Comparative catalytic reduction and degradation with biodegradable sodium alginate based nanocomposite: Zinc oxide/N-doped carbon nitride/sodium alginate.

Sodium alginate (SA) is a biodegradable macromolecule which is used to synthesize nanocomposites and their further use as catalysis. Zinc oxide (ZnO) and nitrogen doped carbon nitride (ND-C3N4) nanoparticles are prepared using solvothermal and hydrothermal methods, respectively. ZnO/ND-C3N4/SA nanocomposites are successfully synthesized by employing in-situ polymerization. The presence of essential functional groups is confirmed by Fourier transform infrared (FTIR) spectroscopic analysis. Controlled spherical morphology for ZnO nanoparticles, with an average diameter of ∼52 nm, is shown by Scanning electron microscopic (SEM) analysis, while rice-like grain structure with an average grain size ∼62 nm is exhibited by ND-C3N4 nanoparticles. The presence of required elements is confirmed by Energy dispersive X-ray spectroscopic (EDX) analysis. The crystalline nature of nanocomposites is verified by X-ray diffraction spectroscopic (XRD) analysis. The investigation of the catalytic efficiency for degradation and reduction of various organic dyes is carried out on nanoparticles and nanocomposites. Thorough examination and comparison of parameters, such as apparent rate constant (kapp), reduction time, percentage reduction, reduced concentration and half-life, are conducted for all substrates. The nanocomposites show greater efficiency than nanoparticles in both reactions: catalytic reduction and catalytic degradation.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) at urban settings in Pakistan: Spatial variations, sources and health risks.

For the first time, this study presents gaseous and particulate-bound (PM2.5) polycyclic aromatic hydrocarbons (PAHs) in ambient air samples collected from eight major cities of Pakistan. Diurnal air samples (gaseous and PM2.5) were collected in summer 2014 on polyurethane foam and quartz fiber filters using high volume-active air sampler. The US-EPA enlisted 16 priority PAHs in particulate and gaseous phase were measured on gas chromatograph equipped with mass spectrometer detector. The total PAHs concentrations ranged between 188 pg m-3 (in Gilgit), and 2340 pg m-3 (in Lahore). The decreasing order of PAHs concentrations in various cities was in the following order: Lahore > Rawalpindi > Multan > Faisalabad > Karachgi > Peshawar > Quetta > Gilgit. Phenanthrene showed the highest concentration, accounted 18% of total PAHs followed by fluoranthene (12% of total PAHs). This study showed that the gaseous fractions were predominant in the ambient air. Source apportionment analysis revealed that biomass combustion, vehicular emissions and diesel combustion in power generators were the potential PAHs emissions sources. The lifetime lungs cancer risk (LLCR) was in the range of 8.28 × 10-7 to 2.09 × 10-5 depicting mild cancer risk to the residents on exposure to atmospheric PAHs. Therefore, it is recommended to monitor atmospheric PAHs throughout the year and also adopt environmentally friendly fuels to reduce PAHs pollution and health risks in the country.

Legacy and emerging flame retardants (FRs) in the urban atmosphere of Pakistan: Diurnal variations, gas-particle partitioning and human health exposure.

Atmospheric concentration of legacy (LFRs) and emerging flame retardants (EFRs) including 8 polybrominated diphenyl ethers (PBDEs), 6 novel brominated flame retardants (NBFRs), 2 dechlorane plus isomers (DP), and 8 chlorinated organophosphate flame retardants (OPFRs) were consecutively measured in eight major cities across Pakistan. A total of 96 samples (48 PM2.5 & 48 PUFs) were analyzed and the concentrations of ∑8PBDEs (gaseous+particulate) ranged between 40.8 and 288 pg/m3 with an average value of 172 pg/m3. ∑6NBFRs ranged between 12.0 and 35.0 pg/m3 with an average value of 22.5 pg/m3 while ∑8OPFRs ranged between 12,900-40,800 pg/m3 with an average of 24,700 pg/m3. Among the studied sites, Faisalabad city exhibited the higher concentrations of FRs among all cities which might be a consequence of textile mills and garment manufacturing industries. While analyzing the diurnal patterns, OPFRs depicted higher concentrations during night-time. The estimated risks of all groups of FRs from inhalation of ambient air were negligible for all the cities, according to USEPA guidelines. Nonetheless, our study is the first to report gaseous and particulate concentrations of FRs in air on a diurnal basis across major cities in Pakistan, offering insights into the atmospheric fate of these substances in urban areas in a sub-tropical region.

