Simulation of heavy metal leaching from cement-stabilized polluted sediments : geochemical modelling

A lot of concern has been raised by individuals and organizations regarding the menace associated with heavy metal contamination of marine sediments in Norway. This has necessitated the remediation of heavy metal contaminated areas. Stabilization and solidification is one of the techniques used to immobilize heavy metals in marine sediments. Laboratory leaching tests are generally used to assess the effectiveness of stabilization and solidification. Results of laboratory leaching tests are, however, used only on short term basis. Geochemical models have evolved into invaluable tools that can be used as a substitute for laboratory leaching experiments. Results from geochemical modelling can be used for future predictions and also help in management options. Previous studies have revealed that several leaching experiments have been successfully simulated with geochemical models. This study, which is in connection with a larger project being carried out by NGI, has been designed with the intent of using geochemical modelling code, PHREEQC to simulate the binding and release of Pb and Cu and their long-term behaviour in cement-stabilized polluted sediments from three Norwegian harbours namely: Hammerfest, Grenland and Bergen. The Freundlich empirical adsorption isotherm was utilized in this study to describe the behaviour of the heavy metals in the three stabilized sediments. Results showed that the Freundlich empirical isotherm could be used to describe the adsorption characteristics of the stabilized sediments for Cu and Pb as the isotherm fitted rather well to experimental data from the three sediments. The sorption capacities of the stabilized sediments for the heavy metals were determined using the nonlinear Freundlich equation. Stabilized sediments from Hammerfest demonstrated the least sorption capacity for both metals with stabilized sediments from Bergen showing the highest capacity to sorb the two heavy metals. The sorption capacity of the stabilized sediment from Grenland was between that of Bergen and Hammerfest. In general, results indicated that the sorption capacities of the sediments were higher for Pb than for Cu. A 1-dimensional transport based on PHREEQC using diffusion and a non-linear sorption was employed to simulate heavy metal releases from the cement-stabilized sediment into sea water and to predict their long-term behaviour using time spans of 2, 10 and 20 years. It followed thus from the results of the fluxes calculated that stabilized sediment from Bergen was effective in retaining the heavy metals and consequently reduced their diffusive transport for all the time spans studied. The fluxes of both metals from Hammerfest stabilized sediment for all the time spans were relatively high due to the inability of the sediment to retain the metals. Fluxes of both metals from Grenland sediments were between those of Bergen and Hammerfest sediments

Hydrogeochemical Studies to Assess the Suitability of Groundwater for Drinking and Irrigation Purposes: The Upper East Region of Ghana Case Study

Groundwater is increasingly being used to help meet the Sustainable Development Goals (SDGs) 2 and 6 in many parts of the world, including Ghana. Against this background, hydrogeochemical and multivariate statistical studies were conducted to determine the physicochemical characteristics and suitability of groundwater in some agrarian communities in the Upper East Region of Ghana for drinking and irrigational farming. Additional analyses were also performed to identify potential health risks associated with the groundwater use and to better understand the hydrogeochemical processes controlling groundwater evolution for its effective management. The results showed that the groundwater is typically fresh; moderate to very hard in character; undersaturated with calcite, dolomite, halite, and gypsum; and supersaturated with quartz and amorphous silica. The physicochemical characteristics of the groundwater are controlled by both anthropogenic and natural activities/processes, such as fertilizer application, irrigation return flows, rock weathering, and forward/reverse cation exchange. The total dissolved solids (TDS) (165–524 mg/L), electrical conductivity (EC) (275–873 μS/cm), sodium percentage (Na%; 9.05–17.74%), magnesium ratios (MR) (29.25–53.3%), permeability index (PI) (36.6–74.6%), and sodium adsorption ratio (SAR) (0.20–0.51) point to the possibility of using the groundwater for irrigation, however, with some salinity control. The water quality and health risk analysis also revealed that the groundwater can be used for drinking; however, the high concentrations of fluoride, which can cause noncarcinogenic health issues such as dental and skeletal fluorosis in both adults and children, must be reduced to the WHO required level of 1.5 mg/L

Hydrogeochemical Studies to Assess the Suitability of Groundwater for Drinking and Irrigation Purposes: The Upper East Region of Ghana Case Study

Groundwater is increasingly being used to help meet the Sustainable Development Goals (SDGs) 2 and 6 in many parts of the world, including Ghana. Against this background, hydrogeochemical and multivariate statistical studies were conducted to determine the physicochemical characteristics and suitability of groundwater in some agrarian communities in the Upper East Region of Ghana for drinking and irrigational farming. Additional analyses were also performed to identify potential health risks associated with the groundwater use and to better understand the hydrogeochemical processes controlling groundwater evolution for its effective management. The results showed that the groundwater is typically fresh; moderate to very hard in character; undersaturated with calcite, dolomite, halite, and gypsum; and supersaturated with quartz and amorphous silica. The physicochemical characteristics of the groundwater are controlled by both anthropogenic and natural activities/processes, such as fertilizer application, irrigation return flows, rock weathering, and forward/reverse cation exchange. The total dissolved solids (TDS) (165–524 mg/L), electrical conductivity (EC) (275–873 μS/cm), sodium percentage (Na%; 9.05–17.74%), magnesium ratios (MR) (29.25–53.3%), permeability index (PI) (36.6–74.6%), and sodium adsorption ratio (SAR) (0.20–0.51) point to the possibility of using the groundwater for irrigation, however, with some salinity control. The water quality and health risk analysis also revealed that the groundwater can be used for drinking; however, the high concentrations of fluoride, which can cause noncarcinogenic health issues such as dental and skeletal fluorosis in both adults and children, must be reduced to the WHO required level of 1.5 mg/L

Using drones to transport suspected COVID-19 samples; experiences from the second largest testing centre in Ghana, West Africa.

BackgroundThe declaration of COVID-19 as a pandemic on March 11 2020, by the World Health Organisation prompted the need for a sustained and a rapid international response. In a swift response, the Government of Ghana, in partnership with Zipline company, launched the use of Unmanned Automated Vehicles (UAV) to transport suspected samples from selected districts to two foremost testing centres in the country. Here, we present the experiences of employing this technology and its impact on the transport time to the second largest testing centre, the Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR) in Kumasi, Ghana.MethodsSwab samples collected from suspected COVID-19 patients were transported to the Zipline office by health workers. Information on the samples were sent to laboratory personnel located at KCCR through a WhatsApp platform to get them ready to receive the suspected COVID-19 samples while Zipline repackaged samples and transported them via drone. Time of take-off was reported as well as time of drop-off.ResultsA total of 2537 COVID-19 suspected samples were received via drone transport from 10 districts between April 2020 to June 2021 in 440 deliveries. Ejura-Sekyedumase District Health Directorate delivered the highest number of samples (765; 30%). The farthest district to use the drone was Pru East, located 270 km away from KCCR in Kumasi and 173 km to the Zipline office in Mampong. Here, significantly, it took on the average 39 minutes for drones to deliver samples compared to 117 minutes spent in transporting samples by road (pConclusionThe use of drones for sample transport during the COVID-19 pandemic significantly reduced the travel time taken for samples to be transported by road to the testing site. This has enhanced innovative measures to fight the pandemic using technology