Sardar Khan - Academia.edu (original) (raw)

Papers by Sardar Khan

Journal of water and health, 2015

The present study was conducted to investigate the physico-chemical characteristics in drinking w... more The present study was conducted to investigate the physico-chemical characteristics in drinking water of Mardan District, Pakistan. Furthermore, water quality was evaluated for the risk assessment of arsenic and heavy metals (HMs) and their contamination sources. Representative groundwater samples of shallow and deep sources were collected in the study area. These samples were analyzed for physical parameters, anions, light metals (LMs) and HMs. Results were compared with the drinking water guideline values set by the World Health Organization and the US Environmental Protection Agency. Average concentrations of anions, LMs and HMs were found within the maximum allowable contaminant levels except for bicarbonates, Fe, Cu, and Pb. Results revealed that hazard quotients >1 were observed for shallow groundwater for 10% samples only, suggesting potential health risk from water consumption. Correlation analysis and principal component analysis showed a relationship among various physi...

Journal of water and health, 2015

This study investigates the drinking water (groundwater and surface water) quality and potential ... more This study investigates the drinking water (groundwater and surface water) quality and potential risk assessment along mafic and ultramafic rocks in the Swat district of Khyber Pakhtunkhwa Provence, Pakistan. For this purpose, 82 groundwater and 33 surface water samples were collected and analyzed for physico-chemical parameters. Results showed that the majority of the physico-chemical parameters were found to be within the drinking water guidelines set by the World Health Organization. However, major cationic metals such as magnesium (Mg), and trace metals (TM) including iron (Fe), manganese (Mn), nickel (Ni), chromium (Cr) and cobalt (Co) showed exceeded concentrations in 13%, 4%, 2%, 20%, 20% and 55% of water samples, respectively. Health risk assessment revealed that the non-carcinogenic effects or hazard quotient values through the oral ingestion pathway of water consumption for the TM (viz., Fe, Cr and Mn) were found to be greater than 1, could result in chronic risk to the ex...

Pakistan journal of zoology

The purpose of this study was to evaluate the effect of commonly used pesticides such as Pendimet... more The purpose of this study was to evaluate the effect of commonly used pesticides such as Pendimethaline, Trifluralin, Glyphosphate, 2, 4-D, and MCPA (Chwastox) on microbial activities in soil. Two types of clean soils were amended with recommended level of pesticides and incubated in the laboratory at 35°C for 15 days. Microbial activities in the form of CO 2 production were measured during incubation at 1, 2, 3, 4, 5, 7, 9, 11, and 15 day intervals. CO 2 production was not affected substantially by any of the applied doses of pesticides. However, the total amount of CO 2 produced during 15 days was suppressed by all pesticides, except MCPA (Chwastox). The effect of pesticides on microbial activities varied greatly with the type of pesticides used. The MCPA Chwastox did not exert any inhibitory effect on the respiratory rate of microbes, while other selected pesticides showed highly toxic effect on soil microbial activity.

Environmental Science and Pollution Research, 2015

Mercury (Hg) is a highly toxic metal which can cause serious health effects. The aim of this rese... more Mercury (Hg) is a highly toxic metal which can cause serious health effects. The aim of this research was to determine the concentrations of total Hg (T-Hg), methyl Hg (Me-Hg), and inorganic Hg (I-Hg) in the biological samples (plasma, red blood cells (RBCs), urine, hair, and nails) of the exposed goldsmith workers. This is the first study that determines the detailed Hg concentrations in the biological samples (plasma, RBCs, urine, hair, and nails) of the exposed goldsmith workers and correlates them with the diseases noted among the workers in a single paper. Biological samples were collected from goldsmith workers (n = 40) and analyzed for T-Hg, Me-Hg, and I-Hg using atomic absorption spectrometer equipped with mercury hydride system. The mean T-Hg concentration in RBCs (33 μg L(-1)), plasma (11.8 μg L(-1)), urine (167 μg L(-1)), hair (4.21 μg g(-1)), and nails (5.91 μg g(-1)) were higher than the control RBCs (1.64 μg L(-1)), plasma (0.55 μg L(-1)), urine (2.72 μg L(-1)), hair (0.35 μg g(-1)), and nails (0.51 μg g(-1)). All workers participated in this study were suffering from physical and mental diseases. The concentration of Hg was found higher among the workers suffering from mental diseases as compared to those suffering from physical diseases. Among the physical diseases, the most serious diseases were sexual dysfunction, skin diseases, and fatigue because the workers suffering from these diseases had higher concentration of Hg than the workers with other diseases. The occurrence of physical diseases (88 %) was greater than the mental diseases (53 %) among the workers. The correlations of physical and mental diseases with experience (years of work) and exposure time were significant (p < 0.05), while nonsignificant (p > 0.05) correlation was observed between demographic parameters and Hg concentrations in the biological samples of the workers. The burning process of amalgamated gold is a significant source of Hg exposure to goldsmith workers; therefore, awareness and precautionary measures are needed to provide protection to them.

Journal of Environmental Sciences, 2011

Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from ... more Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from different age group subjects such as children (1-12 years), adolescent (12-18 years), adults (18-45 years) and old age (above 45 and 55 years for males and females, respectively) from polluted and relatively less polluted areas. The results revealed that the consumption of contaminated food crops, meat and milk have significantly increased the concentrations of selected metals in the human blood. Cu, Zn and Mn concentrations were significantly higher (p < 0.05) in the blood samples collected from the polluted area as compared to control area. Old people had accumulated high concentrations of metals as compared to the younger ones within the same area. Males accumulated higher concentrations of metals as compared to females.

