3) gradient in the SBNF. Annual stand-level dry deposition rates for S and N at CP and CAO were estimated. Further studies are needed to determine if high N deposition loads in the SBNF significantly affect plant/soil nutrient relations, tree health, and the response of ponderosa pine to ozone.     

Dynamics of nitrogen in a PAHs contaminated soil amended with biosolid or vermicompost in the presence of earthworms

Nitrogen mineralization in PAHs contaminated soil in presence of Eisenia fetida amended with biosolid or vermicompost was investigated. Sterilized and unsterilized soil was contaminated with PAHs, added with E. fetida and biosolid or vermicompost and incubated aerobically for 70 days, while dynamics of inorganic N were monitored. Addition of E. fetida to sterilized soil increased concentration of NH(4)(+) 100> mg N kg(-1), while concentrations in unsterilized remained <60 mg N kg(-1) except for soil amended with biosolid plus PAHs where it increased to >80 mg kg(-1). Addition of PAHs had no significant effect on concentration of NH(4)(+) compared to the unamended soil, except in the soil added with biosolid. Addition of E. fetida to sterilized soil increased concentration of NO(2)(-) 15> mg N kg(-1) while concentrations in unsterilized soil remained <7.5 mg N kg(-1) except for soil amended with biosolid where it increased to >20 mg kg(-1). Addition of PAHs had no significant effect on concentration of NO(2)(-) compared to the unamended soil. Addition of biosolid and vermicompost increased concentration of NO(3)(-), while addition of E. fetida decreased concentration of NO(3)(-) in biosolid amended soil. It was found that NH(4)(+) and NO(2)(-) oxidizers were present in the gut of E. fetida, but their activity was not sufficient enough to inhibit a temporarily increase in concentrations of NH(4)(+) and NO(2)(-). Contamination with PAHs induced immobilization of N in biosolid or vermicompost amended soil, as did feeding of E. fetida on biosolid or vermicompost.     

The evaluation of stability and maturity during the composting of cattle manure

We examined chemical, microbiological and biochemical parameters in order to assess their effectiveness as stability and maturity indicators during the composting process of cattle manure. The composting material obtained after 15 d in trenches and at different times during the maturation phase (i.e. 80, 180 and 270 d) were analyzed. We found that the material collected at the end of the active phase was inadequate to be applied to soil as organic amendment due to its high content of NH4+, its high level of phytotoxicity and the low degree of organic matter stability. After a maturation period of 80 d, the stability of the sample increased. This was shown by a reduction in the dissolved organic carbon (DOC) content and NH4+ concentration and also by a reduction in the microbial activity and biomass; however, 180 d of composting were not sufficient to reduce the phytotoxicity to levels consistent for a safe soil application. Among the various parameters studied, the change in DOC with composting time gave a good indication of stability.     

Effect of ammonium and oxygen on methane and nitrous oxide fluxes across sediment-water interface in a eutrophic lake

Eutrophication has decreased the O(2) content and increased the NH(4)(+) availability in freshwaters. These changes may affect carbon and nitrogen transformation processes and the production of CH(4) and N(2)O, which are important greenhouse gases. We studied release of CH(4) and N(2)O from a eutrophic lake sediment under varying O(2) and NH(4)(+) conditions. Intact sediment cores were incubated in a laboratory microcosm with a continuous anoxic or oxic water flows containing 0, 50, 500, 5,000, or 15000 microM NH(4)(+). With the anoxic flow, the sediment released CH(4), up to 7.9 mmol m(-2)d(-1). With the oxic flow, the CH(4) emissions were small indicating limited CH(4) production and/or effective CH(4) oxidation. Addition of NH(4)(+) did not affect sediment CH(4) release, evidence that the CH(4) oxidizing bacteria were not disturbed by the extra NH(4)(+). The release of N(2)O from the sediment was highest, up to 7.6 micromol m(-2)d(-1), with the oxic flow without NH(4)(+) addition. Oxygen was the key factor regulating the production of NO(3)(-), which enabled denitrification and production of N(2)O. However, the highest NH(4)(+) addition increased nitrification and associated O(2) consumption causing a decrease in sediment O(2) content and in accumulation of NO(3)(-) and N(2)O, which were effectively reduced to N(2) in denitrification. In summary, sediment CH(4) and N(2)O dynamics are regulated more by the availability of O(2) than extra NH(4)(+). Anoxia in eutrophic lakes favouring the CH(4) production, is the major contributor to the atmospheric consequences of water eutrophication.     

