Methane emissions of differently fed dairy cows and corresponding methane and nitrogen emissions from their manure during storage

This study investigated the effects of supplementing 40 g lauric acid (C₁₂) kg^-1 dry matter (DM) in feed on methane emissions from early-lactating dairy cows and the associated effects on methane, nitrous oxide and ammonia release from the manure during storage. Stearic acid (C₁₈), a fatty acid without assumed methane-suppressing potential in the digestive tract of ruminants, was added at 40 g kg^-1 DM to a control diet. The complete feed consisted of forage and concentrate in a ratio of 1.5:1 (DM basis). The manure was stored for 14 weeks either as complete slurry or, separately, as urine-rich slurry and farmyard manure representing two common storage systems. Methane release of the cows, as measured in respiratory chambers, was lower with C₁₂ by about 20%, but this was mostly resulting from a reduced feed intake and, partly, from a lower rate of fibre digestion. As milk yield declined less than feed intake, methane emission per kg of milk was significantly lower with C₁₂ (11.4 g) than with C₁₈ (14.0 g). Faeces of C₁₂-fed cows had a higher proportion of undigested fibre and accordingly methane release from their manure was higher compared with the manure obtained from the C₁₈-fed cows. Overall, manure-derived methane accounted for8.2% and 15.4% of total methane after 7 and 14 weeks of storage, respectively. The evolution of methane widely differed between manure types and dietary treatments, with a retarded onset of release in complete slurry particularly in the C₁₂ treatment. Emissions of nitrous oxide were lower in the manures from the C₁₂ treatment. This partially compensated for the higher methane release from the C₁₂ manure with respect to the greenhouse gas potential. The total greenhouse gas potential (cow and manure together) accounted for 8.7 and 10.5 kg equivalents of CO₂ cow^-1 d^-1with C₁₂ and C₁₈, respectively. At unaffected urine-N proportion ammonia and total nitrogen losses from stored manure were lower with C₁₂ than with C₁₈ corresponding to the differences in feed and nitrogen intake. The present results suggest that manure storage significantly contributes to total methane emission from dairy husbandry, and that the identification of effective dietary mitigation strategies has to consider both the digestive tract of the animals and the corresponding manure.     

气相色谱法检测废气中甲烷、非甲烷总烃的问题研究

气相色谱法检测废气中甲烷、非甲烷总烃的方法存在诸多问题。针对标准参考气体的选择、采样方式、样品保存、配气方式、仪器配置等方面做了重点研究。结果表明,使用甲烷作为标准参考气体最佳,根据污染源的实际状况,可选择动力采样或玻璃注射器手动采样。样品气保存在惰性气袋中比玻璃注射器更好,实验分析更推荐双柱配置的气相色谱,手工配制标准气系列、使用填充柱也可很好的满足检测的质量要求。     

全玻璃针筒注射器保存空气中甲烷和总烃的影响因素

采用全玻璃针筒取样/保存、双通道双毛细管柱测定非甲烷总烃分析方法,以甲烷标准气体样品、标准气体样品(TO-14、TO-15),以及3种实际环境空气样品为例,考察了全玻璃针筒注射器取样保存影响检测结果的若干因素。结果表明,样品的保存时间取决于以下因素:(1)样品性质,不同类型样品的保存时间差异大,化学反应活性强的样品,其总烃含量呈现先升高后降低趋势,甲烷则相对稳定;(2)样品浓度水平,相同条件下相同类型样品,浓度高的保存时间短于低浓度样品,如与环境空气浓度相仿的样品保存时间可超过60 h;(3)保存环境的避光程度,对于同一种VOCs标准气体样品,避光、半避光、非避光保存样品回收率迥异,趋势差别极大,对于部分样品即便是避光保存仍发现回收率变化极大;(4)全玻璃材质注射器的气密性,需对照技术规范要求,进行气密性的检查。     

柴油机排放颗粒物组成分析

采用过滤分离、超声洗脱和气质联用等技术,实验测定了柴油机尾气中碳烟颗粒物的质量含量、可溶性有机组分在颗粒物中的质量分数和可溶性有机组分的化学组成。在实验条件下,柴油机尾气中碳烟颗粒物的质量含量为32·6~143·6mg/m3。可溶性有机组分在颗粒物中的质量分数为18·5%~89·4%。可溶性有机组分中检测出有机物100多种,已确定化学结构的有机物73种,其中直链和支链烷烃含量占81·22%,芳烃类化合物17·94%。     