Microchemical Journal, 2011

The present study was conducted to investigate heavy metal (Cu, Co, Cr, Mn, Ni, Pb, Zn and Cd) co... more The present study was conducted to investigate heavy metal (Cu, Co, Cr, Mn, Ni, Pb, Zn and Cd) concentrations of drinking water (surface water and groundwater) samples in Kohistan region, northern Pakistan. Furthermore, the study aimed to ascertain potential health risk of heavy metal (HM) concentrations to local population. HM concentrations were analyzed by using graphite furnace atomic absorption spectrometer (Perkin Elmer, AAS-PEA-700) and were compared with permissible limits set by Pakistan Environmental Protection Agency (Pak EPA) and World Health Organization (WHO). Based on HM concentrations the health risk assessment like chronic daily intake (CDI) and hazard quotient (HQ) was calculated. The values for CDI were found in the order of Zn N Cu N Mn N Pb N Cr N Ni N Cd N Co and the values of HQ were b 1 for all HM in drinking water samples indicating no health risk. Furthermore, multivariate statistical analysis like one-way ANOVA, inter-metal correlation, cluster analysis (CA) and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of water contamination in Kohistan region.

Journal of Soils and Sediments, 2009

Background, aim, and scope In the soil environment, polycyclic aromatic hydrocarbons (PAHs) and h... more Background, aim, and scope In the soil environment, polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are of great environmental and human health concerns due to their widespread occurrence, persistence, and carcinogenic properties. Bioremediation of contaminated soil is a cost-effective, environmentally friendly, and publicly acceptable approach to address the removal of environmental contaminants. However, bioremediation of contaminants depends on plant-microbe interactions in the rhizosphere. The microorganisms that can mineralize various PAHs have PAH dioxygenase genes like nahAc, phnAc, and pdo1. To understand the fate of pyrene in rhizospheric and non-rhizospheric soils in the presence or absence of Pb, pyrene biodegradation, bacterial community structure, and dioxygenase genes were investigated in a pot experiment. Methods Soil was amended with Pb (a representative heavy metal), pyrene, and a Pb/pyrene mixture. After 8 weeks of aging, one set of pot microcosms was cultivated with rye grass (Lolium multiflorum L) seedlings, while another set was not cultivated for the purpose of comparing rhizosphere and non-rhizosphere pyrene degradation. Pyrene was extracted from freeze-dried soil and plant samples using a Soxhlet extraction method and the extracts were dried to 1 mL under gentle nitrogen flow and analyzed using gas chromatograph mass spectrometry (Agilent 6890, USA). Soil DNA was extracted from triplicate samples and the DGGE was performed using a Bio-Rad Dcode™ Universal Mutation Detection System (Bio-Rad, USA). PAH dioxygenase genes, including nahAc, phnAc, and pdo1, were detected using PCR amplification. Similarly, pyrene degraders were also investigated using plate counting technique. Results Biodegradation rates recorded over an 18-week period showed that rye grass promoted significant (P<0.05) pyrene degradation. Pyrene removal efficiency from rhizospheric soils was 59.1±2.1% and 68.7±2.3% in pyreneand Pb/pyrene-amended soils, respectively. The results indicate that pyrene dissipation was significantly (P<0.05) higher in Pb/pyrene-amended soils than only-pyreneamended soils. The plant growth promoted the degradation of pyrene and accounted for 12.1% to 17.0% of dissipation enhancement in the rhizospheric soils. In this study, the DGGE profiles revealed a shift in soil bacterial community structure in all amended soils, with a higher number and greater complexity of banding patterns in Pb/pyreneamended samples than in either Pb-or pyrene-amended samples. In the control and Pb-amended soil, pdo1 and nahAc genes were not detected throughout the incubation period but were detected in the pyrene-and Pb/pyreneamended soils. However, phnAc genes were not detected in either amended or non-amended soils throughout the incubation period. The addition of pyrene had a dramatic effect on the number of pyrene degraders. Discussion Plants contribute to the degradation of PAHs by increasing the size of microbial population, promoting microbial activity, and modifying microbial community

Journal of Geochemical Exploration, 2014

ABSTRACT The present work is a comprehensive evaluation of surface and ground water quality of Ha... more ABSTRACT The present work is a comprehensive evaluation of surface and ground water quality of Haripur basin (comprising an industrial Estate), Pakistan. Heavy metals and trace elements (i.e., Cd, Cr, Cu, Pb, Fe, Ni, Zn, Co, Mn, As and Hg) and physical parameters such as pH, total dissolved solids (TDS) and electrical conductivity (EC) were investigated in 98 sampling points and compared with the WHO guidelines for drinking water. The average metal concentrations in surface and ground water were found in the order of Fe &amp;gt; Mn &amp;gt; Zn &amp;gt; Ni &amp;gt; Pb &amp;gt; Co &amp;gt; Cr &amp;gt; Cu &amp;gt; Cd &amp;gt; As &amp;gt; Hg and Zn &amp;gt; Fe &amp;gt; Pb &amp;gt; Mn &amp;gt; Cr &amp;gt; Cu &amp;gt; Ni &amp;gt; Cd &amp;gt; Co &amp;gt; As &amp;gt; Hg respectively. Furthermore, chronic daily intake (CDI) and hazard quotient (HQ) were also calculated. HQ was found &amp;lt; 1 for all the heavy metals and trace elements, suggesting no health risk. The multivariate techniques (i.e., correlation, principle component analysis and cluster analysis) for the interpretation of the metal data obtained during the monitoring program revealed that there is an increase in the concentrations of heavy metals and trace elements in surface water and shallow water relative to deep water. This can be correlated with the discharge of effluents from the existing industries into the stream water in the basin.

