Throughfall and stemflow nutrient depositions to soil in a subtropical evergreen broad leaved forest in the Wuyi Mountains

１ＩｎｔｒｏｄｕｃｔｉｏｎＰｒｅｃｉｐｉｔａｔｉｏｎｉｓａｎｉｍｐｏｒｔａｎｔｓｏｕｒｃｅｏｆｎｕｔｒｉｅｎｔｉｎｐｕｔｔｏｆｏｒｅｓｔｅｄｅｃｏｓｙｓｔｅｍｓ，ｅｓｐｅｃｉａｌｙｗｈｅｒｅｒｏｃｋｗｅａｔｈｅｒｉｎｇｉｓｓｌｏｗ（Ｐａｒｋｅｒ，１９...     

塔克拉玛干沙漠边缘柽柳对土壤水盐分布的影响

以塔克拉玛干沙漠边缘地区生长的柽柳为研究对象,测定了柽柳灌丛下及周围土壤中Na⁺和K⁺含量、电导率、pH值、水分以及柽柳营养枝Na⁺和K⁺含量等指标.结果表明,柽柳灌丛造成土壤盐分呈现斑块状分布,形成盐岛.柽柳体内较高的盐分含量可能是造成土壤盐分分布变化的重要因素之一(盐岛效应).相关分析表明,盐岛效应强弱与背景土壤水盐条件密切相关.在背景土水盐条件适中的冲积平原中部,盐岛效应最显著;而在背景土盐分最重的冲积平原中下部和水分含量最低的沙漠边缘,盐岛效应消失.在柽柳生长的适宜地下水位,盐岛效应最明显.柽柳还使冠下土壤Na/K发生改变,碱性增加,含水量降低.     

土壤水分对土壤中硝态氮水平运移的影响

对硝态氮示踪的风沙土和黄潮土中水分及其扩散率进行了研究.结果表明,硝态氮水平运移速率受土壤含水量的影响较大,并随土壤含水量增加而增加.硝态氮水平运移速率随土壤水分扩散率的变化呈指数曲线变化趋势.硝态氮水平运移浓度随土壤含水量的增加而减少,并呈幂函数曲线变化,硝态氮水平运移浓度与含水量的相关系数达到极显著水平.硝态氮水平运移浓度还受到土壤水分扩散率的影响,随土壤水扩散率的升高而下降,并在湿润锋(土壤干湿交界)面上达到最大值.     

崇明东滩湿地植被类型和沉积特征对土壤碳、氮分布的影响

滨海湿地碳、氮储量的分布可能受盐沼植被和外源沉积物的综合影响.本文以长江口典型滨海湿地为研究对象,分别在崇明东滩湿地北部、中部和南部设置3条样线,根据外源沉积物的区域特征研究了3种主要盐沼植被(芦苇(Phragmites australis)、互花米草(Spartina alterniflora)、海三棱藨草(Scirpus mariqueter))和土壤中的有机碳(TOC)、总氮(TN)的季节变化及空间特征.结果显示,崇明东滩湿地北、中部为淤积型滩涂,南部呈侵蚀态势.盐沼植被中芦苇和互花米草生物量TOC、TN累积量均显著高于海三棱藨草带.北、中样线的相同植被类型中的土壤TOC、TN显著高于南样线.高潮滩的芦苇带土壤TOC储量高于中潮滩的互花米草带,而互花米草带土壤TN储量略高于芦苇带,海三棱藨草带和光滩土壤TOC、TN储量最低.盐沼植被类型显著影响土壤各层次TOC和TN储量的分布,其中,0~10 cm层次储量受植被类型和表层外源沉积物空间特征的交互作用影响.     

黄土高原半干旱区侧柏林群落土壤呼吸日变化及季节动态变化特征

Desertification is one of the most serious eco-environmental problems around Qinghai Lake. Based on GIS and RS, GIS analysis was used to obtain the information of spatial-temporal change and different pattern of desertification in each county around Qinghai Lake in four phases of 1976, 1987, 1995 and 2006. Using the function of intersect and overlay supported by ARCGIS, with analyzing attributes of vector RS images, we obtained transition data and established transfer matrix of land-use types in recent 30 years, besides, protracted land-use transition maps of all desertification classes. In further, we analyzed transition quantity and direction of desertification in each county, moreover, reconstructed the process of spatial-temporal evolution of desertification. The results are showed below: (1) it′s the transition between desertified land and others but not in the desertified that played the main role in Gangcha and Gonghe County, while the transfer between desertified lands were greater than that with other land-use types in Haiyan County. (2) Extremely severe desertified land mainly distributes in Ketu and Sand Islands that belongs to Haiyan County, and moderate desertified land in riversides of Gangcha County, also, the light desertification expanded too rapidly to become the most desertified land-use type in the surrounding of Qinghai Lake since 1976. (3) By using relative change rate of desertified land, the regional variability rank from top to toe was Gangcha, Haiyan and Gonghe.     