Dietary proxies (δ15N, δ13C) as signature of metals and arsenic exposure in birds from aquatic and terrestrial food chains.

In this study, exposure to arsenic (As), lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) was investigated in the blood, pectoral muscles and tail feathers of two terrestrial (spotted owlet; Athena brama and bank myna; Acridotheres ginginianus) and two aquatic (cattle egret; Bubulcus ibis and pond heron; Ardeola grayii) bird species inhabiting Pakistan. Food chain specimens, as well as the dietary proxies δ15N and δ13C, were also analyzed to validate potential trophic and dietary transfers of metals and As in birds. Zn was found to be the most prevalent metal in the tissues of birds followed by Pb, As, Cu, and Cd. The bioaccumulation of metals and As was higher in tail feathers reflecting the combined effect of both endogenous and exogenous contamination. Pectoral muscle and blood harbored lower levels of As and metals, indicating less recent exposure through diet. Aquatic birds feeding at higher trophic levels accumulated significantly higher concentrations of metals and As in their tissues (P < 0.05) and, therefore, may be at a greater risk of metal and As toxicity than terrestrial birds. Linear regression model depicts δ15N as a strong predictor of metals and As levels in the tissues of both aquatic and terrestrial birds, followed by the δ13C dietary proxy. All metals in aquatic species, except for Cd, as well as terrestrial species, except for Cu, exhibit bioaccumulative potential through the food chain (Trophic transfer factor: TTFs > 1) indicating potential harmful consequences for birds. Elevated concentrations of metals and As in tissues may cause harmful effects in birds potentially leading to declines in their populations.

Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan.

In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. In comparison of species, SOD and tGSH activities were higher in bank myna and cattle egret, while CAT activity and TBARS concentrations were higher in pond heron and cattle egret, respectively. We deduced that tissues with higher accumulation of metal(loid)s such as liver and kidney were under a great risk to oxidative damage. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. Globally, metal- and As-induced oxidative stress is least emphasized in multiple tissues of birds that is needed to be addressed with focus on case-control studies using dose-response approach. Graphical abstract .

Green Synthesis and Characterization of Pullulan Mediated Silver Nanoparticles through Ultraviolet Irradiation.

Nanoparticles (NPs) are, frequently, being utilized in multi-dimensional enterprises. Silver nanoparticles (AgNPs) have attracted researchers in the last decade due to their exceptional efficacy at very low volume and stability at higher temperatures. Due to certain limitations of the chemical method of synthesis, AgNPs can be obtained by physical methods including sun rays, microwaves and ultraviolet (UV) radiation. In the current study, the synthesis of pullulan mediated silver nanoparticles (P-AgNPs) was achieved through ultraviolet (UV) irradiation, with a wavelength of 365 nm, for 96 h. P-AgNPs were formed after 24 h of UV-irradiation time and expressed spectra maxima as 415 nm, after 96 h, in UV-vis spectroscopy. The crystallographic structure was "face centered cubic (fcc)" as confirmed by powder X-ray diffraction (PXRD). Furthermore, high resolution transmission electron microscopy (HRTEM) proved that P-AgNPs were covered with a thin layer of pullulan, with a mean crystalline size of 6.02 ± 2.37. The average lattice fringe spacing of nanoparticles was confirmed as 0.235 nm with quasi-spherical characteristics, by selected area electron diffraction (SAED) analysis. These green synthesized P-AgNPs can be utilized efficiently, as an active food and meat preservative, when incorporated into the edible films.