Journal of Environmental Sciences, 2013

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (M... more The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) were investigated in drinking water sources (surface and groundwater) collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risk of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed by using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency (Pak-EPA) and World Health Organization (WHO). The concentrations of Cd, Cr, Ni and Pb were higher than their respective permissible limits, while Cu, Mn and Zn concentrations were observed within their respective limits set by Pak-EPA and WHO. Health risk indicators such as chronic daily intake (CDI) and health risk index (HRI) were calculated for adults and children separately. CDIs and HRIs of heavy metals were found in the order of Cr > Mn > Ni > Zn > Cd > Cu > Pb and Cd > Ni > Mn > Cr > Cu > Pb > Zn, respectively. HRIs of selected heavy metals in the drinking water were less than 1, indicating no health risk to the local people. Multivariate and univariate statistical analyses showed that geologic and anthropogenic activities were the possible sources of water contamination with heavy metals in the study area.

Journal of Environmental Sciences, 2007

This study focused on the changes of soil microbial diversity and potential inhibitory effects of... more This study focused on the changes of soil microbial diversity and potential inhibitory effects of heavy metals on soil enzymatic activities at different application rates of Cd and/or Pb. The soil used for experiments was collected from Beijing and classified as endoaquepts. Pots containing 500 g of the soil with different Cd and/or Pb application rates were incubated for a period of 0, 2, 9, 12 weeks in a glasshouse and the soil samples were analyzed for individual enzymes, including catalase, alkaline phosphatase and dehydrogenase, and the changes of microbial community structure. Results showed that heavy metals slightly inhibited the enzymatic activities in all the samples spiked with heavy metals. The extent of inhibition increased significantly with increasing level of heavy metals, and varied with the incubation periods. The soil bacterial community structure, as determined by polymerase chain reactiondenaturing gradient gel electrophoresis techniques, was different in the contaminated samples as compared to the control. The highest community change was observed in the samples amended with high level of Cd. Positive correlations were observed among the three enzymatic activities, but negative correlations were found between the amounts of the heavy metals and the enzymatic activities.

Journal of Environmental Management, 2009

This study was conducted to investigate the effectiveness of a continuous free surface flow wetla... more This study was conducted to investigate the effectiveness of a continuous free surface flow wetland for removal of heavy metals from industrial wastewater, in Gadoon Amazai Industrial Estate (GAIE), Swabi, Pakistan. Industrial wastewater samples were collected from the inlet , outlet and all cells of the constructed wetland (CW) and analyzed for heavy metals such as lead (Pb), cadmium (Cd), iron (Fe), nickel (Ni), chromium (Cr) and copper (Cu) using standard methods. Similarly, samples of aquatic macrophytes and sediments were also analyzed for selected heavy metals. Results indicate that the removal efficiencies of the CW for Pb, Cd, Fe, Ni, Cr, and Cu were 50%, 91.9%, 74.1%, 40.9%, 89%, and 48.3%, respectively. Furthermore, the performance of the CW was efficient enough to remove the heavy metals, particularly Cd, Fe, and Cu, from the industrial wastewater fed to it. However, it is suggested that the metal removal efficiency of the CW can be further enhanced by using proper management of vegetation and area expansion of the present CW.

Journal of Cleaner Production, 2013

Access to safe drinking water is one of the basic human rights and essential for healthy life. Th... more Access to safe drinking water is one of the basic human rights and essential for healthy life. The present study investigated the concentrations of various pollutants in drinking water and health risk in Charsadda district, Khyber Pakhtunkhwa, Pakistan. Water samples were collected from dug-wells, tube-wells and hand pumps which were the most common sources of drinking water and analyzed for physical parameters, anions, heavy metals and coliform bacteria using standard methods. The concentrations of nitrate (10.3e14.84 mg L À1) in 13 sites exceeded the permissible limit (10 mg L À1) set by US-EPA, while sulfate concentrations (505e555 mg L À1) in 9 sites exceeded the permissible limit (500 mg L À1) set by WHO. Similarly, the concentrations of Pb, Cd, Ni and Fe exceeded their respective permissible limits set by different organizations in some locations. Furthermore, the coliform bacterial contamination (2e5 MPN 100 mL À1) was also found in some sources of water, confirming the bacterial contamination of drinking water. In the study area, improper disposal of sewage and solid wastes, over application of agrochemicals (pesticides and fertilizers), deteriorating condition of piping network and transportation were the major sources responsible for contamination of drinking water. Water contamination with coliform bacteria was the main source of waterborne diseases like gastroenteritis, dysentery, diarrhea and viral hepatitis as complained by most of the respondents during questionnaire survey. In order to reduce the health risk, it is necessary to immediately stop the uses of drinking water from contaminated sources and government should supply treated/clean water with supply lines far away from solid waste, sludge and sewage sites. The farmers should be properly trained to avoid the overusing of agrochemicals responsible for drinking water contamination, while both women and men should be properly educated with water knowledge through awareness and training programs needed for sustainable use and management of drinking water.

Journal of Applied Sciences, 2002

Environmental Toxicology and Chemistry, 2009

To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation test... more To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination.

