Publications by authors named "L Walter Daessle"

In many cases, shallow coastal lagoons are, on the one hand, vulnerable habitats for birds and marine ecosystems and, on the other hand, threatened by discharging nutrient-laden surface waters and groundwater. In particular, the localization and quantification of submarine groundwater discharge (SGD) is of key concern in this regard. The presented study aimed at investigating SGD into a vulnerable coastal lagoon that is strongly impacted by evaporation applying a multi-tracer approach.

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The identification of nitrate (NO) sources and biogeochemical transformations is critical for understanding the different nitrogen (N) pathways, and thus, for controlling diffuse pollution in groundwater affected by livestock and agricultural activities. This study combines chemical data, including environmental isotopes (δH, δO, δN and δO), with land use/land cover data and a Bayesian isotope mixing model, with the aim of reducing the uncertainty when estimating the contributions of different pollution sources. Sampling was taken from 53 groundwater sites in Comarca Lagunera, northern Mexico, during 2018.

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Article Synopsis
  • The study analyzed the levels of toxic elements (As, Se, Hg, Pb, Cr) and toxaphene in 11 freshwater fish species across various water bodies in the Mexicali valley from August 2015 to April 2016.
  • Arsenic and selenium were found in higher concentrations in specific drain water, while selenium and mercury levels were highest in fish tissues from the Colorado River; some levels exceeded safe consumption limits.
  • Genotoxicity, indicated by micronucleated erythrocytes in Tilapia, was significantly linked to the concentrations of arsenic and selenium in the surrounding water.
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Rapid depletion of aquifers in semiarid and arid regions threatens water security. This holds true especially in emerging countries where insufficient knowledge about aquifer systems precludes the implementation of advanced management measures, such as managed aquifer recharge. This study deals with the generation of baseline knowledge for the assessment of aquifers in arid and semiarid regions where artificial recharge with reclaimed water gains increasing impetus.

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In 2014 reclaimed water (RW) started to be used for agricultural irrigation of 200 ha in Maneadero Valley, Baja California, Mexico. The RW had relatively high electrical conductivity (4-5 dS m), and K, Mg, PO and Cl concentrations relative to irrigation guidelines. However, no accumulation of these elements, nor total nitrogen, was observed in the studied soils.

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