Atmospheric deposition to the edge of a spruce forest in Denmark

Atmospheric deposition was measured during 1 year at the forest edge of a Norway spruce stand in Denmark. Inside the forest the deposition of H(+), Ca(2+), Mg(2+), Na(+), K(+), Cl(-), NO(3)(-), NH(4)(2) and SO(4)(2-) with canopy throughfall varies with the distance from the forest edge. The deposition at the edge is found to be 10-20 times as high as deposition to an open field and 2-8 times as high as deposition inside the stand. An exponential decrease in deposition as a function of the distance from the forest edge is found. Increased deposition of K(+) and non-sea salt Mg(2+), which mainly originates as a result of leaching from the needles may be explained by a larger leaf area index (LAI) at the forest edge. Deposition of particulate substances, especially Na(+), Cl(-), Mg(2+) and to some extent SO(4)(2-), NH(4)(+) and NO(3)(-) is increased much more than the LAI, which we believe to be caused by changes in wind movements at the forest edge.     

Effect of recycle-to-influent ratio on activities of nitrifiers and denitrifiers in a combined UASB-activated sludge reactor system

A laboratory study using a combined upflow anaerobic sludge bed (UASB)-activated sludge (AS) reactor system was undertaken to explore the effect of recycle-to-influent ratio (R(e)=1, 2, and 3) on the activities of nitrifiers and denitrifiers. Suspended-solids pre-settled piggery wastewater was used as the substrate-feed wastewater. At the R(e) of 1-3, the combined reactor system achieved efficient removal of COD (96-97%), TKN (100%) and total nitrogen TN (54-77%). Methanogenesis occurred with nearly-complete denitrification in the UASB reactor, whereas complete nitrification took place in the AS reactor. A higher R(e) (i.e., accompanied with a shorter solids retention time) resulted in a larger amount of high-activity denitrifiers and thereby achieved a higher TN removal efficiency. Compact granules and a high biomass concentration in the UASB reactor were observed. At the R(e) of 1-3, the maximum specific reaction rate of nitrifiers (0.45-0.49 NH(4)(+)-NmgVSS(-1)d(-1)) and the specific nitrification rates of mixed culture (0.18-0.22mg NH(4)(+)-NmgVSS(-1)d(-1)) in the AS reactor varied slightly; whereas the maximum specific reaction rate of denitrifiers (0.18-0.27mg NO(x)(-)-NmgVSS(-1)d(-1)) and the specific denitrification and COD removal rates of mixed culture (0.025-0.050mg NO(x)(-)-NmgVSS(-1)d(-1); 0.24-0.31mgCODmgVSS(-1)d(-1)) in the UASB reactor increased with increasing R(e). The primary finding of the study is that the combined UASB-AS reactor system should be operated at a higher R(e) to maintain high-activity denitrifiers to remove organic materials and nitrogen from piggery wastewater.     

Ammonium-nitrogen transformation and nitrogen retention in broiler manure supplemented with a soil amendment containing nitrifying bacteria

The effect of a soil amendment on ammonium nitrogen transformation and nitrogen retention in broiler manure was evaluated. Prior to incubation, broiler manure was mixed with autoclaved soil or non-autoclaved soil in different ratios to make 1 kg mixtures; broiler manure:non-autoclaved soil=9:1, 5:5, and 1:9 or broiler manure:autoclaved soil=9:1, 5:5, and 1:9. The non-autoclaved soil treatment reduced either numerically or significantly NH(4)(+)-N concentration compared to the autoclaved soil treatment during the 8-wk incubation. Total-N concentration of the non-autoclaved soil treatments was lower than the autoclaved soil treatments from 4 to 8 wk. The lowest manure to non-autoclaved soil treatment (M:S=1:9) had considerably more nitrite and nitrate; however, the higher ratio manure to non-autoclaved soil treatments (M:S=9:1 and 5:5) had slightly higher total nitrite and nitrate levels compared to the same ratio of autoclaved soil treatments. The moisture level of the 9:1, 5:5, and 1:9 M:S treatments were approximately 70, 45, and 30%, respectively. The results indicated that nitrifying bacteria in the non-autoclaved soil reduced the ammonium nitrogen concentrations of poultry manure by converting NH(3) or NH(4)(+) to NO(2)(-) or NO(3)(-). However, the higher moisture levels in treatments with greater manure to soil ratios (M:S=9:1 and 5:5) created anaerobic conditions that allowed for denitrification and greater N losses.     

