Kifayatullah Khan

Heavy metals in agricultural soils and crops and their health risks in Swat District, northern Pakistan.

This study assessed the concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni) and zinc (Zn) in agricultural soils and crops (fruits, grains and vegetable) and their possible human health risk in Swat District, northern Pakistan. Cd concentration was found higher than the limit (0.05 mg/kg) set by world health organization in 95% fruit and 100% vegetable samples. Moreover, the concentrations of Cr, Cu, Mn, Ni and Zn in the soils were shown significant correlations with those in the crops. The metal transfer factor (MTF) was found highest for Cd followed by Cr>Ni>Zn>Cu>Mn, while the health risk assessment revealed that there was no health risk for most of the heavy metals except Cd, which showed a high level of health risk index (HRI⩾10E-1) that would pose a potential health risk to the consumers.

Radiometric analysis of Hazara phosphate rock and fertilizers in Pakistan

Abstract Natural radioactivity due to 40K, 226Ra and 232Th has been measured in phosphate rock samples, collected from various localities of Hazara division of Pakistan, and in locally prepared and imported fertilizer. For data acquisition and analysis, a high-purity germanium (HPGe) detector and a PC-based MCA were used. The 226Ra content was very high and was found to vary from 307.7 Bq kg−1 to 617.5 Bq kg−1. This can result in a significant radiation exposure if the rock and fertilizer are handled in places with poor ventilation that could lead to radon accumulation. These data can be used to determine the radioactivity being spread along with fertilizer on agricultural lands.

Health risks associated with heavy metals in the drinking water of Swat, northern Pakistan

The concentrations of heavy metals such as Cd, Cr, Cu, Mn, Ni, Pb and Zn were investigated in drinking water sources (surface and groundwater) collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risks of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency and World Health Organization. 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. 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.

Quantification of PAHs and health risk via ingestion of vegetable in Khyber Pakhtunkhwa Province, Pakistan

This study was conducted to evaluate the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the soil and vegetable irrigated with wastewater in 11 districts of Khyber Pakhtunkhwa (KPK) Province (Pakistan). The ∑16PAH ranged from 223 to 929 μg/kg in the soils with highest concentration in the soil of high urbanized district (Peshawar), while the lowest concentration in the soil of less urbanized district (Lakki Marwat). PAH concentrations in vegetable ranged from 51.6 to 402 μg/kg on dry weight bases (d.w). Naphthaene, phenanthrene, fluoranthene and pyrene were frequently observed in vegetable. The concentrations of higher molecular weight PAHs were lower in vegetable as compared to low molecular weight PAHs. The highest PAH concentrations were observed in leafy vegetable (lettuce>spinach). The highest TEQ value (7.2) was observed for pyrene following by naphthalene (4.9) for the samples collected from Mardan, while the lowest mean TEQ value (0.12) was found for acenaphthylene followed by benzo[k]fluoranthene (0.26) in Peshawar. The highest TEQ value was 4.1 for flouranthene followed by 3.8 for naphthalene in the KPK province. The uniqueness of this study is the quantification of PAHs in the soil and vegetable collected from a large area of KPK Province which are rapidly urbanizing.

Evaluation of toxicological risk of foodstuffs contaminated with heavy metals in Swat, Pakistan.

This study aimed to assess the concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in the available foodstuffs (crops, milk and water), their bioaccumulation in human body and potential human health risks in Swat valley, northern Pakistan. Heavy metal concentrations in foodstuffs and human blood (adults (18-above) and children (1-12 years)) were analyzed using atomic absorption spectrometer. The results revealed high level of Mn in foodstuffs followed by Cr>Cu>Zn>Ni>Cd>Pb, which significantly increased the levels of heavy metals in the adult׳s blood as compared to that of children in the order of Cr>Zn>Mn>Ni>Pb>Cu>Cd. Principal component analysis showed that selected foodstuffs were the possible sources of metal contamination in human blood, while correlation analysis revealed that the concentrations of Cr, Cu, Mn, Ni, Pb and Zn in foodstuffs significantly correlated with that in human blood. Moreover, risk assessments for individual metals via foodstuffs were found within safe limits, except for Cd (HQ>1); Whereas, for aggregate multiple metals the risk was calculated as 3.97E+00 (HI>1), in which water and milk were perceived as the greater contributors (81 percent) to HI; while fruits, grains and vegetables contributed 5 percent each, and pulses 4 percent.

