Search

In order to understand the hydrogeochemical pattern, ground (n = 23) and surface water (n = 2) samples were collected from three different landscapes (mountain, plain, valley) of Hidalgo State, Central Mexico. Physicochemical characteristics (pH, electrical conductivity, total hardness, alkalinity, total acidity, total solids, total dissolved solids, total suspended solids, CO2; cations (Ca2+, Mg2+, Na+), anions (NO3−, Cl−, PO43−and SO42−) and dissolved geochemical elements (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd and As) were analyzed. Results illustrated they are neutral to slightly alkaline due to the dissolution of carbonates. Average concentrations of anions and cations presented an order of (in mg/l): Na+ (273) > Ca2+ (206) > SO42− (181) > Cl− (163) > Mg2+ (115) > NO3− (11.07) > PO43− (0.12) revealing the local geogenic and anthropogenic influences. High mean concentrations of dissolved trace metals (0.052 mg/l) in the mountains is attributed to their diverse geochemical environment of the terrain and climatic variability. Concentrations of Cr, Cu, Ni and Zn were below the permissible limits set forth by WHO and the Mexican Government. Piper trilinear diagram revealed that they are mainly of Ca-Mg-HCO3 and Ca-Mg-SO4 type. Sodium Absorption Ratio (SAR) indicated that nearly 96% are of excellent quality, while Magnesium Adsorption Ratio (MAR) showed that 68% of them are unsuitable for irrigation purposes.

The unusual winter storm event of March 2016 brought excess rainfall in the Central part of Mexico and this study attempts to determine the moisture sources by characterizing the rainwater isotopes (δ18O, δ2H) and understanding their monthly spatial variations. Rainwater samples from six different stations (Agua Blanca, Molango, Mexico City, Pachuca, Tula and Tulancingo) of Mexico were sampled in March, April and May 2016. Enriched isotopic signatures in Tulancingo during March exhibited a mixture of moisture sources in which the predominant source was from the North followed by the Gulf of Mexico, while the depleted isotopic levels in Pachuca and Tula moisture from the recycling of inland vapour. However, the isotopic characterization in the month of April presented no much variations in δ18O values irrespective of the station (−2.31 to −2.56‰), signifying that the prime moisture source is mainly from the inland sources and migrated from the central parts to the Gulf of Mexico. In contrast, the inland migration of the vapour source from Gulf of Mexico was witnessed in May with both the continental and the amount effect. However, the enriched δ18O values in Tulancingo and Agua Blanca in May were found to be −0.84‰ and −1.44‰ respectively, with significant lesser d-excess values.

Trace metals Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, and As were determined on a monthly basis in a total of 52 rain samples collected from six different locations in the central region of Mexico during March 2016&ndash, April 2017. The average concentrations of trace metals (mg/L) in the rainwater samples showed an order of Zn (0.873) &gt, Fe (0.395) &gt, Mn (0.083) &gt, Cr (0.041) &ge, Cu (0.041) &gt, Pb (0.031) &gt, Ni (0.020) &gt, Co (0.013) &gt, As (0.0003) &gt, Cd (0.002). The differences observed in metal concentrations are related to variations in the influence of continental air masses, local transport, regional advection, and the solubility of trace metals. High concentrations of metals were observed in the months of March to May at all sites, probably due to the less extensive removal of air/air pollutants. The values obtained from the enrichment factor (EF) per metal showed relatively high values for Cd, Zn, Cu, Pb, Co, Ni, and Cr, suggesting anthropogenic origin. Pearson&rsquo, s correlation matrix validated the distribution of trace metal sources and their relationships with local/regional meteorological characteristics. This paper presents relevant basic information for the evaluation of the toxic potential of rainwater and the possible health risks when using this source of water for human consumption.

The tourist beaches of Huatulco and Acapulco on the south Pacific coast of Mexico are being overstressed from the high number of tourists visiting the region. Human-induced activities not only contaminate the water, but also the beach sediments and aquatic organisms that are housed in the environment. Various multidisciplinary aspects such as socioeconomical, geochemical, and management issues were studied on almost 40 tourist beaches to evaluate the pollution status and enrichment of different geochemical elements. In addition, the promoting and depromoting factors of each tourist destination were assessed. Beach management practices and several laws put forth by the Mexican government were also emphasized for a better construal of the study regions. Thus, the present chapter defines an integrated approach for defining the tourism status and coastal management of high impacted tourist destinations for a better sustainable conservation of the ecosystem and its services.

Thirty sediment samples from four different beaches along Bahia Solano and Nuqui (Department of Choco) of eastern Colombia, with tourism and gold mining activities, were analysed to estimate the concentrations of fourteen different acid leachable metals. Metal distribution patterns showed elevated concentrations of Co, Cr, Cu, Pb and Zn compared with the upper continental crust values. Calculation of geochemical indices confirmed that the enrichment is due to periodic gold mining activities (severe to extremely severe enrichment of Cu, Zn, V, Co, Cr and Pb) along with natural (geological) contributions (minor and moderate enrichment of Ca, Mg, Fe, Ti, Mn and Li). Potential ecological risk index revealed that Pb posed the highest risk. Our results together with a global comparison suggest that the observed metal enrichments are mainly caused by mining and to a lesser extent by tourism in this region, thus instigating continuous monitoring of metal concentrations in this region.