Application of principal components analysis to the study of salinization on the Castellon Plain (Spain)

The high salinization in some sectors of the Castellón Plain aquifer (Spain), has been erroneusly attributed to seawater intrusion, because of the high and increasing contents of chloride ions. However, recent studies of this aquifer have shown that the chemical characteristics of groundwaters are the result of three different components: intruding seawater, freshwater from rainfall infiltration and saline water with a characteristic sulphate-calcium-magnesium facies, derived from bordering aquifers. The division into sectors according to hydrochemical features, in addition to the inclusion as variables of both certain minor ions and the ionic deviations of the theoretical mixing of freshwater and seawater,h ave provided a clear characterization of the sahnization processesa ffecting the aquifer. The present study showst he application of statisticalm ethodst o the characterization of the salinizationp rocessesin the coastal aquifer of the Castellon Plain. The application of these statistical methods (cluster analysis and principal components analysis) has lead to the corroboration of the hypotheses developed from the previous hydrochemical study. Inclusion of specific variables (certain minor ions and ionic-h) into the PCA enhances a definition of the degree of the salinitation processes

Environmental Effects of Aquifer Overexploitation: A Case Study in the Highlands of Mexico

There are several environmental processes occurring under aquifer overexploitation conditions. These processes include groundwater table decline, subsidence, attenuation and drying of springs, decrease of river flow, and increased pollution vulnerability, among others processes. Some of these effects have been observed on the Upper Basin of the Lerma River. The Lerma River begins in the SE of the Valley of Toluca at 2,600 m asl, in the wetland known as Lagoons of Almoloya del Rı´o. This wetland is made up of a group of lagoons, which are an important aquatic system from an environmental point of view. The water inflow of this wetland is a discharge of springs, which occur between the fractured volcanic material of the mountain range and granular volcanic– continental deposits of the Valley of Toluca aquifer. The intensive exploitation of the Valley of Toluca aquifer to supply urban and industrial wáter to Mexico City and Toluca began in 1950 and is responsable for a steady decline of piezometric levels of 1–3.5 m/yr. Other effects of this exploitation—the drying of the wetland, the decrease of river flow and the land subsidence— caused serious ecological and social impacts. The authorities declared this aquifer as overexploited in order to reduce the exploitation and preserve the availability of wáter resources in this important región

Phosphorus release kinetics in a soil amended with biosolids and vermicompost

Wastewater biosolids are large potential sources of macronutrients for agriculture, conservation and restoration of soils; there are, however, few studies on phosphorus (P) release in soils amended with biosolids. Biosolids and vermicomposted biosolids were tested in concentrations (5–30 g amendment kg-1 soil) equivalent to 18–100 Mg ha-1. Desorption of P was determined by successive extractions for 65 days. Soil P was low, and biosolid and vermicompost addition released 8 and 6 times more P, respectively, than soil alone. To describe the release of P, zero-, first- and second-order equations, simple Elovich and power functions and the parabolic diffusion lawwere compared based on their coefficient of determination (r2) and standard error (SE). In all treatments, the power function and especially the parabolic diffusion law were the best fit, with 0.898–0.996 r2 and 0.022–0.732 SE. The general behavior of the kinetic parameters mostly depended on the amendment doses. Eutrophication posited to start beyond 16 mg P kg-1 soil was more likely allayed by a maximum vermicompost dose of 50 Mg ha-1, higher than the 36 Mg ha-1 maximum biosolid dose. The higher vermicompost P addition and lower P release could favor gradual and longer-term P absorption by plants and may reduce leaching or runoff P losses

