Lowering Of Water Table Research Articles

Sinkhole development in the Sivas gypsum karst, Turkey

The extensive gypsum karst of Sivas, Turkey is one of the most outstanding examples of bare gypsum karst in the world. It displays a number of remarkable geomorphic features, including: (1) two stepped planation surfaces cut-across folded gypsum developed during an initial phase of slow base level deepening punctuated by periods of stability; (2) unusual deeply entrenched gypsum canyons related to a subsequent phase of rapid fluvial incision and water table lowering; (3) a polygonal karst of superlative quality mainly developed in the upper surface; (4) relict valleys disrupted by sinkholes in the lower erosional surface; (5) a large number of bedrock collapse sinkholes mostly associated with the lower surface; and (6) numerous cover subsidence sinkholes developed in the valley floors. This work analyses the spatial distribution, characteristics and evolution of the sinkholes within the broad Plio-Quaternary geomorphological and paleohydrological evolution of the epigene karst system dominated by autogenic recharge. A cartographic sinkhole inventory has been produced in an area covering 2820 km2 with morphometric data and including 295 bedrock collapse sinkholes and 302 cover subsidence sinkholes. The different sinkhole types show a general spatial zonation controlled by the hydrogeological functioning of the different sectors: (1) solution sinkholes (polygonal karst) in the upper recharge area; (2) bedrock collapse sinkholes in the lower denudation surface and close to the base level, where well developed caves are inferred; and (3) cover subsidence sinkholes, with high densities probably associated with areas of preferred groundwater discharge. The morphology of the bedrock collapse sinkholes, varying from small cylindrical holes to large and deep tronco-conical depressions with gentle slopes reflect to geomorphic evolution of these sinkholes that reach exceptionally large hectometre-scale diameters. Their evolution, involving substantial enlargement and deepening, is attributed to the solutional removal as solute load of large volumes of gypsum by downward vadose flow. This type of morphological evolution with significant post-collapse solutional denudation differs from that observed in carbonate rocks characterised by lower solubility and erodibility. The analysis of historical imagery reveals that bedrock collapse sinkholes currently have a very low probability of occurrence and that buried cover subsidence sinkholes are used for urban development creating risk situations.

Meteorological Controls on Water Table Dynamics in Fen Peatlands Depend on Management Regimes

Fens belong to the most threatened ecosystems in Europe. Maintaining a high water table through rewetting is an effective measure to rehabilitate many of their ecosystem functions. However, the impact of meteorological conditions such as vapor pressure deficit (VPD) and precipitation on water tables is still unclear for rewetted fens. Here, we compare the impact of meteorological factors on water table dynamics in a drained and a rewetted fen, using multiple regression with data from continuous high-resolution (temporal) water level monitoring and weather stations. We find that an increase in the daily mean VPD causes a higher drop in the water table at the drained and degraded fen compared to the rewetted fen. Precipitation contributes to recharge, causing the water table to rise higher at the drained site than at the rewetted site. We attribute the differential influence of meteorological conditions on water table dynamics to different soil specific yield values (i.e., water storage capacity) largely driven by lower water table position at the drained site. Our study underlines the importance of understanding how and why water tables in peatlands vary in response to meteorological factors for management decisions (e.g., rewetting). Continuous monitoring of water table and vegetation development in rewetted fen peatlands is advisable to ensure long-term success especially under climate change conditions and associated drought events.

CO2 fertilization of Sphagnum peat mosses is modulated by water table level and other environmental factors.

Sphagnum mosses account for most accumulated dead organic matter in peatlands. Therefore, understanding their responses to increasing atmospheric CO2 is needed for estimating peatland C balances under climate change. A key process is photorespiration: a major determinant of net photosynthetic C assimilation that depends on the CO2 to O2 ratio. We used climate chambers to investigate photorespiratory responses of Sphagnum fuscum hummocks to recent increases in atmospheric CO2 (from 280 to 400 ppm) under different water table, temperature, and light intensity levels. We tested the photorespiratory variability using a novel method based on deuterium isotopomers (D6S /D6R ratio) of photosynthetic glucose. The effect of elevated CO2 on photorespiration was highly dependent on water table. At low water table (-20 cm), elevated CO2 suppressed photorespiration relative to C assimilation, thus substantially increasing the net primary production potential. In contrast, a high water table (~0cm) favored photorespiration and abolished this CO2 effect. The response was further tested for Sphagnum majus lawns at typical water table levels (~0 and -7cm), revealing no effect of CO2 under those conditions. Our results indicate that hummocks, which typically experience low water table levels, benefit from the 20th century's increase in atmospheric CO2 .

