A Comparative Study on Soil CO2 Flux between a Saline Desert and a Cropped-Oasis Farmland

土壤表面CO2通量作为导致全球气候变化的关键生态过程，已经成为全球碳循环研究的核心问题，其动态变化将对全球碳平衡产生深远的影响。因此研究不同类型陆地生态系统土壤CO2通量的源汇特征及其主要影响因素对于深入理解全球气候变化和解释当今大气中失踪汇等科学难题具有极为重要的科学意义。本研究采用LI-8100自动土壤CO2通量系统观测了阜康原始盐生荒漠和绿洲农田的土壤CO2通量。结果表明：在2005年整个生长季节（05～10月）内，农田平均土壤CO2通量为3.19 μmolCO2?m-2?s-1，盐生荒漠为0.08 μmolCO2?m-2?s-1，农田是盐生荒漠的近40倍；农田土壤CO2通量的日过程呈单峰型，峰值出现在当地时间12：00前后，盐生荒漠则呈双峰型，第一峰值出现在09：00前后，第二峰值在17：00前后；在整个生长季内，农田土壤CO2通量远高于盐生荒漠，盐生荒漠夜间的土壤CO2通量均为负值；农田和盐生荒漠土壤CO2通量的月均最高值分别出现在7月（4.67 μmolCO2?m-2?s-1）和6月（0.17 μmolCO2?m-2?s-1），从9月起，盐生荒漠土壤CO2通量的月均值降为负值。农田和盐生荒漠的土壤CO2通量与土温的相关性都随土壤深度增加而减小，与气温的关系最密切，而且回归系数表明农田土壤CO2通量对温度变化更敏感；湿润事件（灌溉或降雨）对农田和盐生荒漠的土壤CO2通量具有促进作用。盐生荒漠开垦为农田后土壤CO2通量发生了显著变化，不仅改变了土壤CO2通量的量级，甚至改变了通量的方向。由于在2005年观测过程中，发现盐生荒漠夜间的土壤CO2通量呈向下的负值，表现为CO2吸收。为了确定盐碱土CO2的纯吸收通量，2006年比较观测了盐生荒漠、弃耕地和绿洲农田测点灭菌与未灭菌土壤的CO2通量，证实了盐土对大气CO2的吸收是一个单向的无机过程。对盐土CO2通量影响因素的分析表明，盐土的CO2通量分别与0～5 cm、5～10 cm、10～15 cm的土壤电导率（EC）、土壤pH值之间呈显著线性负相关（P<0.0001），且随不同土壤深度呈规律性的变化；灭菌前后土壤的日均CO2通量与气温、2 cm土温、5 cm土温表现为正相关关系，且相关性随土壤深度增加而降低；灭菌后盐土的CO2通量与土壤含水量呈显著线性正相关关系（P<0.0001）。同时证实了碱土也具有和盐土同样的CO2吸收现象，两者吸收强度基本相同。综合考虑各种影响因素确定了盐碱土的日均CO2吸收通量约为0.1～0.5 μmol m-2s-1，结合全球盐碱土的总面积，最后估测出全球7.00亿hm2盐碱土的CO2吸收值约为0.44×1015～4.4×1015 g，其数量级与全球碳循环中的失踪汇相同，进一步证实了盐碱土是大气CO2的一个重要的汇。这对全球碳收支的准确计算以及全球变化趋势的探讨具有重要的科学意义。Soil surface CO2 flux as a key ecological process causing globally climatic change has become a core issue of the global carbon cycle, of which the variation will bring far-reaching influence on the balance of global carbon. As a result, to study the source-sink characteristic and main determinatives of soil CO2 flux in terrestrial ecosystems of different types is of crucially scientific significance for thorough understanding of globally climatic change and explanation of the scientific puzzle of missing sink. In present study, the soil CO2 fluxes were continuously measured at a saline desert and a cropped-oasis farmland reclaimed from the native desert using LI-8100 Automated Soil CO2 Flux system. The results showed that the soil CO2 flux of the farmland averaged 3.19 μmolCO2?m-2?s-1 in the growing season, 39 times higher than that of the saline desert (0.08 μmolCO2?m-2?s-1). The diurnal course of soil CO2 flux was characterized by single-peaked curve for the farmland, but bimodal curve for the saline desert. In addition, the peak of soil CO2 flux in the saline desert appeared at about 8:00 and 17:00 (local time), but 10:00 in the farmland. Soil CO2 fluxes in the farmland were always higher than that in the saline desert throughout the growing season while soil CO2 flux of the saline desert was negative during night. Soil CO2 fluxes also exhibited different seasonal variations at the two sites, with the maximum monthly mean value occurring in June for the saline desert (0.17 μmolCO2?m-2?s-1) and in July for the farmland (4.67 μmolCO2?m-2?s-1). Interestingly, monthly mean soil CO2 flux of the saline desert became negative after September. The CO2 flux was closely related to the air temperature 10 cm above the ground, and its correlation with soil temperature weakened with soil depth at both sites. However, the regression analysis indicated that soil CO2 flux in the farmland was more sensitive to the temperature than that in the saline desert. Furthermore, soil CO2 flux at both sites tended to increase rapidly after typical wetting events (rainfall for the desert and irrigation for the farmland). These results indicated that the soil CO2 flux not only changed its magnitude greatly but also change its direction after the saline desert was reclaimed. Because soil CO2 fluxes in the saline desert appeared negative and downwards to the atmosphere during night in 2005, we measured soil CO2 fluxes contrastively between sterilized and unsterilized soil for saline desert, abandoned farmland and cropped oasis farmland to determine the absorptive CO2 flux of the saline soil. Then we find CO2 absorption by the saline soil is an inorganic and nonreversing process of soils. The analysis of factors influencing the intensity of soil CO2 fluxes in saline soil showed that the soil CO2 fluxes in saline soil before and after sterilization exhibited a significantly (P<0.0001) positive correlation with soil electrical conductivity (EC) and pH values at 0～5 cm、5～10 cm、10～15 cm depth. Differently, the soil CO2 fluxes in saline soil before and after sterilization were positively correlated with air temperature and soil temperature at 2 cm, 5 cm depth, and the correlation with soil temperature weakened with soil depth at both sites. The sterilized soil CO2 fluxes in saline soil were positively correlated with soil water content significantly (P<0.0001). Furthermore, we confirmed that the intensity of CO2 absorption of saline and alkaline soil was very close. After general consideration of various influencing factors，we estimate that the overall daily average of CO2 absorption is 0.1~0.5 μmolCO2?m-2?s-1 for all saline/ alkaline soils globally. Finally, the overall C absorption by the 700 million hm2 saline/alkaline soils on earth is estimated at 0.44×1015 to 4.4×1015 g of C per year, which approximately matches the missing sink in global carbon cycle in magnitude. It approves that saline/alkaline soil is an important CO2 sink of atmosphere and is of crucially scientific significance for exact estimation of global carbon balance and discussion of global change trend

