土壤含水量和电导率对芦苇生长和种群分布的影响

在对芦苇小区调查取样的基础上，利用Pearson关联分析法研究了土壤水、电导率与芦苇生长和种群分布的关系。结果表明土壤电导率空间变率明显，最大值是最小值的2倍。芦苇小区土壤电导率超过110mS／m，且pH值大于10时，芦苇由单一种群落转变成伴生种群落（芦苇＋碱茅）。并随着电导率和pH值的增加，碱茅所占的比例增加。土壤电导率与芦苇生长指标（覆盖度、平均株高、生物量干重、鲜重）呈显著性相关（P〈0．01），说明土壤盐分是影响芦苇种群特征的重要因素。表层土壤含水量（10cm剖面）与芦苇生长指标中的覆盖度、生物量呈显著性相关（户〈0．05）。深层含水量（100cm剖面）与芦苇生长指标均呈显著性相关（P〈0．05），因此表层水和深层水对芦苇的生长具有重要作用。     

基于聚类分析的土壤盐渍剖面特征及其空间分布研究

通过对黄河三角洲地区典型地块土壤盐渍剖面的聚类分析,研究并总结该地区不同盐分剖面类型土壤含盐量在水平方向以及垂直方向的分布特征和规律,运用该规律对各盐渍剖面类型的空间分布进行了探讨。结果表明:研究区土壤盐分剖面可以明显分为表聚型、底聚型和平均型3类,按照垂直分布特征可将0～180cm土体划分为0～20cm、20～80cm、80～120cm和120～180cm四个层次;研究区土壤含盐量在垂直方向和水平方向上变异较强,总体上盐分分布具有一定的表聚性,且各土层含盐量的规律性可以作为判断土壤盐分剖面类型的依据;受结构性因素和随机性因素的共同影响,各土层含盐量均表现为中等的空间自相关性和相同的空间自相关变化尺度。Kriging插值与空间分析结果表明,微地形和气候条件是影响表层土壤盐分空间分布的主要因素,地下水性质主导深层土壤盐分的空间分布;表聚型盐分剖面是研究区最主要的剖面类型,其次分别为底聚型和均匀型;不同盐分剖面类型的空间分布反映了植被类型和土地利用方式的差异,人为农业措施是形成底聚型与平均型盐分剖面的最直接因素。该研究结果为黄河三角洲地区盐渍土地的分区、改良、管理以及合理利用提供了理论基础和实践依据。     

宁夏河套灌区典型区域土壤盐碱化空间变异特征

运用经典统计学和地统计学相结合的方法,以宁夏河套灌区盐碱化最严重的区域作为研究区,研究其土壤盐分含量和pH值的空间变异特征。结果表明:土壤全盐含量在表层为强变异性,在其他层次为中等变异性;pH值为弱变异性,其空间变异格局主要由结构性因素引起。土壤全盐含量和pH值均呈现出西北地势低洼地区高于其他地区的空间分布格局,平行于和垂直于贺兰山和黄河走向的方向上土壤全盐含量变异程度较小,而在以沙湖为中心的对角线方向上土壤全盐含量变异程度较大。研究区土壤盐分剖面类型以表聚型为主,底聚型和平均型盐分剖面主要分布于平行于贺兰山和黄河方向偏东的带状区域内和垂直于该方向偏南的带状区域内。     

黄淮海平原土壤盐渍化状况的数值分类

本文通过ＧＰＳ定位的网格取样和Ｑ型聚类等方法，研究了整个黄淮海平原土壤盐分的剖面特征与水平分布．结果表明：根据黄淮海平原土壤盐分的剖面构型，可将整个黄淮海平原的剖面特征分为４大类，即表聚型、　底聚型、中聚型和平衡型．从其占聚类剖面的数量而言，它们分别占总聚类剖面数的约３０％、５％、１３％和５２％．黄淮海平原各种土壤盐分剖面类型都具有明显的空间集聚性，其中表聚性剖面主要分布在徐淮及滨海地区，底聚剖面主要分布在原来盐渍化严重的豫东黄泛平原，中聚剖面主要分布在黑龙港下游地区．其它为平衡型剖面．这类剖面根据其特点，可分为山前平原土壤盐分淋溶区、鲁西南土壤盐分通体积聚区和浅层咸水影响下的土壤盐分平衡区．整个黄淮海平原土壤剖面中脱盐与积盐比例约为２∶１．所以土壤盐分以脱盐为主．     

