Organic compounds in soils and sediments from unlined waste disposal pits for natural gas production and processing

Samples of soil in dry waste pits and of sediment from waste pits currently in-use for natural gas production in the San Juan Basin of northwest New Mexico were collected for characterization of the presence and concentration of organic compounds. Samples were dried at 25 °C and about 50 g were extracted successively in a Soxhlet apparatus using hexane, benzene, and methanol. Extracts were filtered and condensed to 10 mL. Analyses of hexane extracts of samples using high-resolution gas chromatography showed presence of a complex mixture of 40 to 50 organic compounds in dry soil and in sediment from in-use pits. The range of size for compounds was C₁₀ to C₂₅. Although no compounds were detected in GC analyses of subsequent benzene and methanol extracts of the same soil samples, these extracts were highly colored and contained 5 to 10% of total absorptivity at 254 nm. Total extractable residues in the hexane extracts ranged from 49 to 110 mg g^?1 of soil. Polycyclic aromatic hydrocarbons were detected in hexane extracts at concentrations of 270 to 870μg g^?1 of dry sample.     

Life cycle greenhouse gas emissions from five contrasting rice production systems in the tropics

Carbon footprint (CF) quantification of major rice production systems (RPSs) is a prerequisite for developing strategies for climate change mitigation in agriculture. Total life cycle greenhouse gas emissions (LC-GHGs) from rice production to consumption might provide precise CFs for RPSs. Therefore, we assessed three segments (pre-farm, on-farm, and post-farm) of LC-GHGs under five major contrasting RPSs, i.e., aerobic rice (AR), shallow lowland rice(SLR), system of rice intensification (SRI), ...     

Trace gas emissions from soil of the central highlands of Mexico as affected by natural vegetation: a laboratory study

In the central highlands of Mexico, mesquite (Prosopis laevigata) and huisache (Acacia schaffneri), N₂-fixing trees or shrubs, dominate the vegetation and are currently used in a reforestation program to prevent erosion. We investigated how natural vegetation or cultivation of soil affected oxidation of CH₄, and production of N₂O. Soil was sampled under the canopy of mesquite (MES treatment) and huisache trees (HUI treatment), outside their canopy (OUT treatment) and from fields cultivated with maize (ARA treatment) at three different sites while production of CO₂, and dynamics of CH₄, N₂O and inorganic N (NH₄⁺, and NO₃^–) were monitored in an aerobic incubation. The production of CO₂ was 2.3 times higher and significantly greater in the OUT treatment, 3.0 times higher in the MES treatment and 4.0 times higher in the HUI treatment compared to the ARA treatment. There was no significant difference in oxidation of CH₄ between the treatments, which ranged from 0.019 g CH₄–C kg^–1 day^–1 for the HUI treatment to 0.033 CH₄–C kg^–1 day^–1 for the MES treatment. The production of N₂O was 30 g N₂O–N kg^–1 day^–1 in the MES treatment and >8 times higher compared to the other treatments. The average concentration of NO₃^– was 2 times higher and significantly greater in the MES treatment than in the HUI treatment, 3 times greater than in the OUT treatment and 10 times greater than in the ARA treatment. It was found that cultivation of soil decreased soil organic matter content, C and N mineralization, but not oxidation of CH₄ or production of N₂O.     

Greenhouse gas emissions from farmed organic soils: a review

Abstract. The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO₂ and strong emitters of CH₄. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO₂ and N₂O emissions increase while CH₄ emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO₂, CH₄, and N₂O) by roughly 1t CO₂ equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost-efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.     