沙冬青属(Ammopiptanthus)植物叶片全量氮、磷、钾和土壤环境的关系

本研究采用典型样地法，以沙冬青属（Ammopiptanthus）天然植物群落为研究对象，通过GPS定位，应用实验手段，对样方内的沙冬青属植物叶片的全量氮，磷，钾和分布生境中的土壤养分及其水溶性盐分进行了测定，初步探讨了沙冬青属植物叶片中全量氮、磷、钾和土壤环境因子之间的相关性，以期为沙冬青属植物的迁地保育和就地保育提供参考依据。初步得出以下研究结果：（1）土壤水溶性盐分中对沙冬青（A.mongolicus）叶片中全量氮，磷、钾有明显影响的是：土壤pH、土壤HCO3-和Ca＋＋。（2）土壤水溶性盐分中对新疆沙冬青（A.nanus）叶片中全量氮、磷、钾有明显影响的是：土壤pH、土壤电导率、总盐、全盐、土壤CO3=、Cl-、SO4=、Ca++，K+以及Na+。（3）对沙冬青属植物仆卜片中的全量氮、磷、钾都有明显影响的是土壤pH和土壤Ca++；对沙冬青属植物叶片的全量氮、磷、钾都没有明显影响的是土壤Mg++。（4）土壤养分中对沙冬青叶片中全量氮、磷，钾有明显影响的是：土壤有机质、土壤全氮和全磷；土壤养分中对新疆沙冬青叶片中全量氮、磷，钾含量有明显影响的只有土壤速效氮。（5）土壤养分中对沙冬青属叶片中的全量氮、磷，钾都没有明显影响的是：土壤全钾，土壤速效磷和谏妙钾。（6）沙冬青属叶片中的全量氮、磷、钾受土壤水溶性盐分、土壤养分的共同影响，但土壤水溶性欲分的熬响要大于土壤养分的影响。（7）分布生境的海拔高度对冬青属叶片中全量氮、磷、钾含量的积累有密切关系。（8）沙冬青属植物分布生境的土壤环境条件存在着较明显的差异。This paper selects representative and crude plant community of Ammopiptanthus as a object of research, which distribute in Wuhai and Alax in Inner Mongolia and Wuqia in Xinjiang. By using GPS technique and experimental means, the contents of total N, P, K in leaves of Ammopiptanthus, water-soluble salt and nutrient in soil of its distribution habitat were analysed. We discussed the correlativity between total N, P, K in leaves of Ammopiptanthus and factors of soil environment, attempting to provide reference for the protection of Ammopiptanthus. The primary conclusion were put forward as follows: Of all the water-soluble salinity in soil, soil pH, SO4= and Ca4++ have obvious effects on the contents of total N, P, K in leaves of A. mongolicus. Soil pH, electrical conductivity, total salinity, whole salinity of soil, contents of CO3=,- Cl-, SO4=, Ca-, K+ and Na+ in soil have obvious effects on the contents of total N, P, K in leaves of A. nanus. Both soil pH and content of soil Ca^have obvious effects on the contents of total N, P, K in leaves of Ammopiptanthus; Content of soil Mg^have no obvious effect on the contents of total N, P, K in leaves of Ammopiptanthus. Of all the soil nutrients, contents of organic material, total N, and total P in soil have obvious effects on the contents of total N, P, K in leaves of A. mongolicus; Contents of available N in soil have obvious effects on the contents of total N, P, K in leaves of A. nanus. Of all the soil nutrients, contents of total K, available P and available K in soil have no obvious effects on the contents of total N, P, K in leaves of Ammopiptanthus. The contents of total N, P, K in leaves of Ammopiptanthus are affected by both water-soluble salinity in soil and soil nutrients, and the effects by the contents of water-soluble salinity in soil are more obviously than soil nutrients. (7) Elevation in the distribution habitat of Ammopiptanthus has a restraining effect on the contents of total N, P, K in leaves of Ammopiptanthus. There are many differences between soil environments in distribution habitat of Ammopiptanthus