Environmental Science and Pollution Research, 2009

Background, aim, and scope Soil contamination with heavy metals occurs as a result of both anthro... more Background, aim, and scope Soil contamination with heavy metals occurs as a result of both anthropogenic and natural activities. Heavy metals could have long-term hazardous impacts on the health of soil ecosystems and adverse influences on soil biological processes. Soil enzymatic activities are recognized as sensors towards any natural and anthropogenic disturbance occurring in the soil ecosystem. Similarly, microbial biomass carbon (MBC) is also considered as one of the important soil biological activities frequently influenced by heavy metal contamination. The polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) has recently been used to investigate changes in soil microbial community composition in response to environmental stresses. Soil microbial community structure and activities are difficult to elucidate using single monitoring approach; therefore, for a better insight and complete depiction of the soil microbial situation, different approaches need to be used. This study was conducted in a greenhouse for a period of 12 weeks to evaluate the changes in indigenous microbial community structure and activities in the soil amended with different

Environmental Science and Pollution Research, 2012

Bioaugmentation for the removal of polyaromatic hydrocarbons (PAHs) from wastewater using bacteri... more Bioaugmentation for the removal of polyaromatic hydrocarbons (PAHs) from wastewater using bacteria and yeasts is considered environment-friendly and a costeffective technique. The effectiveness of this biodegradation system depends on the stability of inoculated microorganisms and the availability of nutrients. This study is aimed to investigate the removal of high molecular weight (HMW)-PAHs from biologically treated produced water using different biological systems. Three systems, inoculated with activated sludge (AS), the mixture of five yeast strains (MY), and the mixture of AS and the five yeast strains (SY), respectively, were constructed, and their performance for the removal of HMW-PAHs was compared over 10 weeks. The effluent of the biologically treated produced water from an oilfield was used as the influent after chrysene and benzo(a)pyrene were spiked as HMW-PAHs. Polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescent in situ hybridization (FISH) techniques were used to examine the changes in the structures and abundances of the bacterial and yeast communities in these three systems. Only SY and MY systems were capable to remove chrysene (90.7 % and 98.5 %, respectively) and benzo(a)pyrene (80.7 % and 95.2 %, respectively). PCR-DGGE analysis confirmed that all of the five yeast strains inoculated remained in the SYand MY systems, while FISH results showed that the relative abundance of yeast in the SY and MY systems (10.6 % to 21.9 %, respectively) were significantly higher than AS system (2.3 % to 7.8 %, respectively). The relative abundances of the catechol 2,3-dioxygenase (C23O) indicated that the copy number ratios of benzene ring cleavage gene C23O in the yeast amended systems were much higher than that in the AS system. In this study, all of the three systems were effective in removing the low molecular weight (LMW)-PAHs, while HMW-PAHs including chrysene and benzo(a) pyrene were efficiently removed by MY and SY systems, not by AS system. The high HMW-PAHs removal in the MY and SY bioaugmentation systems possibly attributed to the inoculation of the mixed yeast culture. By combining the PCR-DGGE results with the FISH analyses, it was found that yeast probably consisting mainly of the five inoculated strains inhabited in the two bioaugmentation systems as a dominant population. The relatively higher performance of the SY system might be attributed to the suspended growth type which permitted a more efficient contact between microbial cells and contaminants. The bioaugmentation systems (SY and MY) were successfully established by inoculating with five nonindigenous yeast strains and demonstrated high performance in removal of HMW-PAHs.

Environmental Science and Pollution Research - International, 2008

Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental c... more Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. Materials and methods Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear

Environmental Pollution, 2013

The influence of sewage sludge (SS) and sewage sludge biochar (SSBC) upon biomass yield and the b... more The influence of sewage sludge (SS) and sewage sludge biochar (SSBC) upon biomass yield and the bioaccumulation of PAHs into lettuce plants grown in contaminated soil (∑16PAH 20.2 ± 0.9 mg kg(-1)) is presented. All SSBC amendments (2, 5 and 10%) and the 2% SS amendment significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) increased lettuce biomass. Both SS and SSBC amendments significantly reduced (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) the bioaccumulation of PAHs at all application levels; with reduction in ∑16PAH concentration ranging between 41.8 and 60.3% in SS amended treatments and between 58.0 and 63.2% in SSBC amended treatments, with respect to the control. Benefits in terms of biomass production and PAHs bioaccumulation reduction were greatest where SSBC was used as a soil amendment. At high application rates (10%) SSBC reduced bioaccumulation of PAHs by between 56% and 67%, while SS reduced bioaccumulation of PAHs by less than 44%.

Environment International, 2014

Consumption of rice contaminated with potentially toxic elements(PTEs) isa major pathway for huma... more Consumption of rice contaminated with potentially toxic elements(PTEs) isa major pathway for human exposure to PTEs. This is particularly true in China's so called "Cancer Villages". In this study, sewage sludge biochar (SSBC) was applied to soil (at 5% and 10%) to suppress PTE phytoavailability and as a consequence to reduce PTE levels in rice grown in mining impacted paddy soils. Risk assessment indicate dthat SSBC addition (10%) markedly(P≤0.05) decreased the daily intake, associated with the

Ecotoxicology and Environmental Safety, 2010

This study was conducted to investigate the concentrations of heavy metals in soil and vegetables... more This study was conducted to investigate the concentrations of heavy metals in soil and vegetables, and human health risks through ingestion of contaminated vegetables. Soil and vegetable samples were collected from different locations in Gilgit, northern Pakistan, and analyzed for Cd, Cu, Ni, Pb and Zn. Plant transfer factors (PTF), daily intake of metals (DIM) and health risk index (HRI) were also calculated. The concentrations of Cd, Cu and Zn exceeded their respective permissible limits in soil samples. The highest concentrations of Cu, Ni, Pb and Zn were observed in the edible parts of Malva neglecta, Brassica oleracea, Mintha sylvestris and Brassica campestris, respectively. PTF values were lower for all the selected heavy metals, except for Cd. Furthermore, the HRI values were within the safe limit (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1) except for Pb; therefore, the health risks of metals through ingestion of vegetables were of great concern in the study area.