有机物料还田对冬小麦农田土壤温室气体排放影响的研究

探讨有机物料还田对冬小麦田温室气体排放特性的影响,对提高经济效应和环境效应有积极意义。本研究应用静态箱-气相色谱法对秸秆还田（J）、秸秆还田+牛粪（JF）和秸秆还田+菌渣（JZ）3种有机物料还田下分别施氮肥243 kg （N）·hm^-2（减氮10%,N1）、216 kg （N）·hm^-2（减氮20%,N2）对冬小麦农田N₂O、CO₂和CH₄的排放通量进行监测,探讨了不同施肥措施对麦田温室气体累积排放量、增温潜势的影响。试验期间同步记录每项农事活动机械燃油量、施肥量和灌溉量,测定产量,地上部生物量,估算农田碳截留。结果表明,冬小麦农田土壤N₂O和CO₂是排放源,是CH₄的吸收汇,氮肥施入、灌溉以及强降水促进了土壤N₂O和CO₂的生成,却弱化了CH₄作为大气吸收汇的特征。牛粪+秸秆（JF）处理N₂O和CO₂排放总量最高,分别为3.5 kg （N₂O-N）·hm^-2和19 689.67 kg （CO₂-C）·hm^-2,但CH₄的吸收值最大,为5.33 kg （CH₄-C）·hm^-2,均显著高于菌渣+秸秆（JZ）和秸秆（J）处理（P<0.05）;各处理N₂O和CO₂的总量随施氮量的增加呈升高趋势,CH₄的总量随施氮量的增加而呈降低趋势。JFN2、JN2和JZN2处理农田综合增温潜势（GWP）均为负值,表明有机物料还田且减氮20%条件下农田生态系统为大气的碳汇,麦季净截留碳1 038~2 024 kg·hm^-2,其他处理GWP值均为正。JZN2处理小麦产量为8 061 kg·hm^-2,显著高于JFN2处理（P<0.05）。综上所述,JZN2处理不仅能够保证小麦产量,且对环境效应最有利,为本区域冬小麦较优的施肥管理模式。     

土壤添加沼渣对温室气体排放及小麦生长的影响

Digestate, the product obtained after anaerobic digestion of organic waste for biogas production, is rich in plant nutrients and might be used to fertilize crops. Wheat(Triticum spp. L.) was fertilized with digestate, urea, or left unfertilized and cultivated in the greenhouse for 120 d. Emissions of greenhouse gasses(carbon dioxide(CO_2), methane(CH_4), and nitrous oxide(N_2O)) were monitored and plant growth characteristics were determined at harvest. The digestate was characterized for heavy metals, pathogens, and C and N mineralization potential in an aerobic incubation experiment. No Salmonella spp., Shigella spp., or viable eggs of helminths were detected in the digested pig slurry, but the number of faecal coliforms was as high as 3.6 × 10~4colony-forming units(CFU) g-~(1)dry digestate. The concentrations of heavy metals did not surpass the upper limits established by US Environmental Protection Agency(EPA). After 28 d, 17% of the organic C(436 g kg~(-1)dry digestate) and 8% of the organic N(6.92 g kg~(-1)dry digestate)were mineralized. Emissions of CO_2 and CH_4 were not significantly affected by fertilization in the wheat-cultivated soil, but digestate significantly increased the cumulative N_2O emission by 5 times compared to the urea-amended soil and 63 times compared to the uncultivated unfertilized soil. It could be concluded that digestate was nutrient rich and low in heavy metals and pathogens, and did not affect emissions of CH_4 and CO_2 when applied to a soil cultivated with wheat, but increased emission of N_2O.     

牛粪堆肥方式对温室气体和氨气排放的影响

为明确堆肥过程中温室气体和氨气排放规律以及产生的总温室效应,在云南省大理州开展堆肥试验,并以奶牛粪便为试验材料,研究了农民堆肥(FC)、覆盖堆肥(CC)、覆盖-翻堆堆肥(CTC)和覆盖通风-翻堆堆肥(CATC)4种堆肥方式对温室气体和氨气排放的影响。结果表明:覆盖通风-翻堆堆肥(CATC)可提高堆肥腐熟度,有效降低CH4和N_2O排放,但并没降低CO2和NH_3排放;与农民堆肥(FC)相比,覆盖堆肥(CC)的CH4排放量增加了48.7%,而N2_O和NH3排放量与农民堆肥(FC)基本一致;覆盖-翻堆堆肥(CTC)虽然提高了腐熟度,但CH_4、CO_2和NH_3排放量较大;堆肥结束时,4个处理的总温室效应分别为25.6、32.9、38.1及18.0 kg/t;温度与CH_4、CO_2、N_2O和NH_3排放速率均极显著相关,pH值显著影响N_2O和NH_3的排放。因此,覆盖通风-翻堆堆肥(CATC)不仅能够满足堆肥产品的腐熟度要求,而且能够减少总温室效应,再加上其操作简便,能够在生产中推广应用。     

Effects of land use type and incubation temperature on greenhouse gas emissions from Chinese and Canadian soils

Purpose  

Land use type is an important factor influencing greenhouse gas emissions from soils, but the mechanisms involved in affecting potential greenhouse gas (GHG) emissions in different land use systems are poorly understood. Since the northern regions of Canada and China are characterized by cool growing seasons, GHG emissions under low temperatures are important for our understanding of how soil temperature affects soil C and N turnover processes and associated greenhouse gas emissions in cool temperate regions. Therefore, we investigated the effects of temperature on the emission of N₂O, CO₂, and CH₄ from typical forest and grassland soils from China and Canada.     

