大棚土壤剖面EC25℃值变化研究

选取使用多年10个大棚土壤剖面测定。结果表明,90%的大棚土壤全盐量＞1g/kg,出现盐渍化,但其上蔬菜生长良好;EC     

采伐干扰对东北温带次生林土壤碳矿化和活性有机碳的影响

在黑龙江东部的张广才岭选择典型次生杂木林进行不同采伐处理,一个生长季后测定了土壤潜在碳矿化速率和活性有机碳含量.结果表明:在28℃条件下经过90d的培养,土壤潜在碳矿化速率和碳矿化总量在所测定的土层中(0-10 cm,10-20 cm,20-30 cm)均表现为:50%强度采伐>皆伐后农作>25%强度采伐≌对照>皆伐后造林的变化趋势,但各处理间差异不显著.土壤易氧化碳含量在3个土层50%强度采伐均显著高于对照.土壤微生物碳含量在0-10 cm和10-20 cm土层,50%强度采伐显著高于对照.在0-10 cm土层,皆伐后造林显著低于对照.水溶性有机碳含量在0-10 cm和10-20 cm土层,50%强度采伐显著高于对照,在20-30cm土层,皆伐后造林显著低于对照,这说明在东北温带次生林中,较大强度的择伐短期内可增加土壤活性有机碳含量.而皆伐后造林可导致土壤活性有机碳出现下降趋势.     

宜兴市温室土壤理化性质的调查和分析

对宜兴市的温室和露天土壤的理化性质(包括pH,电导率,各种水溶性离子的含量以及全盐量)进行调查测定,结果表明:宜兴市温室土壤pH值0-20 cm土层比深层低,有酸化趋势;土壤全盐量显著高于露天土壤,盐分已明显在0～20cm土层富集,表层土壤全盐含量均在2.00 g/kg以上;在盐分的离子组成中,阳离子以Ca2 为主,平均占全盐总量的14%,阴离子以NO3-和SO42-为主,分别平均占全盐总量的56%和23%.说明该地区温室土壤己达到中度盐渍化水平.     

河北省蔬菜大棚土壤盐分状况及其影响因素

通过对河北省蔬菜大棚的采样调查研究,结果表明:河北省蔬菜大棚土壤EC平均达到0 62ms·cm-1,0～20、20～40、40～60、60～80cm的土壤EC分别比相邻粮田增加244%、55%、50%、73%;在土壤空间分布上,0～20cm土层盐分含量最高;除HCO3-含量呈降低的趋势外,Ca2 、Mg2 、K 、NO3-、Cl-、SO42-均有不同程度的增加,并且土壤盐分随着种植年限的增加呈增加的趋势,而菜粮轮作可以明显降低土壤盐分含量。     

乌拉特灌域表层土壤盐分空间变异及季节性分布特征

为揭示乌拉特灌域土壤盐分的时空变化特征,明确影响土壤盐渍化的主导因子,运用主成分分析和Kriging插值法,分析研究区 0～ 40 cm土层土壤 pH、全盐量及盐基离子的季节性变化特征及空间分布。结果表明:研究区土壤主要为轻中度盐化土,春夏秋季土壤全盐量平均值在 2 g/kg以上,属于中度盐化土;0～ 20cm土层土壤全盐量比 20～ 40 cm土层土壤高 0.807 g/kg,是盐分的积累层。土壤阳离子以 K ++Na+为主,阴离子以 SO 42-和 Cl -为主。各层土壤盐基离子表现为春季 >秋季 >夏季;阳离子 Mg 2+、K++Na+和 Ca 2+的变异系数在     