Journal of water and health, 2015

The present study was conducted to investigate the physico-chemical characteristics in drinking w... more The present study was conducted to investigate the physico-chemical characteristics in drinking water of Mardan District, Pakistan. Furthermore, water quality was evaluated for the risk assessment of arsenic and heavy metals (HMs) and their contamination sources. Representative groundwater samples of shallow and deep sources were collected in the study area. These samples were analyzed for physical parameters, anions, light metals (LMs) and HMs. Results were compared with the drinking water guideline values set by the World Health Organization and the US Environmental Protection Agency. Average concentrations of anions, LMs and HMs were found within the maximum allowable contaminant levels except for bicarbonates, Fe, Cu, and Pb. Results revealed that hazard quotients >1 were observed for shallow groundwater for 10% samples only, suggesting potential health risk from water consumption. Correlation analysis and principal component analysis showed a relationship among various physi...

Journal of water and health, 2015

This study investigates the drinking water (groundwater and surface water) quality and potential ... more This study investigates the drinking water (groundwater and surface water) quality and potential risk assessment along mafic and ultramafic rocks in the Swat district of Khyber Pakhtunkhwa Provence, Pakistan. For this purpose, 82 groundwater and 33 surface water samples were collected and analyzed for physico-chemical parameters. Results showed that the majority of the physico-chemical parameters were found to be within the drinking water guidelines set by the World Health Organization. However, major cationic metals such as magnesium (Mg), and trace metals (TM) including iron (Fe), manganese (Mn), nickel (Ni), chromium (Cr) and cobalt (Co) showed exceeded concentrations in 13%, 4%, 2%, 20%, 20% and 55% of water samples, respectively. Health risk assessment revealed that the non-carcinogenic effects or hazard quotient values through the oral ingestion pathway of water consumption for the TM (viz., Fe, Cr and Mn) were found to be greater than 1, could result in chronic risk to the ex...

Pakistan journal of zoology

The purpose of this study was to evaluate the effect of commonly used pesticides such as Pendimet... more The purpose of this study was to evaluate the effect of commonly used pesticides such as Pendimethaline, Trifluralin, Glyphosphate, 2, 4-D, and MCPA (Chwastox) on microbial activities in soil. Two types of clean soils were amended with recommended level of pesticides and incubated in the laboratory at 35°C for 15 days. Microbial activities in the form of CO 2 production were measured during incubation at 1, 2, 3, 4, 5, 7, 9, 11, and 15 day intervals. CO 2 production was not affected substantially by any of the applied doses of pesticides. However, the total amount of CO 2 produced during 15 days was suppressed by all pesticides, except MCPA (Chwastox). The effect of pesticides on microbial activities varied greatly with the type of pesticides used. The MCPA Chwastox did not exert any inhibitory effect on the respiratory rate of microbes, while other selected pesticides showed highly toxic effect on soil microbial activity.

Environmental Science and Pollution Research, 2015

Mercury (Hg) is a highly toxic metal which can cause serious health effects. The aim of this rese... more Mercury (Hg) is a highly toxic metal which can cause serious health effects. The aim of this research was to determine the concentrations of total Hg (T-Hg), methyl Hg (Me-Hg), and inorganic Hg (I-Hg) in the biological samples (plasma, red blood cells (RBCs), urine, hair, and nails) of the exposed goldsmith workers. This is the first study that determines the detailed Hg concentrations in the biological samples (plasma, RBCs, urine, hair, and nails) of the exposed goldsmith workers and correlates them with the diseases noted among the workers in a single paper. Biological samples were collected from goldsmith workers (n = 40) and analyzed for T-Hg, Me-Hg, and I-Hg using atomic absorption spectrometer equipped with mercury hydride system. The mean T-Hg concentration in RBCs (33 μg L(-1)), plasma (11.8 μg L(-1)), urine (167 μg L(-1)), hair (4.21 μg g(-1)), and nails (5.91 μg g(-1)) were higher than the control RBCs (1.64 μg L(-1)), plasma (0.55 μg L(-1)), urine (2.72 μg L(-1)), hair (0.35 μg g(-1)), and nails (0.51 μg g(-1)). All workers participated in this study were suffering from physical and mental diseases. The concentration of Hg was found higher among the workers suffering from mental diseases as compared to those suffering from physical diseases. Among the physical diseases, the most serious diseases were sexual dysfunction, skin diseases, and fatigue because the workers suffering from these diseases had higher concentration of Hg than the workers with other diseases. The occurrence of physical diseases (88 %) was greater than the mental diseases (53 %) among the workers. The correlations of physical and mental diseases with experience (years of work) and exposure time were significant (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), while nonsignificant (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05) correlation was observed between demographic parameters and Hg concentrations in the biological samples of the workers. The burning process of amalgamated gold is a significant source of Hg exposure to goldsmith workers; therefore, awareness and precautionary measures are needed to provide protection to them.

Journal of Environmental Sciences, 2011

Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from ... more Heavy metals were analyzed in different foods crops, milk, meat and blood samples collected from different age group subjects such as children (1-12 years), adolescent (12-18 years), adults (18-45 years) and old age (above 45 and 55 years for males and females, respectively) from polluted and relatively less polluted areas. The results revealed that the consumption of contaminated food crops, meat and milk have significantly increased the concentrations of selected metals in the human blood. Cu, Zn and Mn concentrations were significantly higher (p < 0.05) in the blood samples collected from the polluted area as compared to control area. Old people had accumulated high concentrations of metals as compared to the younger ones within the same area. Males accumulated higher concentrations of metals as compared to females.

