Muhammad Zaffar Hashmi

Enrichment and geo-accumulation of heavy metals and risk assessment of sediments of the Kurang Nallah—Feeding tributary of the Rawal Lake Reservoir, Pakistan

Heavy metal concentrations in sediments of the Kurang stream: a principal feeding tributary of the Rawal Lake Reservoir were investigated using enrichment factor (EF), geoaccumulation index (Igeo) and metal pollution index (MPI) to determine metal accumulation, distribution and its pollution status. Sediment samples were collected from twenty one sites during two year monitoring in pre- and post-monsoon seasons (2007-2008). Heavy metal toxicity risk was assessed using Sediment Quality Guidelines (SQGs), effect range low/effect range median values (ERL/ERM), and threshold effect level/probable effect level (TEL/PEL). Greater mean concentrations of Ni, Mn and Pb were recorded in post-monsoon season whereas metal accumulation pattern in pre-monsoon season followed the order: Zn>Mn>Ni>Cr>Co>Cd>Pb>Cu>Li. Enrichment factor (EF) and geoaccumulation (Igeo) values showed that sediments were loaded with Cd, Zn, Ni and Mn. Comparison with uncontaminated background values showed higher concentrations of Cd, Zn and Ni than respective average shale values. Concentrations of Ni and Zn were above ERL values; however, Ni concentration exceeded the ERM values. Sediment contamination was attributed to anthropogenic and natural processes. The results can be used for effective management of fresh water hilly streams of Pakistan.

Heavy metals in eggshells of cattle egret (Bubulcus ibis) and little egret (Egretta garzetta) from the Punjab province, Pakistan

Concentrations of nine trace metals were determined to assess site-specific and species-specific differences using Fast Sequential Atomic Absorption Spectrophotometer (Varian FAAS-240) in eggshells of Bubulcus ibis and Egretta garzetta from seven heronries in the Punjab province, Pakistan. Pattern of metal concentration followed the order: Fe > Zn > Pb > Mn > Cd > Cr > Li > Cu > Ni. Greater mean concentrations of Mn(1.17 μg/g), Ni(0.11 μg/g), Pb(1.49 μg/g), Cd(0.88 μg/g), Cr(0.7 μg/g), Cu(0.20 μg/g) and Li(0.27 μg/g) were recorded in little egret. Mean concentrations of Mn, Pb, and Cr, (3.98, 5.4, 0.8 μg/g) were significantly higher in eggshells collected from Shorkot; Cu, Zn and Ni (0.19, 13.0, 0.12 μg/g) from the Trimu Headwork; Cd (1.23 μg/g) from Jhang Faisalabad Road and Fe (67.98 μg/g) from Mailsi. Multivariate analyses indicated that Mn, Pb, Cd, Ni, Cu, Cr and Zn were associated with anthropogenic activities and Fe and Li with natural origin. This study provides the baseline data for a monitoring program and revealed that egg-shells can serve as a bio-monitor of local metal contamination.

Effects of inorganic and organic amendments on the uptake of lead and trace elements by Brassica chinensis grown in an acidic red soil.

A greenhouse study was conducted to investigate the effects of inorganic (phosphate rock, single superphosphate and calcium magnesium phosphate) and organic amendments (peat, straw manure and pig manure) on the uptake of lead (Pb) and trace elements by Chinese Cabbage (Brassica chinensis) grown in an acidic red soil. The application of all organic amendments increased the soil pH while inorganic amendments such as single superphosphate did not. Both inorganic and organic amendments decreased the availability and uptake of Pb while the organic amendments were superior to the inorganic (phosphate) amendments in reducing the availability of the more labile (soluble and exchangeable Pb) forms of soil Pb. More Pb was taken up by roots than shoots with all soil amendments. Among the organic amendments, straw manure and pig manure caused the largest decrease in Pb availability at 456.5 and 457.3 mg kg(-1), respectively, when a high level of 30 g organic amendments kg(-1) was applied. The organic amendments greatly increased the fraction D targeted to Fe-Mn oxides bound Pb, and decreased the fraction A (water-soluble), B (exchangeable), and C (carbonate-bound), thereby decreasing the solubility and mobility of Pb in soil. The organic amendments also significantly improved the concentrations of Fe, Mn, Cu and Zn in the soil and shoots (except Fe in shoots and/or roots), which are essential for plant nutrition. The organic amendments of straw and pig manure lowered the availability and uptake of Pb but not that of other trace metals. Thus, these amendments have the potential to remediate Pb-contaminated soils in situ.