寿光大棚菜地土壤呼吸强度、酶活性、pH与EC的变化研究

为防治土壤退化、促进农业可持续发展提供科学依据,以寿光地区露地土壤作对照,研究了连作1、5、8和12年大棚蔬菜(番茄)土壤有关生物学指标的变化。结果表明,土壤呼吸强度和脱氢酶活性棚内高于棚外,并随连作年限延长开始增强而后减弱,由于管理差异,12年棚龄土壤又回升。随着连作年限延长,土壤脲酶活性逐渐减弱,而过氧化氢酶活性逐渐增强;土壤呼吸强度和酶活性都由表层向底层逐渐减弱。土壤pH随连作年限增加逐渐下降,而EC逐渐增加,至12年棚龄时,与对照比0—20 cm土层pH下降了1.06单位,其他层次变化不显著。试验还表明,该地区表层土壤pH变化于6.45~7.51,EC 0.5 mS/cm,能较好地满足作物生长需要,同时,EC是影响土壤pH及酶活性变化的重要因素。土壤EC及过氧化氢酶活性可作为反映大棚菜地土壤质量变化的参考指标。     

再生水灌溉对土壤理化性质影响的试验研究

通过室内土柱模拟试验的方法，研究了再生水灌溉对土壤理化性质的影响。结果表明：再生水灌溉对土壤扩散率和饱和导水率的影响与连续灌溉再生水的次数有关，短时间灌溉有降低的作用，但随着灌溉次数的增加，土壤扩散率和饱和导水率有增加的趋势；同时，随着灌溉次数的增加，土壤pH值降低，土壤有机质和全盐量增加；土壤溶液中各离子浓度有显著变化。灌溉5次之后，除0～10cm土层全盐量为0．107％外，其他各层均低于0．1％的限度；0～10，10～20，30～40cm土层的ESP均在5％～10％范围之内，20～30cm土层的ESP基本保持在原始的水平。再生水灌溉对土壤次生盐渍化的影响不显著。     

不同种植年限蔬菜大棚土壤砷含量及形态变化研究

为研究不同种植年限下蔬菜大棚土壤中As的总量和赋存形态的变化,在山东省聊城市市郊某百棚村种植年限为2~14a间的大棚内采集0—20cm和20—40cm土层的土壤,并在大棚外的露天农田设置对照点,分别采用王水消解法和欧盟BCR提取法对土壤中As的总量和赋存形态进行了分析,同时测定土壤pH、粒径、SOM、NO3-、NH4+和有效磷含量等指标。结果表明,大棚内土壤As含量范围为11.3~21.4mg/kg,显著高于山东省土壤环境背景值和农田土壤中As的含量(P0.05),但除种植年限为14a的大棚外,均可达到国家土壤环境质量标准要求,达标率为93.7%;各种植年限大棚土壤中As的潜在生态危害系数均40,具有轻微的生态危害。大棚土壤中As的平均含量随耕种年限先上升后降低,至7a后再次持续上升;在深度变化上,种植年限在5a内和10a以上的大棚0—20cm土层中As含量均高于20—40cm土层,而6~9a间大棚则正好相反。大棚土壤中各形态As所占比例表现为残渣态(87.9%)可还原态(8.0%)可氧化态(2.9%)酸提取态(1.2%);酸提取态As含量随种植年限增加呈持续增加的趋势,且0—20cm土层含量明显高于20—40cm土层。相关分析表明,3种提取态As与土壤理化性质均存在不同程度的相关性,由此说明大棚土壤中非残渣态的活性As可能来源于耕种过程中施用的畜禽粪便、化肥等肥料。     

