中国农业氨排放的时空演变趋势与减排潜力分析

中国雾霾成因比发达国家更为复杂,人为源氨气(NH_3)污染是中国PM2.5指数被持续推高的重要因素,却一直被全社会所忽视。已有研究表明,人为源NH_3排放主要来自农业,农业NH_3减排是雾霾治理最经济有效的方法,因此,研究中国农业NH_3减排潜力对中国控氨治霾具有重要现实意义。本文基于各类统计年鉴和研究成果中的相关数据,参考《大气氨源排放清单编制技术指南(试行)》,构建农业NH_3减排潜力分析模型,应用排放因子法和情景分析法,测算并分析了中国2004—2013年农业NH_3排放演变和2020—2030年农业NH_3减排潜力。结果表明:1)2013年中国农业NH_3排放总量为1 193.92万t,比2004年增长18.59%。2)农业年NH_3排放总量在60万t以上的省市,2004年有河南、山东、河北和内蒙古4省,到2013年演变为河南、内蒙古、河北、山东、新疆和四川6省。3)趋势照常情景(business-as-usual,BAU)下,2020年、2025年和2030年中国农业NH_3排放将比2013年分别提高15.26%、23.60%和30.23%。4)减排情景下,2020年、2025年和2030年的中国农业NH_3排放将比BAU情景分别减少319.40万t、501.31万t和660.40万t,将比2013年分别下降11.49%、18.39%和25.08%。5)未来中国农业NH_3减排的关键取决于中国居民消费畜禽产品的数量和结构,其次是中国畜禽养殖的饲料营养水平改变。6)未来中国农业NH_3减排重点区域在河南、山东、河北、内蒙古和四川。由此可见,BAU情境下未来中国农业NH_3排放将失控,未来中国农业NH_3减排必须从大力削减重点区域排放和加速转变居民畜禽产品消费行为两方面入手。

我国农业氨排放估算方法研究进展

农业大量施用氮肥以及持续扩大的禽畜养殖业是我国氨污染的最大来源。近年来大气环境问题备受关注,氨排放研究的重要性日益凸显,如何客观、科学定量的评估我国区域氨排放的问题尤为重要。通过检索已报道的国内外氨排放估算的研究进展,对我国的氨排放研究进行梳理,比对了氨排放主要估算方法的特点,对其所使用数据类型、获取途径,参数的定量取值方法及不确定性产生等方面进行了分析。针对国内氨排放估算存在计算方法单一,排放因子本地化不足等问题,提出了进一步改善的意见和建议。研究结果以期为我国做好氨排放控制基础研究,开展控制技术试验,制定相关政策文件,加强政府引导和扶持等提供科学依据。

黄淮平原典型城市农业氨排放清单及特征分析——以亳州市为例

亳州市是黄淮平原典型城市,而农业是其最大的氨排放来源。基于亳州市畜禽养殖、氮肥施用、固氮植物、土壤本底、秸秆堆肥、人体粪便6类农业源活动水平数据与排放因子,建立2011—2018年亳州市农业源氨排放清单,分析该市氨排放结构、空间分布、历年变化趋势及不确定性,进一步深入了解黄淮平原典型城市农业氨排放特征。结果表明:2018年亳州市农业氨排放总量为27529.19 t/a,其中畜禽养殖与氮肥施用是农业氨排放量较大的2类源,占比分别为68.81%、16.85%。农业氨排放集中在利辛县与谯城区,分别占全市总排放量的28.9%、27.8%。亳州市农业氨排放量从2011年的35097.97 t/a小幅升至2014年的38441.13 t/a,2015—2017年变化不大,2018年降至27529.19 t/a。从各类农业源氨排放量变化趋势来看,2011—2018年秸秆堆肥、土壤本底的氨排放量出现微小涨幅,畜禽养殖、氮肥施用、固氮植物、人体粪便的氨排放量呈下降趋势。此外,2011—2018年亳州市农业源清单的不确定性处于-22%~26%,清单不确定性较小。

京津冀农业源氨排放对PM2.5的影响

根据收集的京津冀区域农业氨排放源活动水平数据,使用排放因子法建立了2014年京津冀地区农业氨排放清单.结果表明,2014年京津冀地区农业源氨排放总量为1750695t,平均排放强度为8.09t/km2;河北省、北京市和天津市农业氨排放量分别为1594087t、58822t和97786t.;猪和蛋鸡是畜禽养殖业中氨排放的主要来源,分别占31.29%和26.07%.模拟结果表明,农业氨减排使京津冀地区PM2.5的年均浓度下降12.04μg/m3,下降比例约为18.36%,4月份和7月份农业氨减排对PM2.5的影响较大,而1月份影响较低;农业氨减排使无机盐(硫酸盐+铵盐+硝酸盐)的年均浓度下降10.00μg/m3,年均浓度下降比例为41.84%,对硝酸盐的影响最大,铵盐次之,硫酸盐最小.

