新疆绿洲区秸秆燃烧污染物释放量及固碳减排潜力

根据 2004-2013年新疆绿洲区主要作物产量,采用排放因子法对秸秆燃烧污染物排放量和碳释放量进行了估算,结果表明,2013年新疆地区作物秸秆燃烧排放的CO₂、CO、CH₄、NMVOC、OC、BC、SO₂、NO_x、NH₃和PM_2.5的量分别为9.0×10⁶ t、5.5×10⁵ t、1.6×10⁴ t、9.4×10⁴ t、1.9×10⁴ t、3.9×10³ t、2.4×10³ t、1.8×10⁴ t、7.8×10³ t和1.2×10⁵ t,碳排放总量为2.7×10⁶ t;在排放清单中,CO₂和CO是主要污染物,分别占污染物排放总量的91.6%和5.6%;棉花秸秆为排放贡献最大的污染源,占总排放量的43.3%,其次是小麦秸秆和玉米秸秆,分别占28.3%和21.9%.在此基础上,基于生物炭固碳技术,对该区域作物秸秆转化为生物炭的固碳量和碳封存潜力进行了估算,结果表明,若把被燃烧的三类秸秆(棉花、小麦和玉米)转化为生物炭,则每年可减少该区域54.9%的碳排放量;若将作物秸秆全部转化为生物炭,每年将有3.6×10⁶ t碳和1.3×10⁷ t CO₂被长期封存于生物炭中。可见,生物炭具有良好的固碳减排潜力,是一种可持续的碳封存技术。     

土壤侵蚀/水土保持与气候变化的耦合关系

通过综述土壤侵蚀对碳循环的影响、全球气候变化对土壤侵蚀的影响以及水土保持植被恢复对碳循环与土壤碳素积累的影响,研究土壤侵蚀/水土保持与气候变化的耦合关系。结果表明:因侵蚀造成的土壤碳素损失是巨大的,但土壤侵蚀是碳源还是碳汇过程依然存在争议,焦点集中于因侵蚀造成土壤团聚体解体,暴露在空气中的土壤有机碳的矿化速率的大小;随着全球气温升高以及降雨格局的变化,全球土壤侵蚀强度和范围都在不断增加,但土壤侵蚀对全球气候变化的响应程度依然值得深入研究;水土保持生态恢复主要通过改变下垫面性质来改变土壤有机碳含量、影响土壤CO2释放并促进土壤碳素积累,对抑制大气CO2浓度升高能产生积极影响。尽管土壤侵蚀/水土保持与气候变化的耦合关系方面的研究已取得重大进展,但仍有待于在土壤侵蚀过程中碳素变化模型、土壤侵蚀过程中氮素迁移转化特征以及侵蚀劣地生态恢复过程中土壤碳素积累机制等方面加强研究。     

滨梅茎段组织培养研究

以滨梅(Prunus maritima Marshall)带腋芽茎段为外植体进行了组织培养技术的研究。结果表明,植物生长调节物质种类及浓度、碳源、光照度对滨梅不定芽增殖和生长均有显著影响。综合分析单因素试验和正交试验结果表明,在滨梅组织培养中,最佳初代培养基为MS+0.5 mg·L-1TDZ;最佳继代增殖培养基为MS+0.3 mg·L-1TDZ+0.1 mg·L-12,4-D;最佳生根培养基为1/2 MS+0.2 mg·L-1NAA。培养基以质量浓度为30 mg·L-1的葡萄糖为碳源,光照度为3 000 lx。     

新疆三工河流域土壤碳库的估算

以土壤生态系统为基本单元,在对土壤有机碳、无机碳及相关资料调查分析的基础上结合GIS技术,对三工河流域土壤碳库进行了估算。结果表明三工河流域总碳储量约为11. 18Pg,其中有机碳占48. 54%,约为5. 43Pg,无机碳约占到51. 46%,约为5. 75Pg。     