Nutrient Balance as a Tool for Maintaining Yield and Mitigating Environmental Impacts of Acacia Plantation in Drained Tropical Peatland—Description of Plantation Simulator

Responsible management of Acacia plantations requires an improved understanding of trade-offs between maintaining stand production whilst reducing environmental impacts. Intensive drainage and the resulting low water tables (WT) increase carbon emissions, peat subsidence, fire risk and nutrient export to water courses, whilst increasing nutrient availability for plant uptake from peat mineralization. In the plantations, hydrology, stand growth, carbon and nutrient balance, and peat subsidence are connected forming a complex dynamic system, which can be thoroughly understood by dynamic process models. We developed the Plantation Simulator to describe the effect of drainage, silviculture, fertilization, and weed control on the above-mentioned processes and to find production schemes that are environmentally and economically viable. The model successfully predicted measured peat subsidence, which was used as a proxy for stand total mass balance. Computed nutrient balances indicated that the main growth-limiting factor was phosphorus (P) supply, and the P balance was affected by site index, mortality rate and WT. In a scenario assessment, where WT was raised from −0.80 m to −0.40 m the subsidence rate decreased from 4.4 to 3.3 cm yr−1, and carbon loss from 17 to 9 Mg ha−1 yr−1. P balance shifted from marginally positive to negative suggesting that additional P fertilization is needed to maintain stand productivity as a trade-off for reducing C emissions.

Groundwater quality and hydrological stress induced by Lower Gondwana open cast coal mine

Open cast coal mine (OCCM) may impose adverse effects on groundwater quality and on its flow regime. Evaluation of water quality often becomes difficult and confusing due to presence of multiple criteria and index based on different parameters. A novel approach has been introduced which speaks about a single index revealing the effect of all important parameters to determine the quality for a particular use of groundwater. Physico-chemical parameters of groundwater are grouped according to their toxicity and the weightage is permitted to each group using analytic hierarchy process (AHP). Overall groundwater quality is found suitable for drinking (DWQI = 1.5–2) and irrigation (IWQI = 2 to 3) purposes in Barjora area. Effect of acid mine drainage (AMD) is not significant in controlling the quality of groundwater in the study area. Carbonate and silicate weathering are the dominant hydro-geochemical processes occurring in the study area. Saturation index derived through Phreeqc Interactive software shows that calcite and aragonite are at supersaturated condition in close proximities of OCCMs. Buffer reactions of carbonate minerals may attenuate the effect of AMD in the study area. The hydrological stress induced by OCCM has been evaluated in OCCM 2 through numerical modelling using MODFLOW software. Evaluation has been performed in three stages of mine development – pre-mining condition, present mining condition and future extension of mine. It is estimated that groundwater of almost 24,163 m3/d will ingress into the excavation of 2.03 km2 area with maximum depth around 200 m from ground level. Model predicted 4–5 m lowering of water table, as an impact, around 2.86 km2 area of the mine cavity. The irrigation canal passing through this region, will lose 1473 m3/d water during future extension of mine.

Consequences of Increased Variation in Peatland Hydrology for Carbon Storage: Legacy Effects of Drought and Flood in a Boreal Fen Ecosystem

