Effects of Groundwater with Various Salinities on Evaporation and Redistribution of Water and Salt in Saline-sodic Soils in Songnen Plain,Northeast China

Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.

Effect of Initial Soluble Salt Composition of Saline Soil on Salinity Tolerance of Barley Plant

A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.

Experimental study on grain size and soluble salt of saline soil in western Jilin Province, China

Western Jilin Province is a typical seasonal frost region, and is also one of the severest salinization areas of China. In this study, we aim to examine the saline soil in Da＇an and Wukesong areas, western Jilin Province, and mainly analyze the granulometric composition and distribution of salt in soil profiles. Four sampling sites, two in Da＇an and two in Wukesong respectively, are chosen for study. The granulometric composition, especially silt and clay content change in different sites and soil depths are analyzed. Analysis of total and components of soluble salt shows that the surface soil is weak carbonate saline, in which the main cation is Na＋ and the main anion is HCO3-. The total amount of soluble salt presents a decreasing tendency with increasing depth. The comprehensive analysis ofgranulometric composition and soluble salt shows that the clay content and soluble salt content present similar variation tendency with an increase of depth.

Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.

Spatial distribution of chromium in soils contaminated by chromium-containing slag

To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40-60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100-150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area.

Effects of Irrigation with Well Water on Chemical Characteristics of a Weakly Alkaline Soil Used as Rice Field

This paper discussed the effects of irrigation with well water on the salinity and pH of a weakly alkaline paddy soil in Fujin of Heilongjiang Province in the north-eastern part of China.It has been found that after seven years the accumulation of total soluble salts did not occur and that the pH of 0～15 cm layer fell down from 7.92～8.30 to 6.76～7.45,and that the content of anion HCO - 3 and its proportion in the total soluble anions have fallen down.Conversion from paddy soil to upland restored the pH of soil,exchangeable sodium,ESR(exchangeable sodium ratio) to their original levels of upland fields respectively.

Research on the distribution of saline soil along the Chaerhan-Golmud Highway, northwestern China

In order to assess and improve the engineering stability of saline soil with high chloride content along a 40-km section of the Chaerhan-Golmud Highway in northwestern China, more than 200 monitoring points for saline soil soluble salt chemical tests were established. The total salt content distribution, the chloride ion content distribution, and the sulfate ion content distri- bution along both sides of road were determined, and the chlorine-sulfur ratio distribution and the PH value distribution along both sides of road were also determined. These chemical contents can significantly affect soil freezing temperatures, frost heave, and salt expansion, which can undermine subgrade stability, ultimately, cause subgrade damage. Therefore, when subgrade filler is selected for this highway, attention must be paid to its chemical indicators as well as its physical properties.

Analysis Methods for the Determination of Anthropogenic Additions of P to Agricultural Soils

Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.

滨海黏质盐渍土饱和泥浆与不同土水比土壤浸提液电导率的响应关系分析

为统一和精准判定耐盐作物种植地块的土壤盐渍化程度,并针对饱和泥浆制备时饱和点的不确定性及其电导率测定的不稳定性等问题,本试验采用室内化验与统计分析方法,系统研究饱和泥浆与饱和土壤溶液两者间含水量和电导率的响应关系,以及饱和泥浆电导率、全盐含量与土水比1∶0.5、1∶1、1∶2.5、1∶3.5、1∶5土壤浸提液电导率与全盐含量的响应和换算关系。结果表明:在滨海黏质盐渍土区,利用计算田间土壤孔隙度得到的饱和土壤溶液含水量、电导率不能直接代替饱和泥浆含水量、电导率,尽管二者的响应关系达到极显著水平;饱和泥浆电导率、全盐含量分别与土水比1∶1和1∶0.5土壤浸提液的数值差异最小,且与土水比1∶0.5~1∶5间各处理土壤浸提液的相应指标均呈极显著的响应关系;饱和泥浆电导率与土水比1∶5土壤浸提液的电导率、饱和泥浆全盐含量与土水比1∶1土壤浸提液全盐含量相关性最高,可分别用最佳拟合线性模型进行换算,模型分别为ECe(mS/cm)=5.406EC1∶5-0.284 4,TSe(g/kg)=0.836 4TS1∶1-0.135 9。

