Impact of nitrogen fertilizer source on nitrous oxide (N2O) emissions from three different agricultural soils during freezing conditions

ABSTRACT

Nitrogen (N) application is the main agricultural management that increases nitrous oxide (N₂O) concentration in the atmosphere. Freezing conditions are common phenomenon in the northern China that significantly affect soil N₂O emissions through alterations in nutrients availability and microbial population. To develop a comprehensive understanding of how N fertilizer managements affect soil N₂O emissions during the freezing process, a lab incubation was conducted in three typical cultivated soils (black soil, fluvo-aquic soil, or loess soil) by adding different N fertilizer sources, including ammonium chloride, sodium nitrate, or urea at different N levels (0, 80, 200, or 500 mg N/kg) at the start of freezing. The N₂O emissions in the fluvo-aquic soil were significantly higher than in other soils. The application of nitrate in the fluvo-aquic soil promoted N₂O emissions by five- and seven-fold higher compared to ammonium chloride and urea, whereas N₂O emissions in black soil were enhanced by application of ammonium chloride. Data indicate that denitrification is the major pathway for N₂O production in the fluvo-aquic soil during the freezing process, while ammonia oxidation responses accounts for elevated N₂O production in black soil. No significant influence of N fertilizer levels on N₂O emissions were found during soil freezing. These results suggest that agricultural practices that focus on mitigation of N₂O emissions need to avoid selection of nitrate as N fertilizer source in fluvo-aquic soil prior to the freezing season. Future studies need to focus on how the expression of enzymes and/or shifts in microbial communities respond to different N fertilizers during freezing conditions.     

垃圾填埋场的甲烷减排及覆盖层甲烷氧化研究进展

温室效应导致的全球变暖是备受瞩目的环境问题之一,其中垃圾填埋场产生填埋气是全球温室气体的重要来源。文章从垃圾填埋场的CH4产生、CH4减排技术和覆盖层CH4氧化行为及其影响因素等方面对国内外研究现状进行总结,为全面认识垃圾填埋场的CH4减排提供参考。目前,填埋场CH4减排技术包括填埋层原位减排、资源化利用和末端控制技术等,其中准好氧填埋技术和生物覆盖层甲烷氧化技术是适合我国现阶段大量中小型填埋场CH4减排要求的技术。填埋场覆盖层的特性如温度、含水率、有机质含量、pH值、孔隙率、CH4/O2比、植被和无机氮等都会影响其甲烷氧化能力,是填埋场覆盖层甲烷氧化能力研究和调控的主要参数。     

Deponiegas

Investigations were performed concerning whether or not the composition of volatile halogenated carbons in landfill gas (LFG) change when they uncontrolledly leave the aerobic surface of landfill. For this reason, the aerobic biological degradation of chlorofluorocarbons (CFCs), chlorofluorohydrocarbons (HCFCs), and vinyl chloride (VC), which were often measured in LFG of old household-landfills, was investigated. In 1-liter and 126-liter laboratory test reactors, the aerobic milieu conditions of the surface of landfills were simulated. Air with methane and trichlorofluoromethane (R11), dichlorodifluoromethane (R12), and their reductive metabolites dichlorofluoromethane (R21), chlorodifluoromethane (R22), and vinyl chloride (VC) were continuosly pumped through marl and a mixture of biowaste and compost. R21, R22, and VC were degraded, probably cometabolically by methanotrophic bacteria. They have inhibited the methane oxidation. The degradation rates of R21 (only in biowaste and compost) and R22 were up to 2.8 and 10 mg/m³ _material/h, respectively. The maximum degradation rate of VC was 1,3000 mg/m³ _material/h in marl. Under aerobic milieu conditions, a biodegradation of R11 and R12 was not detected.     

封闭垃圾填埋场通过地表向大气释放汞的测定

利用动力学通量箱及自动测汞仪联用技术,于2004年3月中旬对贵阳市的一座封闭生活垃圾填埋场汞通过地表向大气释放的过程进行了研究。3个采样点的汞释放通量日均值分别为559.1、88.2、53.6ng·m-2·h-1,汞释放通量强度与表层基质中的汞含量密切相关,该测定值高于世界背景地区通量的1~2个数量级,说明封闭垃圾填埋场也是大气汞的潜在来源。汞释放通量呈现明显的昼夜变化规律,白天较高并在午间前后达到最大,而夜间降至最低。气相因子中光照强度与汞的释放过程相关性最高,其次分别是气温、相对湿度、地温和风速。氧化态汞的光致还原作用是可能垃圾填埋场Hg0生成的主要途径,降雨初期能促进地表汞的释放。     

