The Toluca Valley is located on the high plains of Mexico, where there are significant industrial zones and large populations. Water needs are almost exclusively met by groundwater, which has brought ...about intense exploitation of the aquifer and indication of some contamination. The present study investigates the effect of urbanization, related to industrialization of the region, on groundwater in the central portion of the Toluca Valley aquifer—a zone with high population density and where the largest industrial park is located. A general decline in the groundwater level has been found over the years, at a rate of as much as 2.5 m/year. The appearance of a large drawdown cone was identified, indicating changes in the direction of groundwater flow. Also identified was the presence of several ground fissures, the location of which coincided with the drawdown cone. In hydrochemical terms, the water type is sodium-magnesium bicarbonate and this characteristic has not changed over time, although it has been possible to detect the presence of larger quantities of sulfates (up to 117 mg/L) and nitrates (up to 47 mg/L) in recent years, likely associated with contamination from industrial and urban wastewater. Factor analysis made it possible to identify ions that would characterize natural processes involving the acquisition of salts (HCO₃ ⁻, Na⁺, Mg²⁺, and Si), as well as anthropic activities (SO₄ ²⁻, NO₃ ⁻, Cl⁻, Ca²⁺, and K⁺).
This work presents the use of multi-criteria decision analysis (MCDA) as a decision tool to facilitate the process of prioritization of drinking wells that would need more protection before ...contamination risk. In this study, three aspects of the protection of the groundwater quality were taken into account: natural, anthropic and technical. From these aspects, elements more representative were selected, which can be quantified with available and easily accessible information. Considering those elements, selection criteria were defined which have been represented by: population distribution indicator, human development index, land use, index for aquifer vulnerability to contamination, well age and well yearly pumping rate. The developed method has been applied to drinking supply wells located in the Toluca Valley aquifer (Mexico), and implied the generation of the thematic maps of the defined selection criteria. For the MCDA, the values of each map were converted to the same scale, each criterion was weighted in function of its importance according to the objective and there were aggregated by the way of a lineal combination. The obtained result is a map that shows the level of protection priority of the supply wells. This map can offer information to the stakeholder in a relative short time and contribute to accelerate the actions aimed to protect the quality of the vital underground liquid.
Golf courses represent an agricultural activity wherein grass is intensively cultivated using large quantities of fertilizers. In the present study, nitrogen and phosphorus leaching was analyzed over ...two years in an experimental green under actual field conditions. The green contained four plots with distinct amendments (P1: hydrogel + peat, P2: peat, P3: hydrogel, and P4: no amendment). The applied doses of nitrogen ranged from 5 to 103 kg/ha and of phosphorus from 9 to 31 kg/ha. The irrigation level varied as a function of the rainfall regime and the water requirements of grass; overall water intake varied from 1550 to 2080 mm/year. Daily, leached water volume was calculated, and samples were taken for chemical analysis. Nitrogen and phosphorus mass balances were calculated for different periods based on the collected data.
The plot amended with peat and hydrogel (P1) had reduced water flow; the percentage of drainage water varied from 8.4 to 29%. As a result, the dissolution and leaching of nitrogen (N) and phosphorus (P) were the lowest in comparison to the other plots. According to the calculated mass balances, the lowest leaching values were also recorded in this plot (P1), ranging from 0.5 to 6.3% for N and from 0.8 to 20.9% for P. The plot without amendment (P4) drained the most water (25.9–44.8%) and leached the highest quantities of N and P, ranging from 9.1–45.7%, and 6–35.9%, respectively. The use of double amendments (hydrogel and peat) therefore represented optimal operating conditions for the green. Moreover, a relationship was found between increasing rates of fertilization and increasing percentages of N and P leaching as well as between higher irrigation levels and greater leaching.
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•Hydrogel amendment reduces N and P leaching as well as water percolation.•Peat amendment does not impact the percentage of leached N.•The largest amount of N and P leached is detected in the plot no amendment.•A larger irrigation rate (>10 mm) favors leaching of N and P, and water percolation.
•Thermal springs from the eastern Trans-Mexican Volcanic Belt were studied•Three water types were identified: Na-Cl, Na-Ca-SO4-HCO3, and Na-HCO3.•High concentrations of B, Li, As, and F− were ...detected.•The presence of geothermal brine and rock-water processes control water chemistry•The geothermometry indicates reservoir temperatures between 90 and 190°C.