中亚五国气溶胶光学厚度时空分布特征研究

气溶胶时空变化是影响气溶胶气候效应不确定性的主要因素之一.在生态环境脆弱的中亚五国(哈萨克斯坦、乌兹别克斯坦、土库曼斯坦、吉尔吉斯斯坦和塔吉克斯坦)研究气溶胶光学厚度(Aerosol Optical Depth,AOD)的时空变化对中亚地区及全球生态环境和气候变化具有重要意义.基于2002-2019年MODIS 04_...     

Study of elemental distribution in soil on the loess plateau of China

Instrument neutron activation analysis (INAA) has been employed in this study to determine 32 elements in soil on the loess plateau. The preliminary results suggest that geochemical characteristics of elements in the soil mainly retained those in the parent materials (loess). It has been found that fractional deposition among grain sizes in the process of loess transportation as well as the bioclimate in which the soil developed are main factors affecting the regional variations of elemental distribution in soil on the plateau. Contour maps of element concentrations plotted from the trend analyses exhibit the major patterns of the distributions and variations on the plateau. Furthermore, the study also provides evidence for the aeolian theory of the loess transportation in China.     

Impact on soil quality of a 10-year-old short-rotation coppice poplar stand compared with intensive agricultural and uncultivated systems in a Mediterranean area

Bioenergy crops play an ecologically and economically fundamental role as an alternative to agri-food productions and as renewable energy sources. Little attention has been focused on soil quality following conversion of agricultural lands to biomass crops. Here, we assessed the impact of a 10-year-old short-rotation coppice (SRC) poplar stand on the main soil chemical parameters, microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi (AMF), compared with intensive agricultural and uncultivated systems. Three different harvest frequencies of poplar SRC (annual T1, biannual T2 and triennial T3 cutting cycles) were evaluated. Multivariate analysis showed that poplar SRC improved soil quality compared with intensive agricultural and uncultivated systems. T1 and T2 positively affected AMF inoculum potential and root colonisation of a co-occurring plant species, while T3 improved the majority of soil chemical and biochemical parameters. Moreover, three different AMF morphospecies belonging to the genera Glomus and Scutellospora were found in poplar SRC, while morphospecies belonging exclusively to genera Glomus were recorded in intensive agricultural and uncultivated systems. Such aspects have agro-ecological implications, since the positive changes of soil nutrient availability and carbon content together with a high abundance and diversity of soil biota show clear soil sustainability of poplar SRC.     

F-对Al在土壤中吸附-解吸行为的影响

研究了F-对Al在土壤中吸附-解吸行为的影响.结果表明,F-可以通过两种方式来影响土壤对Al的吸附.加入的F-与Al形成F-Al络合物后将减少土壤对铝的吸附量;土壤吸附F-时释放的OH-则将提高土壤对铝的吸附量,一定程度上抑制了前一种方式的影响,但F-将降低土壤对Al的吸附量这一规律没有改变.由于土壤对Al有很强的亲合力,能被1.0M KCl解吸下来的铝数量很小,F-对铝的解吸行为没有产生明显的影响.     

太湖真光层深度谱的分布特征及其介质影响探究

基于2010年5月份全湖28个站点分层测量的水体下行辐照度以及各光学介质(有机悬浮物LOI、无机悬浮物ISS、叶绿素a Chl-a)浓度的实测数据,本文运用岭回归分析法,分析了不同湖区5月份真光层深度谱的分布特征及其影响因素.结果表明整个有效光合辐射范围内,3种因素对真光层深度的贡献均为负,ISS浓度是真光层深度的主要贡献因子,贡献率达0.48~0.62;其次为LOI浓度,贡献率为0.34~0.45;Chl-a浓度的贡献最小,贡献率为0.05~0.09.675 nm处,ISS的贡献具有谷值,Chl-a与LOI的贡献却为峰值;520~650 nm处Chl-a贡献值保持低值.此外,按各采样点的真光层深度谱分布的线型向量空间余弦相似度(cosine)进行分步聚类(Ascending Hierarchical),将全湖分为二类,梅梁湾、竺山湾、贡湖湾以及胥口湾以北区域为第一类,其余区域为第二类.结合全湖所有采样点的各介质浓度数据,发现第一类采样点LOI与Chl-a的相对浓度大于第二类,此两类介质浓度凸显了650 nm、675 nm处真光层深度谱分布曲线的波谷特征.     