Microchemical Journal, 2011

The present study was conducted to investigate heavy metal (Cu, Co, Cr, Mn, Ni, Pb, Zn and Cd) co... more The present study was conducted to investigate heavy metal (Cu, Co, Cr, Mn, Ni, Pb, Zn and Cd) concentrations of drinking water (surface water and groundwater) samples in Kohistan region, northern Pakistan. Furthermore, the study aimed to ascertain potential health risk of heavy metal (HM) concentrations to local population. HM concentrations were analyzed by using graphite furnace atomic absorption spectrometer (Perkin Elmer, AAS-PEA-700) and were compared with permissible limits set by Pakistan Environmental Protection Agency (Pak EPA) and World Health Organization (WHO). Based on HM concentrations the health risk assessment like chronic daily intake (CDI) and hazard quotient (HQ) was calculated. The values for CDI were found in the order of Zn N Cu N Mn N Pb N Cr N Ni N Cd N Co and the values of HQ were b 1 for all HM in drinking water samples indicating no health risk. Furthermore, multivariate statistical analysis like one-way ANOVA, inter-metal correlation, cluster analysis (CA) and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of water contamination in Kohistan region.

Journal of Soils and Sediments, 2009

Background, aim, and scope In the soil environment, polycyclic aromatic hydrocarbons (PAHs) and h... more Background, aim, and scope In the soil environment, polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are of great environmental and human health concerns due to their widespread occurrence, persistence, and carcinogenic properties. Bioremediation of contaminated soil is a cost-effective, environmentally friendly, and publicly acceptable approach to address the removal of environmental contaminants. However, bioremediation of contaminants depends on plant-microbe interactions in the rhizosphere. The microorganisms that can mineralize various PAHs have PAH dioxygenase genes like nahAc, phnAc, and pdo1. To understand the fate of pyrene in rhizospheric and non-rhizospheric soils in the presence or absence of Pb, pyrene biodegradation, bacterial community structure, and dioxygenase genes were investigated in a pot experiment. Methods Soil was amended with Pb (a representative heavy metal), pyrene, and a Pb/pyrene mixture. After 8 weeks of aging, one set of pot microcosms was cultivated with rye grass (Lolium multiflorum L) seedlings, while another set was not cultivated for the purpose of comparing rhizosphere and non-rhizosphere pyrene degradation. Pyrene was extracted from freeze-dried soil and plant samples using a Soxhlet extraction method and the extracts were dried to 1 mL under gentle nitrogen flow and analyzed using gas chromatograph mass spectrometry (Agilent 6890, USA). Soil DNA was extracted from triplicate samples and the DGGE was performed using a Bio-Rad Dcode™ Universal Mutation Detection System (Bio-Rad, USA). PAH dioxygenase genes, including nahAc, phnAc, and pdo1, were detected using PCR amplification. Similarly, pyrene degraders were also investigated using plate counting technique. Results Biodegradation rates recorded over an 18-week period showed that rye grass promoted significant (P<0.05) pyrene degradation. Pyrene removal efficiency from rhizospheric soils was 59.1±2.1% and 68.7±2.3% in pyreneand Pb/pyrene-amended soils, respectively. The results indicate that pyrene dissipation was significantly (P<0.05) higher in Pb/pyrene-amended soils than only-pyreneamended soils. The plant growth promoted the degradation of pyrene and accounted for 12.1% to 17.0% of dissipation enhancement in the rhizospheric soils. In this study, the DGGE profiles revealed a shift in soil bacterial community structure in all amended soils, with a higher number and greater complexity of banding patterns in Pb/pyreneamended samples than in either Pb-or pyrene-amended samples. In the control and Pb-amended soil, pdo1 and nahAc genes were not detected throughout the incubation period but were detected in the pyrene-and Pb/pyreneamended soils. However, phnAc genes were not detected in either amended or non-amended soils throughout the incubation period. The addition of pyrene had a dramatic effect on the number of pyrene degraders. Discussion Plants contribute to the degradation of PAHs by increasing the size of microbial population, promoting microbial activity, and modifying microbial community

Journal of Geochemical Exploration, 2014

ABSTRACT The present work is a comprehensive evaluation of surface and ground water quality of Ha... more ABSTRACT The present work is a comprehensive evaluation of surface and ground water quality of Haripur basin (comprising an industrial Estate), Pakistan. Heavy metals and trace elements (i.e., Cd, Cr, Cu, Pb, Fe, Ni, Zn, Co, Mn, As and Hg) and physical parameters such as pH, total dissolved solids (TDS) and electrical conductivity (EC) were investigated in 98 sampling points and compared with the WHO guidelines for drinking water. The average metal concentrations in surface and ground water were found in the order of Fe &amp;gt; Mn &amp;gt; Zn &amp;gt; Ni &amp;gt; Pb &amp;gt; Co &amp;gt; Cr &amp;gt; Cu &amp;gt; Cd &amp;gt; As &amp;gt; Hg and Zn &amp;gt; Fe &amp;gt; Pb &amp;gt; Mn &amp;gt; Cr &amp;gt; Cu &amp;gt; Ni &amp;gt; Cd &amp;gt; Co &amp;gt; As &amp;gt; Hg respectively. Furthermore, chronic daily intake (CDI) and hazard quotient (HQ) were also calculated. HQ was found &amp;lt; 1 for all the heavy metals and trace elements, suggesting no health risk. The multivariate techniques (i.e., correlation, principle component analysis and cluster analysis) for the interpretation of the metal data obtained during the monitoring program revealed that there is an increase in the concentrations of heavy metals and trace elements in surface water and shallow water relative to deep water. This can be correlated with the discharge of effluents from the existing industries into the stream water in the basin.