Identification and assessment of water pollution as a consequence of a leachate plume migration from a municipal landfill site (Tucumán,Argentina)

Landfills constitute potential sources of different pollutants that could generate human health and environmental problems. While some landfills currently work under the protection of a bottom liner with leachate collection, it was demonstrated that migration could take place even yet with these cautions. The purpose of this paper is to assess the pollution caused by a leachate plume from a municipal landfill that is affecting both groundwater and surface waters. The research was carried out at Pacará Pintado landfill in northwestern Argentina. Analysis of water samples indicates that leachate is affecting groundwater under the landfill area and an abandoned river channel hydraulically connected. In the center of the landfill area, the plume is anoxic and sulfate, nitrate, iron and manganese reduction zones were identified. Leachate plume presented high concentration of organic matter, Fe, Mn, NH₄ ⁺, Cl^? and Cr reaching an extension of 900 m. The presence of a leachate plume in a landfill site with a single liner system implies that the use of this groundwater pollution control method alone is not enough especially if permeable sediments are present below.     

The disposal of flue gas desulphurisation waste: sulphur gas emissions and their control

Flue gas desulphurisation (FGD) equipment to be fitted to UK coal-fired power stations will produce more than 0.8 Mtonnes of calcium sulphate, as gypsum. Most gypsum should be of commercial quality, but any low grade material disposed as waste has the potential to generate a range of sulphur gases, including H₂S, COS, CS₂, DMS and DMDS. Literature data from the USA indicates that well-oxidised waste with a high proportion of calcium sulphate (the main UK product of FGD) has relatively low emissions of sulphur gases, which are comparable to background levels from inland soils. However, sulphur gas fluxes are greatly enhanced where reducing conditions become established within the waste, hence disposal strategies should be formulated to prevent the sub-surface consumption of oxygen.     

Toxic effect assessment of aminotetrazoles and high-energetic azotetrazole salts on soil microbial respiration

The influence of energetic heterocyclic high-nitrogen salts on microbial activity in soil enrichment was investigated. 5-Aminotetrazole, a sodium salt of 5-aminotetrazole, ammonium azotetrazolate, sodium azotetrazolate, guanidinium azotetrazolate, triaminoguanidine azotetrazolate and triaminoguanidine hydrochloride were examined. Respiration tests determined the amount and rate of production of CO₂, H₂ and H₂S from microbial activity. Aminotetrazoles, triaminoguanidine azotetrazolate and triaminoguanidine hydrochloride substantially reduced the amount and rate of microbial CO₂ production. The total amount of CO₂ produced in the soil enrichments was affected by the cation from the azotetrazole salt, whereas the azotetrazolate anion did not seem to inhibit microbial CO₂ production. In contrast, all applied compounds stopped the production of H₂S completely and modified the rate of H₂ production in the cultures compared with the control. The influence of ammonium azotetrazolate and sodium azotetrazolate on the activity of isolated sulfate-reducing bacteria was also determined. The compounds did not have bactericidal activity towards sulfate-reducing bacteria, but the compounds decreased the amount of H₂S produced or slowed the growth of these bacteria in comparison with the control.     

Effluents and residues from industrial sites for carbon dioxide capture: a review

The adverse effects of climate change calls for the rapid transformation of manufacturing processes to decrease the emissions of carbon dioxide. In particular, a lower carbon footprint can be achieved by capturing carbon dioxide at the site of emission. Here we review the use of industrial effluents, waste and residues to capture carbon dioxide. Waste include steelmaking slag, municipal solid waste incinerator ashes, combustion fly ash, black liquor, paper mill waste, mining waste, cement waste, construction and demolition waste, waste from the organic industry, and flue gas desulfurization gypsum waste. Capture capacities range from 2 to 800 kg of carbon dioxide per ton of waste, depending on processes, waste type and conditions. Cement waste and flue gas desulfurization gypsum waste show the highest capture capacity per ton of waste.

