Assessment of Groundwater Quality and the Main Controls on Its Hydrochemistry in a Changing Climate in Morocco (Essaouira Basin)

Application of radiological assessment as water quality criterion for effluent release in a Brazilian uranium mine

Uranium mining causes several radiological impacts on the surrounding environment, notably in the water bodies, mainly due to the release of long half-life radionuclides from the ²³⁸U and ²³²Th series. The Ore Treatment Unit, an old uranium mine undergoing decommissioning, has three points of liquid effluent release (#014, #025, and #076). For current study, 78 samples of water were collected at #014, 33 samples at #025, and 63 samples at #076. The radionuclides were analyzed by gross alpha count, gross beta count, and by arsenazo spectrophotometry. Analyses were carried out using the radiological water quality criterion established by World Health Organization and other organizations, together with the Brazilian legislation, to assess if the released effluents may be used unrestrictedly by the individuals of the public. At #014, the mean values of activity concentration (AC), in Bq·L^-1, were as follows: U_nat = 0.107, ²²⁶Ra = 0.035, ²¹⁰Pb = 0.031, ²³²Th = 0.007, and ²²⁸Ra = 0.049. At #025 the mean values of AC, in Bq·L^-1, were as follows: U_nat = 0.086, ²²⁶Ra = 0.015, ²¹⁰Pb = 0.028, ²³²Th = 0.006, and ²²⁸Ra = 0.032. Finally, at point #076, the mean AC values, in Bq·L^-1, were as follows: U_nat = 3.624, ²²⁶Ra = 0.074, ²¹⁰Pb = 0.054, ²³²Th = 0.013, and ²²⁸Ra = 0.069. The current study showed that natural radionuclides were not in secular equilibrium. Despite uranium presented its values outside the limits of guidance levels, it can be state that the unrestricted use of effluents released in the three water bodies is authorized from the radiological point of view. In terms of dose rate, the releases at three points were within the radiological limits of potability. On the other hand, in an additional analysis, #76 presented chemical toxicity above the authorized value, pointing the need of restricted use of water from the point of view of chemical toxicity.

Combining stable isotope and WQI methods to study the groundwater quality: a case study in Essaouira city, Morocco

Groundwater is an important water resource in arid and semi-arid regions. Therefore, this study aimed to assess groundwater's suitability for drinking and irrigation using the Water Quality Index (WQI) and the Irrigation Water Quality Index (IWQI). To this end, groundwater data were collected from 58 sites in 2019 (wet season) and 61 samples in 2020 (dry season) in the Meskala-Ouazzi sub-basin. The Piper diagram showed that Ca–Mg–Cl was the dominant groundwater facies type. The confinement due to COVID-19 has significantly improved the water quality of the Meskala-Ouazzi sub-basin. Instead, approximately 50% of sites showed improved water quality when calculating the WQI and IWQI. However, the sodium adsorption ratio (SAR) showed that most samples below 10 are found in all of the examined samples, which are mostly found, indicating excellent irrigation water, and the Wilcox diagram depicted 20.14% of samples lying in the unsuitable region. Stable isotopes (δ¹⁸O and δ²H) of groundwater reveal that local precipitation is the main source of recharge. However, groundwater recharge is affected by the evaporation process due to the different geological conditions caused by topographic differences in the study area. The present study is useful for proper planning and managing water resources available for consumption and irrigation.

Water quality has improved during lockdown due to COVID-19.

Assessment of water drinking and irrigation by two models (WQI, and IWQI) in a semi-arid environment.

The main source of groundwater recharge in coastal aquifers is rainfall, based on a stable isotope (δ²H, δ¹⁸O).