Rapid Green Synthesis and Characterization of Silver Nanoparticles Arbitrated by Curcumin in an Alkaline Medium.

Green synthesis of silver nanoparticles is desirable practice. It is not only the required technique for industrial and biomedical purposes but also a promising research area. The aim of this study was to synthesize green curcumin silver nanoparticles (C-Ag NPs). The synthesis of C-Ag NPs was achieved by reduction of the silver nitrate (AgNO3) in an alkaline medium. The characterizations of the prepared samples were conducted by ultraviolet visible (UV-vis) spectroscopy, powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and zeta potential (ZP) analyses. The formation of C-Ag NPs was evaluated by the dark color of the colloidal solutions and UV-vis spectra, with 445 nm as the maximum. The size of the crystalline nanoparticles, recorded as 12.6 ± 3.8nm, was confirmed by HRTEM, while the face-centered cubic (fcc) crystallographic structure was confirmed by PXRD and SAED. It is assumed that green synthesized curcumin silver nanoparticles (C-Ag NPs) can be efficiently utilized as a strong antimicrobial substance for food and meat preservation due to their homogeneous nature and small size.

E-Waste Driven Pollution in Pakistan: The First Evidence of Environmental and Human Exposure to Flame Retardants (FRs) in Karachi City.

Informal e-waste recycling activities have been shown to be a major emitter of organic flame retardants (FRs), contributing to both environmental and human exposure to laborers at e-waste recycling sites in some West African countries, as well as in China and India. The main objective of this study was to determine the levels of selected organic FRs in both air and soil samples collected from areas with intensive informal e-waste recycling activities in Karachi, Pakistan. Dechlorane Plus (DP) and "novel" brominated flame retardants (NBFRs) were often detected in high concentrations in soils, while phosphorus-based FRs (OPFRs) dominated atmospheric samples. Among individual substances and substance groups, decabromodiphenyl ether (BDE-209) (726 ng/g), decabromodiphenyl ethane (DBDPE) (551 ng/g), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) (362 ng/g), and triphenyl-phosphate (∑TPP) (296 ng/g) were found to be prevalent in soils, while OPFR congeners (5903-24986 ng/m3) were prevalent in air. The two major e-waste recycling areas (Shershah and Lyari) were highly contaminated with FRs, suggesting informal e-waste recycling activities as a major emission source of FRs in the environment in Karachi City. However, the hazards associated with exposure to PM2.5 appear to exceed those attributed to exposure to selected FRs via inhalation and soil ingestion.

The first exposure assessment of legacy and unrestricted brominated flame retardants in predatory birds of Pakistan.

The exposure to legacy polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs) and unrestricted 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), bis (2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEH-TEBP) and 2-ethylhexyl-2,3,4,5-tetrabromo-benzoate (EH-TBB) was examined in tail feathers of 76 birds belonging to ten predatory species inhabiting Pakistan. In addition, different feather types of six individuals of Black kite (Milvus migrans) were compared for their brominated flame retardant (BFR) levels. Black kite was found to be the most contaminated species with a median (minimum-maximum) tail feather concentration of 2.4 (0.70-7.5) ng g-1 dw for ∑PBDEs, 1.5 (0.5-8.1) ng g-1 dw for ∑HBCDDs and 0.10 ( 0.05 for both). Similarly, no significant concentration differences were observed among different feather types (all P > 0.05) suggesting their similar exposure. While variables such as species, trophic guild and δ15N values were evaluated as major predictors for BFR accumulation in the studied species, we predict that combined effects of just mentioned factors may govern the intra- and interspecific differences in BFR contamination profiles. We urge for further investigation of BFR exposure and potential toxicological effects in predatory birds from Asia with a more extensive sample size per species and location.

Use of feathers to assess polychlorinated biphenyl and organochlorine pesticide exposure in top predatory bird species of Pakistan.