高分子活性剂改良盐渍土力学特性及机理研究

基于三轴剪切试验与可溶盐含量测试,探究高分子活性剂掺量与养护时间对硫酸型盐渍土力学性能与可溶盐含量的影响,揭示土体微观特性及其改良机理.结果表明:CLI型高分子活性剂的掺入能有效提升硫酸型盐渍土的力学强度和抗变形能力,其最佳掺量为8%;活性剂与盐渍土发生置换反应,从而增强盐渍土的保水性能,有效降低盐渍土的可溶盐含量,CLI型高分子活性剂掺量越大,改良效果越好;养护时间达到7 d时,盐渍土的可溶盐含量趋于稳定.

不同改良剂对滨海盐碱地的改良效果

为了探讨不同改良剂对滨海盐碱地的改良效果,采用盆栽试验研究了硫酸钙、硫酸铝、硫酸铁、硫酸亚铁、硫磺对土壤全盐、pH及离子组成的影响。结果表明,改良剂的种类不同,下渗水离子含量差异较大;第一次淋洗,硫酸钙、硫酸铝、硫酸铁处理下渗水中Na^(+)和Cl-含量分别比CK高54.78%和58.25%、35.44%和39.22%、32.65%和34.82%,表明添加这3种改良剂对土壤的降盐效果较好,其中硫酸钙处理效果最好;第二次淋洗,硫酸铁、硫酸钙和硫酸铝处理的Na^(+)含量比CK高75.14%~347.76%。综合2次淋洗效果,表明硫酸钙处理对土壤中的Na^(+)淋洗效果更明显。与CK相比,各改良剂土壤pH均有不同程度的降低,pH降低2.23%~3.84%;不同改良剂对土壤离子的影响各不相同,添加改良剂各处理土壤中的Ca^(2+)和Mg^(2+)含量均高于CK。综合考虑到不同改良剂对土壤pH、Na^(+)和Cl-含量的影响,建议用硫酸铁和硫酸钙组合对滨海盐碱地进行改良。

从离子型稀土镁盐富集物中提取稀土工艺初探

以MgO为沉淀剂沉淀MgSO_(4)稀土浸出母液时,得到的稀土镁盐富集物REO总量较低,需要进一步除去杂质以沉淀富集稀土。以离子型稀土镁盐富集物为原料,进行碳化—酸溶—中和除杂—沉淀等工艺初步探索研究。结果表明:REO在碳化过程中的损失很少甚至可以忽略不计,有24.33%~30.9%MgO由稀土镁盐富集物转化进入碳化后液,在中和除杂过程中Fe去除率约99.5%,Al去除率约98.6%。以碳化后液为沉淀剂沉淀中和除杂后液得到碳酸稀土,经过灼烧,获得了符合《GB/T 20169—2015离子型稀土矿混合稀土氧化物》标准质量要求的稀土氧化物,该工艺总渣率为19.81%~23.22%,REO总收率平均89.43%。为了从离子型稀土镁盐富集物中提取稀土的工艺形成成套工艺技术,获取最优的工艺技术参数,有待于后续深入研究和优化。