山西褐土区设施蔬菜地不同棚龄土壤氮、磷残留特征

设施蔬菜地因其高度集约化的栽培条件和管理方式对土壤养分状况影响极大,但随着种植年限的增加,土壤中氮、磷残留趋势并不清楚。基于此,采取野外调查采样与实验室分析相结合的方法,对山西省晋中市太谷县范村镇象谷村不同种植年限(10、20、30年)温室大棚土壤主要肥力指标进行综合分析,了解褐土区设施蔬菜地土壤主要养分氮、磷残留和迁移特征。结果表明:不同种植年限大棚土壤氮、磷均出现表层(0～20 cm)累积的现象。随着土层深度的增加,不同年限大棚土壤NO^3--N残留量均有降低的趋势,各棚龄土壤0～100 cm土层的硝态氮(NO^3--N)残留量均显著高于100～200、200～300、300～400 cm土层土体的残留量,10、20、30年棚龄土壤0～100 cm土层的NO^3--N残留量分别为100～200、200～300、300～400 cm 土层土体内NO^3--N残留量的34.9%、43.4%、40.9%,且20年的残留量占比最高;不同棚龄相应各层土体NO^3--N残留量均高于大田。随着棚龄增加,土壤0～20 cm土层的有效磷(Olsen-P)含量表现为先升高后降低的趋势,不同棚龄Olsen-P含量(0～40 cm土层)是大田3.8～5.6倍,均以20年棚龄的含量最高。10年棚龄20～40 cm土层和20年棚龄40～60 cm土层的Olsen-P含量均已接近大田表层值(24.66 mg/kg),不同棚龄土壤Olsen-P含量从40 cm土层开始均急剧下降。0～400 cm土层土体内全氮与NO^3--N含量呈显著线性相关,0～100 cm土层土体全磷和Olsen-P含量之间呈乘幂相关关系,由各自的决定系数可知,土壤中50%左右的NO^3--N和Olsen-P含量受全氮量和全磷量的影响。此外,褐土区磷淋溶阈值为45.1 mg/kg,超过此值该区域土壤存在磷淋溶风险。总之,大棚内短期投入大量肥料的生产方式导致土壤中特别是0～20 cm表层土壤氮和磷的大量残留,而长期水肥的高投入又引起有效态氮和磷的淋溶,进而在土壤深层次残留。     

不同潜水埋深下浅层土壤的水盐分布特征

浅层土壤水盐分布是影响植物幼苗生长的主要因子.为探讨潜水埋深对浅层土壤水盐分布特征的影响,以黄河三角洲建群种3年生柽柳苗木栽植的土壤柱体为研究对象,在咸水矿化度下(6.0 g/L),模拟设置0.3、0.6、0.9、1.2、1.5和1.8m共6种潜水水位,测定分析不同潜水埋深下,土壤表层0～ 10和10 ～ 20 cm土层的土壤相对含水量、含盐量及土壤溶液绝对浓度等水盐参数.结果表明:10 ～20 cm土壤相对含水量高于0～10 cm,随潜水水位的增加,土壤相对含水量均显著降低,且0～ 10cm土壤相对含水量随潜水水位降低幅度远高于10 ～20 cm,均在1.2～1.5m处土壤相对含水量减少率最大;0～ 10 cm土层含盐量随潜水水位的增加,表现为先升高后降低,在1.2m潜水水位处含盐量达到最大值(1.38％),比0.3m处增加106.35％.10 ～ 20 cm土层土壤含盐量随不同潜水水位的变化较为复杂,在潜水水位0.3 ～0.9m变化平稳,在1.2m处升高,在1.5～1.8m降低,在1.2m潜水水位处含盐量达到最大值(1.33％),比0.3m处增加304.04％;0～ 10 cm土层土壤溶液绝对浓度随潜水水位的增加,呈指数函数增加,以1.2m处最大(17.12％),10～ 20 cm土层土壤溶液绝对浓度随潜水水位的增加,先升高后降低,以1.2m处最大(10.10％).在0～ 20 cm土层土壤相对含水量与潜水水位呈显著负相关(P＜0.01),与土壤含盐量呈显著正相关(P＜0.05),土壤溶液绝对浓度在0 ～10 cm与潜水水位呈显著(P＜0.01)正相关,与土壤相对含水量呈显著(P＜0.01)负相关,却在10～ 20 cm与土壤含盐量呈显著(P＜0.01)正相关.该研究为黄河三角洲土壤次生盐渍化的防治及柽柳栽植管理,提供理论依据和技术参考.     

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。     

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.     

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...     

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.     

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