Globally important carbon (C) stores in boreal peatlands are vulnerable to altered hydrology through changes in precipitation and runoff patterns, groundwater inputs, and a changing cryosphere. These changes can affect the extent of boreal wetlands and their ability to sequester and transform C and other nutrients. Variation in precipitation patterns has also been increasing, with greater occurrences of both flooding and drought periods. Recent work has pointed to the increasing role of algal production in regulating C cycling during flooded periods in fen peatlands, but exactly how this affects the C sink-strength of these ecosystems is poorly understood. We evaluated temporal trends in algal biomass, ecosystem C uptake and respiration (using static and floating chamber techniques), and spectroscopic indicators of DOM quality (absorbance and fluorescence) in a boreal rich-fen peatland in which water table position had been experimentally manipulated for 13 years. Superimposed on the water table treatments were natural variations in hydrology, including periods of flooding, which allowed us to examine the legacy effects of flooding on C cycling dynamics. We had a particular focus on understanding the role of algae in regulating C cycling, as the relative contribution of algal production was observed to significantly increase with flooding. Ecosystem measures of gross primary production (GPP) increased with algal biomass, with higher algal biomass and GPP measured in the lowered water table treatment two years after persistent flooding. Prior to flooding the lowered treatment was the weakest C sink (as CO2), but this treatment became the strongest sink after flooding. The lower degree of humification (lower humification index, HIX) and yet lower bioavailability (higher spectral slope ratio, Sr) of DOM observed in the raised treatment prior to flooding persisted after two years of flooding. An index of free or bound proteins (tyrosine index, TI) increased with algal biomass across all plots during flooding, and was lowest in the raised treatment. As such, antecedent drainage conditions determined the sink-strength of this rich fen—which was also reflected in DOM characteristics. These findings indicate that monitoring flooding history and its effects on algal production could become important to estimates of C balance in northern wetlands.

Ecosystem‐Atmosphere Exchange of CO2, Water, and Energy in a Basin Mangrove of the Northeastern Coast of the Yucatan Peninsula

AbstractCoastal settings variations are linked to composition, structural, and functional differences among mangrove ecotypes. Basin mangroves undergo larger flooding and salinity fluctuations, yet remain understudied, compared to other ecotypes. We evaluated the effect of flooding and air temperature (T a) on the surface energy balance and eddy covariance‐derived net CO2 ecosystem exchange (NEE) of a basin mangrove with sporadic freshwater flooding. During the study period (June 2017–November 2018) the site was more frequently not flooded. Under these conditions, in combination with high T a (>27°C), daytime CO2 uptake was significantly lower, while evapotranspiration and sensible heat flux were higher than when flooded. CO2 uptake increased with T a and vapor pressure deficit, but after exceeding a threshold (29°C and 1.4 kPa), uptake declined. Flooding extended this T a threshold by 3°C and increased the radiation saturation point of NEE. The ecosystem is a net sink of CO2 annually (709 ± 09 g C m−2 yr−1), however, it turned a net source of CO2 for 3 months of prolonged rainfall deficit. Most of the precipitation input is returned to the atmosphere (evaporative index: 0.94) and on average, for each gram of atmospheric carbon assimilated into the ecosystem, 2.21 ± 0.50 kg of water was returned to the atmosphere. This ecosystem‐level water‐use efficiency decreased with flooding, but the correlation was not strong. Future temperature increases and lower precipitation (local and regional), combined with lower water table (and/or stronger saline intrusion), imply important losses of primary productivity and stored soil carbon in basin mangroves of northeast Yucatan Peninsula.

Analyzing the extent of drought in the Rajasthan state of India using vegetation condition index and standardized precipitation index

Drought is the most complex but least understood of all natural hazards that impacts around 55 million people globally every year. A hydrological drought (drought here after) is when the lack of rainfall goes on long enough to empty rivers and lower water tables and causes severe water shortage. In recent years, Geographic Information System (GIS) and remote sensing (RS) have played a crucial role in studying different hazards either natural or man-made. This study stresses upon the use of RS technique for drought risk assessment in Rajasthan state of India for the year 2002 and 2019. In this study, an effort has been made to analyze the extent of drought using two drought indices, namely vegetation-based vegetation condition index (VCI) and meteorology-based standardized precipitation index (SPI). For VCI calculation, which indicates impact of soil moisture on vegetation, we used moderate resolution imaging spectroradiometer (MODIS), Normalized difference vegetation index (NDVI) data from year 2000 to 2019. Monthly SPI was calculated using rainfall data obtained from the Rajasthan water resource department. SPI values were interpolated to get the spatial pattern of meteorological drought. Whole area categorised into five drought classes including extreme drought, severe drought, moderate drought, mild drought and no drought, following the recommended value breaks. The results revealed that about 83.87% area was under drought in the year 2002 thus considered as drought year. It has also been calculated that only 15.62% area was showing drought condition in year 2019 especially in the western part of Rajasthan. Correlation analysis performed between VCI and SPI resulted in a coefficient of correlation of 0.92 and 0.79 in year 2002 and 2019, respectively. The high correlation endorses the reliability of RS data for drought-related analysis.