This study was aimed at investigating the hydrogeochemical and isotopic characteristics of low-temperature hydrothermal springs in six study sites located in the eastern portion of the Trans-Mexican Volcanic Belt, in order to evaluate the source of the thermal water, rock-water interactions, and reservoir temperature. In addition, based on this, possible similarities and differences among these thermal springs were explored. Samples of thermal waters (12 samples) and non-thermal waters (6 samples) were collected during dry and rainy seasons. Stable isotopes (18O, 2H) as well as major, minor, and trace ions were analyzed for, and saturation indices and reservoir temperatures were estimated. Thermal water temperatures ranged from 33 to 55°C and the pH was slightly acid (and slightly basic in only one case). The electrical conductivity ranged widely, from 0.2 to 27 mS/cm, although most samples had > 8 mS/cm. Using a Piper diagram, three hydrochemical facies were identified: Na-Cl, Na-Ca-SO4-HCO3, and Na-HCO3. The notable minor and trace elements and ions were B, Li, As, and F− . δ18O and δ2H values plot very close to the meteoric water line, although samples from three of the study sites showed a possible isotope exchange between water and minerals at high temperatures. By estimating reservoir temperatures using solute geothermometers and saturation indices, it was possible to determine similarity among the values obtained (90 to 190°C). These data indicate that the hydrochemistry of the thermal waters reflects a water source that is related to geothermal brines in some cases, and with the mixing of a thermal fluid and a recently infiltrated water in other cases, as well as water-rock interactions (mostly with silicates) and carbonate precipitation.
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This study addresses the benefits of incorporating flexible DC links into radial distribution networks, which are subject to continuous load growth and higher levels of distributed generation ...penetration. To compare the use of DC links with conventional network reinforcement measures, an optimisation framework is developed. The main feature of the proposed formulation is that, irrespective of the criterion chosen to quantify the benefits of adding DC links, the same objective function is handled. Maximising or minimising a single-objective function, subject to the same set of constraints, allows different planning criteria to be assessed. The proposed optimisation framework is applied to actual networks embedding distributed generation. Two- and three-terminal voltage source converter-based DC links are considered in order to numerically illustrate the potential benefits of this technology in distribution systems.
The high content of toxic elements, such as As, in thermal water can cause water-quality problems when thermal water mixes with groundwater and/or surface water destined for human consumption. The ...objective of the study was to evaluate the mixing process between thermal and non-thermal waters in the Ixtapan de la Sal-Tonatico region of Mexico and to determine the resulting impacts on the quality of water for human consumption. The thermal springs of the study area had an average temperature of 35 °C and 5 g/L of total dissolved solids (TDS). The dominant ions were Cl
−
and Na
+
. The concentrations of As (1.7 mg/L), Fe (2.2 mg/L), and Mn (0.15 mg/L) and the water hardness (2087 mg CaCO
3
/L) exceeded the permissible limits for drinking water. Non-thermal springs, well water, and surface water were characterized as Ca–Na–Cl–HCO
3
, Ca–Mg–HCO
3
, and Na–Ca–Cl types, respectively, and had TDS values of 0.8, 0.2, and 0.4–3.9 g/L, respectively. The percentages of mixing were calculated based on the concentrations of conservative ions, such as Cl, B, Sr, and Li. The percentage of thermal water spring mixed with non-thermal spring water was around 11% and with surface water ranged from 10 to 30%. This variability is likely related to the proximity of surface water sources to the discharge points of thermal springs. As a result of mixing processes, the non-thermal water (non-thermal springs and surface waters) presents TDS, Cl
−
, Na
+
, hardness, As, Fe, and Mn values above those permitted by Mexican regulations for drinking water.
The Ixtapan de la Sal–Tonatico hot springs are located in the geological setting of the Trans-Mexican Volcanic Belt, on the border of the Morelos–Guerrero Basin, which is carbonated region with ...limestone and silicic rocks. The temperature, electrical conductivity and pH of the thermal waters are 25.7–37.2 °C, 9520–13,920 µS/cm and 5.90–6.88, respectively. The hydrochemical family is NaCl (Cl
−
mean concentration of 2198 mg/L and Na
+
mean concentration of 1396 mg/L). The minor and trace elements that are notable for their high concentrations are B (19.69–23.58 mg/L), Li (6.09–8.06 mg/L), Sr (4.80–6.18 mg/L) and As (0.30–1.97 mg/L). Isotope data (
δ
18
O,
δ
2
H) show
δ
18
O enrichment of the thermal waters, which may be a result of isotopic exchange with the host rock at high temperatures, although the value was very small, which may be due to mixing with groundwater near the surface. The water samples were oversaturated with calcite, dolomite and quartz, verified in the field by the presence of precipitated rocks (travertines). The samples were undersaturated with chalcedony, silica gel, cristobalite, celestite and strontianite. Several chemical geothermometers and the results from multicomponent equilibrium suggest a reservoir temperature between 90 and 130 °C. Meanwhile, a temperature of 129 °C was estimated with the Cl–enthalpy mixing model. According to the conceptual model of the functioning of this system, considering that flow is characterized by the heating of water at deep zones due to the high geothermal gradient caused by recent tectonic activity. This water rises to the surface through fractures and faults. As it rises, thermal water mixes in different proportions with Ca-HCO
3
groundwater.