山东省农业源氨排放清单研究

为建立山东省农业源氨排放清单,根据《山东统计年鉴2016》数据,采用排放因子法估算了山东省2015年农业源氨排放清单。结果表明,山东省2015年农业源氨排放量为105.831万t,排放强度为6.71 t·km^(-2)。畜禽养殖是最大的排放源,排放量为68.673万t,占总排放量的64.89%,猪和家禽是畜禽养殖排放量的最大贡献源,两者占畜禽养殖排放量的72.88%;其次是氮肥施用,排放量为30.835万t,占总排放量的29.14%;生物质燃烧、人体排放、土壤本底的氨排放量分别为2.173、2.117、1.943万t,分别占总排放量的2.05%、2.00%、1.84%;固氮植物的氨排放量最小,仅为0.09万t,不足总排放量的1%。菏泽、德州、潍坊、临沂、济宁、聊城是山东省农业源氨排放大市,氨排放量为7.910～13.662万t。研究表明,应从规范畜禽养殖规模和合理施肥两方面着手,精准施策,以减少山东省农业源氨排放量。

深圳市2019年非农业源氨排放清单及特征分析

根据收集的深圳市非农业源的活动数据,采用排放系数法建立了该城市2019年非农业源氨排放清单,结果表明:2019年深圳市非农业源氨排放总量为4950.98 t;垃圾填埋是非农业源的首要贡献源,占排放总量的30.85%,其次是道路移动源和垃圾焚烧,分别占30.62%、18.80%;轻型汽油车对道路移动源排放贡献最大,占该类排放源氨排放总量的68.99%;在空间结构上,道路移动源氨排放量集中于路网密度高、车流量大的中心城区;罗湖区的垃圾填埋、南山区的烟气脱硝、宝安区的垃圾焚烧对深圳市非农业点源氨排放贡献较大,分别占32.44%、16.88%、15.24%。固体废物处理、火电厂烟气脱硝、轻型汽油车将是深圳市非农业源氨减排的重点管控对象。

四川省2005～2014年农业源氨排放清单及分布特征

根据收集到的四川省2005~2014年农业源氨活动水平数据,采用合理的估算方法和排放因子,建立了该地区2005~2014年农业源氨排放清单,利用GIS建立了3 km×3 km的网格化清单,并分析了农业源氨排放与PM_(10)之间的关系.结果表明2005~2014年间,四川省农业源氨排放总体上呈现出下降趋势,2006年排放量最高;21个市(州)农业源氨变化趋势各不相同,年际变化较大的城市包括成都市、眉山市、自贡市、泸州市、宜宾市、攀枝花市、阿坝州和甘孜州;畜禽养殖和氮肥施用均为农业源氨主要排放来源,研究期间的贡献率分别为72%~79%和20%~27%;畜禽养殖中,绝大部分城市氨排放量较大的为生猪、家禽和牛,而自贡市由于特殊的饮食习惯,兔为氨排放量最高的牲畜,贡献率为39%;成都及周边地区、川东北地区和川南地区是四川省农业源氨排放的主要贡献地区;空间分布上,农业源氨主要分布在四川省东部,且主要来源于城市周边区县;农业源氨排放量与PM_(10)质量浓度的变化趋势呈现出较好的一致性,表明农业源氨排放对颗粒物生成有较大影响.

