盐碱生荒地滴灌覆膜甜菜肥水效应的研究

通过对开垦的高盐碱生荒地,在滴灌条件下,覆膜甜菜的肥和水效应分析：在盐碱地土壤相对含水率在６５．９７％,氮肥用量在１２９．１４ｋｇ／ｈｍ＾２范围内,产量随用水量和氮肥投入增加而增加,超过此用量,产量反而下降,而最经济的用量是土壤相对含水率为４４．３１％,氮肥用量为１２７．２０ｋｇ／ｈｍ＾２。     

吉林省大安市苏打碱土碱化参数之间的关系

选择典型苏打碱化土壤,对土壤碱化度(ESP)、钠吸附比(SAR)、残余碳酸钠(RSC)、总碱度和pH等进行了测定计算,分析了各碱化参数之间的关系,得出了各参数之间的相关方程。结果表明,除pH外,苏打碱土各碱化参数之间均具有极显著的相关性,各参数之间关系密切。土壤pH与ESP和SAR之间的关系变异性较大,利用pH推算该区苏打碱土碱化状况将会产生很大的不确定性。     

Conjunctive use of groundwater and surface water to reduce soil salinization in the Yinchuan Plain,North-West China

Abstract

Poor water resource management is an important factor in soil salinization in arid areas. In this study, the status of soil salinization and its controlling factors are summarized for the Yinchuan Plain, North-West China. The conjunctive use of surface water diverted from the Yellow River and groundwater abstracted from a shallow aquifer is proposed to alleviate soil salinization in the plain. Scenarios are designed and simulated to determine the optimal proportions at which groundwater should be exploited for irrigation in the three cities of the plain. Policies and suggestions regarding sustainable water resources and soil salinization research in the plain are recommended.     

基于特征空间的黄河三角洲垦利县土壤盐分遥感提取

土壤盐渍化是实现土地资源可持续利用所面临的重要挑战,在我国滨海的黄河三角洲区域遥感定量反演适宜方法可为区域盐渍化监测与防治提供技术方法参考。研究以Landsat 8 OLI数据和野外实测数据为基础,提取关键地表特征参量,定量化探讨土壤盐分与地表生物物理参数之间的规律及关系,建立黄河三角洲土壤盐分最优反演模型。结果表明:Albedo-MSAVI、SI-Albedo、SI-NDVI反演精度分别为83.4%、88.8%和80.6%。分析认为SI-Albedo模型最适用于滨海地区盐渍化程度反演,对滨海地区土壤盐分的预测能力较强;Albedo-MSAVI、SI-NDVI模型对内陆干旱、半干旱地区的盐渍化信息提取具有一定的参考意义。基于精度最高的SI-Albedo所反演的结果来看,垦利县盐渍化程度自东向西总体呈高低高走向,与该区域盐分积聚的成因机理相符。     

Remote Sensing Extraction of Soil Salinity in Yellow River Delta Kenli County based on Feature Space

Soil salinization is an important challenge to achieve sustainable use of land resources. The appropriate method for remote sensing quantitative inversion in the coastal Yellow River Delta region of China can provide technical reference for regional salinization monitoring and prevention. Utilizing Landsat 8 OLI image and field measured data, we extracted key surface characteristic parameters, quantitatively discussed the law and relationship between soil salinity and surface biophysical parameters and established a soil salinity inversion model. The results show that the inversion precisions of Albedo-MSAVI, SI-Albedo and SI-NDVI feature space are 83.4%, 88.8% and 80.6% respectively. The analysis shows the SI-Albedo model is suitable for the inversion of salinization level in Binhai areas. For Albedo-MSAVI and SI-NDVI models, they have certain reference significance for salinization information extraction in inland arid and semi-arid areas. Based on the inversion of the SI-Albedo feature space with the highest accuracy, the level of salinization in Kenli County is generally high-low-high trends from the east to the west, which is consistent with the formation mechanism of salt accumulation in this area.     

Study of Rejim Maatoug groundwater in southern Tunisia using isotope methods

The Rejim Maatoug aquifer, which located in south-western Tunisia, constitutes a good example of overexploited resources. Hydrogeological and geochemical data were examined to determine the main factors and mechanisms controlling the groundwater chemistry and the hydrodynamic functioning of this aquifer based on a multi-tracer approach. Thirty-one groundwater samples from the CT Miocene aquifer of Rejim Maatoug and Djerid regions were collected in 2010 for major chemical element analysis. Physical parameters such as temperature, pH and electrical conductivity (EC) were measured in the field. Three groundwater samples were selected for ¹⁴C measurements. Four groundwater samples were chosen for ³H measurements. The chemical data indicates that dissolution of evaporate minerals, evaporation and cation exchange processes seem to be the main factors controlling groundwater mineralization. The geological and hydrogeological studies show the important role of the deep existing faults in controlling the hydrodynamic functioning of the aquifer systems in southern Tunisia. The isotopic data shows that groundwater in this area is a mixture of recent shallow waters located in the Mio-Plio-Quaternary sands and paleo-deep waters of the carbonate Senonian aquifer. Low ³H and ¹⁴C contents, observed in some sampled wells (³H = 0.15 TU in C1N1, ¹⁴C = 8.8 pmc in Matr2), indicates that the recharge of the Miocene aquifer occurs mainly through upflow leakage of Senonian deep aquifer while there is no evidence of significant recharge in major part of the plain and mountains piedmonts that can be observed.     