Investigation on Temporal Variation in Methane Emission from Different Rice Cultivars under the Influence of Weeds

A study of temporal variation in methane efflux from the rice-fields indicated that weeds could modulate the CH4 emission by transporting atmospheric O2 more efficiently than rice plants to the rhizosphere, which suppressed CH4 formation in the oxic condition, inhibiting methanogenic activity. A more oxic environment in the sediment was reflected by the higher redox potential in the weed growing plots. Besides, cultivar differences in methane efflux might be attributed to various plant activities, more importantly root exudation, development of aerenchyma and the biomass. Peak emission of CH4 at the flowering stage in all the rice cultivars was associated with maximum extension of root mat, releasing exudates, which serve as carbon source for the methanogenic bacteria for CH4 formation.     

三亚河水体中甲烷和氧化亚氮的分布、释放及影响因素研究

甲烷(CH₄)和氧化亚氮(N₂O)是大气中重要的温室气体,对全球变暖和大气化学有重要作用。受人为活动影响较大的河流、河口是大气中CH₄和N₂O的重要源。于2019年春季、2020年秋季台风前后沿三亚河从下游到上游采集了11个站位的样品,测定三亚河水体中CH₄、N₂O浓度及相关参数,并估算了水-气界面释放通量。结果表明：春季、秋季以及台风后CH₄平均浓度分别为(15.92±23.04)、(364.43±265.41)、(666.02±502.60) nmol/L,N₂O平均浓度分别为(24.37±19.88)、(8.47±5.19)、(47.48±33.47) nmol/L,台风后大于台风前。水体中CH₄、N₂O主要受溶解氧(DO)和降雨影响,下游河段主要受潮汐作用影响。现场产生和沉积物释放是水体中CH₄的主要源,硝化作用是水体中N₂     

甲烷对非分散红外吸收法测定固定污染源废气中二氧化硫的干扰

二氧化硫是中国重点管控的废气污染物。固定污染源废气二氧化硫测定有定电位电解法、非分散红外吸收法、碘量法等,其中非分散红外吸收法具有选择性好、寿命长、灵敏度高等优势,是固定污染源废气二氧化硫测定的常见方法。在波长为7.3 μm附近的红外吸收波段,甲烷和二氧化硫的特征吸收峰有明显重叠,造成交叉干扰。实验研究表明：甲烷将对二氧化硫的测定引入5%左右的正干扰。现场验证表明：对于含有高浓度甲烷的焦化废气,非分散红外吸收法测定二氧化硫结果显著偏高,经过数学修正后与其他方法可比。在应用非分散红外吸收法测定二氧化硫时,应确认烟气中不含甲烷或其浓度很低,否则应当采取有效手段消除或减小甲烷的干扰。     

桂林市细颗粒物部分典型排放源的粒径谱及成分分析

采用在线单颗粒气溶胶质谱技术源解析方法,对桂林市PM2.5典型排放源的粒径和化学成分进行质谱分析,采集燃煤/燃气源、工业工艺源、扬尘源、油烟源4类共计7个典型排放源。结果表明,桂林市4类排放源细颗粒物的粒径分布为0.25~1.25μm,80%以上的细颗粒分布在0.2~1.0μm的小粒径范围,峰值约0.68μm。细颗粒物离子成分含有Na~+、Mg~+、K~+、NH~+4、Fe~+、Pb~+、Cd~+、V~+、Mn~+、Li~+、Al~+、Ca~+、Cu~+、Zn~+、Cr~+、CN~-、PO_3~-、NO_2~-、NO_3~-、Cl~-、SO_4~(2-)、SiO_3~-等成分,桂林市细颗粒物为元素碳、有机碳元素碳、有机碳、富锰颗粒、富铁颗粒、富钾颗粒、矿物质、左旋葡聚糖以及其他金属等9类。     

Effect of application of phosphate and organic manure-based fertilizers on arsenic transformation in soil columns

The mobility of arsenic in Cambisol under the influence of added barnyard manure and application of a phosphate solution to the soil was described on the basis of column experiments. A soil sample containing 126 mg/kg total As and 3.72 mg/kg specifically-sorbed As was extracted using demineralized water (DIW) or a 28 μmol/l phosphate solution in a column containing untreated soil and in a column with added barnyard fertilizer. The pH, Eh, alkalinity, main components, including DOC, and selected trace elements (Al, Mn, Pb, Cu, Zn, Cd, Cr, Co, Ni, Ba and As) were determined in the extracts. Hydrodynamic tests of the flow and transport of the substances in the columns were carried out. The addition of barnyard manure was manifested in elevated concentrations of the main inorganic components, DOC and Al and a decrease in the Eh value and Mn concentration. Application of a phosphate solution was manifested in a decrease in the NO₃ and SO₄ concentrations, probably as a result of the effect of increased biological fixation. The As concentration in extracts varied from 8.8 to 15.5 μg/l and was not dependent on the composition of the extracting solution or the addition of barnyard fertilizer.     