     

Effect of nitrogen supply on nitrogen uptake,accumulation and assimilation in Porphyra perforata (Rhodophyta)

Porphyra perforata J. Ag. was collected from a rocky land-fill site near Kitsilano Beach, Vancouver, British Columbia, Canada and was grown for 4 d in media with one of the following forms of inorganic nitrogen: NO ₃ ^- , NH ₄ ⁺ and NO ₃ ^- plus NH ₄ ⁺ and for 10 d in nitrogen-free media. Internal nitrogen accumulation (nitrate, ammonium, amino acids and soluble protein), nitrate and ammonium uptake rates, and nitrate reductase activity were measured daily. Short initial periods (10 to 20 min) of rapid ammonium uptake were common in nitrogen-deficient plants. In the case of nitrate uptake, initial uptake rates were low, increasing after 10 to 20 min. Ammonium inhibited nitrate uptake for only the first 10 to 20 min and then nitrate uptake rates were independent of ammonium concentration. Nitrogen starvation for 8 d overcame this initial suppression of nitrate uptake by ammonium. Nitrogen starvation also resulted in a decrease in soluble internal nitrate content and a transient increase in nitrate reductase activity. Little or no decrease was observed in internal ammonium, total amino acids and soluble protein. The cultures grown on nitrate only, maintained high ammonium uptake rates also. The rate of nitrate reduction may have limited the supply of nitrogen available for further assimilation. Internal nitrate concentrations were inversely correlated with nitrate uptake rates. Except for ammonium-grown cultures, internal total amino acids and soluble protein showed no correlation with uptake rates. Both internal pool concentrations and enzyme activities are required to interpret changes in uptake rate during growth.     

Bioreduction of nitrate in groundwater using a pilot-scale hydrogen-based membrane biofilm reactor

A long-term pilot-scale H₂-based membrane biofilm reactor (MBfR) was tested for removal of nitrate from actual groundwater. A key feature of this second-generation pilot MBfR is that it employed lower cost polyester hollow fibers and still achieved high loading rate. The steady-state maximum nitrate surface loading at which the effluent nitrate and nitrite concentrations were below the Maximum Contaminant Level (MCL) was at least 5.9 g·N·(m²·d)^?1, which corresponds to a maximum volumetric loading of at least 7.7 kg·N·(m³·d) ^?1. The steady-state maximum nitrate surface area loading was higher than the highest nitrate surface loading reported in the first-generation MBfRs using composite fibers (2.6 g·N·(m²·d)^?1). This work also evaluated the H₂-utilization efficiency in MBfR. The measured H₂ supply rate was only slightly higher than the stoichiometric H₂-utilization rate. Thus, H₂ utilization was controlled by diffusion and was close to 100% efficiency, as long as biofilm accumulated on the polyester-fiber surface and the fibers had no leaks.     

细颗粒物(PM_(2.5))主要组分模拟溶液对发光细菌的光抑制分析

为明确NH_4~+、 NO_3~-、SO_4~(2-)及金属等组分在水溶性提取液对发光细菌的光抑制过程中所起的作用,参照PM_(2.5)样品提取液浓度,模拟配制与3级以上PM_(2.5)样品提取液中主要组分:硫酸盐、硝酸盐、氨盐相同浓度的溶液,同时选取与PM_(2.5)可溶性提取液发光抑制率相关性较强的铅、锌,配制不同浓度级别模拟溶液,测试各单一组分对发光细菌的发光抑制率及其混合溶液对发光细菌的联合影响效应。基于毒性单位法(TU)、相加指数法(AI)和混合毒性指数法(MTI)评价了混合体系联合影响的作用类型。结果表明,与3~6级PM_(2.5)可溶性提取液中硫酸氨、硫酸氢氨、硝酸氨、硫酸锌和硝酸铅浓度相同的模拟溶液对发光细菌的发光没有抑制作用。不同的评价方法对PM_(2.5)主要组分混合体系联合效应评价结果具有较好的一致性,硫酸氨、硝酸氨、硫酸氢氨混合溶液中,对发光细菌的光抑制均为硫酸氢氨的独立作用,硫酸锌与硝酸铅的混合体系,锌和铅对发光细菌的联合影响效应表现为协同,硫酸氨、硝酸氨、硫酸氢氨与硫酸锌、硝酸铅的多元混合体系呈现协同作用。     

A comprehensive model to estimate the simultaneous release of acidic and basic gaseous pollutants from swine slurry under different scenarios

Swine slurry is a source of atmospheric pollutants. Emissions of basic and acidic compounds from slurry are largely dependent on the surface pH. In a storage system, the pH at the surface layers changes over time due to the volatilisation of ammonia (NH₃), carbon dioxide (CO₂) and acetic acid (HAc). In this article, a comprehensive gas emission–pH (GE–pH) coupled model is proposed to describe the simultaneous release of acidic and basic gaseous pollutants from swine slurry. The model was applied to describe the release of NH₃, CO₂, HAc and hydrogen sulphide (H₂S) from standard slurries stored in animal houses, outside storage tanks and lagoons. The modelled results agreed well with values reported in the literature and could be reasonably interpreted. The key parameters affecting the release of gases were: initial pH, initial concentration of total ammonium nitrogen and inorganic carbon, slurry temperature and air velocity. This study suggests that future modelling studies on gas emissions from animal slurry should consider the concentration of inorganic carbon and the frequency in which the slurry surface is mixed or altered, because they affect the surface pH and the release of gaseous pollutants from slurry.     