碧流河水库下游河道生态需水分析及应对措施研究

天津滨海平原水库普遍存在的水质咸化问题,以北大港水库为研究对象,采用野外调查和取样分析方法,识别了北大港水库不同季节水质咸化垂直分布规律,同时分析了水库水质咸化机理及其影响因素。研究结果表明:从电导率、氯离子和总溶解性固体(TDS)等代表性咸化指标来看,相对于引黄水,水库水各站点均存在咸化现象,并且出库口水质咸化程度明显高于进水口;不同站点电导率、氯离子浓度和总溶解性固体(TDS)值分别为867.5μS/cm、0.41g/L和1.46g/L,水体呈弱碱性;北大港水库水质咸化程度有季节性变化,为夏季略高于春季;水库各站点氯离子浓度和TDS值垂向上均随深度的增加而降低,但不明显;而电导率则随着深度的增加而增加,且变化明显。研究还发现,水库水质咸化受土壤含盐量、温度和混合作用的影响:从各站点水平分布来看,越靠近海岸线土壤含盐量越高,水质咸化现象越严重;温度的升高会影响底泥盐分的释放,温度越高,底泥中Cl-越容易释放;引黄水进入水库后,水库水体垂向发生了混合作用,导致氯离子和TDS垂向方向变化很小。     

Desalination of reclaimed wastewater to prevent salinization of soils and groundwater

The complete utilization of Israel's water potential (safe yield) (1800 Mm³/y) was combined with wide and intensive reuse of most wastewaters (300 Mm³/y), reduced to minimum water outflows to the sea. Irrigation is a “consumptive” type ofwateruse-most ofthe waterbeing “lost” by evapo-transpiration, leavingthe mineral salinity in the soil solution and in the excess (residual) water seeping, penetrating to underlying unsaturated layers on its way to groundwater. Thus, the complete use and reuse of water bring about a high rate of salt accumulation in soils, in the unsaturated zones, and eventually in groundwater. This poses a serious risk of salinization of the country's lands and aquifers. Effects of salinization of soil and water are felt on a time-scale of tens of years. In several regions in Israel, salinization of the soil has already been encountered, and there is a permanent increase in water salinity at the coastal aquifer. Reports of many studies indicate a significant salinity increase in the unsaturated zones and at upper interface layers of the groundwater table. Also, accumulation (fixation) of specific heavy metals can be seen in soils irrigated with reclaimed wastewater. Though negative effects of heavy metals have not been felt up to now, the rate of accumulation predicts such effects in 10 to 30 years of continuing practices of such irrigation. The accumulation of salinity in general, combined with the accumulation of specific elements, can be defined as a chemo-desertifrcation process. Partial desalination (using membrane processes) of reclaimed wastewater is needed to reduce the salinity load, to “purge salt” from the country, and to prevent salinization of land and water to enable sustainable reuse.     

Investigating the restoration of Lake Urmia using a numerical modelling approach

We assessed the effectiveness of multiple hydrologic restoration scenarios for Lake Urmia, as well as the variation of its salinity regime under no intervention, using a 2D shallow water model. Tested scenarios, proposed by Urmia Lake Restoration Program Committee, include: Preservation of current lake status (no intervention), complete closing of Shahid Kalantari causeway, dyke construction in the southern part of Lake Urmia, water transfer from Zarrinehrood River to Siminehrood River and reduction of agricultural water consumption by best agricultural practices. Results indicate that neither the closure of the causeway nor the construction of the southern dyke would significantly improve lake conditions when compared to preservation of current lake status. The water transfer alternative doesn’t seem to have any effect on the current lake conditions either. However, the reduction on water diversions by improving agricultural practices in the lake's basin leads to a partial restoration of the lake in terms of water level, surface area and volume. If current conditions persist, salinity in the northern part of Lake Urmia will reach supersaturation levels (340?g/L), generating further salt deposits.     

Spatial and seasonal variations in the water quality of the Amu Darya River (Central Asia)

Although the use of the water resources in Uzbekistan is strongly limited by their quality, it has to be noted that there is a lack of information and data within the international scientific literature with regard to the water chemical characteristics of the Amu Darya River, one of the main water resources in Central Asia. To add to such knowledge, this paper examines the spatial and temporal variation of the water quality of the Amu Darya River in order to assess its degree of degradation and the main causal factors. The functional relationships of the pollutants with respect to the flow regime are investigated. Finally an "opportune temporal window" for water withdrawal for filling the reservoirs, in relation to human consumption, will be indicated. The high salinization levels of the waters are mainly due to the presence of sulphates and chlorine. At the up-stream site salinity, although presenting elevated concentrations, does not exceed palatability levels; after the 450 km point the opportune temporal window for water withdrawal with acceptable salinity values is reduced to the period from May to September. Two main driving forces govern the temporal variation of the salinity of the Amu Darya water: a low drainage density of the area which limits the salt loads induced by the natural runoff processes, and snow and glacier melting in the upper catchment area which promotes dilution of the dissolved salts during the high-flow period. During low-flow periods salinity is strongly influenced by the return of waters used for land washing and irrigation.