Influence of Urban Sprawl on Microclimate of Abbottabad, Pakistan

Urban centers are expanding rapidly due to quickly-increasing population which results in microclimate change due to lack of urban planning. Factors like degradation of green areas, trees, and vegetation are defining a new regime of urban environment giving rise to a lack of drinking water and lowering water tables. Consequently, unplanned urban sprawl with all its varied facets is having adverse impacts on the environment. Rapid variations in some of its climatic factors in the immediate vicinity are alarming and need to redress at war footings. This paper is an endeavor to present a hypothesis that urban sprawl plays a vital role in impacting and the influencing the microclimate of the city or the area. In this research, geospatial approaches were adopted to identify urban sprawl. Rise in land surface temperature (LST) for the last 25 years (from 1990 to 2016) has been highlighted using Landsat (5 TM, 7 ETM+ and 8 TIRS) satellite images. Weather data collected from Meteorological Department is used to identify temperature rising trends. Result of the research clearly indicates that rapid urban sprawl has adverse impacts on microclimate by increasing LST. Built-up area has been changed from 178 to 477 sq. km within the years of 1990 to 2016. Vegetated area has decreased from 770 to 602 sq. km. Water areas have been decreased from 524 to 360 sq. km within the span of last 26 years. The bare land has increased from 494 sq. km to 742 sq. km. LST in winters has risen from 17 °C to 23 °C and at times shot up to 31 °C, which is alarming. Annual mean air temperature increased by 3 °C to 4 °C from the 1980s to 2016. During summers, the average air temperature rose to a startling 33 °C from 28 °C and LST has had a steady rise from 28.4 °C to 35 °C. The alarming urban sprawl in relation to temperature rise warrants measures which are required to plan the urban planning, forestation, and ecological measures to mitigate the disastrous trends which may result in flash floods, landslides, soil erosion and sediment transport endangering downstream reservoirs, water quality and depletion in ground water table in the valley.

Formation of plinthite mediated by redox fluctuations and chemical weathering intensity in a Quaternary red soil, southern China

Widely distributed Quaternary red soils (QRSs) in southern China represent the product of intense chemical weathering under a warm and humid climate. Soil containing plinthite is an important part of China’s QRSs, yet the soil environment and mechanism of formation of QRS with plinthite have been insufficiently studied. By comparing iron and clay mineralogy, magnetic properties, visible- and near-infrared (VNIR) spectral behavior, and chemical weathering and redox conditions between the plinthic soil and the overlying homogeneous soil, we determined the environmental conditions and mechanism by which plinthic soil forms. Weathering intensity scale (WIS)-related plots, as well as vertical profiles and ANOVA plots of several mineralogical parameters related to chemical weathering, indicate generally more intense weathering in the plinthic horizon (PH) compared to the homogeneous horizon (HH). Soil VNIR spectral parameters differed for the PH and HH mainly due to differences in mineralogical composition related to horizon-specific pedogenic processes. Horizon-specific pedogenic dynamics also resulted in differences in rare earth element + yttrium (REY) distributions. Based on our integrated geochemical and mineralogic dataset, we infer that the PH formed in a relatively warmer and periodically water-saturated environment with seasonal redox fluctuations, whereas the HH formed in a cooler/drier environment with less rainfall and a lower water table, reflecting transient aridification of local climate during glacial stages. Based on environmental analysis, we propose a model for the formation/development mechanism of plinthic QRS, in which soil pedogenic environment plays a key role in pedogenesis in particular iron mineral transformation. Our findings are of importance for understanding pedogenesis in tropical/subtropical regions and iron cycling and mineral transformation in the Earth’s critical zones.