Sugarcane bagasse biochars impact respiration and greenhouse gas emissions from a latosol

Purpose

A paucity in knowledge remains on the influence of biochar production temperature and the rate of application on greenhouse gas emissions from soil. The objective of this column experiment was to evaluate a biochar thermosequence by doses on CO₂, N₂O, and CH₄ emissions from a latosol following nitrogen fertilizer application following a pre-incubation period.

Materials and methods

Biochar was produced from sugarcane bagasse pyrolyzed at 300, 500, and 700 °C (BC 300, BC 500, and BC 700, respectively). Biochars were added to air-dried latosol columns at rates of 0, 0.5, 1, 2, 5, 10, and 15 % (w/w), and the water content was brought to 95 % of water-filled pore space (WFPS). The emissions from columns were tested on days 1, 3, 7, 15, and 30 following a 30-day pre-incubation.

Results and discussion

All treatments showed a decrease in respiration across the study period. The higher doses of biochar of BC 300 and BC 700 resulted in significantly higher respiration than controls on days 15 and 30. Neither biochar dose nor temperature had a significant effect on CH₄ emissions during the study period. Application of all biochars suppressed the emissions of N₂O at all doses on days 1 and 3, compared to the control. N₂O emissions from higher temperature biochar-amended soil at 2, 5, 10, and 15 % were greater than that from corresponding treatments of lower-temperature biochar-amended soil on days 15 and 30.

Conclusions

Soil respiration and overall greenhouse gas emission from latosol increased with biochar dose and pyrolysis temperature in the 30-day study period due to increasing water retention facilitated by biochar. Careful consideration is needed when applying bagasse biochar as it changes N cycling and soil physical properties.

     

规模化奶牛场温室气体排放量评估

为了对组织层次上温室气体排放进行量化,为企业选择最有效的减排措施提供依据。该文以河北保定一规模化奶牛场为案例,利用气候变化框架公约（UNFCCC）清洁发展机制理事会批准的相关方法学、IPCC排放系数法及相关文献,在组织层次上量化了该奶牛场运行过程中的温室气体的排放与清除。案例研究结果表明,采用规模化运行管理方式及粪便管理系统时,该2 300头存栏的奶牛场年排放温室气体为11 333.2 t CO2-e或者说每头存栏奶牛年排放温室气体 4.9 t CO2-e,并提出了组织温室气体的减排建议。这对同类牛场温室气体排放量的评估具有参考意义。     

砾石覆盖对小麦玉米轮作农田碳排放强度的影响

为研究砾石覆盖对农田土壤水热条件及温室气体排放的影响,探讨小麦-玉米轮作农田碳排放强度对砾石覆盖的响应,开展了基于静态暗箱-气象色谱法的小麦-玉米轮作田间试验,测定了土壤CO2、CH4和N2O3种温室气体的排放,结合产量、全球增温潜势和碳排放强度等指标评估砾石覆盖的农田生态效应及固碳减排作用.试验在作物关键需水期设置0和50mm2个灌溉水平,土壤表面设置无覆盖和100%覆盖2个砾石覆盖度水平,形成无覆盖对照(W0M0)、灌溉对照(W1M0)、砾石覆盖(W0M1)和灌溉砾石覆盖(W1M1)4个处理.结果表明:1)砾石覆盖能有效改善土壤水热状况,显著增加作物产量.与对照处理W0M0相比,W1M0,W0M1和W1M13个处理的作物年际总产量分别增加了18.1%、32.6%和51.8%;2)各处理对3种温室气体排放的影响具体表现为,相比W0M0处理,W1M0,W0M1和W1M13个处理的CO2年际排放总量分别降低了7.8%、12.1%和18.0%,CH4年际吸收总量分别增加了32.5%、80.2%和124.3%,而各处理N2O年际排放总量差异不显著;3)砾石覆盖显著降低了农田温室气体碳排放强度,W1M0,W0M1和W1M13个处理的碳排放强度相比W0M0处理分别降低了14.9%、20.7%和33.6%.比较产量和碳排放强度,经济产量越高,固碳潜力越大,碳排放强度越小.双因素方差分析表明砾石覆盖结合农田灌溉使得作物产量达到最高,碳排放强度最小.综合考虑,砾石覆盖结合农田灌溉能有效改善土壤水热状况,有利于增加作物产量和降低农田温室气体碳排放强度,该研究为干旱半干旱地区实现稳定增产和固碳减排提供一种可行途径.     

