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.

Spatio-temporal variations of soil water content and salinity around individual Tamarix ramosissima in a semi-arid saline region of the upper Yellow River, Northwest China

Ecological restoration by Taman＇x plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissiraa Ledeb. were invetigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity （EC）, sodium adsorption ratio （SARa）, and salt ions （including Na＋, K＋, Ca2＋, Mg2＋ and 8042-） were measured at different soil depths and at different distances from the trunk of T. ramasissima in May, July, and September 2016. The soil water content at the 20-80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0-20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SAR at the 0-20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SAR~ at the 60-80 cm depth in May and July were significantly higher than those at the 0-60 cm depth and higher than that at the corresponding depth in September. The distribution of Na＋ in the soil was similar to that of the SAI, while the concentrations of K＋, Ca2＋, and Mg2＋ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARa, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarx plants and avoiding planting herbaceous plants inside the canopy of T. ramodssima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.

灌溉水盐分组成对番茄生长及土壤盐碱的影响

[目的]为探究适宜于干旱、半干旱区番茄大田栽培的灌溉水盐度和盐分组成。[方法]在宁夏银北灌区开展3年番茄膜下滴灌野外田间试验,设置3种不同盐分浓度(1,2,3 g/L)和5个Na∶Ca摩尔浓度比(1,3,5,7,9)的灌溉水源。[结果]在较低的灌溉水盐度(1 g/L)下,适当增加灌溉水Na∶Ca摩尔比有利于番茄植株的干物质和氮磷钾素积累;番茄单果重、商品果产量和总产量随灌溉水Na∶Ca摩尔比增加而线性下降,且灌溉水Na∶Ca摩尔比每增加1,番茄商品果产量下降5761.7~6036.7 kg/hm^(2);“高盐度(2,3 g/L)、低Na∶Ca摩尔比(1,3)”的灌溉水较“低盐度、高Na∶Ca摩尔比”的灌溉水,更有利于番茄增产;膜内表层40 cm土壤钠吸附比和表层100 cm土壤积盐量随灌溉水Na∶Ca摩尔比的增加线性增加。[结论]为在宁夏银北灌区大田栽培番茄生育期内减少积盐并获得相对高产,推荐土壤基质势控制下限-20 kPa下膜下滴灌的适宜灌溉水盐度为2 g/L且Na∶Ca摩尔浓度比为5。

Characteristics of produced water during coalbed methane （CBM） development and its feasibility as irrigation water in Jincheng, China

Water resources are scarce in Jincheng. Huge quantities of water are pumped out in the dewatering course, and the disposal of CBM water is one of the most important problems during the extracting of CBM. Based on the data of CBM water production, chemical characteristics, the irrigational conditions for major crops, and China irrigation water standard, the feasibility of CBM water as irrigation water is discussed. The result shows the CBM water quality doesn＇t fully meet irrigation water quality standards in Jincheng, its high salinity and sodium adsorption ratio （SAR） in CBM water might affect crops growth and lead to yield loss, and can＇t be used as irrigation water directly, but with the treatment of the reverse osmosis （RO） to lower the salinity and SAR of CBM water, the CBM water can be used as irrigation water.

咸淡组合淋洗对土壤水盐分布特征的影响

为了缓解干旱半干旱地区淡水资源紧缺问题,最大限度地利用浅层地下微咸水,以全部淡水和全部咸水为对照,采用两咸一淡组合淋洗的方法对垂直土柱淋洗后土壤剖面的水、盐分布规律及土壤理化性质的变化进行研究,结果表明在累积入渗量相同的前提下,咸淡组合次序对土壤大孔隙的形成有影响,导致土壤透水性不同,通过入渗进入土壤的总盐量是土壤含盐量的主要影响因素;入渗历时的延长有助于提高土壤剖面脱盐深度,淡—咸—咸的组合次序洗盐效果最好;各种咸淡组合次序均导致20 cm深度处的钠吸附比较初始值增大,尤其是全部咸水入渗会降低土壤的渗透性,有可能导致土壤发生次生盐渍化.该研究为微咸水的田间合理利用提供了依据.