Quantification of Heavy Metals in Mining Affected Soil and Their Bioaccumulation in Native Plant Species

Several anthropogenic and natural sources are considered as the primary sources of toxic metals in the environment. The current study investigates the level of heavy metals contamination in the flora associated with serpentine soil along the Mafic and Ultramafic rocks northern-Pakistan. Soil and wild native plant species were collected from chromites mining affected areas and analyzed for heavy metals (Cr, Ni, Fe, Mn, Co, Cu and Zn) using atomic absorption spectrometer (AAS-PEA-700). The heavy metal concentrations were significantly (p < 0.01) higher in mine affected soil as compared to reference soil, however Cr and Ni exceeded maximum allowable limit (250 and 60 mg kg−1, respectively) set by SEPA for soil. Inter-metal correlations between soil, roots and shoots showed that the sources of contamination of heavy metals were mainly associated with chromites mining. All the plant species accumulated significantly higher concentrations of heavy metals as compared to reference plant. The open dumping of mine wastes can create serious problems (food crops and drinking water contamination with heavy metals) for local community of the study area. The native wild plant species (Nepeta cataria, Impatiens bicolor royle, Tegetis minuta) growing on mining affected sites may be used for soil reclamation contaminated with heavy metals.

Kinetic and mechanism investigation on the gamma irradiation induced degradation of endosulfan sulfate.

The gamma irradiation was investigated for potential removal of endosulfan sulfate, an emerging water pollutant and central nervous system disruptor. A removal efficiency of 99.5% of initially 1.30 μM endosulfan sulfate was observed at an absorbed dose of 1020 Gy. Aqueous electron (eaq(-)) was found to play primary role in the removal of endosulfan sulfate which was possibly due to greater reactivity of eaq(-) with endosulfan sulfate, considering the second-order rate constant of 8.1×10(9) and 3.4×10(10) M(-1) s(-1) for hydroxyl radical (·OH) and eaq(-), respectively, with endosulfan sulfate. The removal efficiency of endosulfan sulfate was affected by the pH of aqueous solution, with observed removal efficiency of 99.5%, 98.3% and 31.3% at pH 6.2, pH 10.0, and pH 2.6, respectively. The efficiency was also influenced by inorganic anions and humic acid in the order of nitrate>nitrite>bicarbonate>carbonate ≃ humic acid. The initial degradation rate increased while degradation constant decreased with increasing initial concentrations of endosulfan sulfate. The degradation pathways showed that oxidative pathway was initiated at the SO2 bond while reductive pathways at the chlorine attached to the ring of endosulfan sulfate. The mass balance showed removal of 98% chloride and 72% sulfate ions from endosulfan sulfate at an absorbed dose of 1020 Gy. The removal of endosulfan sulfate followed by subsequent loss of by-products under extended treatment showed that gamma irradiation is potential technique for the remediation of organic pollutants from a water environment.

The eco-toxic effects of pesticide and heavy metal mixtures towards earthworms in soil