苏北滨海盐土区土壤盐分剖面特征及其理化特性

以淮河入海口两侧河漫滩为研究对象,运用聚类分析和相关性分析等方法对土壤盐分剖面类型、土壤理化特性及其相关关系进行了研究。结果表明:研究区土壤盐分剖面类型具有明显区段性,距入海口近、中、远,土壤盐分剖面类型依次为表聚型、震荡型、平均型;土壤颗粒组成以粉粒和砂粒为主,黏粒含量极少,不同部位质地差异不大,表聚型土壤含盐量与土壤质地有较好的相关性,震荡型和平均型土壤含盐量与土壤质地的相关性差;研究区0—350cm土体有机质均属低水平,震荡型盐分剖面土壤有机质与含盐量显著负相关(p0.05),表聚型和平均型盐分剖面土壤有机质与含盐量相关性差;土壤整体为弱碱性,部分为碱土。     

西藏土壤钙、镁、钾、钠的迁移和聚集特征

采用统计分析方法,研究了西藏土壤钙、镁、钾、钠的含量变化和迁移聚积特征。结果表明,碳酸盐土的盐基氧化物总量高于硅铝土,且以CaO占优势,后者则以K2O占优势。土壤各类盐基元素含量的剖面层间变异系数(CVP)的大小趋势为CaO最大,MgO次之,Na2O与K2O均较小,显示钙是盐基迁移聚积中最活跃的元素。据土壤剖面的盐基聚积指数(BAIP),西藏主要土壤盐基的迁移聚积可分为盐基表聚型(BAIP1.0)和底聚型(BAIP1.0)两种基本模式。土壤盐基迁移聚积主要由钙(有时伴有镁)的迁移聚积引起,一般与钾、钠无关,故概括为积钙作用。积钙作用按其成因分为:①表聚型生物积钙;②化学积钙,又可分为底聚型和亚表聚型;③表聚型化学-生物积钙。     

不同耕种时间下土壤剖面盐分动态变化规律及其影响因素研究

以新疆奇台县绿洲不同耕种时间土壤含盐量为研究对象,运用聚类分析与相关分析法对其含盐量变化规律、盐分剖面类型及其影响因素进行了研究。结果表明:在荒地转化成人类熟作的农田(5 a以上)过程中,土壤剖面盐分特征变化依次为表聚型、均匀型、震荡型和底聚型。未耕地土壤含盐量高,是典型的盐渍土,且表层聚集现象明显,含盐量在表层(0～20 cm)占整个剖面的34.31%。耕种5 a、10 a的土壤,多为底聚型盐分剖面。随耕种时间加长,土壤各层含盐量的活跃程度变化依次为活跃层、次活跃层和较稳定层;土壤含盐量与有机质含量的关系由极显著正相关转变为极显著负相关,而与土壤pH的关系变化则相反。有耕作活动的土壤盐渍化发生了逆向演替,耕种10 a土壤平均含盐量仅为未耕地的20.90%,脱盐速度随着时间的增加而减小,由早期(0～3 a)的1.56 g kg-1a-1,下降为后期(5～10 a)的0.04 g kg-1a-1。     