Rainwater chemistry at the summit and southern flank of the Itatiaia massif, Southeastern Brazil

Wet deposition and related rainwater chemistry were studied at the Itatiaia massif, on which is settled the Itatiaia National Park (INP). Samples were simultaneously collected on a weekly basis over 12 months, using automated wet and dry samplers, at the INP-Headquarters (INP-Hq; altitude=820 m) and the Itatiaia Plateau (It-Pt; altitude=2460 m). Conductivity, pH, Na(+), K(+), Mg(2+), Ca(2+), NH(4)(+), Cl(-), NO(3)(-) and SO(4)(2-) were determined in 36 rainwater samples. Volume-weighted mean (VWM) pH was lower at the INP-Hq (4.9) than at the It-Pt (5.3). Very strong correlation between Cl(-) and Na(+) was found for the INP-Hq (r=0.99). At the Itatiaia massif, SO(4)(2-), NO(3)(-), and NH(4)(+) comprised together about 60% of the total inorganic ions and appear to exert the major control on rainwater pH.     

Particulate and dissolved organic carbon in cloud water in southern Scotland

Total particulate carbon (TPC), which includes both elemental carbon and particulate organic carbon, total suspended particulate matter (TSP) and dissolved organic carbon (DOC) were measured in 53 cloud water samples collected using a passive 'Harp-wire' cloud collector at weekly intervals at a hill-top site in southern Scotland (Dunslair Heights, 602 m above sea level) between December 1990 and April 1992. The concentrations of TPC, TSP and DOC were in the range 0.03-6.9 mg 1(-1) (median 1.05 mg l(-1)), 2.6-51.6 mg l(-1) (median 13.6 mg l(-1)) and 0.-14 mg l(-1) (median 3.6 mg l(-1)), respectively. The concentrations of TPC, TSP and DOC were greatest in winter (December-February), up to 6.9, 42 and 4.6 mg l(-1) respectively in 1990-1991 and up to 6.0, 51 and 14 mg l(-1), respectively, in 1991-1992. Particulate carbon in cloud water samples comprised 1-47% of the TSP. Concentrations of major anions (Cl(-), NO(-)(3), SO(2-)(4)) and pH were measured on the same water samples. Estimates of cloud liquid water content from January to April 1992 were derived from measured wind speeds and volumes of water collected. These estimates suggested that the air contained up to 1.2 microg TPC m(-3), 16 microg TSP m(-3) and 2.3 microg DOC m(-3), which are typical of concentrations to be expected in rural air. There was no correlation between concentrations of DOC in cloud water and either TPC or TSP, indicating that the sources and partitioning of DOC and TPC in the atmosphere are different. The largest concentrations of TPC coincided with the largest concentrations of non-marine sulphate, and although there was a significant linear correlation between the two sets of data, the log-transformed data were not correlated. Concentrations of TPC were significantly correlated with concentrations of other particulate matter (TSP-TPC), suggesting that similar sources and/or partitioning processes were involved in determining concentrations in cloud. Concentrations of DOC in cloud were significantly correlated (p < 0.02) with concentrations of nitrate, suggesting that sources of DOC were related to the emission and chemistry of nitrogen oxides. The very large concentrations of particulate carbon, especially in winter, indicate that carbon-catalysed oxidation of sulphur dioxide by molecular oxygen in cloud water may be a significant pathway when concentrations of hydrogen peroxide are small.     

Bulk deposition in a rural area located around a large coal-fired power station, northeast Spain

This work focuses on bulk deposition in a rural area located around a large coal-fired power station in northeast Spain. Deposition chemistry was characterised by high concentrations of SO(4)(2-), Ca(2+) and NH(4)(+), which were relatively high when compared with other rural areas. Monthly bulk deposition evolution of major ions was the result of two superimposed patterns: one pattern related to the volume of precipitation and the other showed the seasonal influence of the major ionic sources. A major local origin was attributed to bulk deposition of SO(4)(2-), NH(4)(+), and Ca(2+), whereas a relatively higher contribution of an external source was deduced for NO(3)(-), Na(+) and Cl(-). The SO(4)(2-) concentrations showed a significant correlation with the local SO(2) emissions. High levels of Ca(2+) were due to the high alkalinity of soils in the study area, although an external origin was attributed to the frequent air mass intrusions from the Sahara. Sources of NH(4)(+) were related to intensive livestock farming in the area. Total suspended particles exert a marked influence over bulk deposition and neutralisation. Thus, despite the high emissions of SO(2) in the area, neutral pH values have always been attained given that the concentrations of Ca(2+) and NH(4)(+) account for the total neutralisation of NO(3)(-) and SO(4)(2-).     