Journal of Environmental Sciences, 2013

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (M... more The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) were investigated in drinking water sources (surface and groundwater) collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risk of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed by using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency (Pak-EPA) and World Health Organization (WHO). The concentrations of Cd, Cr, Ni and Pb were higher than their respective permissible limits, while Cu, Mn and Zn concentrations were observed within their respective limits set by Pak-EPA and WHO. Health risk indicators such as chronic daily intake (CDI) and health risk index (HRI) were calculated for adults and children separately. CDIs and HRIs of heavy metals were found in the order of Cr > Mn > Ni > Zn > Cd > Cu > Pb and Cd > Ni > Mn > Cr > Cu > Pb > Zn, respectively. HRIs of selected heavy metals in the drinking water were less than 1, indicating no health risk to the local people. Multivariate and univariate statistical analyses showed that geologic and anthropogenic activities were the possible sources of water contamination with heavy metals in the study area.

Journal of Environmental Sciences, 2007

This study focused on the changes of soil microbial diversity and potential inhibitory effects of... more This study focused on the changes of soil microbial diversity and potential inhibitory effects of heavy metals on soil enzymatic activities at different application rates of Cd and/or Pb. The soil used for experiments was collected from Beijing and classified as endoaquepts. Pots containing 500 g of the soil with different Cd and/or Pb application rates were incubated for a period of 0, 2, 9, 12 weeks in a glasshouse and the soil samples were analyzed for individual enzymes, including catalase, alkaline phosphatase and dehydrogenase, and the changes of microbial community structure. Results showed that heavy metals slightly inhibited the enzymatic activities in all the samples spiked with heavy metals. The extent of inhibition increased significantly with increasing level of heavy metals, and varied with the incubation periods. The soil bacterial community structure, as determined by polymerase chain reactiondenaturing gradient gel electrophoresis techniques, was different in the contaminated samples as compared to the control. The highest community change was observed in the samples amended with high level of Cd. Positive correlations were observed among the three enzymatic activities, but negative correlations were found between the amounts of the heavy metals and the enzymatic activities.

Journal of Environmental Management, 2009

This study was conducted to investigate the effectiveness of a continuous free surface flow wetla... more This study was conducted to investigate the effectiveness of a continuous free surface flow wetland for removal of heavy metals from industrial wastewater, in Gadoon Amazai Industrial Estate (GAIE), Swabi, Pakistan. Industrial wastewater samples were collected from the inlet , outlet and all cells of the constructed wetland (CW) and analyzed for heavy metals such as lead (Pb), cadmium (Cd), iron (Fe), nickel (Ni), chromium (Cr) and copper (Cu) using standard methods. Similarly, samples of aquatic macrophytes and sediments were also analyzed for selected heavy metals. Results indicate that the removal efficiencies of the CW for Pb, Cd, Fe, Ni, Cr, and Cu were 50%, 91.9%, 74.1%, 40.9%, 89%, and 48.3%, respectively. Furthermore, the performance of the CW was efficient enough to remove the heavy metals, particularly Cd, Fe, and Cu, from the industrial wastewater fed to it. However, it is suggested that the metal removal efficiency of the CW can be further enhanced by using proper management of vegetation and area expansion of the present CW.

Journal of Cleaner Production, 2013

Access to safe drinking water is one of the basic human rights and essential for healthy life. Th... more Access to safe drinking water is one of the basic human rights and essential for healthy life. The present study investigated the concentrations of various pollutants in drinking water and health risk in Charsadda district, Khyber Pakhtunkhwa, Pakistan. Water samples were collected from dug-wells, tube-wells and hand pumps which were the most common sources of drinking water and analyzed for physical parameters, anions, heavy metals and coliform bacteria using standard methods. The concentrations of nitrate (10.3e14.84 mg L À1) in 13 sites exceeded the permissible limit (10 mg L À1) set by US-EPA, while sulfate concentrations (505e555 mg L À1) in 9 sites exceeded the permissible limit (500 mg L À1) set by WHO. Similarly, the concentrations of Pb, Cd, Ni and Fe exceeded their respective permissible limits set by different organizations in some locations. Furthermore, the coliform bacterial contamination (2e5 MPN 100 mL À1) was also found in some sources of water, confirming the bacterial contamination of drinking water. In the study area, improper disposal of sewage and solid wastes, over application of agrochemicals (pesticides and fertilizers), deteriorating condition of piping network and transportation were the major sources responsible for contamination of drinking water. Water contamination with coliform bacteria was the main source of waterborne diseases like gastroenteritis, dysentery, diarrhea and viral hepatitis as complained by most of the respondents during questionnaire survey. In order to reduce the health risk, it is necessary to immediately stop the uses of drinking water from contaminated sources and government should supply treated/clean water with supply lines far away from solid waste, sludge and sewage sites. The farmers should be properly trained to avoid the overusing of agrochemicals responsible for drinking water contamination, while both women and men should be properly educated with water knowledge through awareness and training programs needed for sustainable use and management of drinking water.

Journal of Applied Sciences, 2002

Environmental Toxicology and Chemistry, 2009

To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation test... more To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination.