基于电磁感应数据棉田土壤盐分剖面时空变异特征研究

针对新疆南疆塔里木河绿洲地区土壤盐渍化发生反复性与南疆水资源日益匮乏等问题,以该地区典型地块为研究对象,运用电磁感应仪快速获取土壤盐渍化信息技术,结合地统计插值对新疆塔里木河绿洲地区土壤盐分剖面类型进行研究,并用表观电导率ECv_(1.5)与ECv_(0.75)比值对研究区土壤盐分剖面进行分级并对土壤盐分剖面类型空间分布进行探讨。结果表明,不同时期ECv_(0.75)数据在空间分布上均表现为强变异强度,棉花整个生育期,土壤盐分呈现累积状态。不同时期ECv_(1.5)与ECv_(0.75)比值半方差函数均符合指数模型,土壤盐分剖面空间自相关性从棉花播种前由随机性因素作用类型过渡到棉花花铃期的随机性与结构性共同作用类型,再转变为棉花收获后土壤盐分剖面由随机性因素作用类型。不同时期土壤盐分剖面类型空间分布图表明,土壤盐分剖面类型呈现底聚型-表聚型-底聚型状态分布。土壤质地、微地形、温度、地下水埋藏深度是造成土壤盐分剖面类型分布格局最直接的因素。该研究结果对灌溉制度的科学制定具有一定的指导作用。     

环渤海平原区土壤盐渍化反演与水盐耦合分析

为明晰土壤盐渍化多维空间分布特征、水盐耦合关系，以环渤海平原的山东部分为研究区，通过野外实测和室内分析获取数据，基于经典统计方法对土壤水盐特征进行描述性统计分析；利用GIS软件分析土壤含盐量、含水量的二维空间分布，GMS软件可视化分析土壤盐渍化三维空间分异特征；构建土壤水盐耦合协调模型，定量分析不同因素对水盐耦合协调度的影响程度。结果表明：(1)研究区土壤含盐量中位数为2.08 g/kg,以中度盐渍土为主，土壤含盐量整体呈自上而下逐渐增大趋势，表层土壤含水量均值为15.38%,全区域较缺水；(2)二维空间上，土壤含水量<20%的面积为17 519.48 km²,共占86.64%;表层(0—20 cm)土壤含盐量以轻度盐渍土为主，面积为10 051.87 km²,占总面积49.71%。土壤含水量、土壤含盐量均呈自南向北增加趋势；三维空间上，土体盐渍化分布类型以均质型、底聚型为主，局部存在表聚、两端集聚类型，土体盐渍化分布特征复杂；(3)东营区以北区域水盐耦合度多>0.66,以南区域(除平度、莱州市外)耦合度多为0.40～0.66,形...     

晋西黄土丘陵沟壑区人工林下草本植物生物多样性研究

以长武王东沟小流域径流小区为试验点,研究了于黄土高原高塬沟壑区坡面表层土壤水分特征,分析了降雨量、植被覆盖度对地表土壤水分的影响,旨在为该区植被恢复和水土流失治理提供科学的理论依据。研究结果表明,0—30cm土层土壤含水量呈现中等变异。15°阳坡土壤含水量小于35°半阳坡土壤含水量。土壤水分的变化趋势与降雨量的变化趋势基本一致,0—10cm土层土壤含水量与降雨量具有良好的同步性,而10—20cm土层和20—30cm土层土壤含水量的同步性较差。植被覆盖度越高,其土壤平均含水量就越高,植被覆盖度达到40%时,中坡和下坡的剖面各层土壤含水量随深度增加而减少的趋势更加明显。土壤平均含水量从坡顶到坡底逐渐增加。0—30cm土层土壤含水量随深度增加而减少。     

Sediment denitrification in waterways in a rice-paddy-dominated watershed in eastern China

Purpose

Rice-paddy-dominated watersheds in eastern China are intensively cultivated, and lands with two crops receive as much as 550–600 kg?ha^–1?year^–1 of nitrogen (N), mainly through the addition of N-based fertilizers. However, stream N concentrations have been found to be relatively low. Waterways in the watersheds are assumed to be effective “sinks” for N, minimizing its downstream movement. We directly measured net sediment denitrification rates in three types of waterways (ponds, streams/rivers, and a reservoir) and determined the key factors that control net sediment denitrification. Such information is essential for evaluating the impact of the agricultural N cycle on the quality of surface water.

