Kazi Suleman Memon

Drinking water quality assessment in Southern Sindh (Pakistan)

The southern Sindh province of Pakistan adjoins the Arabian Sea coast where drinking water quality is deteriorating due to dumping of industrial and urban waste and use of agrochemicals and yet has limited fresh water resources. The study assessed the drinking water quality of canal, shallow pumps, dug wells, and water supply schemes from the administrative districts of Thatta, Badin, and Thar by measuring physical, chemical, and biological (total coliform) quality parameters. All four water bodies (dug wells, shallow pumps canal water, and water supply schemes) exceeded WHO MPL for turbidity (24%, 28%, 96%, 69%), coliform (96%, 77%, 92%, 81%), and electrical conductivity (100%, 99%, 44%, 63%), respectively. However, the turbidity was lower in underground water, i.e., 24% and 28% in dug wells and shallow pumps as compared to open water, i.e., 96% and 69% in canal and water supply schemes, respectively. In dug wells and shallow pumps, limits for TDS, alkalinity, hardness, and sodium exceeded, respectively, by 63% and 33%; 59% and 70%, 40% and 27%, and 78% and 26%. Sodium was major problem in dug wells and shallow pumps of district Thar and considerable percent in shallow pumps of Badin. Iron was major problem in all water bodies of district Badin ranging from 50% to 69% and to some extent in open waters of Thatta. Other parameters as pH, copper, manganese, zinc, and phosphorus were within standard permissible limits of World Health Organization. Some common diseases found in the study area were gastroenteritis, diarrhea and vomiting, kidney, and skin problems.

Characterization and Quantification of Iron Oxides Occurring in Low Concentration in Soils

Iron (Fe) oxides control plant nutrient and contaminant redistribution in soils, but their phase identification and quantification is complicated by their low concentration and poor crystallinity and by the high detection limits of the current techniques. Cyclic voltammetry using a carbon paste electroactive electrode was tested to characterize soil iron oxides. Twenty‐eight clays (<2 µm) from eight soils varying in parent material and pedological development were separated, and Fe phases were determined by x‐ray diffraction (XRD) before and after preconcentration treatment with 5M sodium hydroxide (NaOH). Morphology of Fe phases was determined by electron microscopy, and total extractable Fe phases in soil were determined by citrate bicarbonate dithionite. The preconcentration treatment was effective in phase identification. Goethite and hematite were found, depending upon origin of the soil clays. The samples with less than 2% hematite needed preconcentration. Three percent goethite in clays was on the edge of the XRD limit. The electrochemical signals of re‐oxidation of Fe2+ released from reductive dissolution of free Fe oxides was quantitatively related to their content in the sample. Voltammetry effectively quantified goethite and hematite or both in a mixture with detection limit as low as 0.025 mg 100−1 mg in clay. The technique can be used for quick estimate of low content of Fe oxides in clays and can be adapted for free Fe estimation in soils.

Heavy-Metal Phytoextraction Potential of Spinach and Mustard Grown in Contaminated Calcareous Soils

Laboratory batch and greenhouse pot experiments were conducted to determine the extraction efficiency of ethylenediaminetetraacetic acid (EDTA) for solubilizing lead (Pb) and cadmium (Cd) and to explore the natural and chemically induced Pb and Cd phytoextraction efficiencies of spinach and mustard after EDTA application. The EDTA was applied at 0, 1.25, 2.5, and 5.0 mM kg−1 soil in three replicates. Addition of EDTA increased significantly the soluble fraction Pb and Cd over the control and maximum increases for Pb (1.42- and 1.96-fold) and Cd (1.45- and 1.38-fold) were observed with the addition of 5.0 mM EDTA kg−1 in Gujranwala and Pacca soils, respectively. Similarly, addition of EDTA increased significantly the Pb and Cd concentrations in the plant shoots, soil solution, bioconcentration factor, and phytoextraction rate. Mustard exhibited better results than spinach when extracting Pb and Cd from both contaminated soils.

Quantifying the Effect of Temperature on Ammonium Bicarbonate Diethylene Triamine Penta‐acetic Acid Extractable Potassium and Developing a Novel Correction Factor to Express the Data

Soil testing is an important diagnostic tool in determining nutrient imbalances and providing a basis for fertilizer application. The reliability and reproducibility of nutrient determination in soils is affected by the temperature of the extracting solution. We carried out laboratory investigations to account for the effect of temperature of the extractant on ammonium bicarbonate diethylene triamine penta‐acetic acid (ABDTPA)–extractable potassium (K), and developed a correction factor to standardize the results to a standard temperature. Forty soil samples with a wide range of characteristics were analyzed for ABDTPA‐extractable K at five laboratory temperatures, ranging from 15 to 35 °C. The soils represented soil textures varying from loamy sand to heavy clays. The electrical conductivity (EC) ranged from 0.14 to 47.8 dS m−1 (average 2.78 dS m−1), pH from 7.2 to 8.4 (average 8.0), lime from 3.7 to 22.4% (average 12.9%), organic matter from 0.25 to 1.43% (average 0.72%), and ABDTPA‐extractable K at 25 °C from 42 to 489 mg kg−1 (average 167 mg kg−1). The ABDTPA‐extractable K was positively correlated with temperature. Average values increased from 129 mg kg−1 at 15 °C to 225 mg kg−1 at 35 °C with R2 ranging from 0.63 to 0.997, and regression coefficient “b” ranged from 2.14 to 8.94. From the data, a temperature correction factor, Y = 2.85 + 0.01X (R2 = 0.46), was developed to convert ABDTPA‐extractable K determined at room temperature to a standard temperature of 25 °C.

Development of a Correction Factor to Account for the Effect of Temperature on Olsen's Soil Phosphorus

Variable laboratory temperatures adversely affect the reliability and reproducibility of the analysis of soil phosphorus (P). This study was conducted to quantify the effect of temperature on Olsen P content of the soil and to develop a temperature correction factor to standardize the results to a given temperature. Sixty‐eight alkaline calcareous soils with a wide range of characteristics were analyzed for Olsen P at six laboratory temperatures, ranging from 15 to 40 °C. Average Olsen P was 4.26 mg kg−1 at 15 °C and 9.47 mg kg−1 at 40 °C. The correlation coefficient between temperature and Olsen P contents was highly significant for all soils (average r = 0.96**). The linear regression equations were determined for each soil, which showed that Olsen P increased linearly with temperature with r2 values ranging from 0.71 to 0.99 (average = 0.93). It was noted that the regression coefficients were positively related to P status of the soils. Using the regression coefficients and the Olsen P data for each soil, a temperature correction factor was developed for converting Olsen P values determined at different room temperatures to the one at standard temperature (25 °C). The correction factor so developed is of practical significance for the analytical laboratories with inadequate or total lack of temperature control systems.