Evaluating the hydrological response of a boreal fen following the removal of a temporary access road

Peatlands dominate the landscape (~50% of total area) in the Athabasca Oil Sands Region (AOSR) in northern Alberta, and as such, are susceptible to hydrological disturbance from oil sands mining and exploration. In this study, we explore the hydrochemical response of a disturbed fen (Firebag Fen) in the AOSR following the removal of a temporary access road that was operational from 2007 to 2013. Prior to road removal flow was impeded at Firebag Fen, evidenced by inundation on the up-gradient side, and a lower water table on the down-gradient side of the road. Reclamation included the road removal of the ~0.5 m thick road, including 0.15 m of clay, 0.3 m of mud and organics, and 0.05 m of gravel, which left a surficial depression following removal. Peat samples (n = 139) collected immediately following road removal demonstrated significantly greater bulk densities on the down-gradient side relative to the up-gradient side of the fen, and in the road-removed area relative to up- and down-gradient areas. These combined changes decreased the average hydraulic conductivity of the fen by ~79%, which reduced water discharge across the site. Another peat sampling campaign in 2016 (n = 48), three years after removal, showed a significant decrease in bulk density where the road was removed, to within the range of values observed at areas up and down-gradient of the road. These changes increased the average hydraulic conductivity of the entire system by 64%, compared to that which was measured in 2013, with water discharge 9 and 12% higher than in 2013, during characteristically dry and wet periods, respectively. Some changes to the water chemistry (n = 24–28 for each sampling date) of the fen were also detected but patterns were different among parameters measured. For example, median concentrations on the down-gradient side of the road were 1651% (NO3–), 280% (SO42−) and 135% (Cl−) higher relative to the up-gradient side of the road. Over time following road removal, differences were reduced to 100% for nitrate, 192% for sulphate, 108% for chloride, while other parameters remained relatively unchanged (Ca2+, Mg2+, K−). Continued peat rebound (thus increasing hydraulic conductivity) may occur over time; however, elucidating this would require long-term monitoring. It is concluded that despite the impacts that were caused to the site, the natural hydrologic regime of the fen was able to operate following removal. Removal and reclamation should be considered as a worthwhile venture for roads that extend through fens and are no longer in use.

水位下降对若尔盖泥炭地垂直剖面土壤甲烷产生及厌氧氧化潜势的影响

泥炭地是主要的甲烷（CH₄）排放源，甲烷循环过程对水位变化响应敏感。研究选取两块具有水位差异的泥炭地土壤，通过厌氧培养实验探究水位变化对泥炭地甲烷产生和甲烷厌氧氧化（Methane Anaerobic Oxidation，AOM）潜势的影响，并分析影响其潜势大小的生物地球化学因子。结果显示，高水位泥炭地（0 cm） CH₄产生累积量为（0.89±0.01）μg/g，要显著高于低水位（-30 cm：（0.70±0.03）μg/g）泥炭地甲烷产生量，但低水位AOM累积量要显著高于高水位泥炭地（0 cm：（2829.93±35.99）μg/g），低水位泥炭地AOM量为（3588.06±24.78）μg/g。通过相关性分析发现甲烷产生潜势与含水量和DOC具有显著相关性，AOM潜势与含水量、pH、DOC具有显著相关性，含水量和DOC是影响若尔盖泥炭地甲烷产生及AOM潜势大小的重要因子。此外，发现高水位泥炭地甲烷产生潜势对温度升高的响应较为明显，特别是表层土壤（0-20 cm）。本研究明确了水位变化对若尔盖泥炭地甲烷产生及AOM潜势的影响特征，估算了全国泥炭地甲烷产生及AOM潜势的大小，以期为减缓全球气候变暖提供一定的理论支撑。;Peatland is one of main sources of methane (CH₄) emissions, and the process of methane cycle is sensitive to the change of water table. In this paper, soil from two peatlands with the differed water table were cultivated without oxygen to explore the effects of water table change on methane production potential and methane anaerobic oxidation (AOM) in peatland and analyze the potential impact biogeochemical factors. Results showed that CH₄ production from high water table peatland (water table=0 cm:(0.89±0.01) μg/g) was significantly higher than that from low water table (water table=-30 cm:(0.70±0.03) μg/g) peatland. The AOM in the low water table peatland ((3588.06±24.78) μg/g) was significantly higher than that in the high water table peatlands ((2829.93±35.99) μg/g). The correlation analysis showed that methane production potential is significantly correlated with water content and DOC, and the AOM potential is significantly correlated with water content, pH and DOC. Water content and DOC are important factors affecting the methane production and AOM of the Zoige peatland. Our results also showed that the methane production potential at high water table peatland was significantly sensitive to warming, especially at surface soil (0-20 cm). This study clarified the influence of water table on methane production and AOM potential of Zoige peatland, estimated the methane production and AOM potential of peatlands from nationwide, and provided theoretical support in mitigating global change.