Little is known about the levels of organochlorines (OCs) in predatory bird species from Asia or the factors governing their concentrations. This study is the first report on concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in predatory birds of Pakistan. The concentrations of PCBs and OCPs were investigated using tail feathers of ten different species of predatory birds. In addition, concentration differences among body, tail, primary and secondary feathers were investigated for six individuals of black kite (Milvus migrans). Ranges of concentrations were highest for dichlorodiphenyldichloroethylene (p,p'-DDE: 0.11-2163ngg(-1) dry wt.) followed by dichlorodiphenyltrichloroethane (p,p'-DDT: 0.36-345ngg(-1) dry wt.), hexachlorobenzene (HCB: 0.02-34ngg(-1) dry wt.), ∑PCBs (0.03-16ngg(-1) dry wt.) and trans-nonachlor (TN; 0.01-0.13ngg(-1) dry wt.). CB 118, 153, 138, and 180 along with p,p'-DDE were found as the most prevalent compounds. ∑PCBs and ∑DDTs were significantly different among species (both p<0.01) and omnivorous, scavengers, carnivorous and piscivorous trophic guilds (all p<0.03). Only ∑PCBs were significantly differentamong different families of birds (p<0.01). Values of stable isotopes (δ(13)C and δ(15)N) differed significantly (all p<0.01) among species, families, trophic guilds as well as terrestrial and aquatic habitat but not between nocturnal and diurnal predators (p=0.22 for δ(13)C; p=0.50 for δ(15)N). Concentrations of ∑PCBs, ∑DDTs and trans-nonachlor, but not HCB (p=0.86), were significantly different among different feather types (all p<0.01). Trophic and taxonomic affiliation as well as dietary carbon sources (δ(13)C) for species were identified as the variables best explaining the observed variation in exposure to the studied compounds. The significance of contributing factors responsible for OC contamination differences in predatory birds should be further elucidated in future studies.

Construction of a high-density genetic map by specific locus amplified fragment sequencing (SLAF-seq) and its application to Quantitative Trait Loci (QTL) analysis for boll weight in upland cotton (Gossypium hirsutum.).

BACKGROUND: Upland Cotton (Gossypium hirsutum) is one of the most important worldwide crops it provides natural high-quality fiber for the industrial production and everyday use. Next-generation sequencing is a powerful method to identify single nucleotide polymorphism markers on a large scale for the construction of a high-density genetic map for quantitative trait loci mapping. RESULTS: In this research, a recombinant inbred lines population developed from two upland cotton cultivars 0-153 and sGK9708 was used to construct a high-density genetic map through the specific locus amplified fragment sequencing method. The high-density genetic map harbored 5521 single nucleotide polymorphism markers which covered a total distance of 3259.37 cM with an average marker interval of 0.78 cM without gaps larger than 10 cM. In total 18 quantitative trait loci of boll weight were identified as stable quantitative trait loci and were detected in at least three out of 11 environments and explained 4.15-16.70 % of the observed phenotypic variation. In total, 344 candidate genes were identified within the confidence intervals of these stable quantitative trait loci based on the cotton genome sequence. These genes were categorized based on their function through gene ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis and eukaryotic orthologous groups analysis. CONCLUSIONS: This research reported the first high-density genetic map for Upland Cotton (Gossypium hirsutum) with a recombinant inbred line population using single nucleotide polymorphism markers developed by specific locus amplified fragment sequencing. We also identified quantitative trait loci of boll weight across 11 environments and identified candidate genes within the quantitative trait loci confidence intervals. The results of this research would provide useful information for the next-step work including fine mapping, gene functional analysis, pyramiding breeding of functional genes as well as marker-assisted selection.

Organochlorine pesticides (OCPs) in the Indus River catchment area, Pakistan: Status, soil-air exchange and black carbon mediated distribution.

