Bioremediation of Acetochlor in Soil and Water Systems by Cyanobacterial Mat

This study investigated the bioremediation of organic pollution in soil and water systems by cyanobacterial mats collected from Wadi Gaza. Acetochlor, a model compound of herbicide, was used as a standard organic pollutant. Various concentrations of acetochlor were injected in soil and water samples pre-treated with cyanobacterial mat for several periods of time. Percentage of growth of wheat as a test plant was taken as indicator of bioremediation of acetochlor. Results showed that acetochlor was degraded in both soil and water systems. Degradation was?much?faster in the water system than in the soil system. Concentrations of acetochlor above the field rate did not affect the bioremediation process in the water system whereas it did in soil pots. Furthermore, bioremediation in water system was nearly completed in 15 days whereas it did not reach high percentage?in the soil system. These encouraging results are new contribution in field of bioremediation of pesticide by cyanobacterial mats and suggest that application of cyanobacterial mat could be a fast and suitable methodology for bioremediation of organic pollutant in the ecosystem.

Bioremediation of Diuron in Soil Environment: Influence of Cyanobacterial Mat

Diuron is a herbicide widely used in the Middle East;its field application creates many environmental problems. This study investigated the bioremediation of Diuron in soil environment by Cyanobacterial mats collected from Gaza Wadi. Various concentrations of Diuron were injected in water saturated soil samples pre-treated with Cyanobacterial mat for several periods. Percent growth of Jews mallow as a test plant was taken as indicator of biodegradation of Diuron. Results showed that Diuron was degraded in soil and degradation was more pronounced when Diuron was incubated with Cyanobacterial in the irrigation water. Larger applied rate of Cyanobacterial mat did not affect the biodegradation of Diuron. These encouraging results suggest that application of Cyanobacterial mat could be a suitable method to remediate soil pollution.

Zonal Differences in Correlation Patterns Between Soil Organic Carbon and Climate Factors at Multi-extent

Studying the relationship between climate factors and soil organic carbon(SOC) is vitally important. However, how SOC responses to climate(temperature and precipitation) at cohesive extents is poorly studied. Two transects of approximately the same length(transect P and transect T) were selected to examine the variation of SOC content in relation to mean annual temperature(MAT) and mean annual precipitation(MAP). The coefficients of partial correlation between SOC density and MAT(Rt) and MAP(Rp) were determined to quantify the relationships between SOC density and the two climate factors. The results indicated that for transect T, Rt was statistically significant once the extent level was greater than or equal to two fundamental extent units, while for transect P, Rp showed statistical significance only at extent levels which were greater than two fundamental extent units. At the same extent levels but in different transects, Rts exhibited no zonal difference, but Rps did once the extent level was greater than two fundamental extent units. Therefore, to study the relationship between SOC density and different climate factors, different minimum extent levels should be examined. The results of this paper could deepen the understanding of the impacts that SOC pool has on terrestrial ecosystem and global carbon cycling.

Influence of the Elastic Modulus of the Soil and Concrete Foundation on the Displacements of a Mat Foundation

In this paper, we suggest to study the behavior of a mat foundation on subsoil from the plate theory taking into account the soil-structure interaction. The objective is to highlight the soil-structure interaction particularly the influence of the rigidities of the soil and the concrete on the subgrade reaction (k) and the displacements of the mat foundation subjected to vertical loads. From plate theory and the soil-structure interaction, the general equation is reached. This equation depends more on the subgrade properties than the concrete foundation properties. Consequently, the behavior of the mat foundation is more influenced by soil properties than the concrete.

Influence of the Soil-Structure Interaction in the Behavior of Mat Foundation

This article focuses on the study of the behavior of a soil mass under a plate subjected to a uniformly distributed load. The aim of this paper is to highlight the soil-structure interaction with a linear variation of the mechanical properties of the soil with the depth. The theory of plates and the soil-structure interaction has allowed reaching the general equation of the problem which depends on both the mechanical properties of the concrete and the subgrade. This study shows that the linearity of the elastic modulus of subgrade leads to larger displacements when this modulus is assumed to be constant in the soil mass. It also shows that the Poisson’s ratio of soil and mechanical properties of the concrete have an insignificant influence on the displacements. This analysis also shows that the points in the upper half-thickness of soil are the most sensitive to the parameters of the model.