暗沟排盐对西辽河平原苏打盐碱荒地改良效果的研究

为探究暗沟排盐技术对西辽河平原苏打盐碱荒地改良效果的影响,在科左中旗胜利乡盐碱荒地,通过设置暗沟并应用不同的改良措施,暗沟间距分别设置5 m(L1)、10 m(L2)和15 m(L3),以及无暗沟(CK)处理,在此基础上施入脱硫石膏30 t/hm^(2),腐殖酸4.5 t/hm^(2)(F1)和9 t/hm^(2)(F2),共8个处理,对暗沟排盐工程结合化学改良措施对苏打盐碱荒地土壤的脱盐效果进行研究。研究结果表明,暗沟排盐技术对降低苏打盐碱荒地的土壤盐分有显著效果,0~40 cm深度土壤全盐量平均降低1.74 g/kg,暗沟间距越小,脱盐效果越显著。此外,施入腐殖酸对降低土壤盐碱度也有显著影响,平均降低了5.7%,其中间距5 m,施用量4.5 t/hm^(2)处理的降低幅度最大,达到了8.2%。从试验结果来看,暗沟间距10 m和施用4.5 t/hm^(2)腐殖酸的组合是最佳的改良效果。研究结果可为西辽河平原盐碱荒地的合理开发利用提供了理论依据。

海相淤泥质固化土强度劣化规律试验研究

针对海相淤泥质软土中水泥搅拌桩成桩效果不佳的问题,选取天津地区某地铁工程施工现场海相淤泥质黏土,通过室内水泥土无侧限抗压强度试验,研究了可溶性盐和有机质含量对海相淤泥固化的无侧限抗压强度(UCS)的影响,并通过扫描电镜(SEM)和X射线衍射(XRD)对其微观结构和物相特征进行分析。结果表明:土壤水泥的强度随可溶性盐和有机质含量的增加而降低,其主要通过破坏和抑制水泥水化产物的形成,进而降低水化产物的胶凝性能,破坏了水泥土结构,导致强度降低。该研究结果对解释海相淤泥质软土固化效果不佳的现象具有重要的意义。

氟离子选择电极法测定土壤中水溶性氟化物和总氟化物含量

采用氟离子选择电极法测定土壤中水溶性氟化物和总氟化物。结果表明,氟化物含量在5~500μg范围内具有良好的线性关系(>0.999),水溶性氟化物方法检出限为0.5 mg/kg,相对标准偏差(RSD,n=6)为3.8%~6.7%,总氟化物方法检出限为43 mg/kg,相对标准偏差(RSD,n=6)为4.0%~4.2%,满足标准方法的测定要求。有证标准物质RMU044和RMU045测定结果均在标准范围内,水溶性氟化物相对误差为-3.3%~-2.4%,相对标准偏差为4.0%~4.7%,总氟化物相对误差为0.9%~1.3%,相对标准偏差为1.0%~2.2%。实际样品加标回收率试验时,水溶性氟化物平均加标回收率为100%,总氟化物的平均加标回收率为94%,该实验方法重现性好,准确度高,操作简单。

复合改良剂作用下宁夏引黄灌区低洼农田盐渍化土壤改良效果研究

宁夏引黄灌区低洼地区地下水位较高,导致土壤出现严重盐渍化现象,而添加土壤改良剂是解决土壤盐渍化问题的一种有效途径。为研究不同改良剂对宁夏引黄灌区低洼区域盐渍化土壤改良效果,在位于银北地区南梁农场的一块地势低洼的盐渍化耕地,选用不同改良剂进行改良试验。设置对照组、单一施用糠醛渣、单一施用脱硫石膏、复合施用糠醛渣+脱硫石膏及不同用量,共10个处理组,将研究区域分成若干小区,每个小区施用不同处理组改良剂,并种植油葵作物,比较分析不同处理组下油葵生长指标和产量及油葵收获后土壤全盐量、各盐分离子、pH,探究该区域盐渍化土壤的最优改良方案。结果表明,在表层土壤,施用糠醛渣+脱硫石膏复合改良剂后全盐量下降较为明显,低、中、高3种不同施用量下与对照组相比盐分含量降低了10.44%、10.14%、0.88%,单一施加脱硫石膏和糠醛渣一种改良剂盐分降低不明显。总体而言,施用糠醛渣+脱硫石膏复合改良剂对降低土壤全盐量、钠吸附比和提高作物产量效果较为显著,糠醛渣与脱硫石膏的最佳配合比为7:3,最佳施用量为17960 kg/hm^(2)。

