Papers by Ahmed Al-Mikhlafi
Waste that is generated from healthcare establishments is potentially harmful to human beings and... more Waste that is generated from healthcare establishments is potentially harmful to human beings and environment. The objective of this study is to assess the environmental and health risk associated with processes of the current handling of medical waste in hospitals of Sana'a city, Yemen. The observations and follow up the current handling of medical waste were done through frequent visits to the studied hospitals. A preliminary risks analysis (PRA) technique was applied as an analysis tool to identify and to evaluate the potential hazards of the activities and processes of the current handling of medical waste in the studied hospitals. Eighteen events related to containment, segregation, collection, transportation, waste storage, and waste treatment were analyzed. The results obtained in this study showed that 89% of the events of waste handling processes, which have been analyzed, were in high-risk levels. All events were in high-risk levels, 2 suggesting need to prioritize all these processes' events. For minimizing or interrupting the potential risks of the current handling of hospitals waste, the hospitals' management and the relevant ministries in the Yemeni government should cooperate to develop comprehensive plan for management of medical waste, taking into account the results of this study.
Journal of Asian Earth Sciences, Jan 1, 2006
The sediment geochemistry, including REE, of surface and core samples from Mansar Lake, along wit... more The sediment geochemistry, including REE, of surface and core samples from Mansar Lake, along with mineralogical investigations, have been carried out in order to understand the provenance, source area weathering, hydrolic sorting and tectonic setting of the basin. The geochemical signatures preserved in these sediments have been exploited as proxies in order to delineate these different parameters.The major element log values (Fe2O3/K2O) vs (SiO2/Al2O3) and (Na2O/K2O) vs (SiO2/Al2O3) demarcate a lithology remarkably similar to that exposed in the catchment area. The chondrite normalized REE patterns of lake samples are similar to Post Archaean Australian Shale (PAAS) with LREE enrichment, a negative Eu anomaly and almost flat HREE pattern similar to a felsic and/or cratonic sedimentary source. However, the La–Th–Sc plot of samples fall in a mixed sedimentary domain, close to Upper Continental Crust (UCC) and PAAS, suggesting sedimentary source rocks for the Mansar detritus. It also indicates that these elements remained immobile during weathering and transportation. The mineralogical characteristic, REEs, and high field strength elements (HFSE), together with the high percentage of metamorphic rock fragments in the Siwalik sandstone, support a metamorphic source for lower Siwalik sediments. A very weak positive correlation between Zr and SiO2, poor negative correlation with Al2O3, negative correlation of (La/Yb)N and (Gd/Yb)N ratios with SiO2 and positive correlation with Al2O3, suggest that Zr does not dominantly control the REE distribution in Mansar sediments. The petrographic character and textural immaturity indicate a short distance transport for the detritus. The distribution of elements in core samples reflect fractionation. The higher Zr/Th and Zr/Yb ratios in coarse sediments and PAAS compared to finer grained detritus indicate sedimentary sorting. Plots of the geochemical data on tectonic discrimination diagrams suggest that the sediments derived from the lower Siwalik were originated within a cratonic interior and later deposited along a passive margin basinal setting. It therefore reveals lower Siwalik depositional history.
Arabian Journal of Geosciences, Jan 1, 2010
One hundred thirty boreholes of volcanic aquifers in rural Yemen Highland Groundwaters (YHGs) wer... more One hundred thirty boreholes of volcanic aquifers in rural Yemen Highland Groundwaters (YHGs) were chemically investigated to assess the suitability of water for drinking. Focus is to identify inorganic constituents of significant risk to health that occur in groundwaters of this area. Results showed that a number of boreholes contain, apart from fluoride, levels of nitrate, some heavy metals, total dissolved solids, and sulfates that could pose a health risk for consumers. The lateral variations of major ions with depth varied within the same aquifer based on the dynamic equilibrium of groundwater and hydrogeological conditions. The main inorganic groundwater contaminant in volcanic YHG is fluoride which is attributed to groundwater lithology and water type. Fluoride appears high in Capoor groundwater and where cation exchanges of Ca for Na are dominant. High F concentration in YHG is an extension of East African fluoride-rich groundwater. Majority of tube wells show that Fe concentration exceeds WHO guideline many folds. Much of the iron and manganese in groundwaters are naturally occurring, since the source rocks are enriched in ferromagnesian minerals. NO 3 − and Cl − concentrations that have been detected in some wells may indicate sewage and/or agricultural runoff. Elevated concentration of chemical constituents in groundwater is a sign of groundwater degradation.
Environmental Geology, Jan 1, 2008
The concentration rare earth elements and Yttrium (REE + Y) were determined in coral sands from K... more The concentration rare earth elements and Yttrium (REE + Y) were determined in coral sands from Kavaratti Island, Arabian Sea, India. Chondrite-normalized REE + Y patterns show: (1) high REE concentration particularly light REE (LREE) enrichment; (2) consistent negative Ce anomaly; (3) nearly chondritic Y/Ho ratios. All these features are consistent with the geochemistry of well oxygenated seawater with significant terrestrial contribution. The seawater composition of Nd/Yb ratio inferred from the coral record point to the dominance of LREE more than the heavy REE (HREE). The high terrestrial input rich in LREE and property of adsorption/scavenging processes of LREE than that of HREE may be the cause. Terrigenous contributions were detected on the basis of cooccurring trace element concentrations (Sc, Hf and Th) and Y/Ho ratio. Except for La, the REE distribution coefficients, KD(REE)s, are between 100 and 300. KDs are high comparing to the other elements in biogenic calcite which is attributed to detrital contamination during elemental incorporation. This study may not reflect original seawater chemistry but it can be a good proxy to indicate proximity of corals to terrigenous input sources.
Environmental Geology, Jan 1, 2003
The chemistry of major elements (Ca, Mg, Na, K and Si) and anions (HCO 3 , SO 4 and Cl) in the wa... more The chemistry of major elements (Ca, Mg, Na, K and Si) and anions (HCO 3 , SO 4 and Cl) in the water of Mansar Lake was studied, based on seasonal data. The results show that total dissolved solid (TDS) concentration in a particular season is similar, but varies slightly in different seasons with a variation factor of less than 2. This is because the collections were made in the dry seasons and the Caprecipitation is the cause for the seasonal variability. The major element chemistry of Mansar Lake is mainly controlled by rock weathering, with HCO 3 and Ca dominating the major ion composition because of the abundance of carbonate rocks in the basin. The results also indicate that the lake water is saturated with respect to calcite and/or dolomite during the spring season whereas it is undersaturated in the summer season. This contrast brings out seasonal variability. The lake shows disequilibrium with atmospheric CO 2 as a result of carbonate dissolution in the drainage basin. The study also shows that physical weathering/erosion is dominant and that chemical weathering is incipient. This is consistent with the Chemical Index of Alteration (CIA) data.
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Papers by Ahmed Al-Mikhlafi