Ecological Consequences of Climate Condition Changes (CCC) in Lake Kinneret Watershed

The Hula Valley which is part of the Lake Kinneret watershed (2730 km²) in northern Israel is part of the Syrian–African Great Rift Valley. During mid-1980`s-2017 changes in the climate condition (CCC) were recorded in the watershed: Dryness symptoms of rainfall and headwater river discharges have been declining and air temperature has been increasing. The most recent periodical dryness (drought) was recorded in 2014–2019. Although the Hula Valley comprises only about 10% of the entire drainage basin, it is a significant environmental regional component contributing pollutants which is utilized for agricultural cultivation and eco-tourism infrastructure. Until the late 1950s, this valley was covered by swampy wetlands and a shallow old Lake Hula of mean 1.5 m depth and 13 km² surface area. The valley was drained and converted for agricultural development. The objective of this paper is an evaluation of long-term record of the CCC consequences within the Hula Valley: Headwater discharges, precipitation, air temperature, underground water table (GWT), wind regime (velocity, direction), evaporation, relative humidity, and solar radiation. A partial of CCC within the Hula Valley was confirmed, mostly temperature increase, water deficiency, and ground water table (GWT) lowering. Results indicates that the impact of CCC threatened the optimal appropriate maintenance of the valley. Conclusive future perspectives of supplemental water supply from lake Kinneret to the Hula Valley combined with enhancement of desalinized sea water input into the lake that might improve Hula Valley management and the Kinneret water quality are discussed.

Découverte de charophytes et ostracodes de l’Yprésien inférieur dans les Monts des Ksour (Algérie) : biostratigraphie et paléoécologie

A stratigraphic, palaeontological and sedimentological study was carried out in the red beds cropping out on the left side of Oued Tafarahit, south-east of the Ksour Mountains (Algeria). The studied succession consists of a non-marine fining-upward detrital formation, including microconglomerate, sandstone and clay beds, which were previously attributed to the Cenozoic sensu lato, since no palaeontological evidence was available. Sedimentology suggests deposition in a fluvial environment. The clayey levels yielded the assemblage formed by the charophytes Peckicharaatlasensis, Maedleriellacristellata,Nitellopsis (Tectochara) thaleri,Grovesichara sp., and Lamprothamniumpapulosum and the ostracods Neocyprideismeguerchiensis, Herpetocypris? sp. and Cyprinotus? sp. This assemblage allows constraining the age of the detrital series from Oued Tafarahit to the Ypresian. Ostracods are typical of freshwater to euryhaline environments. The freshwater taxa (Herpetocypris? sp. and Cyprinotus? sp.) would indicate phases of desalinisation during periods of flood. However, the brackish water species (Neocyprideis meguerchiensis) is characteristic of saline phases related to low water table periods. Moreover the charophyte and ostracod assemblage confirms a close palaeobiogeographic relationship between North Africa and Southern Europe during the Lower Eocene.

The Loma de Hierro Ni-laterite deposit (Venezuela): Mineralogical and chemical composition