盐渍土地区路基填料易溶盐控制要点及施工中应用

文章通过在中国西北地区公路路基盐渍土地区施工中,路基填土易溶盐控制从增强检测人员检测业务水平、规定检测设备器具及溶液试剂选择、确认工程使用水源选择、确定料场探坑覆盖面积及探坑深度数量、明确路基取土点分层取样准确性及代表性、监控路基土料源取土场地表土清除、确定挖装方式及取土部位和使用部位几方面阐述了盐渍土地区路基填料易溶盐控制要点及公路工程施工中控制要点及施工中的应用。

Nutrient Accumulation and Distribution in Cotton Promoted by Removal of Mulch Film

Plastic film mulching affects changes in nutrient contents in soil and absorption and utilization of nutrients in plants were by changing hydrothermal condition of soil.The temporal and spatial variation of the total soil salt and nutrient contents with mulch film removed at three different times during the early cotton growth stage and its effects on nutrient absorption and accumulation in cotton plants were studied over 2015-2017.The film removal treatments reduced salt accumulation in normal rainfall year(2017).Film removal increased contents of soil organic matter,the total phosphorus and available potassium at the end of growth stage,increased contents of soil hydrolyzable nitrogen and the total nitrogen in the surface soil layer(0-10 cm),and increased the total nitrogen contents in the deep soil layer(40-50 cm).Film removal increased accumulation of nitrogen and phosphorus nutrients in cotton plants in 2017 and accumulation of nitrogen,phosphorus and potassium nutrients in cotton plants in heavy rainfall year(2016).These experimental results indicated that removal of mulch film at an appropriate and targeted time in the bud stage of cotton promoted nutrient absorption.

连云港滨海地区沉积物含盐特征及其对工程基础的影响

土体含盐特征是环境演化、工程地基基础设计和城市绿地建设的重要参考指标。通过采集连云港滨海地区土样616件,根据测试结果以及土层划分结果对研究区80 m以浅土层含盐特征进行了系统分析。研究结果表明:80 m以浅土层盐分主要受3次海侵控制,盐分以NaCl为主,其中Cl~-含量占比最高达到了62.01%,NaCl含量占比最高达到了94.25%。各土层含盐量介于0.020%~7.149%。全新世土层含盐量高,以中盐渍土为主。随着深度的增加,土体含盐量有着递减的趋势。含盐量最高土层出现在2-1层黏土中。更新世土层含盐量较高,除了8-2砂层外,均有弱盐渍土出现。受海侵影响,海相土层含盐量均高于其上覆和下伏土层。海侵对下伏地层具有侵染作用,使得陆相地层含盐量增加。同一层组的土层细粒土含盐量一般大于砂土。各土层ESR(交换性钠)值较高,均大于当地地表淡水SAR(钠吸附比)。ESR最大值103出现在3-1软土层,为当地地表淡水ESR值的32倍。各土层统计平均值γ_(Mg)/γ_(Ca)范围值为0.80~2.67,均大于当地地表淡水的γ_(Mg)/γ_(Ca)值,说明各土层不同程度受到海水入侵的影响。各层土γ_(Mg)/γ_(Ca)最大值出现在3-1软土层,说明该层土沉积受控于海侵。各层土pH值均大于7.7,浅部2-1层与3-1层pH值高,土体改良需施加酸性或者钙质改良剂。各土层易溶盐的腐蚀性主要表现在Cl~-对混凝土结构中钢筋的腐蚀性,强腐蚀土层主要分布在25 m以浅土层,对应土层为3-1层软土和2-1层黏土。给出了土体中Cl~-对混凝土结构中钢筋的腐蚀性界限含盐量,工程建设中应注意基础防腐工作。