生物炭及生物硝化抑制剂添加对黄土区设施菜地土壤温室气体排放的影响

通过室内培养试验研究生物炭及生物硝化抑制剂添加对黄土区设施菜地土壤N2O和CO₂排放的影响,并与化学合成硝化抑制剂作对比。试验设置6个处理:不施肥(CK)、施氮(N)、施氮+生物炭(N+BC)、施     

Mitigation of greenhouse gas emissions from soil under silage production by use of organic manures or slow-release fertilizer

Abstract. Grassland is a major source of nitrous oxide (N₂O) and methane (CH₄) emissions in the UK, resulting from high rates of fertilizer application. We studied the effects of substituting mineral fertilizer by organic manures and a slow-release fertilizer in silage grass production on greenhouse gas emissions and soil mineral N content in a three-year field experiment. The organic manures investigated were sewage sludge pellets and composted sewage sludge (dry materials), and digested sewage sludge and cattle slurry (liquid materials). The organic manures produced N₂O and carbon dioxide (CO₂) consistently from time of application up to harvest. However, they mitigated N₂O emissions by around 90% when aggregate emissions of 15.7 kg N ha⁻¹ from NPK fertilizer were caused by a flux of up to 4.9 kg N ha⁻¹ d⁻¹ during the first 4 days after heavy rainfall subsequent to the NPK fertilizer application. CH₄ was emitted only for 2 or 3 days after application of the liquid manures. CH₄ and CO₂ fluxes were not significantly mitigated. Composting and dried pellets were useful methods of conserving nutrients in organic wastes, enabling slow and sustained release of nitrogen. NPK slow-release fertilizer also maintained grass yields and was the most effective substitute for the conventional NPK fertilizer for mitigation of N₂O fluxes.     

Effects of effluents from a sewage treatment plant on the aquatic organisms

The effects of sewage pollution on the distribution and abundance of some orgnanisms over a period of 4 mo at the Ahmadu Bello University Main Campus sewage treatment plant and Kubanni river were studied. Physico-chemical parameters such as dissolved oxygen; temperature; hydrogen ion concentration (pH); electrical conductivity and chemical oxygen demand influenced by pollution were measured with respect to the population of aquatic organisms. The organisms were used as biological indices to monitor the ecological imbalance caused by the effluent. The variations in concentrations of some heavy metals were also measured. The studies revealed that at the source of pollution there were no organisms except for some insect larva such as Eristalis, Psychoda, and some microscopic algae like Oscillatoria, Anaebaena, and Polysystis. A location (site 5) on Kubanni river just before the confluence of the sewage effluent and the river was taken as the control. There was a wide variety of organisms (crustaceans, rotifers, and fish) at the control point.     

大气CO2 浓度升高对华北夏玉米地温室气体排放的影响

开展大气CO₂ 浓度升高对华北夏玉米地温室气体排放的影响可为未来气候变化下农业温室气体减排提供依据。研究基于已稳定运行10 年的华北典型一年两季自由大气CO₂ 富集平台进行,于 2017 年设置2 个处理,即常规浓度CO₂(aCO₂,平均400 μmol·mol-1)和高浓度CO₂(eCO₂,550 μmol·mol-1),2018 年在不同CO₂ 浓度下增设低氮(LN)和高氮(HN)水平下的不同CO₂ 浓度处理(即aCO₂-LN、aCO₂-HN、eCO₂-LN、eCO₂-HN)开展试验,监测和分析不同处理下土壤CO₂ 及N2O 排放通量特征,结合土壤硝化潜势和反硝化潜势测定解析N2O排放量变化的可能原因。结果表明,eCO₂ 下夏玉米生育期农田N2O 和CO₂ 累积排放量分别比aCO₂ 下显著增加45.5% ～ 65.9% 和16.7% ～ 19.2%;N2O 排放增加主要发生在施肥、灌溉和降雨后,而土壤CO₂ 在玉米营养生长期排放量较高。eCO₂ 条件下土壤硝化潜势和反硝化潜势分别比aCO₂ 下提高了36.4% 和59.0%,对土壤N2O 排放有贡献潜力。eCO₂ 下,N2O 减排需结合排放机理采取合理的田间管理和水肥调控措施。     

Effects of biochar application in forest ecosystems on soil properties and greenhouse gas emissions: a review

Purpose

Forests play a critical role in terrestrial ecosystem carbon cycling and the mitigation of global climate change. Intensive forest management and global climate change have had negative impacts on the quality of forest soils via soil acidification, reduction of soil organic carbon content, deterioration of soil biological properties, and reduction of soil biodiversity. The role of biochar in improving soil properties and the mitigation of greenhouse gas (GHG) emissions has been extensively documented in agricultural soils, while the effect of biochar application on forest soils remains poorly understood. Here, we review and summarize the available literature on the effects of biochar on soil properties and GHG emissions in forest soils.