Uranium and phosphate behaviour in the vadose zone of a fertilised corn field

Phosphate fertilizers contain approximately 200 mg.kg–1 of uranium. The uranium and phosphate can move through the vadose zone and reach groundwater. Therefore, the knowledge of the ways in which these two elements are distributed, their partition relationships and their mobility behavior is of great interest. In order to study the latter, suction cup samplers, intended to collect soil water at different depths, were installed in an experimental site in a high plain of Mexico, where corn is cultivated and phosphate fertilizers are systematically applied. It was observed that the vadose zone contains high concentrations of uranium (1–50 mg.k –1) and phosphates (22–33 mg.kg–1), which decrease at greater depths. Uranium concentration in the soil water varies between 10 and 3 mg.l–1 and phosphates between 1 and 0.3 mg.l–1. Their evolution throughout the profile of the vadose zone is determined by the decrease in concentrations, due to the physico-chemical processes involved

Territorial approach to increased energy consumption of water extraction from depletion of a Highlands Mexican aquifer

This work proposes a method to estimate increased energy consumption of pumping caused by a drawdown of groundwater level and the equivalent energy consumption of the motor-pump system in an aquifer under intensive exploitation. This method has been applied to the Valley of Toluca aquifer, located in the Mexican highlands, whose intensive exploitation is reflected in a decline in the groundwater level of between 0.10 and 1.6 m/year. Results provide a summary of energy consumption and a map of energy consumption isopleths showing the areas that are most susceptible to increases in energy consumption due to pumping. The proposed method can be used to estimate the effect of the intensive exploitation of the Valley of Toluca aquifer on the energy consumption of groundwater extraction. Finding reveals that, for the year 2006, groundwater extraction in the urban zone required 2.39 times more energy than the conditions observed 38 years earlier. In monetary terms, this reflects an increase of USD$ 3 million annually, according to 2005 energy production costs

Groundwater monitoring network design using GIS and multicriteria analysis

The objective of this investigation was to use multicriteria analysis to analyze and model the main criteria that influence the optimal design of a network to monitor groundwater levels. The multicriteria analysis was performed using a GIS (IDRISI Selva). The Toluca Valley aquifer (Mexico) was chosen as the case study. The definition and importance of the criteria (factors and constraints) that influence the design of the monitoring network were based on available information and consultations with experts in the topic. The factors considered were: rate of decline in groundwater levels, decline in groundwater levels, rise in groundwater levels, cracks, vertical hydraulic gradient, and density of wells. The Analytical Hierarchy Process (AHP) was used to weight the factors, resulting in a consistency ratio of 0.08. The weighted linear combination (WLC) method was then applied which resulted in a map identifying the locations of the priority areas to be monitored. The results show that 1.0 % of the study region corresponds to very high priority monitoring areas, 1.8 % to high priority areas, another 1.8 % to medium priority, 4.4 % to low priority and 91 % to very low priority monitoring areas. The proposed method can be used by government and public and private organizations to determine monitoring strategies that support water resources management

Nitrate and phosphate leaching in a phaeozen soil treated with biosolids, composted biosolids and inorganic fertilizers

The use of organic wastes in agriculture may increase the production of crops by incorporating organic matter and nutrients into the soil, and by improving its physical characteristics; however, this use may cause environmental problems such as the leaching of certain ions. The objective of this study was to establish possible nitrogen and phosphorus leaching under real field conditions in Phaeozem soils. The experimental work was performed in a corn (Zea mays L.) field where three plots were conditioned with inorganic fertilizer, three plots with 4.5 Mg ha 1 of biosolids on dry basis, and three plots with the same amount of composted biosolids. The quality of biosolids and composted biosolids complied with the Mexican Official Standards. Soil water samples were collected with suction cups during two agricultural cycles and were analysed. Soil samples were also taken and analysed. The N–NO3 concentrations in soil water fluctuated between 0.9 and 98 mg L 1 in the composted biosolid treatment, between 0.7 and 64 mg L 1 in the biosolid treatment, and between 1 and 61 mg L 1 in the inorganic fertilizer treatment. The maximum concentration of N–NO2 and N–NH3 in soil water was 1.02 and 2.65 mg L 1, respectively. The greatest percentage of nitrogen leached is produced when inorganic fertilizer is used (37.4% and 24.0% N leached in the first and second years, respectively), followed by composted biosolids (17.1% and 13.5% N leached in the first and second years, respectively) and last by biosolids (11% for both years). This difference could be related to the form in which nitrogen is present in the fertilizers, while commercial fertilizer is as inorganic nitrogen, organic wastes are basically presented as organic nitrogen. The maximum PO3 4 concentration in soil water was 1.9 mg L 1 in the composted biosolid treatment, 1.7 mg L 1 in the biosolid treatment and 0.9 mg L 1 in the inorganic fertilizer treatment. The estimated percentage of leached phosphorus was less than 1% for all treatments. The minimum leaching that occurred seemed to be due to a sorption–precipitation process