种植苜蓿对河北省黄骅盐碱地改良作用研究

[目的]指出在黄骅种植苜蓿对盐碱地改良的优劣势,并针对黄骅苜蓿产业发展存在的问题提出对策。[方法]对现有盐碱地苜蓿种植研究进展加以整合,结合黄骅盐碱地成因,分析种植苜蓿对盐碱地改良作用。[结果]苜蓿能够较好地适应黄骅土壤、气候特点,同时在降低盐碱地土层含盐量、增加土壤有机质含量等方面作用显著。[结论]在黄骅盐碱地种植苜蓿,是改良盐碱地较为有效的措施之一,值得大面积推广种植。

古龙酸母液混制肥和草席覆盖措施对新疆旱区牧草生长和土壤养分含量的影响

古龙酸母液(RAE)是工业上通过二步发酵法生产维生素C过程中产生的废液,胶质芽胞杆菌(Bacillus mucilaginosus)是解钾细菌,二者在改善土壤质量、提升土壤肥力和促进植物生长方面具有重要意义。使用RAE与胶质芽胞杆菌的混合液作为古龙酸母液混制肥(RB),设RB施加量为0%(CK)、0.5%、1.0%的3个处理,并设置草席覆盖和未覆盖处理,开展田间小区试验,对紫花苜蓿(Medicago sativa)和披碱草(Elymus dahuricus)的生长、生理指标、土壤养分指标及相关关系进行分析。结果表明,相同覆盖处理下,RB总体上显著提高了牧草的生长和生理指标,表现为1.0%>0.5%>CK,在1.0%RB处理下,紫花苜蓿的地上生物量平均提高了112%,披碱草平均提高了80.1%。相同RB施加量处理,覆盖处理的牧草总体上发芽率、发芽势、株高、地上生物量和根系发育显著高于未覆盖处理,紫花苜蓿和披碱草发芽率平均提高164%和194%,地上生物量平均提高64.3%和24.9%。相同覆盖处理下,土壤有机碳和速效养分含量均随RB处理有效提高,1.0%RB将土壤有机碳和速效钾分别显著提高了33.1%和105%。相同RB施加量下,覆盖处理能提高土壤的有机碳含量,平均提高了2.75%。双因素方差分析表明RB和草席覆盖措施对牧草的生长、生理指标和土壤养分含量具有显著的交互影响。冗余分析和Pearson相关性分析表明影响牧草生长生理指标的环境因子主要为有机碳、铵态氮、有效磷、速效钾,建议采用1.0%RB与草席覆盖联用来改良新疆旱区土壤促进牧草生长。研究结果为古龙酸母液、胶质芽胞杆菌资源化利用和新疆旱区土地资源开发提供了科学依据。

Field Study of HPTRM Combined with Vegetation and Anchor to Protect Newly Excavated Expansive Soil Slope

Anchor reinforced vegetation system(ARVS)comprises high performance turf reinforcement mats(HPTRM),vegetation and anchors.It is a new attempt to apply the system in expansive soil slope protection.The goal of this paper was to evaluate the effectiveness of ARVS in protecting newly excavated expansive soil slopes.The field tests on the bare slope,grassed slope and ARVS protective slope were carried out,including natural and artificial rainfall.During the test,the soil water content,soil deformation,and anchor axial force were monitored,and then the slope protection mechanism of ARVS was analyzed.It was found that ARVS can effectively protect expansive soil slopes compared with bare slopes and grassed slopes.The vegetation and HPTRM form a reinforced turf,and the anchors fix it to the slope surface,thus restraining the expansion deformation.The axial force on the anchor of ARVS includes frictional resistance and tensile force transmitted by HPTRM,which is maximum at the early stage of support.The neutral point of the anchor of ARVS moves deeper under atmospheric action,but the vegetation and HPTRM on the slope surface can limit this movement.

草毡寒冻雏形土CO_2释放特征

研究了植物生长季节海北高寒草甸生态系统高寒嵩草草甸覆被下草毡寒冻雏形土的 CO2 释放速率。其结果表明 :CO2 释放速率有明显的日变化和季节动态。日最大排放速率多出现在 1 4 :0 0～ 1 6:0 0时 ,最小排放速率在 6:0 0～ 8:0 0时。植物生长季日最大振幅为 797.75mg/m2·h,最小振幅 1 97.33mg/m2·h。CO2 排放白天大于夜晚。不同物候期 CO2 释放速率不同 ,其顺序为草盛期 >枯黄期 >返青期。生长季土壤 CO2 释放速率的范围是 4 41 .72 mg/m2 · h± 1 55.2 9mg/m2· h,最大日均值为 681 .0 6mg/m2 · h( 7月 1 6日 ) ,最低值 1 76.65mg/m2 · h ( 6月 1日 )。退化草地土壤 CO2 释放速率明显低于未退化草地 ,生长季平均日均值低 1 37.4 7mg/m2·h。相关分析表明 :土壤 CO2 排放速率与气温、地表温度、土壤5cm、1 0 cm、1 5cm、2 0 cm、30 cm地温均呈显著和极显著相关关系。温度是影响土壤 CO2 释放速率的主要因子。