Organochlorine pesticides (OCPs) were investigated in passive air and soil samples from the catchment area of the Indus River, Pakistan. ∑15OCPs ranged between 0.68 and 13.47 ng g(-1) in soil and 375.1-1975 pg m-(3) in air. HCHs and DDTs were more prevalent in soil and air compartments. Composition profile indicated that ß-HCH and p,p'-DDE were the dominant of all metabolites among HCHs and DDTs respectively. Moreover, fBC and fTOC were assessed and evaluated their potential role in the distribution status of OCPs. The fTOC and fBC ranged between 0.77 and 2.43 and 0.04-0.30% respectively in soil. Regression analysis showed the strong influence of fBC than fTOC on the distribution of OCPs in the Indus River catchment area soil. Equilibrium status was observed for ß-HCH, δ-HCH, p,p'-DDD, o,p'-DDT, TC, HCB and Heptachlor with ff ranged between 0.3 and 0.59 while assessing the soil-air exchange of OCPs.

Rhizobiales-like Phosphatase 2 from Arabidopsis thaliana Is a Novel Phospho-tyrosine-specific Phospho-protein Phosphatase (PPP) Family Protein Phosphatase.

Cellular signaling through protein tyrosine phosphorylation is well established in mammalian cells. Although lacking the classic tyrosine kinases present in humans, plants have a tyrosine phospho-proteome that rivals human cells. Here we report a novel plant tyrosine phosphatase from Arabidopsis thaliana (AtRLPH2) that, surprisingly, has the sequence hallmarks of a phospho-serine/threonine phosphatase belonging to the PPP family. Rhizobiales/Rhodobacterales/Rhodospirillaceae-like phosphatases (RLPHs) are conserved in plants and several other eukaryotes, but not in animals. We demonstrate that AtRLPH2 is localized to the plant cell cytosol, is resistant to the classic serine/threonine phosphatase inhibitors okadaic acid and microcystin, but is inhibited by the tyrosine phosphatase inhibitor orthovanadate and is particularly sensitive to inhibition by the adenylates, ATP and ADP. AtRLPH2 displays remarkable selectivity toward tyrosine-phosphorylated peptides versus serine/threonine phospho-peptides and readily dephosphorylates a classic tyrosine phosphatase protein substrate, suggesting that in vivo it is a tyrosine phosphatase. To date, only one other tyrosine phosphatase is known in plants; thus AtRLPH2 represents one of the missing pieces in the plant tyrosine phosphatase repertoire and supports the concept of protein tyrosine phosphorylation as a key regulatory event in plants.

Significance of black carbon in the sediment-water partitioning of organochlorine pesticides (OCPs) in the Indus River, Pakistan.

This study was conducted with the aim of assessing the levels and black carbon mediated sediment-water partitioning of organochlorine pesticides (OCPs) from the Indus River. ∑OCPs ranged between 52-285 ng L(-1) and 5.6-29.2 ng g(-1) in water and sediment samples respectively. However, the ranges of sedimentary fraction of total organic carbon (f(TOC)) and black carbon (f(BC)) were 0.82-2.26% and 0.04-0.5% respectively. Spatially, OCPs concentrations were higher at upstream sites as compared to downstream sites. Source diagnostic ratios indicated the technical usage of HCH (α-HCH/γ-HCH>4) and significant presence of DDT metabolites with fresh inputs into the Indus River as indicated by the ratios of (DDE+DDD)/∑DDTs (0.27-0.96). The partitioning of OCPs between the sediments and water can be explained by two carbon Freundlich adsorption model which included both organic carbon and black carbon pools as partitioning media.

Concentrations and patterns of organochlorines (OCs) in various fish species from the Indus River, Pakistan: A human health risk assessment.