Nickel laterite deposits developed on ultramafic rocks have traditionally been a significant source of Ni and Co and recently of Sc. Although the Loma de Hierro deposit (Venezuela) has been in operation for more than 50 years, it lacks detailed studies on the mineralogical and geochemical composition of the lateritic profile. In this study, we present a geochemical and mineral description of the main carrier phases of Ni and Co in a complete profile of the deposit. The selected weathering profile has been developed from a partially serpentinized harzburgitic protolith and has a well-developed saprolitic horizon covered by a thin limonitic horizon. The geochemical signature of the profile is characterized by a significant Mg and Si decrease towards the top of the saprolite, with a clearly visible Mg discontinuity. The main Ni-bearing minerals are secondary serpentine (1–4 wt.% NiO) and kerolite-pimelite-dominated garnierite mixtures with serpentine (18–22 wt.% NiO). Limonite is rich in goethite (0–1.85 wt. % NiO), gibbsite, and Mn-oxy-hydroxides. The latter have intermediate compositions between lithiophorite and asbolane (2–13 wt.% CoO). The highest Sc grades (40–68 ppm) were observed in the limonite with amounts positively correlated with Fe content. Rare earth elements are mainly concentrated in the upper part of the saprolite horizon (60–80 ppm), while they have a lower content in the limonite (7–45 ppm). In this horizon, rare earth elements are clearly associated with Fe, indicating adsorption and/or coprecipitation. This association was not observed in the saprolite, suggesting that other minerals (e.g., clay minerals) are controlling their concentration; more information is needed to identify the rare earth element-bearing minerals. The lateritic profile of Loma de Hierro can be classified as representative of hydrated Mg silicate deposits, and was formed in a context of continuous tectonic uplift and a low water table conditions favoring the development of a thick saprolitic horizon and the precipitation of kerolite-pimelite-dominated garnierites.

Appraisal of geochemical composition and hydrodynamic sorting of the river suspended material: Application of time-integrated suspended sediment sampler in a medium-sized river (the Sava River catchment)

The suspended particulate matter (SPM) carried by the rivers shows a wide range of particle size classes, mineralogical and chemical compositions and is mainly influenced by hydrodynamic sorting and provenance during the transport. Here, we have investigated the composition of the SPM in the Sava River and its tributaries (Ljubljanica, Savinja and Krapina) using a time-integrated suspended sediment sampler (TIMS). The representativeness of material collected by TIMS was evaluated comparing fine-grained sediments, single-point SPM and SPM collected using a shallow and deep-positioned sampler. The main results have revealed that the mineralogical and geochemical composition of the material is largely dependent on hydrological conditions. The differentiation of element composition is especially emphasized at low water stage when most of the SPM consists of slow-settling mineral phases (clay minerals and metal oxyhydroxides) which can be trapped in the sampler. During periods of high discharges, differentiation is less prominent, and homogenization of the SPM occurs, mainly as a part of bed load is also taken into suspension. These conditions have proven unfavorable for sampler efficiency, as at least part of the finest particles could not be retained. Additional issues that may occur during TIMS employment relate to biologically driven carbonate precipitation, which is triggered by changes in physico-chemical conditions at low water table in the summer period. Increased concentration of Ca, related to that process, influences the elemental composition of the SPM, which is particularly important when anthropogenic impact or sediment source is assessed. Hence, in order to interpret the geochemical and mineralogical data collected by TIMS, these factors should be taken into account. Our findings emphasize the need for detailed studies of chemical composition of the SPM (time-integrated) in medium-sized rivers and point out the significance of evaluating sampling representativeness during different hydrological conditions.

Land Reclamation in Iraq

Reclamation in Iraq was known in 1950s, where the problems salinity and waterlogging are mainly apparent in the middle and south of Iraq. The early interventions in reclamation sectors was simple, not precise, or calibrated properly, hence, salinization and water-logging aggravated. Since the reclamation activities are time and resources consuming, which may last in several years, these are highlighting the fact that most of the beneficiaries could not afford the conducting of this activity. Therefore, Iraqi government take the decision in 1970s to carry out the reclamation and improve the agricultural processes vertically. There are millions of donums were reclaimed along Iraq. There are key steps adopted to conduct the sophisticated reclamation in order to get rid of salinity, lowering water table to acceptable depths, and prevent future salinization. The reclamation is not just an engineering project, the full reclamation are also may include, rural development, capacities building for operators and beneficiaries, educational development, research development, and social development. Keywords: Land reclamation, Salinity, water logging, Iraq.