植物生长季退化草毡寒冻雏形土CO_2释放特征

对中国科学院海北高寒草甸生态系统定位站地区退化草毡寒冻雏形土CO2 释放的全天候连续观测结果表明 ,退化草毡寒冻雏形土CO2 的释放有明显的日变化和季节动态 ,日最大释放速率出现于12∶0 0～ 14∶0 0 ,最小释放速率出现于 6∶0 0～ 8∶0 0 ;植物生长季的最大振幅为 4 6 2 .4 9mg·m-2 ·h-1(8月 18日 ) ,最小振幅为 114 .97mg·m-2 ·h-1(5月 9日 ) ,CO2 释放速率白天大于夜晚 .不同物候期CO2 释放速率亦不同 ,草盛期 >枯黄期 >返青期 .最大日均值为 4 80 .76mg·m-2 ·h-1(8月 18日 ) ,最小日均值为 14 0 .77mg·m-2 ·h-1(5月 9日 ) .释放速率与气温、地表温度及土壤 5cm地温均呈显著或极显著相关关系 ,表明温度是决定CO2

草毡寒冻雏形土土壤CO_2释放量估测方法初探

应用 1 998年 5月～ 1 999年 4月草毡寒冻雏形土土壤CO2 释放通量的实测资料 ,通过对常用的三种土壤CO2 释放量估测方法的比较分析 ,提出了适合草毡寒冻雏形土土壤CO2 日及年释放量的估测方法。土壤CO2 日释放量的估测是以土壤CO2 释放通量为因变量 ,时间为驱动变量 ,建立时间与土壤CO2 释放通量的一元四次多项式 ,通过对时间的求导积分 ,得出土壤CO2 日释放量。土壤CO2 年释放量的估测是以测定日的土壤CO2 日释放量为因变量 ,以气候、土壤环境因子 (降水、蒸发、日照、气温、土壤 0～ 30cm地温等 )为驱动变量 ,建立土壤CO2 的日释放量与气候、土壤环境因子之间的多元非线性经验公式 ,应用气象站气候、土壤环境因子有关资料 ,逐日计算出其土壤CO2 的日释放量 ,最后应用累积法 ,可估测土壤CO2

生态垫对流动沙地土壤温湿度和养分的影响

流动沙地铺设生态垫后,对土壤温度、水分、养分等方面产生一定的影响。研究结果表明:流动沙地铺设生态垫后,能够明显降低土壤20 cm以上的温度,表层土壤温度变化明显,日均温可降低4.5℃;各层的土壤日温差均小于裸地,在表层最为明显,可降低8.1℃。在观测期间,铺垫后能够显著提高土壤0-15 cm的含水量,相对裸地提高167.33%,15-30 cm,30-45 cm的含水量相对提高53.10%,52.56%。铺设生态垫后,除土壤速效钾的含量有明显提高外,其它指标变化不明显。

生态垫对河滩造林地土壤温湿度和杂草的影响

生态垫在华北干旱地区调查季节内 ,能够明显降低土壤 15cm以上的温度 ,表层温度变化尤为明显 ,日均温可降低 10 3～ 13 8℃ ,并且不同土壤深度的日温差 ,都要低于不铺垫的 ;铺设生态垫后 ,在初春能够显著地提高土壤 0～ 2 0cm的含水量 ,比不铺设的要高出 4 4 3% ,对 4 0cm以下土壤含水量影响不大 ;生态垫可以有效抑制杂草生长 ,铺设生态垫后 ,杂草的盖度、高度、生物量等都要低于不铺垫的 ,其中杂草种类降低了 4 0 %之多 ,生物量降低99%之多。

生态垫覆盖对沙漠土壤水分和温度的影响

在流动沙丘迎风坡覆盖生态垫后,通过对土壤水分和温度的连续观测发现:在生态垫覆盖林地的生长季内,表层0—20 cm的土壤温度和20—60 cm的土壤含水量受覆盖影响最明显。覆盖与未覆盖生态垫的流动沙丘相比,可提高20—40 cm处土壤含水量为56%,提高40—60 cm处土壤含水量58%;7月可降低土壤表层温度14.27℃,且覆盖后土壤各层之间温度变化平缓,对10 cm以下土壤有保温作用。

膨胀岩裂隙发育的现场观测及描述方法研究

基于图像灰度化及二值化的数值处理技术,提出了膨胀岩裂隙度的概念及定量描述方法。在南水北调中线新乡潞王坟试验段进行了膨胀岩裂隙观测试验,定量分析了膨胀岩边坡在干湿循环中的裂隙的变化规律及其与含水率的相关关系。分析表明,膨胀岩裂隙的发育与天气变化密切相关,随着干湿循环的发展,裂隙的宽度和裂隙度逐渐增加,利用Matlab数字图像处理方法得到的裂隙率可以较好地描述裂隙的发育和发展情况。