再生水灌溉高尔夫球场潜在的问题及解决方法

随着城市水资源的短缺,污水回用越来越引起人们的关注,用再生水灌溉高尔夫球场是有效的节水方法之一。通过5个方面论述了再生水灌溉对高尔夫球场的影响,分析了盐度、钠、氯化物、碳酸氢盐、pH值、细菌群、重金属等可能带来的问题,提出了相应的解决方法,为再生水在高尔夫球场中的应用提供理论依据。

渠井用水比例对土壤脱盐与地下水化学特征的影响

【目的】通过研究华北典型井渠结合灌区不同用水模式对区域土壤盐分分布、根层土壤脱盐、地下水化学特征的影响,探讨华北井渠结合灌区适宜的渠井用水比例。【方法】2013—2015年在人民胜利渠灌区选择西三干渠控制范围为典型区域,监测控制范围内降水量、地表水灌溉量、地下水灌溉量、0—100 cm土层土壤含盐量、地下水矿化度,分析不同用水模式对根层土壤盐分洗脱、地下水化学特征的影响。【结果】2013—2015年一支渠、二支渠、三支渠渠井用水比例分别介于0.72—1.03、2.50—2.63、0.65—1.26之间;2013—2015年冬小麦苗期,不同用水模式下0—100 cm土层土壤盐分垂向分布均表现为上高、中低、下高,尤其是0—20 cm土层土壤盐分表聚明显;2013—2015年冬小麦苗期一支渠控制范围内0—20 cm根层土壤盐分均值大于0.32 mS·cm^(-1)面积分别占到控制范围的60.38%、25.99%、41.16%,二支渠控制范围内0—20 cm根层土壤盐分均值大于0.32 mS·cm^(-1)面积分别占到控制范围的59.61%、0.94%、8.81%,三支渠控制范围内0—20 cm根层土壤盐分均值大于0.32 m S·cm^(-1)面积分别占到控制范围的84.40%、41.87%、52.49%,表明渠井用水比例与支渠控制范围内表层土壤含盐量大于0.32mS·cm^(-1)的面积呈负相关;对比2013年同期,2014年典型区内0—20 cm土壤脱盐率介于15.61%—25.85%,2015年典型区内0—20 cm土壤脱盐率介于13.33%—23.15%;不同渠井用水比例典型区域地下水水化学特征均表现为:地下水中阳离子由枯水期钙钠型转化为平水期的钠钙型,平水期地下水水文化学相具有强烈的碱化趋势,特别是平水期二支渠地下水溶解性总固体增幅分别为一支渠、三支渠的1.23、3.48倍,表明较大渠井用水比例地表水灌溉驱动了根层土壤脱盐,增加了地下水中可溶性盐分浓度;对比2014年平水期,2015年同期一支渠、二支渠和三支渠控制范围地下水钠吸附比分别降低了23.58%、36.82%和55.47%,且区域地下水钠吸附比均低于18分级值。【结论】综合2013—2015年0—100 cm土层土壤脱盐率、地下水化学特征变化,在华北典型井渠结合灌区采用较大的渠井用水比例可以促进耕层土壤的脱盐、抑制土壤盐分表聚,同时短期内改善地下水环境。

松嫩平原盐碱土饱和浸提液与土水比1：5浸提液间化学参数的换算关系

采用饱和浸提液与土水比1:5浸提液两种方法分析了松嫩平原94份盐碱土样品的电导率、钠吸附比、主要阳离子(Na+、K+、Ca2+、Mg2+)以及总阳离子浓度等化学参数,并对两种方法测定的盐碱化参数相关性进行了研究。结果表明:饱和浸提液电导率、钠吸附比、总阳离子浓度、Na+离子浓度与土水比1:5浸提液相应参数存在极显著的相关关系,其关系方程可用于松嫩平原盐碱土饱和浸提液与1:5浸提液间化学参数的换算;而K+、Ca2+、Mg2+离子浓度在两种浸提液间不存在相关性。

咸水结冰融化过程中水质与水量的变化规律初步研究

在室内利用相同水量、不同矿化度和钠吸附比(SAR)的咸水进行结冰融化,以研究其在融化过程中水质和水量的变化过程。结果表明,咸水冰在融化过程中淡化效果明显,其中利用10g/L的咸水冰,融出49%小于3g/L的微咸水和淡水;矿化度越高的咸水冰,在融化初期融出水的矿化度、体积和SAR越高,而淡化效果越差,融化1h后15g/L的咸水冰融出水的矿化度和SAR分别为136.8g/L和67.5,高于5g/L和10g/L的咸水冰处理;高SAR的咸水冰,在融化初期融出水主要表现在SAR较高,利用SAR为5、10和30的咸水冰进行融化,融化1h后,融出水的SAR值分别为82.5、56.4和22.3,其中矿化度和体积无显著差异;在以上基础上,建立了关于不同水质的咸水冰在不同温度条件下的二元回归方程,利用该方程可知,矿化度较低的咸水冰在低的温度条件下融化,淡化效果越好。