Estimation of interannual trends of ammonia emissions from agriculture in Jiangsu Province from 2000 to 2017

As the only alkaline gas in the atmosphere,ammonia could react with sulfur dioxide and nitrogen oxides to form the secondary particles.A large amount of NH3 in the atmosphere accelerates the rate of formation of fine particles;it therefore plays an important role in haze pollution.Livestock and poultry farming and nitrogen fertilizer application are the two main NH3 emission sources.Jiangsu Province contributes the largest proportion of NH3 emissions from agriculture in key areas of national air pollution control in China.The aims of this study are to investigate NH3 emissions from agriculture in Jiangsu Province using the emissions factor method,and analyze and summarize the characteristics and trends of NH3 emissions from 2000 to 2017.Results show that the NH3 emissions from agriculture in Jiangsu Province from 2000 to 2017 were mainly contributed by livestock and poultry farming(78.08%)and nitrogen fertilizer application(21.92%).Furthermore,a general fluctuation trend of an initial decrease and then an increase,of NH3 emissions from agriculture,could be found from 2000 to 2012,with minimum NH3 emissions in 2007(708.76 kt yr−1)and maximum emissions in 2012(837.64 kt yr−1);and then a decreasing trend was apparent from 2012(837.64 kt yr−1)to 2017(690.64 kt yr−1).A detailed estimation of the interannual trends and potential measures are also proposed.This study provides a solid theoretical foundation for the development of NH3 emissions control in Jiangsu Province.

Effects of Agricultural Practices on Soil Organic Nitrogen Fractions in an Inceptisol of a Cocoa Plantation

The effect of agricultural practices on soil organic nitrogen （N） fractions in a cocoa plantation has not been much revealed till now. Despite the fact that soil organic N has been long admitted for its importance to maintain soil fertility. Presented field experiment was conducted in Kaliwining Experimental Station, Indonesian Coffee and Cocoa Research Institute （ICCRI）, Jember, East Java, Indonesia, to investigate the effect of cocoa farm management, namely fertilization, weeding and soil tillage on the content of soil organic N fractions. The design of experiment was arranged in a split-split plot with two levels of weeding as main plots, two levels of soil tillage as subplot and three different fertilizer treatments as sub-sub plot. The analysis of soil N including total N and soil organic N fractions, namely, total hydrolized N, ammonium N, amino sugar N and amino acid N, were performed. The result showed that the effect of fertilization treatment was significant to the content of total N, ammonium N, amino sugar N and amino acid N. No-tillage treatment resulted in total N and amino sugar-N content increasing by 8% and 24%, respectively, over tillage treatment. Slashing treatment caused increase of the total N by 3% from herbicide treatment, whilst decrease of ammonium N and amino sugar N by 7% and 24%, respectively.

An ammonia emissions inventory for agricultural sources in Hefei,China

A comprehensive agricultural inventory of ammonia emissions for 2017 in Hefei was established on the basis of the specific emission factors and county-level activity data.The emissions over a 1 km×1 km grid and the associated monthly variations were distributed on the basis of land-use type and meteorological conditions,respectively.The total ammonia emissions were 27,242.7 t in 2017 in Hefei,to which livestock was the top contributor,accounting for 54.5%.Two major contributors to livestock waste were broilers and laying hens,which contributed 34.5%and 22.2%of the total emissions,respectively.Changfeng,Feixi,and Feidong counties,with more developed agriculture than other counties,accounted for a large proportion of the total ammonia emissions—as much as 28.5%,24.5%,and 21.0%,respectively.The average emissions density of the whole region was 2.4 t km−2,and the higher values were mostly in areas with denser populations.Seasonally,peak ammonia emissions occurred in summer.

Chemical synthesis of a cyclotide via intramolecular cyclization of peptide O-esters

Cyclotides constitute a fascinating family of circular proteins containing ca.30 amino acid residues.They have a unique cyclic cysteine knot topology and exhibit remarkable thermal,chemical and enzymatic stabilities.These characteristics enable them to have a range of biological activities and promising pharmaceutical and agricultural applications.Here,we present a practical strategy for the chemical synthesis of cyclotides through the intramolecular ligation of fully unprotected peptide O-esters.This strategy involves the mild Fmoc solid-phase peptide synthesis of the peptide O-ester backbone,the head-to-tail cyclization of the cyclotide backbone by native chemical ligation,and the oxidative refolding to yield the natural knot protein.The simplicity and high efficiency of the strategy can be employed in the synthesis of artificial cyclotides for pharmaceutical applications.