Environmental Science and Pollution Research, 2009

Background, aim, and scope Soil contamination with heavy metals occurs as a result of both anthro... more Background, aim, and scope Soil contamination with heavy metals occurs as a result of both anthropogenic and natural activities. Heavy metals could have long-term hazardous impacts on the health of soil ecosystems and adverse influences on soil biological processes. Soil enzymatic activities are recognized as sensors towards any natural and anthropogenic disturbance occurring in the soil ecosystem. Similarly, microbial biomass carbon (MBC) is also considered as one of the important soil biological activities frequently influenced by heavy metal contamination. The polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) has recently been used to investigate changes in soil microbial community composition in response to environmental stresses. Soil microbial community structure and activities are difficult to elucidate using single monitoring approach; therefore, for a better insight and complete depiction of the soil microbial situation, different approaches need to be used. This study was conducted in a greenhouse for a period of 12 weeks to evaluate the changes in indigenous microbial community structure and activities in the soil amended with different

Environmental Science and Pollution Research, 2012

Bioaugmentation for the removal of polyaromatic hydrocarbons (PAHs) from wastewater using bacteri... more Bioaugmentation for the removal of polyaromatic hydrocarbons (PAHs) from wastewater using bacteria and yeasts is considered environment-friendly and a costeffective technique. The effectiveness of this biodegradation system depends on the stability of inoculated microorganisms and the availability of nutrients. This study is aimed to investigate the removal of high molecular weight (HMW)-PAHs from biologically treated produced water using different biological systems. Three systems, inoculated with activated sludge (AS), the mixture of five yeast strains (MY), and the mixture of AS and the five yeast strains (SY), respectively, were constructed, and their performance for the removal of HMW-PAHs was compared over 10 weeks. The effluent of the biologically treated produced water from an oilfield was used as the influent after chrysene and benzo(a)pyrene were spiked as HMW-PAHs. Polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescent in situ hybridization (FISH) techniques were used to examine the changes in the structures and abundances of the bacterial and yeast communities in these three systems. Only SY and MY systems were capable to remove chrysene (90.7 % and 98.5 %, respectively) and benzo(a)pyrene (80.7 % and 95.2 %, respectively). PCR-DGGE analysis confirmed that all of the five yeast strains inoculated remained in the SYand MY systems, while FISH results showed that the relative abundance of yeast in the SY and MY systems (10.6 % to 21.9 %, respectively) were significantly higher than AS system (2.3 % to 7.8 %, respectively). The relative abundances of the catechol 2,3-dioxygenase (C23O) indicated that the copy number ratios of benzene ring cleavage gene C23O in the yeast amended systems were much higher than that in the AS system. In this study, all of the three systems were effective in removing the low molecular weight (LMW)-PAHs, while HMW-PAHs including chrysene and benzo(a) pyrene were efficiently removed by MY and SY systems, not by AS system. The high HMW-PAHs removal in the MY and SY bioaugmentation systems possibly attributed to the inoculation of the mixed yeast culture. By combining the PCR-DGGE results with the FISH analyses, it was found that yeast probably consisting mainly of the five inoculated strains inhabited in the two bioaugmentation systems as a dominant population. The relatively higher performance of the SY system might be attributed to the suspended growth type which permitted a more efficient contact between microbial cells and contaminants. The bioaugmentation systems (SY and MY) were successfully established by inoculating with five nonindigenous yeast strains and demonstrated high performance in removal of HMW-PAHs.

Environmental Science and Pollution Research - International, 2008

Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental c... more Background, aim, and scope Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. Materials and methods Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear

Environmental Pollution, 2013

The influence of sewage sludge (SS) and sewage sludge biochar (SSBC) upon biomass yield and the b... more The influence of sewage sludge (SS) and sewage sludge biochar (SSBC) upon biomass yield and the bioaccumulation of PAHs into lettuce plants grown in contaminated soil (∑16PAH 20.2 ± 0.9 mg kg(-1)) is presented. All SSBC amendments (2, 5 and 10%) and the 2% SS amendment significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) increased lettuce biomass. Both SS and SSBC amendments significantly reduced (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) the bioaccumulation of PAHs at all application levels; with reduction in ∑16PAH concentration ranging between 41.8 and 60.3% in SS amended treatments and between 58.0 and 63.2% in SSBC amended treatments, with respect to the control. Benefits in terms of biomass production and PAHs bioaccumulation reduction were greatest where SSBC was used as a soil amendment. At high application rates (10%) SSBC reduced bioaccumulation of PAHs by between 56% and 67%, while SS reduced bioaccumulation of PAHs by less than 44%.

Environment International, 2014

Consumption of rice contaminated with potentially toxic elements(PTEs) isa major pathway for huma... more Consumption of rice contaminated with potentially toxic elements(PTEs) isa major pathway for human exposure to PTEs. This is particularly true in China's so called "Cancer Villages". In this study, sewage sludge biochar (SSBC) was applied to soil (at 5% and 10%) to suppress PTE phytoavailability and as a consequence to reduce PTE levels in rice grown in mining impacted paddy soils. Risk assessment indicate dthat SSBC addition (10%) markedly(P≤0.05) decreased the daily intake, associated with the

Ecotoxicology and Environmental Safety, 2010

This study was conducted to investigate the concentrations of heavy metals in soil and vegetables... more This study was conducted to investigate the concentrations of heavy metals in soil and vegetables, and human health risks through ingestion of contaminated vegetables. Soil and vegetable samples were collected from different locations in Gilgit, northern Pakistan, and analyzed for Cd, Cu, Ni, Pb and Zn. Plant transfer factors (PTF), daily intake of metals (DIM) and health risk index (HRI) were also calculated. The concentrations of Cd, Cu and Zn exceeded their respective permissible limits in soil samples. The highest concentrations of Cu, Ni, Pb and Zn were observed in the edible parts of Malva neglecta, Brassica oleracea, Mintha sylvestris and Brassica campestris, respectively. PTF values were lower for all the selected heavy metals, except for Cd. Furthermore, the HRI values were within the safe limit (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1) except for Pb; therefore, the health risks of metals through ingestion of vegetables were of great concern in the study area.