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Muhammad Sadiq 《Water, air, and soil pollution》1983,20(3):247-255
Ten agricultural soils were spiked with 100 μg of Cu, Zn, and Pb g?1 of soil. The complexation of Pb by 10?4 M DTPA was determined after 60 days of metal equilibrium. A theoretical stability model of Fe, Mn, Cu, Zn, Ca, and Pb, between pH 1 and 10 was developed. It showed that CuL3? (55.4 to 63%), CuHL2? (0.1 to 9.4%), PbL3? (29.1 to 33.3%), PbHL2? (0.01 to 2.5%) and MnL3? (2.8 to 3.2%) as the predominant species between pH 6 and 9. Other species like CaL3?, CaHL2?, FeL2?, FeHL?, FeL3?, FeHL2?, ZnL3?, ZnHL2? and MnHL2? were less than 0.1% between pH 6 and 9. In the experimental soils, DTPA-Pb complexes accounted for 12.3 to 21.2% of metal complexed after 3 days of DTPA equilibriation. DTPA-Cu complexes were the major complexed species in the soils ranging between 72.5 and 82.2% after 3 days equilibriation with 10?4 M DTPA. The proportion of Zn complexed by DTPA (3.8 to 10.1%) was much greater than predicted by the theoretical model. On the contrary, Mn was not complexed in appreciable amounts by DTPA. 相似文献
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The interactions between the adsorption characteristics of 27 experimental soils and the sorption of Cd and Ni from the municipal wastewaters were investigated in this study. The removal of these elements from soil solution was followed for 50 days. All the adsorption characteristics, except cation exchange capacity and organic matter, were significantly correlated to the sorption of Cd after one day shaking. After 7 days of shaking, none of the soil adsorption characteristics except free CaCO3 was significantly correlated to Cd removal from wastewater. The soil saturated paste pH and suspension pH were strongly correlated to Cd sorption throughout this experiment. The behavior of Ni in soils was different from that of Cd. Surface area, total Fe, and total Al were significantly correlated to Ni sorption. The correlation between Ni removal and pH was the strongest than any other parameter studied. After 7 days shaking, clay content and total Ca were not significantly correlated to Ni sorption. The cation exchange capacity of the soils was not significantly correlated to Cd or Ni sorption in this experiment. It seems that in the experimental soils, concentration of Cd and Ni were probably not controlled by adsorption process. The precipitation process was probably playing a major role in the removal of these elements from the municipal wastewaters. As observed in this experiment, the cation exchange capacity of experimental soils was a poor parameter to define sorption capacity of these soils for Cd and Ni. The guidelines for determining the soil sludge load, which are mainly based on the cation exchange capacity of soils, should be revised. 相似文献
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Water samples from 18 springs and 13 drainage canals and subcanals were collected from Al-Ahsa Oasis. Concentrations of total dissolved salts, Cl, SO4 HCO3, B, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, V, Ti, and Zn were determined. The soil salinity development (SSD), the adjusted Na ratio (adj. SAR), the adjusted Na adsorption ratio (adj. RNa), and exchangeable Na percentage (ESP) were calculated. Sodium was the most abundant cation in all water samples followed by Ca, Mg, Sr, and K in descending order. Concentrations of all other metals were below 0.1 mg L–1. Chloride was the most abundant anion, followed by SO4 and HCO3 in these waters. A significant correlation (P < 0.05)=" between=" na=" and=" cl=" in=" water=" samples=" was=" found.=" thermodynamic=" calculations=" revealed=" that=" an=" appreciable=" fraction=" of=" ca=" and=" mg=" in=" spring=" and=" drainage=" waters=" were=" associated=" with=">4 and HCO3 ions. Calcium increased from less than 10 meq L–1 in spring waters to > 16 meq L–1, Mg was doubled, and Na and Cl increased several times in the drainage waters. The salinity and sodicity hazards of the spring and drainage waters were classified as C4S2 i.e. high salinity with medium sodicity problems. 相似文献
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The analgesic activity of the methanolic extracts of the roots and leaves of Calliandra portoricensis was investigated in mice and rats using acetic acid-induced writhing and formalin tests. The extracts given orally at the doses of 200, 400, 600 mg/kg showed a dose-dependent activity in the tests used. 相似文献
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Chlorine is the most commonly used disinfectant for watertreatment but when in contact with organic precursors it producestoxic compounds known as trihalomethanes (THMs). Chloroform isthe most commonly occurring THM and constitutes approximately90% of the THM concentration. A study was conducted inNewfoundland for estimating the chloroform content in thedrinking water supplies in Clarenville and St. John's. Thesampling program was conducted in two stages, July and October-November. Higher concentrations of chloroform were observed in Clarenville but in St. John's the concentrations werewithin Health Canada guidelines. The chloroform is a probablehuman carcinogen and is categorised as `B2' by U.S. EnvironmentalProtection Agency (U.S. EPA). The human health risk associatedwith consumption of drinking water was estimated by performingprobabilistic analysis. In the first phase bootstrap simulations(B = 250) were performed to calculate the variability in thedata. The normal distribution was found the best-fitted distribution to chloroform concentration data. For eachbootstrapped run 1000 Monte