Growth, bioluminescence and shoal behavior hormetic responses to inorganic and/or organic chemicals: A review

A biphasic dose response, termed hormesis, is characterized by beneficial effects of a chemical at a low dose and harmful effects at a high dose. This biphasic dose response phenomenon has the potential to strongly alter toxicology in a broad range. The present review focuses on the progress of research into hormetic responses in terms of growth (in plants, birds, algae and humans), bioluminescence, and shoal behavior as end points. The paper describes how both inorganic and organic chemicals at a low dose show stimulatory responses while at higher doses are inhibitory. The article highlights how factors such as symbiosis, density-dependent factors, time, and contrasting environmental factors (availability of nutrients, temperature, light, etc.) affect both the range and amplitude of hormetic responses. Furthermore, the possible underlying mechanisms are also discussed and we suggest that, for every end point, different hormetic mechanisms may exist. The occurrences of varying interacting receptor systems or receptor systems affecting the assessment of hormesis for each endpoint are discussed. The present review suggests that a hormetic model should be adopted for toxicological evaluations instead of the older threshold and linear non-threshold models.

Risk assessment of heavy metals pollution in agricultural soils of siling reservoir watershed in Zhejiang Province, China.

Presence of heavy metals in agriculture soils above the permissible limit poses threats to public health. In this study, concentrations of seven metals were determined in agricultural soils from Yuhang county, Zhejiang, China. Multivariate statistical approaches were used to study the variation of metals in soils during summer and winter seasons. Contamination of soils was evaluated on the basis of enrichment factor (EF), geoaccumulation index (I geo), contamination factor (C f), and degree of contamination (C deg). Heavy metal concentrations were observed higher in winter as compared to summer season. Cr and Cd revealed random distribution with diverse correlations in both seasons. Principal component analysis and cluster analysis showed significant anthropogenic intrusions of Zn, Cd, Pb, Cr, and Cu in the soils. Enrichment factor revealed significant enrichment (EF > 5) of Zn, Cd, and Pb, whereas geoaccumulation index and contamination factor exhibited moderate to high contamination for Zn, Cr, Cd, and Pb. In light of the studied parameters, permissible limit to very high degree of contamination (C deg > 16) was observed in both seasons.

Heavy metal accumulation in edible fish species from Rawal Lake Reservoir, Pakistan.

The aim of the present study was to describe the accumulation of trace metals in the liver, kidney, gills, muscles, and skin of four edible fish species (Tor putitora, Cirrhinus mrigala, Labeo calbasu, and Channa punctatus) of Rawal Lake Reservoir, Pakistan. The fish samples were collected in the pre-monsoon (May 2008) and post-monsoon (October 2007) seasons and were analyzed for heavy metals by using an atomic absorption spectrometer. Kidney and liver showed relatively high concentrations of heavy metals. The accumulation of metals in the different organs of the fish (skin, muscles, and gills) in post-monsoon was higher than in pre-monsoon. In pre-monsoon, the metals followed the trend Zn > Pb > Fe > Cr > Ni > Mn > Co > Cu > Cd > Li, while in the post-monsoon season, the trend was Fe > Pb > Cr > Ni > Zn > Cu > Co > Mn > Cd > Li. The concentrations of Ni, Cr, and Pb in the muscle of all fish species were higher than the WHO guideline values of heavy metals in fishes for human consumption except in T. putitora. Cu level was nearly equal to the WHO maximum levels in C. mrigala and L. calbasu, while it was lower in T. putitora and C. punctatus. It is strongly advocated that risk assessment studies should be conducted and there is an urgent need for water quality restoration and management of Rawal Lake Reservoir.