盐生荒漠与绿洲农田土壤CO_2通量的对比研究

为定量确定干旱区土地利用变化对土壤CO2通量的影响,采用LI-8100观测了原始盐生荒漠和垦荒农田的土壤CO2通量.结果表明:在整个生长期内,农田土壤CO2通量平均速率为3.19μmol.m-2.s-1,盐生荒漠为0.08μmol.m-2.s-1.农田土壤CO2通量的日过程呈单峰型,盐生荒漠则呈双峰型;农田土壤CO2通量远高于盐生荒漠,盐生荒漠夜间的土壤CO2通量均为负值.绿洲农田最高月均值出现在7月(4.67μmol.m-2.s-1);荒漠最高出现在6月(0.17μmol.m-2.s-1),9月后荒漠土壤CO2通量的月均值降为负值.进一步研究表明:盐生荒漠垦荒前后土壤CO2通量与土壤温度的相关性都随土壤深度增加而减小,而与近地面10cm气温关系最密切;湿润事件对土壤CO2通量具有促进作用.盐生荒漠开垦为农田后不仅改变了土壤CO2通量的量级,且在一定程度上改变了通量的方向

荒漠-绿洲土壤微生物群落组成与其活性对比

结合野外观测与实验室研究方法,对比研究了准葛尔盆地南缘盐生荒漠与绿洲农田土壤微生物活性与其群落组成的变化特征,并分析了土壤温度与湿度对荒漠-绿洲土壤微生物活性的影响。结果表明:荒漠开垦为绿洲后,土壤细菌明显增加,真菌无明显变化,放线菌显著减少。细菌在绿洲农田土壤矿化作用中占主导,真菌则在荒漠中占优势,绿洲农田土壤微生物活性(包括真菌与细菌活性)明显高于荒漠。温度对荒漠-绿洲土壤微生物活性的影响只在一定土壤湿度范围内作用显著,绿洲农田受其影响较大;荒漠有机质含量明显高于绿洲农田,但水分与盐分因素抑制了微生物对其的分解和矿化。不同土地利用方式导致了荒漠绿洲间土壤湿度及盐份的较大差异,加之与土壤温度极显著的交互作用,使得开垦后土壤有机碳的易得性增强,微生物群落结构发生显著改变,进而有机碳的矿化速率加快,土壤碳库随之消减

Effect of Returning Farmland to Forest (Pasture) and Changes of Precipitation on Soil Erosion in the Yanhe Basin