Carlo Simulations (MCS) wereperformed in the second phase. The cancer risk was estimatedusing dose-response relationship of chloroform. Appropriateprobability density functions (PDFs) were defined subjectivelyfor intake rate, body weight, exposure duration, exposurefrequency and averaging time. The excess lifetime human cancerrisk varied from 0.5 × 10-4 to 4.0 × 10-4, and zero to 1.0 × 10-4 for Clarenvilleand St. John's, respectively. The average cancer risks in Clarenville and St. John's communities were 1.2 × 10-4 and 2.5 × 10-5. The estimated probabilitiesof exceedences above 100 ppb (μg L-1), were 100 and 2.5% for Clarenville and St. John's, respectively which emphasised the need for water treatment. Granular Activated Carbon (GAC) was proposed as one of the potential treatment technology for risk reduction in St. John's community. The treatment efficiency of a proposed technology was assumed uniformly distributed and revised risks were calculated. Theaverage risk in St. John's can be reduced to 8.0 ×10-6 after treatment. 相似文献
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Sadiq Rehan Husain Tahir Al-Zahrani A. M. Sheikh Anwar Khalil Farooq Shaukat 《Water, air, and soil pollution》2003,143(1-4):41-63
The objective of this study is to examine the reuse of wastewaterfor beneficial purposes. To accomplish this objective, the efficiency of slow sand filters in removing total coliforms (TC) was studied using a probabilistic method. Three pilot scale slowsand filters were constructed at Alkhobar wastewater treatment plant, Dhahran, Saudi Arabia. The removal efficiency of filters was estimated under different operating control parameters, which included filtration rate (q), sand bed depth (d) and sand grain size (c). The Type III extreme value distribution best fitted theremoval efficiency data. A multiple linear regression analysis was performed to develop a relationship for mean removal efficiency as a function of control parameters. The predicted mean response and experimental results of previous studies werecompared to validate the empirical regression model. The controlparameters and influent concentrations of total coliform were used in Monte Carlo (MC) simulations for calculating the reliability index (β). The reliability index and corresponding risk were calculated for lognormally distributedsafety margins (SM). An effluent standard of 100 total coliform/100 mL was defined as capacity of the filter to ascertainthe risks of exceedence, which was approximately less than 50 for95% of the time. Pre and/or post disinfection would be necessaryto meet the stipulated effluent standards for unrestricted agriculture use. 相似文献
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Groundwater samples were collected from shallow aquifers underneath an industrial complex in the Eastern Province of Saudi Arabia. Arsenic (As) concentrations in the groundwater samples varied between 10?8.6 and 10?6.8 M (0.18 and 11.14 µg L?1), with an average of 10?7.5 M (2.19 μ L?1). The analysis of variance for the analytical data showed that sampling locations had significantly affected As concentrations in the groundwater samples. Analytical and thermodynamic calculations showed that H2ASO4 ? was the most predominant As species in acidic groundwater samples, and HAsO4 2? was the most abundant species in alkaline groundwater samples. Concentrations of H3AsO4° and AsO4 3? were too low to be important in this study. Reduced As chemical forms were also expected to be very low. All the groundwater samples were undersaturated with respect to the thermodynamic solubility isotherms of Ca3(AsO4)2(c), Fe3(AsO4)2(c), and Mn3(AsO4)2(c) minerals. Lack of reliable thermodynamic data for these arsenates could be responsible for differences between the theoretical and measured concentrations of As in the shallow groundwater samples. The general trend in the distribution of HAsO4 2? activities in the groundwater samples was parallel to that of the Ca3(AsO4)2 solubility isotherm but different from those of Fe3(AsO4)2(c), and Mn3(AsO4)2(c). These data suggest that As concentrations in the groundwater samples were probably controlled by the precipitation and dissolution of Ca3(AsO4)2 type mineral. A three step hypothesis for As interactions in groundwater/soil system is proposed that combines both solid phase formation and adsorption of As onto the solid colloidal surfaces. This hypothesis is expected to better represent As behavior in groundwater/soil environment. 相似文献
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Wheat Breeding in a Water-stressed Environment. I. Delineation of Drought Tolerance and Susceptibility 总被引：1，自引：0，他引：1
To elucidate genotypic differences expressed through the grain yield of drought-stressed wheat, 21 commercial varieties and advanced lines were evaluated in the field under a range of soil water levels to induce varying degrees of drought stress. This paper presents data on grain yield and yield-based indices to indicate drought tolerance and drought susceptibility. AZS-4 was identified as drought tolerant and AZS-17 and ‘Pavon’ as drought susceptible. High gram yield under stress can be explained in terms of high yield potential, thus grain yield proved to be the best indicator of drought tolerance. 相似文献
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Szewczuk-Karpisz Katarzyna Tomczyk Agnieszka Grygorczuk-Płaneta Katarzyna Naveed Sadiq 《Journal of Soils and Sediments》2022,22(10):2620-2639
Journal of Soils and Sediments - Industrialization and application of large amount of fertilizers together with animal wastes increased pollution of environment with antibiotics and heavy metals.... 相似文献