Relationship between heavy metals concentrations in egret species, their environment and food chain differences from two Headworks of Pakistan

Concentration of ten metals (Cd, Cr, Co, Cu, Fe, Li, Mn, Ni, Pb and Zn) were analyzed in the egg contents, prey and soil samples of little egret (Egretta garzetta) and cattle egret (Bubulcus ibis) from two Headworks to determine habitat and species-specific differences; to assess the importance of prey and habitat contamination as an exposure source for heavy metals. Concentration of Cu, Mn, Cr and Pb in egg contents, Fe, Co, Cu, Mn, Zn in prey and Fe, Co, Cu, Ni, Li in surface soils were significantly different (P<0.05). Mean metal concentrations of Cr, Pb and Cd were relatively higher in little egret whereas Cu and Mn were higher in the egg contents of cattle egret. The mean concentrations of Cu, Mn and Zn were higher in prey samples of cattle egrets and Cr, Cd and Pb in prey samples of little egrets. In soil samples collected from little egret heronries metal concentrations were higher except Cu and Ni. Correlation Analysis and Hierarchical Agglomerative Cluster Analysis (HACA) identified relatively similar associations of metals and their source identification. Metals such as Fe, Cu, Mn, and Li were related with geochemical origin from parent rock material as well as anthropogenic input whereas Cr, Cd, Pb, Ni, Co and Zn were associated mostly with anthropogenic activities. The study suggested that eggs are useful bio-monitor of local heavy metal contamination.

Identification, characterization and molecular analysis of the viable but nonculturable Rhodococcus biphenylivorans

Numerous bacteria, including pollutant-degrading bacteria can enter the viable but nonculturable state (VBNC) when they encounter harsh environmental conditions. VBNC bacteria, as a vast majority of potent microbial resource can be of great significance in environmental rehabilitation. It is necessary to study the VBNC state of pollutant-degrading bacteria under various stress conditions. The aim of this study was to determine whether Rhodococcus biphenylivorans could enter the VBNC state under oligotrophic and low temperature conditions, and to examine the changes of morphology, enzymatic activity and gene expressions that might underline such state. The obtained results indicated that R. biphenylivorans TG9T could enter into the VBNC state and recover culturability under favorable environmental conditions. Results from Illumina high throughput RNA-sequencing revealed that the up-regulated genes related to ATP accumulation, protein modification, peptidoglycan biosynthesis and RNA polymerase were found in the VBNC cells, and the down-regulated genes mainly encoded hypothetical protein, membrane protein and NADH dehydrogenase subunit, which render VBNC cells more tolerant to survive under inhospitable conditions. This study provides new insights into prevention and control of the VBNC state of pollutant-degrading bacteria for their better capabilities in environmental rehabilitation.

Influence of Heavy Metals and PCBs Pollution on the Enzyme Activity and Microbial Community of Paddy Soils around an E-Waste Recycling Workshop

Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m). The concentration of Cd (2.16 mg·kg−1) and Cu (69.2 mg·kg−1) were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg−1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

Paddy field--a natural sequential anaerobic-aerobic bioreactor for polychlorinated biphenyls transformation.

The environmental pollution and health risks caused by the improper disposal of electric and electronic waste (e-waste) have become urgent issues for the developing countries. One of the typical pollutants, polychlorinated biphenyls (PCBs), is commonly found in farmland in Taizhou, a major hotspot of e-waste recycling in China. This study investigated the amount of PCB residue in local farmlands. Biotransformation of PCBs was further studied under different water management conditions in paddy field with or without rice cultivation, with a special focus on the alternating flooded and drying processes. It was found that paddy field improved the attenuation of PCBs, especially for highly chlorinated congeners. In the microcosm experiment, 40% or more of the initial total PCBs was removed after sequential flood-drying treatments, compared to less than 10% in the sterilized control and 20% in the constant-drying system. Variation in the quantity of PCBs degrading and dechlorinating bacterial groups were closely related to the alteration of anaerobic-aerobic conditions. These results suggested that alternating anoxic-oxic environment in paddy field led to the sequential aerobic-anaerobic transformation of PCBs, which provided a favorable environment for natural PCB attenuation.