通过定量评估退耕还林(草)和降雨变化对延河流域土壤侵蚀的影响,为延河流域水土保持效益评价、流失治理和环境建设提供决策参考。【方法】利用延河流域日降雨、数字高程模型、土壤类型图、土地利用图和植被覆盖图,运用RUSLE模型,在ArcGIS平台的支持下计算流域1997年和2000年土壤侵蚀量,并分别模拟了退耕还林(草)和气候变化对土壤侵蚀的影响。【结果】由于降雨的变化,研究区年降雨侵蚀力均值由1997年的775.32MJ&middot;mm&middot;hm-2&middot;h-1&middot;a-1增加到了2000年的1292.07MJ&middot;mm&middot;hm-2&middot;h-1&middot;a-1,降雨大大加剧了流域土壤侵蚀;由于退耕还林(草)政策的实施,坡耕地面积大大减少,林草面积增加,植被覆盖和管理因子值显著减少,由退耕还林(草)前的0.1714下降到了退耕还林(草)后0.1592,减小了流域土壤侵蚀;由于退耕还林(草)的实施、气候变化以及水土保持工程措施和耕作措施变化共同影响,单位面积平均土壤侵蚀量由退耕还林(草)前的3012t&middot;km-2&middot;a-1增加到了退耕还林(草)后4671t&middot;km-2&middot;a-1,年土壤侵蚀总量2314&times;104t增加到了3589&times;104t。【结论】降雨变化使得..

梭梭(Haloxylon ammodendron)生理与个体用水策略对降水改变的响应

随着全球变化的加剧,降水改变正导致荒漠生态系统中植物用水策略的适应性变化;对降水变化响应的种间差异性影响着荒漠植物群落组成。研究将生理生态与个体形态尺度相结合,调查中亚荒漠关键种梭梭Haloxylon ammodendron对降水变化导致的自然生境中水分条件改变的响应与适应。实验于2005年生长期开展,在古尔班通古特沙漠南缘原始盐生旱生荒漠中设置3个降水梯度(自然、双倍和无降水);观测并比较不同降水条件下光合作用、蒸腾作用、叶水势、水分利用效率、地上生物量累积和根系分布的变化。结果表明,梭梭主要利用降水形成的浅层土壤水维持生存;有效的形态调节和较强的气孔控制是其维持光合能力以及适应降水变化的主要机制;降水增多对其产生正效应,预示着梭梭可能在未来种间竞争和群落演替中占有优势

光合有效辐射与地下水位变化对柽柳属荒漠灌木群落碳平衡的影响

全球气候变化和人类活动的加剧,正导致古尔班通古特沙漠南缘原始盐生旱生荒漠地区的地下水位发生显著改变。大气污染导致该地区太阳辐射减少。以盐生荒漠建群种多枝柽柳(Tamarix ramosissima)为研究对象,选择地下水位在2.9?4.5m波动的典型原始生境,观测了生长期内光合有效辐射和地下水位变化时的光合作用、蒸腾作用和叶水势等生理活动的季节变化,调查了根系分布特征;并利用涡度相关系统测定了生态系统碳水通量,估算群落碳同化能力、蒸腾耗水量与叶面积指数的季节变化,旨在揭示光合有效辐射和地下水位等环境因素对柽柳属(Tamarix)荒漠灌木群落光合作用的影响。研究结果表明:降水造成的潜土层水分状况变化对多枝柽柳的碳平衡没有显著影响。深根系与气孔调节是多枝柽柳碳平衡适应荒漠环境水分状况的两个关键机制。特殊的气孔行为体现了多枝柽柳以高水分消耗为代价将其碳获取最大化的适应对策;多枝柽柳生理与群落尺度的水分平衡和碳获取均依赖于深根系获取的稳定地下水源,缓和的地下水位波动将不会扰动其现有的碳/水平衡,地下水位剧烈下降将危及多枝柽柳的生存。此外,光合有效辐射是另一个主要影响因素,与群落碳获取呈显著正相关关系。群落碳同化能力的季节变化是光合有效辐射和地下水位共同影响下光合作用物候学特征的体现。过度开采地下水和直接破坏原生植被的行为,将会严重地干扰多枝柽柳群落的生存,进而破坏该区域现有的生态水文过程

Development of Complex Microbial Agent for Deodorization in Pigsty

从畜禽养殖场、堆肥场、鱼塘等场所分离筛选除臭功能菌,获得6株具有显著除臭作用的微生物,分别为酵母菌Y-1、霉菌M-1、乳酸菌L-1、芽孢杆菌B-1和B-2、光合菌P-1。采用正交试验对功能菌进行优化组合,研制除臭复合菌剂。结果表明:Y-1、M-1、L-1、B-1、B-2、P-1的最优比例为1∶1∶1∶1∶3∶3,其对综合恶臭、TVOC、NH_3和H_2S的平均去除率分别为54.97%、18.66%、13.12%、41.18%,对综合恶臭、TVOC、NH_3和H_2S的最大去除率分别为72.95%、35.26%、20.20%、81.28%。复合菌剂能够明显减少猪粪中恶臭的产生量