三江源果洛地区牧草长势特征及其与气象条件的关系

利用2003—2016年三江源果洛地区6县牧草观测资料和同期气象观测资料,对果洛地区牧草长势变化特征及其与牧草生育期(4—9月)气温、降水量、日照等气象条件的相关性进行分析。结果表明,果洛地区6县中班玛、久治牧草长势最好,玛沁、甘德、达日次之,玛多最差;就平均长势而言,近14年果洛地区牧草长势趋于良好,牧草高度、覆盖度、产量均呈增加趋势。通过对牧草长势和牧草生育期的气温、降水量、日照时数的相关性分析表明,随着降水量的增加,牧草产量也相应的增加;而随着日照时数增加,牧草产量却呈减少趋势。     

毛竹林生态系统植硅体的分布及其影响因素

在浙江省临安市青山、安吉县船坝、新昌县巧英和新昌县大市聚等4个地点选取毛竹Phyllostachys edulis竹叶及林地土壤,运用微波消解及Walkley-Black方法,研究不同岩性土壤上发育的同一竹龄毛竹竹叶和同一岩性土壤上发育的不同竹龄毛竹竹叶中植硅体的产生和分布规律,为毛竹林植硅体碳汇调控提供科学参考。结果表明:①毛竹竹叶中植硅体质量分数为50.8~99.1 g·kg-1,基本上是由上部到下部递减,在不同岩性间的差异表现为花岗岩>花岗闪长岩>玄武岩>页岩。②毛竹竹叶中植硅体的产生通量变化范围为154.9~605.9 kg·hm-2·a-1,在不同岩性间的差异表现为花岗岩>花岗闪长岩>玄武岩>页岩。③若按目前全国毛竹林面积3.3×106hm2,植硅体产生通量209.5~420.2 kg·hm-2·a-1以及植硅体中碳含量(3±1)%计算,那么中国毛竹林通过叶植硅体约可以固定二氧化碳(76.1~152.5)×106kg·a-1。     

森林生态系统碳循环研究方法概述

介绍了森林生态系统碳循环研究方法,对当前森林生态系统碳循环研究的几种主要方法模型进行了概述,主要有Miami模型和Thornthwaite模型、Chikugo模型和生物量转换因子连续法等。     

种植绿肥与稻秸协同还田对单季稻田土壤有机碳库和酶活性的影响

种植绿肥和秸秆还田是稻田土壤培肥的重要措施。研究江汉平原单季稻田冬闲期种植绿肥及稻秸不同利用模式对土壤有机碳库和土壤酶活性的影响,为合理利用秸秆和土地资源提供科学依据。该研究基于3 a田间定位试验,以稻秸不还田不种绿肥(CK1)和不施肥空白(CK0)为对照,分析了冬闲期稻秸全量覆盖单独还田(RSM)、稻秸原位焚烧还田(RSB)、单种绿肥(GM)以及稻秸全量覆盖与种植绿肥协同还田利用(RSM+GM)等处理模式下土壤有机碳各组分含量、碳库管理指数、酶活性的变化及其与水稻产量的关系。结果表明:与CK1和CK0相比,RSB处理3 a后显著降低了土壤稳态有机碳含量,对土壤总有机碳、活性有机碳含量以及碳库管理指数均无显著影响;而GM、RSM及RSM+GM处理3a后显著提高了土壤活性有机碳含量、碳库指数、碳库活度、碳库活度指数和碳库管理指数,尤其是RSM和RSM+GM处理还可显著提高土壤总有机碳含量,且多数指标均以RSM+GM处理增幅为最大,其次是RSM处理。与CK1相比,RSB处理3a后显著提高了过氧化氢酶和蔗糖酶活性,但对土壤脲酶活性无显著影响;而RSM、GM及RSM+GM处理模式3 a后均可显著增加土壤过氧化氢酶、脲酶和蔗糖酶活性,其中RSM+GM处理模式在1 a后即可显著提高土壤脲酶活性,2 a后显著提高土壤过氧化氢酶和蔗糖酶活性,3 a后土壤过氧化氢酶和蔗糖酶活性增幅均是最大。相比于CK1,RSM和RSB处理模式3 a的稻谷增产效果均不显著,而GM和RSM+GM处理模式连续3 a显著提高了稻谷产量,增幅分别为6.88%～11.67%和6.00%～13.40%。相关性分析表明,土壤总有机碳、活性有机碳、碳库管理指数、土壤酶活性与水稻产量之间均呈极显著正相关关系。综上,在江汉平原单季稻作条件下,冬闲期稻秸全量覆盖还田或种植绿肥均可改善土壤肥力,增加作物产量,但前者更有助于土壤有机碳积累,后者更利于作物产量提升。为了兼顾秸秆资源利用、土壤质量改善和作物增产稳产,稻田冬闲期稻秸全量覆盖与种植绿肥协同还田利用模式是一种较好的选择。     