Materials and methods

The pond–stream–reservoir continuum was sampled every 2 months at nine sites in an agricultural watershed between November 2010 and December 2011. Net sediment N₂ fluxes/net sediment denitrification rates were determined by membrane inlet mass spectrometry and the N₂/Ar technique. A suite of parameters known to influence denitrification were also measured.

Results and discussion

Net denitrification rates ranged between 28.2?±?18.2 and 674.3?±?314.5 μmol N₂–N?m^–2?h^–1 for the streams, 23.7?±?23.9 and 121.2?±?38.7 μmol N₂–N?m^–2?h^–1 for the ponds, and 41.8?±?17.7 and 239.3?±?49.8 μmol N₂–N?m^–2?h^–1 for the reservoir. The mean net denitrification rate of the stream sites (173.2?±?248.4 μmol N₂–N?m^–2?h^–1) was significantly higher (p?<?0.001) than that of the pond sites (48.3?±?44.5 μmol N₂–N?m^–2?h^–1), and the three types of waterways all had significantly higher (p?<?0.01) mean net denitrification rates in summer than in other seasons. Linear regression and linear mixed effect model analysis showed that nitrate (NO₃ ^?–N) concentration in surface water was the primary controlling factor for net sediment denitrification, followed by water temperature. Using monitoring data on NO₃ ^?–N concentrations and temperature of the surface water of waterways and an established linear mixed effect model, total N removed through net sediment denitrification in the pond–stream–reservoir continuum was estimated at 46.8?±?24.0 t?year^–1 from July 2007 to June 2009, which was comparable with earlier estimates based on the mass balance method (34.3?±?12.7 t?year^–1), and accounted for 83.4 % of the total aquatic N. However, the total aquatic N was only 4.4 % of the total N input to the watershed, and thus most of the surplus N in the watershed was likely to be either denitrified or stored in soil.

Conclusions

High doses of N in a rice-paddy-dominated watershed did not lead to high stream N concentrations due to limited input of N into waterways and the high efficiency of waterways in removing N through denitrification.     

中国华北地区近40年物候春季变化

根据华北地区7个观测站物候资料,分析了华北地区1963-1996年及北京1963-2005年物候春季的变化特征及其与气温的关系。结果表明:华北地区的物候春季有明显提早来临的趋势,而造成这一变化的主要因素是本地区近40 a来冬春季气温的明显上升。其中1963-1996年间华北地区1-3月及4月的平均气温分别上升了2.3℃与1.7℃,物候春季起止日期分别提前了9d和4d,因而使得春季长度也延长了5d;北京1963-2003年间1-3月及4月的平均气温分别上升了3.5℃与2.6℃,物候春季的起止日期分别提前了11d和10d,但春季长度没有明显变化。     

Patterns in trace elements in lichens

Water, Air, & Soil Pollution - Epiphytic lichens were sampled in a Dutch national monitoring survey, which was carried out twice within 5 yr. The samples were analyzed by neutron activation...     

Trace metals in precipitation in Sweden

Trace metals (Cd, Cu, Fe, Mn, Pb, and Zn) concentrations in atmospheric precipitation have been routinely monitored in Sweden since the autumn of 1983. Concentrations are highest in southern Sweden and decrease northward. It is postulated that the long range transport of anthropogenic pollutants from the rest of Europe is the major source of Cd, Pb, and Zn in precipitation. Evidence for this hypothesis is that enrichment factors indicate anthropogenic origin, and Swedish atmospheric emissions of Zn and Cd are 2 to 3 times smaller than deposition fluxes. Also, Cd, Pb, and Zn concentrations are correlated in both space and time and are also well correlated with exSO₄ ⁺, a substance known to be of anthropogenic origin transported long distances.     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