Effect of long-term fertilization on soil nitrate distribution

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青藏高原土壤有机碳密度垂直分布研究

通过对青藏高原土壤普查数据的整理分析,定量研究了青藏高原28个典型土壤类型、14个主要生态系统类型0～20cm、20～50em及50～100cm深度内土壤有机碳密度的垂直分布规律.结果表明,青藏高原28个典型土壤类型3个土层的有机碳密度平均值为(6.16±1.08)kg·m-2、(5.06 ±0.85)kg·m-2、(5.30±0.82)kg·m-2;在0～100cm土层内,暗棕壤、沼泽土的有机碳密度显著高于其它土壤类型,而高山漠土、灰棕漠土、亚高山漠土的有机碳密度不仅远远低于区域平均水平,而且显著低于其它土壤类型.14个典型生态系统土壤的有机碳密度均值为(7.47±1.38)kg·m-2、(6.07±1.24)kg·m-2、(6.46±1.16)kg·m-2;其中,以沼泽草甸、针叶林土壤的有机碳密度最高,而温性荒漠、高寒荒漠、高寒草原及亚高山草原土壤有机碳密度显著低于其它生态系统.这不仅体现了青藏高原土壤-植被显著的地带性分布,而且为青藏高原土壤有机碳循环模型,及有机碳对全球变化的响应研究提供重要的基础数据.     

五种农药对土壤转化酶活性的影响

测定了5种农药(多菌灵、百菌清、多菌灵-百菌清混剂、吡虫啉、氯氰菊酯)对长春市郊大棚土壤转化酶活性的影响,对农药作用下的大棚土壤与农田土壤的转化酶活性进行了比较研究.结果表明,百菌清、百菌清-多菌灵混剂、氯氰菊酯在实验浓度范围内(0.1～50mg/g)明显抑制土壤转化酶活性;多菌灵、吡虫啉浓度低于0.1mg/g时,对转化酶有激活作用,而浓度高于0.5mg/g时抑制转化酶活性;百菌清和多菌灵联合使用,会使农药毒性明显增强;不同农药对大棚土壤、农田土壤转化酶活性的影响不同.     

Influence of chlorsulfuron herbicide on size of microbial biomass in the soil

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季节性缺氧水库铁、锰垂直分布规律及优化分层取水研究

经多年对阿哈水库Ｆｅ，Ｍｎ污染的研究表明，Ｆｅ，Ｍｎ分布随着季节为化、水库水温分层而变化，呈现明显的垂直分布规律，高浓度Ｆｅ、Ｍｎ主要出现在水温分层期水库中、下层、与库底缺氧、ＰＨ下降，沉积物中的Ｆｅ、Ｍｎ向上覆水释放造成的二次污染等密切相关，为自来水厂优化分层取水提供了依据。     

Modeling the impacts of temperature and precipitation changes on soil CO2 fluxes from a Switchgrass stand recently converted from cropland

Switchgrass(Panicum virgatum L.) is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide(CO_2) fluxes and mitigate climate change. However, information on how these CO_2 fluxes respond to changing climate is still lacking. In this study, CO_2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean(Glycine max L.) in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO_2 fluxes. An improved methodology CPTE[Combining Parameter estimation(PEST) with "Trial and Error" method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO_2 emissions based on different climate change scenarios. This study showed that:(i) the measured soil CO_2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term(2015–2070) provided a pattern of polynomial curve;(ii) the simulated CO_2 fluxes provided different patterns with temperature and precipitation changes in a long-term,(iii) the future CO_2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO_2 fluxes from soil as a result of temperature and precipitation changes to some extent.     

长江三角洲大气气溶胶光学厚度分布和变化趋势研究

利用2000～2005年MODIS Level 2气溶胶产品分析了长江三角洲区域气溶胶光学厚度的分布和季节变化特点.结果显示,近年来长江三角洲气溶胶光学厚度值较高的区域逐年增加,光学厚度大于1.0的区域面积增加最快.根据城市气溶胶季节变化特征研究,发现长江三角洲地区各主要城市近年气溶胶有逐渐增加的趋势.统计结果表明,平原城市群气溶胶年峰值出现在夏季;山区城市群气溶胶年峰值出现在春季.平原城市群光学厚度增加速度大于山区城市群.