Nitrogen-retaining property of compost in an aerobic thermophilic composting reactor for the sanitary disposal of human feces

Aerobic composting is a method for the sanitary disposal of human feces as is used in bio-toilet systems. As the products of composting can be utilized as a fertilizer, it would be beneficial if the composting conditions could be more precisely controlled for the retention of fecal nitrogen as long as possible in the compost. In this study, batch experiments were conducted using a closed aerobic thermophilic composting reactor with sawdust as the bulk matrix to simulate the condition of a bio-toilet for the sanitary disposal of human feces. Attention was paid to the characteristics of nitrogen transformation. Under the controlled conditions of temperature at 60°C, moisture content at 60%,anda continuous air supply, more than 70% fecal organic removal was obtained, while merely 17% fecal nitrogen loss was observed over a two-week composting period. The nitrogen loss was found to occur mainly in the first 24 h with the rapid depletion of inorganic nitrogen but with an almost unchanged organic nitrogen content. The fecal NH₄-N which was the main component of the inorganic nitrogen ( > 90%) decreased rapidly in the first day, decreased at a slower rate over the following days, and finally disappeared entirely. The depletion of NH₄-N was accompanied by the accumulation of NH₃ gas in the ammonia absorber connected to the reactor. A mass balance between the exhausted NH₃ gas and the fecal NH₄-N content in the first 24 hours indicated that the conversion of ammonium into gaseous ammonia was the main reason for nitrogen loss. Thermophilic composting could be considered as a way to keep a high organic nitrogen content in the compost for better utilization as a fertilizer.     

Influence of fertilizer and sewage sludge compost on yield and heavy metal accumulation by lettuce grown in urban soils

Previous research has demonstrated that many urban soils are enriched in Pb, Cd and Zn. Culture of vegetable crops in these soils could allow transfer of potentially toxic metals to foods. Tanya lettuce (Lactuca sativa L.) was grown in pots of five urban garden soils and one control agricultural soil to assess the effect of urban-soil metal enrichment, and the effect of soil amendments, on heavy metal uptake by garden vegetables. The amendments included NPK fertilizer, limestone, Ca(H₂PO₄)₂, and two rates of limed sewage sludge compost. Soil Cd ranged from 0.08 to 9.6 mg kg^–1; soil Zn from 38 to 3490 mg kg^–1; and soil Pb from 12 to 5210 mg kg^–1. Lettuce yield on the urban garden soils was as great as or greater than that on the control soil. Lettuce Cd, Zn and Pb concentrations increased from 0.65, 23, and 2.2 mg kg^–1 dry matter in the control soil to as high as 3.53, 422 and 37.0 mg kg^–1 on the metal-rich urban garden soils. Adding limestone or limed sewage sludge compost raised soil pH and significantly reduced lettuce Cd and Zn, while phosphate fertilizer lowered soil pH and had little effect on Zn but increased Cd concentration in lettuce. Urban garden soils caused a significant increase in lettuce leaf Pb concentration, especially on the highest Pb soil. Adding NPK fertilizer, phosphate, or sludge compost to two high Pb soils lowered lettuce Pb concentration, but adding limestone generally did not. On normally fertilized soils, Pb uptake by lettuce was not exceptionally high until soil Pb substantially exceeded 500 mg kg^–1. Comparing garden vegetables and soil as potential sources of Pb risk to children, it is clear that the risk is greater through ingestion of soil or dust than through ingestion of garden vegetables grown on the soil. Urban dwellers should obtain soil metal analyses before selecting garden locations to reduce Pb risk to their children.     

Effect of the nitrification inhibitor dicyandiamide on microbial communities and N<Subscript>2</Subscript>O from an arable soil fertilized with ammonium sulphate

Nitrous oxide (N₂O) affects climate change as a greenhouse gas and indirectly contributes to stratospheric ozone depletion. The main source of N₂O in soils is denitrification which requires high soil moisture, carbon and nitrate. Nitrification inhibitors can be used to mitigate emissions of N₂O from soils. In Portugal, fertilisers are often applied when soils are still relatively warm and moist conditions conducive to denitrification. A Portuguese arable soil was inhibited with dicyandiamide, a nitrification inhibitor and the effect on soil microbiological activity and composition was determined after 46 days. Soils were then incubated and received carbon and ammonium under high soil water conditions and mineral N and N₂O fluxes were measured during 22 days. We found that dicyandiamide decreased microbial populations and activity, but did not alter composition. Pre-conditioning of the soil with dicyandiamide was 80% more effective in reducing fluxes of N₂O than simultaneous application with fertiliser.     