The present study was conducted to reveal the concentrations and patterns of organochlorines [i.e., organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)] in freshwater fish species collected from four ecologically important sites of the Indus River i.e., Taunsa (TAU), Rahim Yar Khan (RYK), Guddu (GUD) and Sukkur (SUK). In the fish muscle tissues, concentrations of 15 OCPs (∑15OCPs) and 29 PCBs (∑29PCBs) varied between 1.93-61.9 and 0.81-44.2 ng/g wet weight (ww), respectively. Overall, the rank order of OCs was DDTs>PCBs>hexachlorocyclohexanes (HCHs)>chlordanes (CHLs). The patterns of PCBs showed maximum contribution of tri-CBs (59%). Ratios of individual HCH and DDT analytes contributing to the summed values indicated both recent and past use of these chemicals in the region, depending upon fish species. To assess the associated health risks, carcinogenic and non-carcinogenic risks were calculated through hazard ratios (HRs). For carcinogenic risk, HR was >1 at both 50th and 95th percentile concentrations, suggesting that the daily exposure to OCPs and PCBs yields a lifetime cancer risk of 1 in a million. HR for non-cancerous risk was <1 at both the percentiles, signifying no adverse effect by OCs exposure in native population.

High Resolution Consensus Mapping of Quantitative Trait Loci for Fiber Strength, Length and Micronaire on Chromosome 25 of the Upland Cotton (Gossypium hirsutum L.).

Cotton (Gossypium hirsutum L.) is an important agricultural crop that provides renewable natural fiber resources for the global textile industry. Technological developments in the textile industry and improvements in human living standards have increased the requirement for supplies and better quality cotton. Upland cotton 0-153 is an elite cultivar harboring strong fiber strength genes. To conduct quantitative trait locus (QTL) mapping for fiber quality in 0-153, we developed a population of 196 recombinant inbred lines (RILs) from a cross between 0-153 and sGK9708. The fiber quality traits in 11 environments were measured and a genetic linkage map of chromosome 25 comprising 210 loci was constructed using this RIL population, mainly using simple sequence repeat markers and single nucleotide polymorphism markers. QTLs were identified across diverse environments using the composite interval mapping method. A total of 37 QTLs for fiber quality traits were identified on chromosome 25, of which 17 were stably expressed in at least in two environments. A stable fiber strength QTL, qFS-chr25-4, which was detected in seven environments and was located in the marker interval between CRI-SNP120491 and BNL2572, could explain 6.53%-11.83% of the observed phenotypic variations. Meta-analysis also confirmed the above QTLs with previous reports. Application of these QTLs could contribute to improving fiber quality and provide information for marker-assisted selection.

Mass burden and estimated flux of heavy metals in Pakistan coast: sedimentary pollution and eco-toxicological concerns.

Heavy-metal contamination in coastal areas poses a serious threat to aquatic life and public health due to their high toxicity and bio-accumulation potential. In the present study, levels of different heavy metals (Cu, Cd, Cr, Ni, Co, Pb, Zn, and Mn), their spatial distribution, geochemical status, and enrichment indices (Cu, Cd, Cr, Ni, Co, Pb, Zn) were investigated in the sediment samples from 18 coastal sites of Pakistan. The analyses of coastal sediments indicated the presence of heavy metals in order such as Cr > Zn > Cu > Pb > Ni > Mn > Co > Cd. Geo-accumulation index (I geo), enrichment factor (EF), and contamination factor (CF) showed diverse range in heavy-metal enrichment site by site. Pollution load index (PLI) has shown that average pollution load along the entire coastal belt was not significant. Based on the mean effect range medium quotient, coastal sediments of Pakistan had 21% probability of toxicity. The estimated sedimentary load of selected heavy metals was recorded in the range of 0.3-44.7 g/cm(2)/year, while the depositional flux was in the range of 0.07-43.5 t/year. Heavy-metal inventories of 9.8 × 10(2)-3.8 × 10(5) t were estimated in the coastal sediments of Pakistan. The enrichment and contamination factors (EF and CF) suggested significant influence of anthropogenic and industrial activities along the coastal belt of Pakistan.

Influence of taxa, trophic level, and location on bioaccumulation of toxic metals in bird's feathers: a preliminary biomonitoring study using multiple bird species from Pakistan.