生活垃圾焚烧二噁英排放对人群健康影响研究进展

综述了二噁英对人体健康的危害特性, 以及我国生活垃圾焚烧厂二噁英排放浓度水平,及其周边环境空气和土壤中二噁英污染浓度水平、人群暴露途径、剂量和健康影响。指出,现有研究显示,我国生活垃圾焚烧排放的二噁英浓度在合理范围之内,垃圾焚烧厂周边人群二噁英暴露量普遍低于世界卫生组织（WHO）推荐的容许标准,但也有研究发现,垃圾焚烧会导致周边环境介质中二噁英浓度水平增高。提出,应重点关注垃圾焚烧排放二噁英的长期低剂量暴露对人群健康的影响。     

大型火电机组二氧化硫排放规律研究

选取35台装机容量30万千瓦以上大型火电机组,进行了为期2年的监测。总结出大型火电机组二氧化硫排放规律,对大型火电机组燃煤含硫量、脱硫设施脱硫效率和二氧化硫排放浓度三者间的关系进行了统计分析,建立了线性回归方程,进而对燃用不同含硫量燃煤的火电机组执行不同排放标准时,配套脱硫设施需要达到的脱硫效率进行了预测。     

生活垃圾与危险废物焚烧二噁英类排放特征研究

对某省52家焚烧企业(21家生活垃圾和31家危险废物)排放烟气数据进行了分析,结果表明,两类焚烧企业二噁英类17种单体分布有所不同,生活垃圾焚烧烟气中浓度较高的是O8CDD和O8CDF;危险废物焚烧烟气中较大的是2,3,4,7,8-P5CDF、2,3,7,8-T4CDD和1,2,3,7,8-P5CDD;两类焚烧企业二噁英类单体对I-TEQ贡献最高的都是2,3,4,7,8-P5CDF,贡献率分别为0. 7%～45%和10%～67%;两者的17种二噁英类与I-TEQ的相关性分析表明,1,2,3,7,8-P5CDF在2类焚烧炉中与I-TEQ均存在较高的相关性,其相关系数分别0. 932和0. 927,可以作为潜在的测定指示物。     

A Note on the Emission of Nitrogen Oxides from Silage in Opened Bunker Silos

The evolution of NO_x from grass and maize silages wasmeasured using chemiluminescence in samples kept in airtightcontainers, in the silos and in a 750 kg mass removed to a mixer waggon. Measurements were made on the grass and maizesilos in two consecutive years. The results show that thereis continuous evolution of NO_x after silos have been opened and that high concentrations persist in the mass whichare rapidly released on agitation at the feed-out. The maximumrecorded concentrations of NO and NO₂ were 1985 and 152 ppbv respectively. These values are orders of magnitude greaterthan for rural background levels and exceed the maximum hourlyexposure of 50 ppbv for NO₂ recommended by the UK expertpanel for quality standards.     

固定源排气中可凝结颗粒物排放与测试探讨

阐述了可凝结颗粒物的定义及国内外颗粒物的测定方法,并就可凝结颗粒物的量级及危害进行了初步讨论,提出可凝结颗粒物应为被忽略的固定源颗粒状污染物,揭示出我国现存颗粒物采样方法存在的问题,并对此问题进行探讨,指出下一步工作的方向。     

常州市裸露地面风蚀扬尘排放清单及分布特征研究

以2014年为基准年,以常州市行政边界为研究区域,利用卫星遥感解译的土地利用类型和裸土面积信息,并通过国土、气象等部门提供的土壤类型、气象因子等相关资料获取本地化因子和参数,估算常州市行政区域内裸露地面土壤扬尘中颗粒物的年排放量。结果表明:常州市裸露地面主要分布在金坛市、溧阳市和武进区,市中心区域最少,裸露土地利用类型主要为农田、滩涂、裸露山体、荒地及未硬化或未绿化的空地等;2014年常州市行政区域内裸露地面风蚀扬尘中TSP、PM 10、PM 2.5的年排放量分别为62.66 t、5.63 t、0.24 t,其中,金坛市土壤起尘量最大,其次为武进区,再次为新北区、溧阳市,市中心区域土壤扬尘最少。     