盐分浓度和钠浓度对蒙脱土保水性的影响

为了预测使用干燥地、半干燥地的再利用水灌溉给土壤构造带来的影响,调查了盐分浓度和钠吸附比(SAR)给蒙脱土的保水性带来的影响.用电导率(EC)表示盐分浓度,使用了NaCl12,20,50mol·m-3和SAR5,10,20组合的溶液进行试验.当NaCl2mol·m-3时由于EC低,所以全部的SAR显示高的保水性.因为EC变高,当NaCl20molm-3时SAR5跟SAR10相比保水性大幅度降低.在凝集条件下,保水性与SAR同时增加,在分散条件下没发现保水性的变化.在凝集状态下EC越高或SAR越低的时候,保水性降低.可以认为蒙脱土显示低保水性的时候会变成凝集构造.要控制蒙脱土的物理性质,盐分浓度和SAR的组合是很重要.

覆砂下微咸水盐度和钠吸附比对水盐入渗及分布的影响

为探讨覆砂条件下灌溉水盐度及钠吸附比对土壤水分入渗过程及水盐分布的影响规律,通过室内土柱模拟试验,研究了灌溉水盐度(EC为0,1.0,2.5,5.0,7.5 dS/m,SAR为5.8(mmol/L)^(0.5))和钠吸附比(SAR为3.9,7.0,12.7,22.7(mmol/L)^(0.5),EC为2.5 dS/m)对土壤累积湿润锋和入渗量以及水盐分布的影响.结果表明,随灌溉水盐度的增加,累积湿润锋呈增加趋势,而累积入渗量呈减少趋势.与去离子水相比,7.5 dS/m处理的累积湿润锋较蒸馏水增加了7.0%,而土壤平均含水率降低了36.0%.累积湿润锋和入渗量随灌溉水钠吸附比增加先增大后减小,土壤含水率受灌溉水钠吸附比的影响较小.土壤含盐量随灌溉水盐度增加而呈幂函数增加,但与钠吸附比无明显关系.灌溉水的钠吸附比提高了土壤pH值.

三种材料复合施用对盐碱土壤改良效果的研究

为研发对盐碱土壤脱盐和对土壤结构具有同步改良效应的复合改良材料,选取脱硫石膏(A)、改性腐植酸(B)和高分子材料(C),通过室内土柱模拟方法,采用正交试验设计,探究三种材料对盐碱土壤盐分淋洗和结构改良同步增效的最优组合,分析不同材料对盐碱土壤的改良机理。结果表明:三种材料复合施用对盐碱土壤盐分淋洗和结构改良有明显效果,对盐碱土壤改良效果最优的组合为A3B1C3(脱硫石膏、改性腐植酸、高分子材料的添加量分别为60、2、0.1 g·kg^-1),与对照(CK)相比,其淋溶液体积减少了14.22%,土壤钠吸附比(SAR)降低了30.43%,土壤团聚体含量增加24.45个百分点。研究表明,三种材料复合施用能够在改良盐碱土壤化学性质的同时改良盐碱土壤结构。

Short-term effects of biochar and gypsum on soil hydraulic properties and sodicity in a saline-alkali soil

Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production.The reclamation potential of biochar(BC,wheat straw biochar applied at\%by weight),gypsum(G,0.4%by weight),and gypsum coupled with biochar(GBC)was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil(silt loam)with no amendment as a control(CK).Saline ice and fresh water(simulated rainfall)were leached through soil columns to investigate changes in salt content,sodium adsorption ratio(SAR),alkalinity,and pH of the leachate and the soil.Results showed that saturated water content and field water capacity(FWC)significantly increased by 4.4%and 5.6%,respectively,in the BC treatment after a short incubation time.Co-application of biochar and gypsum(GBC)increased soil saturated hydraulic conductivity(Ks)by 58.4%,which was also significantly higher than the sole addition.Electrical conductivity(EC)of the leachate decreased sharply after saline ice leaching;subsequent freshwater leaching accelerated the removal of the rest of the salts,irrespective of the amendment application.However,the application of gypsum(G and GB)significantly enhanced the removal of exchangeable Na^+and reduced leachate SAR.After leaching,the soil salt content decreased significantly for all treatments.The application of gypsum resulted in a significantly lower soil pH,exchangeable sodium percentage(ESP),SAR,and alkalinity values than those recorded for the CK and BC treatments.These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.