Relationship between air pollutants emission patterns and concentrations

Emission patterns of NO_x and S‐compounds are analyzed to study their influence on the concentrations of SO₂, NO_x, sulphate and nitrate in the air. Air mass trajectories, emission inventories and cluster analysis are used to define the emission patterns.

The scheme that characterized most of the days is defined by low emissions from 48 hours until 18 hours before the measurements and it produces average concentrations. High concentrations are due to emission peaks. The time between these emission peaks and the measurement determines the importance of the emission peak on the concentration.     

A sustainable sulfate process to produce TiO2 pigments

Titanium dioxide (TiO₂) is a widely used white pigment. TiO₂ production in 2006 was about 1,400,000 metric tons in the USA. The two major processes to manufacture TiO₂ are the chloride process and the sulfate process. Currently, the TiO₂ industry finds the waste generated in the chloride process less than the waste generated in the sulfate process in its present design, despite generating large quantities of process-related carbon dioxide and carbon monoxide. As a consequence, the sulfate process appears less economical, notably due to the production of green vitriol, FeSO₄·7H₂O, as a major waste. Here, we describe a more sustainable sulfate process based on an earlier study on thermal decomposition of iron(II) sulfates. In the sustainable sulfate process, FeSO₄·7H₂O waste is used for greener production of sulfuric acid, H₂SO₄, used in turn for the digestion of ilmenite. Theoretical and actual yields of waste byproducts per metric ton of TiO₂ produced are used to show the environmental and economic advantages of the sustainable sulfate process.     

Growth of zooxanthellae in culture with two nitrogen sources

Physiological characteristics of zooxanthellae were examined under nutrient-saturated conditions created by mixing ammonium (¹⁵NH₄) with nitrate (¹⁵NO₃) to give 0.88 mM total nitrogen. Growth rate varied with the form of nitrogen provided. Ammonium alone resulted in the lowest C:N and C:chl-a ratios. Although zooxanthellae took up nitrate in the absence of ammonium, ammonium assimilation was 1.3 times higher than nitrate assimilation. Ammonium strongly inhibited nitrate assimilation. While high-ammonium treatments resulted in the highest ¹⁴C incorporation into intermediate compounds, high nitrate levels resulted in the highest ¹⁴C incorporation into protein, suggesting that the intermediate compounds are produced prior to the subsequent production of protein when ammonium is the dominant N source. The enhanced production of intermediate compounds at the expense of carbon directed to protein synthesis in the presence of ammonium might be analogous to the “host factor” observed in zooxanthellae–host symbioses, since growth rate is depressed due to low production of protein. Received: 16 March 2000 / Accepted: 26 August 2000     

Coupled aerobic and anoxic biodegradation for quinoline and nitrogen removals

Quinoline (C₉H₇N) commonly occurs in wastewaters from the chemical, pharmaceutical, and dyeing industries. As quinoline is biodegraded, nitrogen is released as ammonium. Total-N removal requires that the ammonium-N be nitrified and then denitrified. The objective of this study was to couple quinoline biodegradation with total-N removal. In a proof-of-concept step, activated sludge was sequenced from aerobic to anoxic stages. The ammonium nitrogen released from quinoline biodegradation in the aerobic stage was nitrified to nitrate in parallel. Anoxic biodegradation of the aerobic effluent then brought about nitrogen and COD removals through denitrification. Then, simultaneous quinoline biodegradation and total-N removal were demonstrated in a novel airlift internal loop biofilm reactor (AILBR) having aerobic and anoxic zones. Experimental results showed that the AILBR could achieve complete removal of quinoline, 91% COD removal, and 85% total-N removal when glucose added as a supplemental electron donor once nitrate was formed.     

Environmental protection by utilization of the slag from magnesium production in building materials

This paper presents the results of research on the utilization of slag produced as the waste material of metallic magnesium production. This material is a fine powder with a high magnesium content. The characterization of slag was performed by XRD, DTA and TG analysis. Chemical composition and mechanical properties of slag were also determined. By using a mixture this slag and limestone aggregate, it is possible to obtain dry mortar which, mixed with water, gives a material fully satisfying for plastering mortar. By adding inorganic pigments (Fe₂O₃, Ca₂O3, etc.) decorative mortars are obtained, and when they are spread over the foundation made of brick or concrete, they retain their colour on the entire coating and surface of the mortar.