生态垫覆盖对沙丘土壤温度的影响

2004年8月,对甘肃省河西走廊中部铺设生态垫与不铺设生态垫的沙丘不同层次(0 cm,5 cm,10 cm,15 cm,20 cm)土壤温度进行观测和分析。结果表明,铺设生态垫后土壤温度的日平均值及各层平均值均比未铺设生态垫的流动沙丘低,铺垫后的沙丘各层日平均温度比流动沙丘分别降低5.5℃,4.0℃,2.4℃,2.1℃,1.6℃。铺设生态垫后土壤不同层次的温差均低于对照地流动沙丘,各层温差分别减小8.8℃,5.0℃,4.5℃,2.8℃,2.8℃,随着土层的加深,温差变化幅度也逐渐减小。研究初步认为,铺设生态垫能够显著降低沙丘表层15 cm以内的土壤温度,显著减缓15 cm以内的土壤温度日变幅。

稻草编织物覆盖对坡耕地水土流失及玉米产量的影响

为了研究稻草编织物覆盖在坡耕地水土流失控制上的作用,于2008—2010年在雨季对不同覆盖方式下径流小区径流量、侵蚀量进行监测,对玉米整个生长期内各种生物性状及产量进行测定。结果表明:雨强越大,径流量越大,侵蚀量也越大;稻草编织物覆盖能有效地减少水土流失,稻草编织物覆盖的小区年均径流量为295.98m3/hm2,侵蚀量为3.95t/hm2,分别比无覆盖小区减少64.11%、94.01%;在中强度降雨下,稻草编织物覆盖对坡耕地蓄水保土的作用更为显著;稻草编织物覆盖对玉米生长有增产效应,2010年覆盖种植玉米理论产量为11.14t/hm2,实际产量为10.42t/hm2,比无覆盖种植分别增产47.5%、45.7%。说明坡耕地玉米稻草编织物覆盖能有效减轻水土流失、促进玉米生长发育,是增加玉米产量的有效措施。

青藏公路黑马河试验段碎石垫层路基工程效果初步分析

基于青藏公路黑马河试验段碎石垫层路基近1 a的温度、水分监测资料,初步分析了碎石垫层路基温度,水分的发展与分布特征以及造成这些差异的原因,并与传统的砂砾垫层比较.结果表明:碎石垫层加隔水土工布能够更好的削弱毛细水自下而上的迁移,起到了一定的隔水排水效果,对于防治季节性冻土路基冻胀病害具有积极作用.

绿洲-荒漠交错带不同沙丘土壤水分时空动态变化规律

绿洲-漠交错带是植被恢复的一个重要区域，而植被恢复的关键又是了解沙丘土壤水分的变化规律。从2003年10月到2004年10月，对甘肃省张掖绿洲-荒漠交错带沙丘土壤水分进行了连续观测，并研究了生态垫在沙漠治理中的应用。结果表明：土壤水分时空动态变化主要受降雨、植被以及地表覆盖等因素的影响，沙丘土壤水分月变化滞后于降水变化。沙丘剖面土壤水分变异系数随土层深度的增加而减小，铺设生态垫减小了沙丘土壤水分的空间变异（CV=4．43％），流动沙丘0～40cm的含水量（0．19％～1.27％）低于固定沙丘（1.61％～1．75％），而其它各层的含水量（1．52％～1．73％）都高于固定沙丘（1．11％～1．38％）；流动沙丘含水量（1．27％～1．73％）从上部到下部依次升高，而固定沙丘（1．75％～1．11％）则与此相反；利用标准差和变异系数对沙丘土壤水分垂直变化进行分层，得出了土壤水分剖面分别为速变层、活跃层和次活跃层，并运用相关分析方法分析了生态垫覆盖下沙丘各层间土壤含水量及其与沙丘剖面平均含水量的关系。研究初步认为，生态垫能有效地保持沙丘土壤水分，将为沙漠治理提供一种新型的治沙模式。

季节冻土区路基冻胀翻浆防治措施试验研究

根据位于青海省109国道橡皮山试验段所观测的温度及水分数据,系统分析了传统砂砾垫层路基与隔水土工膜加碎石垫层路基在外界气候环境作用下,路基内各个观测位置温度与水分的变化以及造成这些变化的原因.比较了两个断面下路基各个观测位置的水分变化率的差异以及造成这些差异的原因,分析了这些差异对路基冻胀翻浆的影响.研究结果表明,在橡皮山地区,不仅仅存在地表水自上而下的迁移,而且在冬季土体负温度梯度和毛细作用还会促使水分自下而上的迁移,因此,相对于传统砂砾垫层路基,隔水土工膜加碎石垫层路基对于预防季节性冻土区路基冻胀翻浆效果更好.