Effects of different amendments (organic matter and hydrogel) on the actual evapotranspiration and crop coefficient of turf grass under field conditions

The irrigation schedule in arid areas has to be efficient in order to reduce losses due to evaporation and deep infiltration. Irrigation optimization poses the need to establish with precision the value of actual evapotranspiration (ETa), and the crop coefficient (Kc). The water soil availability can be increased using hydrogel and organic matter amendments, and their effects could vary ETa and Kc. The aim of this study was to determine the ETa, and Kc of an experimental site with lysimeters on the Spanish Mediterranean coast cropped with a turf grass variety, Agrostis stolonifera ‐L‐93, under field conditions, and amended with hydrogel and organic matter. Reference evapotranspiration (ET0) was determined from meteorological data (FAO‐Penman‐Monteith equation). ETa was calculated from the water balance, and Kc was obtained by dividing ETa by ET0. Kc was calculated and compared on a yearly, monthly and daily basis. In summer, the differences between amendments become manifest:Unamended lysimeter (100% sand) had Kc values (0.92‐1.16), similar to organic matter amended lysimeter (0.99‐1.17). Maximum and minimum Kc values for the hydrogel amended lysimeters (1.04‐1.52) were higher than those from the other because of the ability of this compound to retain water, which facilitated evapotranspiration. Finally, hydrogel helped to maintain the turf grass quality

Removal of groundwater arsenic using a household filter with iron spikes and stainless steel

Arsenic (As) in groundwater for domestic use poses a worldwide threat to public health, most notably in rural areas. The aims of this study were: first, determine groundwater composition in a mining area in central Mexico (Huautla); second, assess As exposure through human groundwater consumption and; third, develop and test a household filter to obtain drinking water for these rural communities. From the 17th century through the 1990s, mines in the area produced Ag-galena and sphalerite from volcanic rock. Groundwater flooded the mines when they were abandoned due to low silver prices. Local households now use the water to meet domestic needs.Water from the mines was found to have high As content (0.04e0.26 mg L_1) and Fe, Mn, Pb and Cd were also above Mexican drinking water standards and WHO guidelines. All the population in the Huautla community was exposed to the metalloid through water used in food preparation. The best As removal was obtained with a filter using oxidized commercial fiber (HCl 2N as oxidant).Concentrations in the effluent were below Mexican drinking water standards (0.025 mg As L_1 water) during the 105-day (2520 h) filter operation, with a maximum As removal efficiency of 95.4%. The household filter was simple, low-cost and may be very attractive for As removal in rural areas in developing countries

Sistemas de información geográfica (SIG) como herramienta en la estimación de la demanda de agua para uso urbano

de información geográfica. Este método proporciona una mayor precisión en la estimación de la superficie que abarca las zonas de suministro de agua potable pero, sobre todo, certidumbre en la cantidad de agua demandada debido al detalle que ofrece la información usada: las Áreas Geo-Estadísticas Básicas (AGEB).Para el año de estudio 2005, una comparación entre las estimaciones de la demanda de agua realizadas por el organismo operador del agua en Toluca, México y el presente método utilizando las AGEB‟s concluyeron que problemas como una distribución inadecuada del agua puede ser resuelta por medio de este método utilizando representaciones espaciales de la demanda proyectada. Además el monitoreo sobre el gasto de agua proyectada y suministrada permitirá un análisis sobre la dotación requerida por tipo de consumo y su reducción dentro del marco de cultura de ahorro de agua