微生物生理群在猪粪秸秆高温堆肥碳氮转化中的作用

在自制的强制通风静态堆肥反应箱中,猪粪与秸秆以鲜重7∶1的比例进行了堆肥化实验,在堆制的23 d里根据堆温变化分阶段采集堆肥样品,利用MPN法测定了堆料中纤维素分解菌和氮素微生物生理群的数量变化,同时测定了相应的碳、氮含量。结果表明,纤维素分解菌在稳定腐熟阶段较多,对于后期有机碳的降解和腐殖质含量的增大起了很大的作用,在堆制的23 d里,腐殖质增加了2.4%。整个堆制过程中,氨化细菌的数量最大且与氨气释放浓度和铵态氮含量呈显著正相关,都在高温期增加,降温期后减少,氨化细菌的数量在高温期的增加率远高于降温期后的减少率,而铵态氮在高温期的增加率远低于在降温后期的减少率,铵态氮总体上减少了74.1%;亚硝化细菌数量与硝态氮呈正相关;反硝化细菌数量在降温期上升幅度较大,堆制结束时为堆制初期的13倍,且与堆肥中硝态氮含量呈正相关;硝态氮含量增加了87.5%;堆肥后期硝态氮的增加可能与堆肥中存在能进行硝化作用的反硝化细菌有关。固氮菌数量在堆制结束时达堆制初期的2.61倍,主要在降温期增加较多,对堆肥中有机氮的形成起很大作用。     

Effects of nitrogen with and without acidified sulphur on an ectomycorrhizal community in a Sitka spruce (Picea sitchensis Bong. Carr) forest

This preliminary study investigated the effects of enhanced nitrogen (NH4NO3 at 48 kg ha(-1) y(-1)), sulphur (Na2SO4 at 50 kg ha(-1) y(-1)), acidified nitrogen and sulphur (H2SO4 + NH4NO3) at pre-stated doses (pH 2.5), and acidified nitrogen and sulphur deposition at double these doses on the ectomycorrhizal community associated with a 13-year-old Sitka spruce (Picea sitchensis) forest. Sulphur deposition had little impact on below ground ectomycorrhizal diversity, but stimulated sporocarp production. Nitrogen inputs increased below ground colonisation compared to acidified nitrogen and sulphur, largely due to an increase in Tylospora fibrillosa colonisation. Sporocarp production and ectomycorrhizal root colonisation by Lactarius rufus were reduced in the nitrogen treated plots. These observations suggest that nitrogen deposition to a young plantation may suppress ectomycorrhizal fungi producing large sporocarps. It is proposed that enhanced nitrogen deposition increases ectomycorrhizal nitrogen assimilation, consuming more carbon and leaving less for extrametrical mycelium and sporocarp development.     

The contribution of ammonia emissions from agriculture to the deposition of acidifying and eutrophying compounds onto forests

In the vicinity of a large ammonia emission area, dry and wet deposition of acidifying and eutrophying compounds onto Douglas Fir forests was studied by sampling throughfall, stemflow and bulk precipitation. Deposition amounts of NH(4)(+) and SO(4)(2-) were recognised to be among the highest of Central Europe, resulting in extremely high inputs of (potential) acid to the forest soils (13.1 kEq ha(-1) year(-1)). The contribution of NH(3) emissions from agriculture to the total acid deposition to the forests was 52%. The total nitrogen deposition amounted to 115.0 kg ha(-1) year(-1), 83% originating from NH(3) emissions and 17% from NO(x) emissions. Calculated mean dry deposition velocities of NH(3) and SO(2) were much larger than reported in the literature. A synergistic effect between NH(3) and SO(2) in the process of dry deposition is suggested and evidence for this effect is discussed. When deposition models do not take this interaction into account, they will underestimate NH(3) and SO(2) deposition amounts in areas with intensive animal husbandry.     

Dry deposition, ionic species measured and source interpretation during seasonal cycle at offshore areas near Taiwan Strait

The characterization for water-soluble species of total suspended particulate (TSP), dry deposition flux, and dry deposition velocity (V(d)) were studied at Taichung Harbor (TH) and Wuchi traffic sampling sites at offshore sampling site near Taiwan Strait of central Taiwan during March 2004-January 2005. The average concentrations of TSP and dry deposition flux at the TH sampling site were higher than at the WT sampling site during the sampling period. The samples collected were analyzed by a ion chromatography (DIONEX-100) for the ionic species (Cl(-), SO(4)(2-), NO(3)(-), NH(4)(+), Na(+), Ca(2+), and Mg(2+)) analysis. The dominant ionic species for TSP are SO(4)(2-), NO(3)(-), and NH(4)(+) of the total mass of the inorganic ions at both sampling sites. In addition, the results indicated that the NH(4)(+), NO(3)(-) and SO(4)(2-) showed higher concentrations in winter and lower in summer for both TH and Wuchi sampling sites. Statistical methods such as correlation coefficient and principal component analysis were also used to identify the possible pollutant source.