Increasing concentrations of heavy metals in the environment and their effects on ecosystems and biota is still an imminent threat, particularly in developing parts of the globe. The aim of the present study was to screen the heavy metal concentrations in multiple bird species across Pakistan and to preliminary evaluate the influence of taxa, trophic level, and geographical location on heavy metal accumulation in various bird species. For this purpose, we measured the concentration of 9 heavy metals (Pb, Cd, Cr, Ni, Co, Cu, Fe, Zn and Mn) in feathers of 48 bird species from different localities in Pakistan. Species exhibited heterogeneous levels of heavy metals in feathers with marked inter and intra specific variations. Mean concentrations of studied metals in feathers followed the trend Fe>Zn>Cu>Pb>Mn>Cr>Ni>Co>Cd. Species belonging to closely related taxa (families) showed comparable metal concentrations in their feathers, inferring potential phylogenetic similarities in metal exposure or accumulation. In general, concentrations of metals were greatest in carnivorous species followed by omnivorous and insectivorous birds, and granivores showing minimal levels (p<0.000). Furthermore, concentrations of metals varied significantly between locations (p<0.000) exhibiting highest concentrations in Punjab province and Baluchistan, probably due to higher industrial and agricultural activity and runoff, respectively. With certain limitation, influence of trophic level, taxonomic affiliation and sampling location of birds on toxic metal accumulation was also statistically corroborated through principal component analysis (PCA). This study highlights that despite restricted emissions, heavy metals persist in the local environment and may pose elevated risks for the studied bird species in Pakistan.

Spatial and interspecific variation of accumulated trace metals between remote and urbane dwelling birds of Pakistan.

The current study was designed to evaluate the hypothesis that birds of urbanized and/or industrialized origin depict higher metal accumulation as compared to remote dwellers. We selected seven representative species from three families (Anatidae, Motacillidae and Sturnidae) at two different locations; Baroghil valley (remote location) and Soan valley (urbanized location) of Pakistan and analyzed the concentrations of 8 metals Pb, Cd, Cr, Ni, Cu, Mn, Fe and Zn in feathers of these species. Feathers from Soan valley which is under higher anthropogenic influence exhibited significantly (P<0.001) higher metal concentrations when compared with the feathers of the same species at Baroghil valley which has negligible anthropogenic input. Terrestrial birds of the Baroghil valley revealed greater metal loads than aquatic birds while at Soan valley it was vice versa. In general, elevated concentrations of metals were recorded in insectivorous species as compared to omnivorous species. Within each location, species belonging to Anatidae and Motacillidae revealed similar metal contamination patterns. Principal component Analysis (PCA) based on correlation matrices depicted a clear tendency of metals towards the species originating from areas with greater pollution load (Soan valley) than relatively undisturbed sites (Baroghil valley) and hence corroborated our hypothesis. The pattern of metal accumulation in feathers of both the locations suggested that there may be a flux of migration between the two regions and/or trans-boundary movement of pollutants/metals, which either singly or synergistically influence the overall metal profile in the studied bird species.

Assessing the relationship and influence of black carbon on distribution status of organochlorines in the coastal sediments from Pakistan.

Levels of total organic carbon (TOC) and black carbon (BC) were determined together with those of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the selected eighteen coastal sites (n = 285) along the Arabian Sea from Pakistan. Results showed that the total concentration of TOC, BC, ∑OCPs and ∑26PCBs ranged between 0.3 and 2.9% dw, 0.1-0.2% dw, 0.9-110 ng g(-1) dw and 6.2-1200 ng g(-1) dw, respectively. Correlation analysis of BC (r = 0.26-0.89) and TOC (r = 0.06-0.69) revealed a stronger association with studied compounds. The sedimentary depositional fluxes (D) for ∑OCPs and ∑26PCBs were calculated as 1.7 and 4.9 tons yr(-1), respectively. In the coastal belt of Pakistan, sedimentary mass inventories (I) indicated the presence of 13 and 37 metric tons of ∑OCPs and ∑26PCBs, respectively.