Soil Organic Carbon,Black Carbon,and Enzyme Activity Under Long- Term Fertilization

The present study aims to understand the effects of long-term fertilization on soil organic carbon （SOC）, black carbon （BC）, enzyme activity, and the relationships among these parameters. Paddy field was continuously fertilized over 30 yr with nine different fertilizer treatments including N, P, K, NP, NK, NPK, 2NPK （two-fold NPK）, NPK＋manure （NPKM）, and CK （no fertilization）, N, 90 kg urea-N ha^-1 yr^-1; P, 45 kg triple superphosphate-P205 ha^-1 yr^-1; K, 75 kg potassium chloride-K20 ha^-1 yr^-1; and pig manure, 22 500 kg ha^-1 yr^-1. Soil samples were collected and determined for SOC, BC content, and enzyme activity. The results showed that the SOC in the NPKM treatment was significantly higher than those in the K, P, and CK treatments. The lowest SOC content was found in the CK treatment. SOC content was similar in the N, NP, NK, NPK, 2NPK, and NPKM treatments. There was no significant difference in BC content among different treatments. The BC-to-SOC ratios （BC/SOC） ranged from 0.50 to 0.63, suggesting that BC might originate from the same source. Regarding enzyme activity, NPK treatment had higher urease activity than NPKM treatment. The urease activity of NPKM treatment was significantly higher than that of 2NPK, NP, N, P, K, CK, and NPKM treatment which produced higher activities of acid phosphatase, catalase, and invertase than all other treatments. Our results indicated that long-term fertilization did not significantly affect BC content. Concurrent application of manure and mineral fertilizers increased SOC content and significantly enhanced soil enzyme activities. Correlation analysis showed that catalase activity was significantly associated with invertase activity, but SOC, BC, and enzyme activity levels were not significantly correlated with one another. No significant correlations were observed between BC and soil enzymes. It is unknown whether soil enzymes play a role in the decomposition of BC.     

Regulation of amino acid biodegradation in soil as affected by depth

Dissolved organic nitrogen (DON) and in particular free amino acids represent a key pool in the terrestrial soil C and N cycle. The factors controlling the rate of turnover of this pool in soil, however, remain poorly understood. We investigated the factors regulating the rate of amino acid turnover at different depths (up to 1.2 m) in five low-input, acid soil profiles. Within the root zone (0–60 cm), amino acids constituted 8% of the DON and represented only a small fraction of plant available N. In all the soil profiles, the rate of amino acid mineralisation decreased progressively with depth. The average half-life of the exogenously added amino acids in the soil was 5.8 h in topsoils (0–10 cm), falling to 20 h at a depth of 50 cm and to 33 h at 100 cm. Generally, the rate of amino acid mineralisation correlated positively with total soil C and N, soil microbial activity (basal soil respiration rate) and soil content. The relatively rapid rates of microbial amino acid assimilation in subsoils below the root zone (>60 cm) indicate that long-term transport of amino acids (e.g. from soil to freshwaters) will be low. Based upon the C-to-N ratio of the amino acid substrate and the microbial C assimilation efficiency, we estimate that approximately 40–60% of the amino acid-N will be excreted as . In conclusion, the rapid rate of free amino acid turnover and their low concentration in soil solution indicate that the formation of inorganic N ( and ) in soil is limited primarily by the rate of free amino acid appearance in soil and not by the rate of amino acid mineralisation.