Spelling suggestions: "subject:"groundwater"" "subject:"grondwater""
1 |
Isotopic Evaluation of Carbon Dioxide in Soil Gas in Utah for a More Accurate Input Variable in Groundwater Age Determining ModelsHart, Rachelle 19 October 2009 (has links)
In order to achieve a more accurate input value for groundwater age determining models, δ13CVPDB values for soil gas were evaluated at 50 cm depths in locations throughout Utah in order to define correlations between δ13C and environmental parameters. 16 sites were chosen that exploited large changes in elevation and latitude which provided variations in climate, precipitation, plant community, etc. Gas samples were collected over 1-1½ years, and soil samples were collected at depth during installations. Field and laboratory studies were also used to evaluate CO2 and δ13C change with depth. It was discovered that in mountainous recharge areas, the mean δ13C value was −21.8 ± 2.8‰ (2σ). Use of this value reduced the uncertainty in groundwater age models by close to half relative to the current assumed range of -13‰ to -28‰. One arid and one semi-arid site were located at Pilot Valley (mean -11.0‰ ± 2.0, 2σ) and the mouth of Cedar Canyon (mean -17.5‰ ± 0.8, 2σ). The high values at these locations may be due to low root respiration and low microbial activity rates caused by high temperatures, low precipitation, and low vegetation density. Correlations among environmental parameters and δ13C values were discovered with ANOVA, but the differences were small enough that for practical purposes they are insignificant.
|
2 |
An evaluation of the impact of acid mine drainage on water quality of the lower Olifants River, South AfricaMohale, Thabang January 2021 (has links)
Thesis (M. Sc. (Geography)) -- University of Limpopo, 2021 / Acid Mine Drainage (AMD) is the acidic water emanating from the mine tailing dams into
the surrounding environment. AMD is regarded as a major environmental threat
associated with mining. The lower Olifants River in the Kruger National Park (KNP) is
considered an environmentally sensitive area, which exhibits high levels of aquatic
ecosystems and supports a variety of terrestrial ecosystems within and around the KNP.
The Phalaborwa mining industries have been discharging the acid mine drainage
contaminated-water into the Ga-Selati River, a tributary to the Olifants River. Although
the impacts in the upper Olifants River catchment have been well documented, it was
the amount of AMD witnessed at KNP and the dying of fish within the lower Olifants
River that raised issues of concerns. Hence, the study investigated the impact of acid
mine drainage on water quality of the lower Olifants River, modelled the distribution of
the dissolved heavy metals in the stream, and evaluated the applied mine wastewater
management strategies at Phalaborwa mining industries.
In this study, water samples were collected seasonally (winter, spring, and summer)
from 2019 to 2020, and the analytical methods and procedures were optimized for the
determination of selected elements in the water samples. During the study, ion
chromatography (IC) was used to detect chloride (Cl), sulphate (SO4
-
), nitrate (NO3),
and fluoride (F), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES)
was used to detect pH, turbidity, electrical conductivity (EC), total dissolved solids
(TDS), magnesium (Mg), manganese (Mn), sodium (Na), potassium (K), aluminium (Al)
and calcium (Ca). Modelling of the distribution of dissolved heavy metals was performed
using the inverse distance weighted (IDW) interpolation technique available in ArcGIS
10.8 software. The range of pH across four sampling sites was between 7.77 and 9.11,
indicating an alkaline pH. The concentration of measured parameters elevated
downstream points with some exceeding the target water quality range (TWQR) for
aquatic ecosystems. The elevated concentration of SO4
-
at sites 3 and 4 (downstream
points) showed that the acid mine drainage is still a matter of concern at the lower
Olifants River catchment. However, the GIS models showed a decreasing trend of the
concentration of heavy metal towards the KNP.
|
Page generated in 0.0568 seconds