Previous studies performed on the volcanic-sedimentary aquifer of the Tenancingo Valley (Mexico) reports high concentrations of Fe, Mn, and NO3−, and water from several wells receives purification ...treatments due to presence of Fe and Mn. These studies have not achieved conclusive results regarding the origin of Fe and Mn, nor have hydrogeochemical evaluations of the aquifer been performed. The present study aimed to evaluate the physicochemical characteristics of the water and identify the geochemical processes that determine presence of Fe and Mn in groundwater. This characterization was based on physicochemical data from well and spring samples (16 samples) during dry and rainy seasons (June and November 2012, respectively).
The EC, temperature and pH ranged from 125 to 793μScm−1, 14.5 to 24.9°C and 6.5 to 8.5pH units, respectively. The Eh values ranged from −219 to 327mV, indicating the existence of both reducing and oxidizing zones. Presence of Fe and Mn was detected in both springs and wells; concentrations were higher in well, exceeding 4mgFeL−1 and 0.5mgMnL−1. Content of Si ranged from 12 to 47mgL−1.
A model of the hydrogeochemical behavior of the aquifer was created to highlight the following: i) processes involved in water-rock interactions, including fluctuations in silicate levels that determine anionic and cationic content of water, and ii) redox reactions as the major control processes of Fe and Mn.
Water quality for human use is restricted by Fe and Mn content and pH. For irrigation use, significant limitations were not presented.
•Physicochemical composition of volcanic-sedimentary aquifer groundwater was studied.•Hydrochemistry data reflect the water-rock interactions (alteration of silicates and ion exchange).•Fe and Mn have been found in springs and wells.•Iron and Mn concentration depends of salinity and redox conditions.•Iron and manganese concentrations of water were higher than the permissible limits in drinking water.
Abstract Introduction We present the protocol of a large population-based case-control study of 5 common tumors in Spain (MCC-Spain) that evaluates environmental exposures and genetic factors. ...Methods Between 2008-2013, 10,183 persons aged 20-85 years were enrolled in 23 hospitals and primary care centres in 12 Spanish provinces including 1,115 cases of a new diagnosis of prostate cancer, 1,750 of breast cancer, 2,171 of colorectal cancer, 492 of gastro-oesophageal cancer, 554 cases of chronic lymphocytic leukaemia (CLL) and 4,101 population-based controls matched by frequency to cases by age, sex and region of residence. Participation rates ranged from 57% (stomach cancer) to 87% (CLL cases) and from 30% to 77% in controls. Participants completed a face-to-face computerized interview on sociodemographic factors, environmental exposures, occupation, medication, lifestyle, and personal and family medical history. In addition, participants completed a self-administered food-frequency questionnaire and telephone interviews. Blood samples were collected from 76% of participants while saliva samples were collected in CLL cases and participants refusing blood extractions. Clinical information was recorded for cases and paraffin blocks and/or fresh tumor samples are available in most collaborating hospitals. Genotyping was done through an exome array enriched with genetic markers in specific pathways. Multiple analyses are planned to assess the association of environmental, personal and genetic risk factors for each tumor and to identify pleiotropic effects. Discussion This study, conducted within the Spanish Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), is a unique initiative to evaluate etiological factors for common cancers and will promote cancer research and prevention in Spain.
Neutron peripheral contamination in patients undergoing high-energy photon radiotherapy is considered as a risk factor for secondary cancer induction. Organ-specific neutron-equivalent dose ...estimation is therefore essential for a reasonable assessment of these associated risks. This work aimed to develop a method to estimate neutron-equivalent doses in multiple organs of radiotherapy patients. The method involved the convolution, at 16 reference points in an anthropomorphic phantom, of the normalized Monte Carlo neutron fluence energy spectra with the kerma and energy-dependent radiation weighting factor. This was then scaled with the total neutron fluence measured with passive detectors, at the same reference points, in order to obtain the equivalent doses in organs. The latter were correlated with the readings of a neutron digital detector located inside the treatment room during phantom irradiation. This digital detector, designed and developed by our group, integrates the thermal neutron fluence. The correlation model, applied to the digital detector readings during patient irradiation, enables the online estimation of neutron-equivalent doses in organs. The model takes into account the specific irradiation site, the field parameters (energy, field size, angle incidence, etc) and the installation (linac and bunker geometry). This method, which is suitable for routine clinical use, will help to systematically generate the dosimetric data essential for the improvement of current risk-estimation models.
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