Responses of Ammonia-Oxidizing Bacteria and Archaea in Two Agricultural Soils to Nitrification Inhibitors DCD and DMPP: A Pot Experiment

Taking two important agricultural soils with different pH, brown soil （Hap-Udic Luvisol） and cinnamon soil （Hap-Ustic Luvisol）, from Northeast China, a pot culture experiment with spring maize （Zea mays L.） was conducted to study the dynamic changes in the abundance and diversity of soil ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA） populations during maize growth period in response to the additions of nitrification inhibitors dicyandiamide （DCD） and 3,4-dimethylpyrazole phosphate （DMPP） by the methods of real-time polymerase chain reaction （PCR） assay, PCR-denaturing gradient gel electrophoresis （DGGE）, and construction of clone library targeting the amoA gene. Four treatments were established, i.e., no urea （control）, urea, urea plus DCD, and urea plus DMPP. Both DCD and DMPP inhibited growth of AOB significantly, compared to applying urea alone. Soil bacterial amoA gene copies had a significant positive linear correlation with soil nitrate content, but soil archaeal amoA gene copies did not. In both soils, all AOB sequences fell within Nitrosospira or Nitrosospira-like groups, and all AOA sequences belonged to group 1.1b crenaxchaea. With the application of DCD or DMPP, community composition of AOB and AOA in the two soils had less change except that the AOB community composition in Hap-Udic Luvisol changed at the last two growth stages of maize under the application of DCD. AOB rather than AOA likely dominated soil ammonia oxidation in these two agricultural soils.

Perspectives of Using L-Tryptophan for Improving Productivity of Agricultural Crops: A Review

Plant growth regulators are biologically active signaling molecules that regulate a number of plant physiological processes. Auxin(indole-3-acetic acid) is an important plant growth regulator and is synthesized within plant tissues through L-tryptophan(L-TRP)-dependent and-independent pathways. It has been found that plants respond to exogenously applied L-TRP due to insufficient endogenous auxin biosynthesis. The exogenous application of L-TRP is highly significant for normal plant growth and development.L-tryptophan is applied through foliar spray, seed priming, and soil application. Soil-applied L-TRP is either directly taken up by plants or metabolized to auxin by soil microbiota and then absorbed by plant roots. Similarly, foliar spray and seed priming with L-TRP stimulates auxin synthesis within plants and improves the growth and productivity of agricultural crops. Furthermore, L-TRP contains approximately 14% nitrogen(N) in its composition, which is released upon its metabolism within a plant or in the rhizosphere and plays a role in enhancing crop productivity. This review deals with assessing crop responses under the exogenous application of L-TRP in normal and stressed environments, mode of action of L-TRP, advantages of using L-TRP over other auxin precursors, and role of the simultaneous use of L-TRP and auxin-producing microbes in improving the productivity of agricultural crops. To the best of our knowledge, this is the first review reporting the importance of the use of L-TRP in agriculture.

Nitrogen Isotopic Fractionation Related to Nitrification Capacity in Agricultural Soils

A laboratory-based aerobic incubation was conducted to investigate nitrogen （N） isotopic fractionation related to nitrification in five agricultural soils after application of ammonium sulfate （（NH4）2804）. The soil samples were collected from a subtropical barren land soil derived from granite （RGB）, three subtropical upland soils derived from granite （RQU）, Quaternary red earth （RGU）, Quaternary Xiashu loess （YQU） and a temperate upland soil generated from alluvial deposit （FAU）. The five soils varied in nitrification potential, being in the order of FAU 〉 YQU 〉 RGU 〉 RQU 〉 RGB. Significant N isotopic fractionation accompanied nitrification of NH4＋. 615N values of NH4＋ increased with enhanced nitrification over time in the four upland soils with NH4＋ addition, while those of NO3 decreased consistently to the minimum and thereafter increased. 515N values of NH4＋ showed a significantly negative linear relationship with NH4＋-N concentration, but a positive linear relationship with NO3-N concentration. The apparent isotopic fractionation factor calculated based on the loss of NH4＋ was 1.036 for RQU, 1.022 for RGU, 1.016 for YQU, and 1.020 for FAU, respectively. Zero- and first-order reaction kinetics seemed to have their limitations in describing the nitrification process affected by NH4＋ input in the studied soils. In contrast, N kinetic isotope fractionation was closely related to the nitrifying activity, and might serve as an alternative tool for estimating the nitrification capacity of agricultural soils.