Earthworms are the key soil organisms, contribute to many positive ecological services that could be degraded by pesticides and other soil pollutants such as heavy metals. Chemicals usually occur as mixtures in the environmental systems which can lead synergistic effects. The assessment and characterization of soil pollutants that effects risks are very difficult due to the complexity of soil matrix, poor understanding about the fate and effects of chemical combinations like pesticide and metal mixtures in terrestrial systems, and scarcity of toxicological data on mixtures of pollutants. In this review we summarized the current studies on individual and joint effects of pesticides and metals on earthworms and indicate the mixture that cause the synergistic interactions. The review explores the methods and models used previously to evaluate the toxicity of chemical mixtures, and suggests the perspective approaches for a better knowledge of combine effects as well as research methods The summarized report indicates that pesticide and metal mixtures at all organization levels affect the earthworms negatively. Whereas, the combined pollution generated by mixtures of pesticides and metal ions could induce the DNA damage, disruption in enzyme activities, reduction in individual survival, production and growth rate, change in individual behavior such as feeding rate, and decrease in the total earthworm community biomass and density. Among the pesticides organophosphates were identified the most toxic pesticides causing the synergistic effects. The findings indicate the scarcity of toxicological data concerning the assessment of pesticide and metal mixtures at genome level; while the mechanisms causing synergism were still not sufficiently explored.

Crop bioaccumulation and human exposure of perfluoroalkyl acids through multi-media transport from a mega fluorochemical industrial park, China

Significant quantities of perfluoroalkyl acids (PFAAs) are released to the environment from fluorochemical manufacturing processes through wastewater discharge and air emission in China, which may lead to human exposure and health risks through crop bioaccumulation from PFAAs-contaminated soil and irrigation water. This paper systematically studied the distribution and transport of PFAAs in agricultural soil, irrigation water and precipitation, followed by crop bioaccumulation and finally human exposure of PFAAs within a 10km radius around a mega-fluorochemical industrial park (FIP). Hotspots of contamination by PFAAs were found near the FIP and downstream of the effluent discharge point with the maximum concentrations of 641ng/g in agricultural soil, 480ng/g in wheat grain, 58.8ng/g in maize grain and 4,862ng/L in precipitation. As the distance increased from the FIP, PFAAs concentrations in all media showed a sharp initial decrease followed by a moderate decline. Elevated PFAA concentrations in soil and grains were still present within a radius of 10 km of the FIP. The soil contamination was associated with the presence of PFAAs in irrigation water and precipitation, and perfluorooctanoic acid (PFOA) was the dominant PFAA component in soil. However, due to bioaccumulation preference, short-chain perfluoroalkyl carboxylic acids (PFCAs), especially perfluorobutanoic acid (PFBA), became the major PFAA contaminants in grains of wheat and maize. The bioaccumulation factors (BAFs) for both grains showed a decrease with increasing chain length of PFAAs (approximately 0.5 log decrease per CF2 group). Compared to maize grain, wheat grain showed higher BAFs, possibly related to its higher protein content. The PFCA (C4-C8) concentrations (on a log10 basis) in agricultural soil and grain were found to show a linear positive correlation. Local human exposure of PFOA via the consumption of contaminated grains represents a health risk for local residents, especially for toddlers and children.

Removal and bioaccumulation of heavy metals from aqueous solutions using freshwater algae.

Four freshwater algae, including Cladophora glomerata, Oedogonium westii, Vaucheria debaryana and Zygnema insigne, were tested for their bioaccumulation capacity for cadmium (Cd), chromium (Cr) and lead (Pb) in a controlled environment with an average temperature of 18 °C, and light/dark duration of 12:12 h. Experiments were performed in aqueous solutions containing selected heavy metals (HM) (ranging from 0.05 to 1.5 mg L(-1)) with 0.5 g of living algae at 18 °C and pH 6.8. The results indicated that C. glomerata was observed to be the most competent species for the removal of Cr, Cd and Pb from aqueous solutions. HM removal trends were in the order of Cd>Cr>Pb while the removal efficiency of selected algae species was in the order of C. glomerata, O. westii, V. debaryana and Z. insigne. The bioaccumulation capacity of C. glomerata, V. debaryana and Z. insigne was observed for different HM. Removal of HM was higher with low levels of HM in aqueous solutions. The results indicated that C. glomerata, O. westii, V. debaryana and Z. insigne had significant (P≤0.01) diverse bioaccumulation capacity for Cr, Cd and Pb.