Safe potable water is essential for good health. Worldwide, school-aged children especially in the developing countries are suffering from various water-borne diseases. In the study, drinking water supplies for primary school children were monitored at Magura district, Bangladesh, to ensure safe potable water. APHA standard analytical methods were applied for determining the physicochemical parameters of the water samples. For determination of the essential physicochemical parameters, the samples were collected from 20 randomly selected tube wells of primary schools at Magura. The metal contents, especially arsenic (As), iron (Fe), and manganese (Mn), in the water samples were analyzed by atomic absorption spectroscopy. The range of physicochemical parameters found in water samples were as follows: pH 7.05-9.03, electrical conductivity 400-2340 μS/cm, chloride 10-640 mg/L, hardness 200-535 mg/L as CaCO, and total dissolved solids 208-1216 mg/L. The level of metals in the tube well water samples were as follows: As 1 to 55 μg/L, Fe 40 to 9890 μg/L, and Mn 10 to 370 μg/L. Drinking water parameters of Magura district did not meet the requirement of the World Health Organization drinking water quality guideline, or the Drinking Water Quality Standards of Bangladesh.
The influence of soil properties
on PFOS sorption are not fully
understood, particularly for variable charge soils. PFOS batch sorption
isotherms were conducted for 114 temperate and tropical soils from
Australia and Fiji, that were well-characterized for their soil properties,
including total organic carbon (TOC), anion exchange capacity, and
surface charge. In most soils, PFOS sorption isotherms were nonlinear.
PFOS sorption distribution coefficients (K
d) ranged from 5 to 229 mL/g (median: 28 mL/g), with 63% of the Fijian
soils and 35% of the Australian soils showing K
d values that exceeded the observed median K
d. Multiple linear regression showed that TOC, amorphous
aluminum and iron oxides contents, anion exchange capacity, pH, and
silt content, jointly explained about 53% of the variance in PFOS K
d in soils. Variable charge soils with net positive
surface charges, and moderate to elevated TOC content, generally displayed
enhanced PFOS sorption than in temperate or tropical soils with TOC
as the only sorbent phase, especially at acidic pH ranges. For the
first time, two artificial neural networks were developed to predict
the measured PFOS K
d (R
2 = 0.80) in the soils. Overall, both TOC and surface
charge characteristics of soils are important for describing PFOS
sorption.
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