燃煤锅炉湿法脱硫烟气中颗粒物排放特征

选择北京市典型燃煤锅炉进行研究,结果表明:烟气中可凝结颗粒物在总颗粒物中占有较高比例,供热燃煤锅炉总颗粒物排放水平明显高于电厂燃煤锅炉;颗粒物中水溶性离子含量较高,供热燃煤锅炉硫酸根比例尤其显著;烟气总颗粒物中存在大量不稳定的易被氧化的组分;同为燃煤源,不同的烟气净化工艺排放的PM2.5组分特征差异明显;现有标准和技术规范存在不足,无法满足全面、准确监测污染源排放总颗粒物的实际需要。建议建立总颗粒物、可凝结颗粒物的监测技术规范,全面测算燃煤锅炉硫、氮化合物排放情况,科学评估脱硫及脱硝效率。     

典型燃煤电厂机组二氧化碳排放测试及核算研究

为验证二氧化碳排放量的测试技术适用性及可行性,获取燃煤电厂机组碳排放特征,系统比较不同测试方法之间碳排放量的差异,对某典型火电机组二氧化碳排放开展测试,结果表明,不同测试原理及设备二氧化碳排放实测体积分数均较为接近。测试机组CO₂实测体积分数为11.28%～14.21%,与负荷变化呈一定的正相关关系,不同负荷下基准氧含量(体积分数6%)基本无变化。测试机组排放量与负荷正相关,使用了缺省值的指南排放量最高,与其他方法排放量相对偏差均值为31.6%;使用入炉煤实测数据的指南排放量差异不大,相对偏差为0.1%;使用入炉煤实测数据的2版指南排放量高于直接测量法,相对偏差均值为4.9%;直接测量各类方法间相对偏差均值为1.0%,其中在线法与手工法间相对偏差均值为1.2%。CO₂排放强度与负荷负相关,实验条件下,机组负荷越高,碳排放强度越低。     

生活垃圾焚烧烟气中重金属排放水平及影响因素分析

通过对浙江省生活垃圾焚烧炉排放烟气中重金属的监测,分析生活垃圾焚烧烟气中重金属排放水平。结果表明,汞及其化合物的检出率最高,为95.7%,其次为铬和锰,检出率均为60%,且在不同的焚烧炉中重金属排放浓度差异较大,检出率最低的为铊和镉,且排放浓度均较低;焚烧炉排放烟气中汞及其化合物、镉+铊及其化合物、锑+砷+铅+铬+钴+铜+锰+镍及其化合物排放浓度均低于国标排放限值,最大占标率分别为76%、4%、21.9%。焚烧烟气中的重金属含量与焚烧垃圾中的重金属含量有关,烟气通过废气处理设施,可有效地减少重金属等污染物的排放。     

生物技术行业废弃物排放现状及调查评价

由于生物技术的特殊性,生物技术行业所产生生物废弃物的环境排放,对人体健康和生态环境可能带来安全隐患。目前对生物技术行业产生的生物废弃物监管也尚未形成专门的法规和监测评估体系。在实地调研和实验分析的基础上,归纳分析了上海生物技术行业生物废弃物排放种类和管理现状,探讨了生物废弃物的监测评价技术。     

西宁市金属冶炼和压延加工业大气颗粒物排放清单

大气污染物排放清单是了解大气污染特征和控制对策的前提。根据排放因子方法,建立了2018年西宁市金属(包括黑色和有色金属)冶炼和压延加工业PM_2.5、PM₁₀大气污染物的排放清单,并对其时空分布特征和清单不确定性进行了分析。结果表明:西宁市黑色金属冶炼和压延加工业PM_2.5、PM₁₀的总排放量分别是4.88×10³、8.37×10³ t;该行业对PM_2.5、PM₁₀排放量贡献率最大的是城北区,分别为58.36%、49.61%。有色金属冶炼和压延加工业PM_2.5、PM₁₀的总排放量分别是1.85×10³、2.78×10³ t,该行业对PM_2.5、PM₁₀贡献率最大的是大通县,分别为53.51%、56.99%。黑色金属冶炼和压延加工业对PM_2.5、PM_10<...