天津半干旱地区不同种植年限菜田土壤微生物变化特征的研究

对天津周边半干旱地区不同种植年限的菜田土壤微生物状况调查研究表明 ,该地区土壤微生物以细菌为主 ,夏季微生物总量大大高于冬季 ;随着种菜年限的增加 ,耕层和亚耕层微生物总量都有增加趋势 ,其中细菌和放线菌增加明显 ,真菌有下降趋势 ;真菌类群分析表明 ,少数纤维素分解菌 ,如青霉 (Penicillium)、木霉 (Trichoderma)等为优势菌 ,而糖和木质素分解菌仅占少数。用尖孢镰刀霉 (Fusariumuoxysporum)、大肠杆菌 (Escherichia coli)接种不同种菜年限土壤 ,检测土壤拮抗菌状况发现 ,拮抗菌仅在种植年限长的老菜田的放线菌中发现。表明北方半干旱地区菜田土壤细菌为优势菌 ,主要存在于土壤微孔隙中 ;而适于生活在土壤疏松大孔隙中的真菌数量极少。应注意土壤结构的改良 ,为丰富土壤微生物提供良好的生态环境     

Trends in soil science in Switzerland

Phytoremediation is an emerging technology based on the use of green plants to remove, contain, inactivate or destroy harmful environmental pollutants. Recent developments in Europe and the USA show that the approach is somewhat different on both sides of the Atlantic. In Europe, phytoremediation has more basically been research driven and, based on the outcomes, applications have been envisaged. By contrast, the approach in the USA is more application and experience driven. In spite of a growing track record of commercial success, more demonstration projects are needed to prove that phytoremediation is effective in order to rigorously measure its underlying economics, and to expand its applications. More fundamental research is also required to better understand the complex interactions between pollutants, soil, plant roots and micro-organisms at the rhizosphere level, to increase the bioavailability of pollutants, to fully exploit the metabolic diversity of plants and, thus, to successfully implement this new green technology.     

沈阳市城市表土中微生物区系变化的初步研究

在沈阳市远郊-近郊-市区等不同城市化水平区内选取林地、草地和路边土几种不同利用方式下的表层土壤,对土壤中的微生物状况进行了初步分析。结果表明,随着城市化水平的提高,土壤中微生物的数量表现为明显的减少趋势。其中变化较大的是细菌,而真菌和放线菌的变化不明显。     

Changes in proteolytic bacteria in paddy soils in response to organic management

Proteolytic bacterial communities, which mineralize organic nitrogen, play a key role in agricultural systems. In this study, alkaline metalloprotease (apr) gene fragments from proteolytic bacteria were investigated in bulk and rhizosphere paddy soil from four fields under organic management (for 2, 3, 5, and 9 years), and from one field under conventional management (for 2 years). We analyzed the abundance and structure of the proteolytic bacterial communities using real-time quantitative PCR and denaturing gradient gel electrophoresis. Our results showed that the abundance of proteolytic bacteria ranged from 1.57?×?10⁸ to 8.02?×?10⁸?copies/g of soil. In addition, the abundance of the proteolytic bacteria in the paddy soils under organic management was significantly higher than those in the paddy soil under conventional management. Moreover, the gene copy numbers in the rhizosphere soils were significantly higher than those in the bulk soils. The abundance of proteolytic bacteria tended to increase with the duration of organic management, with the highest abundance being found in the soil that had been under organic management for 5 years. However, the proteolytic bacteria communities in the paddy soils were not significantly affected by management practices. Phylogeny analysis showed that all gel bands obtained represented genes from Pseudomonas. Additionally, correlation analysis and canonical correspondence analysis showed that C/N, C, and N were important factors that influenced the abundance and community structure of the proteolytic bacteria. These results suggest that proteolytic bacteria are indicators in organic management systems, depolymerize organic N and hence maintain soil sustainability.

Abbreviations: CM: conventional management; OM: organic management; DGGE: denaturing gradient gel electrophoresis; qPCR: real-time quantitative PCR detecting system; COFCC: China organic food certification center; CCA: canonical correspondence analysis