Materials and methods

This review focuses on (1) the effect of biochar application on soil physical, chemical, and microbial properties in forest ecosystems; (2) the effect of biochar application on soil GHG emissions in forest ecosystems; and (3) knowledge gaps concerning the effect of biochar application on biogeochemical and ecological processes in forest soils.

Results and discussion

Biochar application to forests generally increases soil porosity, soil moisture retention, and aggregate stability while reducing soil bulk density. In addition, it typically enhances soil chemical properties including pH, organic carbon stock, cation exchange capacity, and the concentration of available phosphorous and potassium. Further, biochar application alters microbial community structure in forest soils, while the increase of soil microbial biomass is only a short-term effect of biochar application. Biochar effects on GHG emissions have been shown to be variable as reflected in significantly decreasing soil N₂O emissions, increasing soil CH₄ uptake, and complex (negative, positive, or negligible) changes of soil CO₂ emissions. Moreover, all of the aforementioned effects are biochar-, soil-, and plant-specific.

Conclusions

The application of biochars to forest soils generally results in the improvement of soil physical, chemical, and microbial properties while also mitigating soil GHG emissions. Therefore, we propose that the application of biochar in forest soils has considerable advantages, and this is especially true for plantation soils with low fertility.

     

运用生命周期评价方法评估奶牛养殖系统温室气体排放量

准确评估奶牛养殖系统温室气体排放量是寻求有效减排措施和引导奶牛养殖业低碳发展的基础。该文应用生命周期评价方法,结合中国奶牛养殖业现状,建立了奶牛养殖系统温室气体排放量评估方法;并以此方法分析了西安郊区典型的规模化奶牛场的奶牛养殖系统温室气体排放特点和排放量。结果表明,该奶牛养殖系统主要的温室气体排放环节是奶牛肠道发酵CH4排放、饲料生产与加工、粪便贮存,其排放量分别占整个系统的48.86%、18.97%和16.39%。主要排放的温室气体是CH4、N2O,排放量分别占整个系统的55.56%和26.9%。该奶牛养殖系统每生产1kg按脂肪和蛋白质纠正的原奶(FPCT)的温室气体排放量(以CO2当量计)为1.52kg,低于全球平均的混合饲养模式原奶生产的排放量,而高于欧洲国家原奶生产的排放水平,说明减排潜力还很大。通过改善饲料、改进粪便管理模式和肥料田间管理等措施均能够减少单个环节的温室气体排放量,而不同措施对整个系统减排的贡献率还应通过生命周期评价方法进行分析。因此,建议开展不同减排措施下的生命周期评估,以获得对系统减排更有效的措施。     

Chromium-resistant microorganisms isolated from evaporation ponds of a metal processing plant

Chromium occurs naturally at trace levels in most soils and water, but disposal of industrial waste and sewage sludge containing chromium compounds has created a number of contaminated sites, which could pose a major environmental threat. This study was conducted to enumerate and isolate chromium-resistant microorganisms from sediments of evaporation ponds of a metal processing plant and determine their tolerance to other metals, metalloids and antibiotics. Enumeration of the microbiota of Cr-contaminated sediments and a clean background sample was conducted by means of the dilution-plate count method using media spiked with Cr(VI) at concentrations ranging from 10 to 1000 mg L^?1. Twenty Cr(VI) tolerant bacterial isolates were selected and their resistance to other metals and metalloids, and to antibiotics was assessed using a plate diffusion technique. The number of colony-forming units (cfu) of the contaminated sediments declined with increasing concentrations from 10 to 100 mg L^?1 Cr(VI), and more severely from 100 to 1000 mg L^?1 Cr(VI). The background sample behaved similarly to 100 mg L^?1 Cr(VI), but the cfu declined more rapidly thereafter, and no cfu were observed at 1000 mg L^?1 Cr(VI). Metals and metalloids that inhibited growth (from the most to least inhibitory) were: Hg > Cd > Ag > Mo = As(III) at 50 μg mL^?1. All 20 isolates were resistant to Co, Cu, Fe, Ni, Se(IV), Se(VI), Zn, Sn, As(V), Te and Sb at 50 μg mL^?1 and Pb at 100 μg mL^?1. Eighty-five percent of the isolates had multiple antibiotic resistance. In general, the more metal-tolerant bacteria were among the more resistant to antibiotics. It appears that the Cr-contaminated sediments may have enriched for bacterial strains with increased Cr(VI) tolerance.