Bio-remedial Properties of Moringa oleifera Seed Powder against Contaminated Water

ABSTRACT: Urbanization and various human activities are adversely affecting freshwater resources. The lowering of ground water table every day and drained water contamination is an alarming threat to potable water for the Lahore city. So, there is need to improve water quality and bioremediation is found as very useful application for reclamation of polluted water. In the current study 4g seeds of Moringa oleifera were used for treatment of one liter sewerage/polluted water. The water samples were collected by completely randomized design (CRM) from six primary drains [Cantt. Drain (CNTD), Sattu Katla Drain (SKD), Lower Chotta Ravi Drain (LCRD), Upper Chotta Ravi Drain (UCRD), Shalimar Escape Channel Drain (SECD) and Shahdra Drain (SHD)] and four houses located within 500m distance around each drain. The houses were named as H1, H2, H3 and H4. Samples were examined for physicochemical parameters including turbidity, pH, Ts, Salinity (%), TSS, TDS, COD, BOD and heavy metals (Pb, Cu, Cd and Ca) before and after adding Moringa oleifera. Turbidity decreased by 95% after treatment with Moringa oleifera Seed Powder. After treatment with Moringa seeds, there was an increase in values of pH, NaCl (%), TS (mg/l), TSS (mg/l), BOD, Electrical conductivity and TDS (ppm) of all collected samples. Moreover COD of all samples was reduced which is a good measure for water pollution. Mean levels of trace metals were found to be reduced after treatment with MOSP at all sites which strongly advocates for the use of this product for reclamation of polluted waters.

Groundwater vulnerability mapping using the Susceptibility Index (SI) method: Case study of Takelsa aquifer, Northeastern Tunisia

The Takelsa phreatic aquifer currently shows stress signs and the contamination risk of groundwater by different chemical elements and pesticides is a likely concern. Here we assessed the aquifer vulnerability using the Susceptibility Index (SI) method, considered as a specific vulnerability method that takes into consideration the impact of land uses chemical fertilizers, anthropogenic activities and natural factors as a source of contaminants in groundwater. WetSpass and MODFLOW models were applied to quantify groundwater recharge and water table depth, the two of the most important parameters in groundwater vulnerability mapping.The obtained recharge map for 2015 showed values ranging between 0 and 342 mm/year with an average value of 111 mm/yr, corresponding to about 16% of the annual average rainfall. Regarding the groundwater flow model and for a steady and transient state, a reasonable correlation between the observed and simulated values was obtained confirming that results can be used to establish the vulnerability map.The Susceptibility Index (SI) results showed that the groundwater vulnerability of the studied aquifer ranges from low to very high. Most of the area (90%) has moderate to very high pollution susceptibility mainly due to low slope, agricultural land, high recharge rate, sandy soil dominance and low water table depth. The validation of the obtained map was undertaken through a comparison of areas of high salinity hazard with their relative vulnerability index. For most wells, the different salinity hazard parameters matched with areas of moderate to high vulnerability.The integration between the SI method and WetSpass and MODFLOW models for the study area is a valuable and applicable approach for the assessment of the groundwater vulnerability.

ASSESSMENT OF SPATIO-TEMPORAL FLUCTUATIONS IN GROUNDWATER LEVEL AND ITS IMPACT ON TUBEWELL ENERGY NEXUS

Over exploitation of groundwater to fulfill the crop water requirements due to insufficient canal water supply can pose a major threat of water table lowering in semi-arid regions like Pakistan. So, it is necessary to analyze the seasonal groundwater level variations for appropriate management strategies to sustainable groundwater use. Water table declining has adverse economic impacts on total cost of agricultural inputs, as more than 50% of irrigation demand is being fulfilled from groundwater resources. Therefore, this research was aimed to draw the groundwater level zones and to determine the impacts of lowering water table on tubewell energy nexus in district Hafizabad, Pakistan. Water table depth was categorized in three zones i.e., shallow (<10 m), moderate (10-15 m) and deep (>15 m) for years 2003, 2008 and 2013. It was found that water table was shallow on north-east boundary, moderate on the Centre and deep on west-south boundary. During the study period, the area under shallow water table zone reduced from 38.6 to 23%, moderate area expanded from 52.3 to 59.2% and deep area increased from 9.1 to 17.9%. The difference between total cost of shallow and moderate water table was minor. The total cost (construction and operational) of tubewell for 36 m deep water table was 3 times higher than shallow depth (9 m). Thus, lowering of water table should be controlled by increasing share of canal water in deeper zone and introducing artificial recharge methods