Unpolluted freshwater is a crucial component for maintaining the health of humans. This study aimed to investigate the bioaccumulation and potential health hazards of heavy metal contaminants (Fe, Cd, Cr, Cu, Pb) in water, sediments, and tissues of the golden mahseer fish (Tor putitora) from Zhob River to assess their suitability for human consumption. Samples (soil, water, and fish) were collected from the Zhob River, and Flame Atomic Absorption Spectrometry (FAAS) was employed to measure the concentration of these metals found in soil, water, and various fish body tissues (muscles, skin, gills, and liver). The overall results revealed that water quality parameters, i.e., temperature and pH were found within tolerable ranges, while electrical conductivity and turbidity exceeded the permissible limits of FAO/WHO for fish. Furthermore, this study also identified elevated concentrations of Pb in water and soil, as well as Fe and Cd in soil beyond the standards set by the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA). In contrast, the concentrations of other targeted metals examined in fish body tissues were found below the permissible limits set by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), indicating the suitability of this fish species for human consumption. The estimated daily intake (EDI) of these targeted metals in various fish body tissues was found to be within the recommended dietary allowance (RDA), suggesting no associated health risks for the local population. Furthermore, both the Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ) values measured in this study were less than one, indicating the absence of potential non-carcinogenic health risks related to the consumption of this riverine mahseer fish, but combined metal intake may pose potential health risks. Carcinogenic risk assessment for some metals like Cd, Cr, and Pb revealed no cancer risk for consumers. Moreover, our present research observed comparatively high bioaccumulation (BAF) of each targeted metal in the fish liver from both Zhob River water and soil as compared to other body tissues. Multivariate analysis, including the correlation matrix, revealed strong and significant correlations (P < 0.05) among heavy metal pairs (Fe/Cr, Fe/Pb, Cr/Fe, Cr/Pb, Pb/Fe, Pb/Cr). Hierarchical cluster analysis and Principal Component Analysis (PCA) were utilized to trace the origins of these metals, attributing their presence to nearby rock weathering, mining, as well as municipal and agricultural activities. These factors were recognized as potential sources of heavy metal bioaccumulation in riverine fish. Thus, our current study concluded that the Zhob River was contaminated with these heavy metals and emphasized the need to prevent domestic and industrial sewage inflow. The monitoring of these metals in the food chain was also underscored as crucial for reducing all kinds of associated health risks. This study provides the first report on heavy metal distribution in highly abundant and edible mahseer fishes of the Zhob River.

Mangrove ecosystem faces significant threats from the various pollutants including microplastic (MPs). The aim of this study was to assess variations in MP distribution in mangrove sediments of rhizosphere (R) and non-rhizosphere (NR) regions. A total of 14,960 MP particles were identified from Sandspit backwater (SS-1 & SS-2) and Creek areas (PQ & KC). Notably, the NR showed higher MP counts (7848) compared to the R region (7112). Analysis revealed variations in MP types, with beads being predominant in both R and NR, followed by film, fiber, and fragments. KC exhibited highest MP contamination, followed by PQ, SS-2, and SS-1. Fourier-transform infrared (FTIR) analysis confirmed the presence of polyethylene terephthalate and polyethylene in sediments samples. This first detailed report on MP in mangrove sediments and other limited studies from Pakistan establishes the widespread distribution of MPs in the coastal area and provide a baseline for further elaboration in future.

Introduction: Among other aquatic animals, fish can also accumulate a large number of toxic metals in their various body organs, which may enter in the human body and cause serious health issues. Therefore, the basic aim of this study was to observe the level of some heavy metals (i.e., Pb, Fe, Cu, Cd, Cr) found in the different tissues of Decapterus macarellus collected from the Karachi and Gwadar coasts of Pakistan.Methods: About 200 fish samples of five different size groups of Decapterus macarellus were collected from Gwadar and Karachi fish harbors during April to September 2020. Total 10 samples of each size group i.e., S1, S2, S3, S4 & S5 were collected from each coast. Heavy metals were analyzed in fish samples by using the atomic absorption spectrophotometer (AAS).Results: The overall results revealed that some metals like Cu, Pb, Cd & Cr contents were high in the stom-ach, while less in the muscles. Whereas, the concentration of Fe was found to be high in the liver, while low in skin of fish. The average values of bioaccumulation of these heavy metals (BAF) were found in decreasing order of Cu > Cd > Fe > Cr > Pb. In this study, except Cd and Cr, all metals were found within the permissible limits. Both sediment and water from the selected site areas were also analyzed to observe their pollution levels in the order of; sediment > water > fish tissues.Conclusion: Thus, it was concluded that the Karachi environment was much more polluted than the Gwadar environment because it is in an industrial unit and a busy sea site for trade. Moreover, consuming muscles from this species is safe for human health except for iron toxicity, but the use of the liver is not beneficial for all selected metals. Thus, the present work will also be helpful to monitor these toxic metals in a food chain and maintain a healthy life, and reduce all kinds of health risks associated with them.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The present study was aimed to assess the efficacy of individual and combined effects of novel fuller earth, rock phosphate, and biochar (grapefruit peel) at 1% dosage on maize plant growth, soil chemical properties anduptake of toxic metals (TMs), such as Cu, Zn, Fe, and Cd, by maize plant sown in Korangi (district of Karachi, Pakistan) heavily polluted and Korangi less polluted (K-HP and K-LP) soils. The obtained results indicate that the dry biomass of maize crop increased by 14.13% with combined (FE1% + GBC1%) on K-HP soil and 18.24% with combined (FE 1% + GBC 1%) effects on K-LP soil. The maximum immobilization of Cu, Zn, Fe, and Cd was observed by 36% with GBC1%, 11.90% with FE1%, 98.97% with combined RP1% + GBC1%, 51.9% with FE1% + GBC1% for K-HP, 11.90% with FE1%, 28.6% with FE1%, 22.22% with RP1% + GBC1%, and 57.05% with FE 1% + GBC 1% for K-LP soil. After the addition of proposed substances, modification of soil OM, SOC, TOC, and pH level appeared this lead to the changes in the phyto-availability of Cu, Zn, Fe, and Cd in maize plant. It was concluded that the application of individual and combined effects of novel fuller earth, rock phosphate, and biochar (grapefruit peel) have potential to stabilize pollutants from multi-metal polluted soils for safe crop production.

Coastal wetlands primarily serve as natural sinks of trace metals and their importance for phytoremediation is well known at global level. There are some reports on trace metal availability in soil sediments of the Karachi coast but studies on accumulation and translocation to harvestable (Shoot) parts among halophytes of the littoral zones have not been conducted. Hence, phytoremediation potential of six naturally existing halophytes (Aeluropus lagopoides, Arthrocnemum macrostachyum, Atriplex stocksii, Avicennia marina, Cressa cretica and Suaeda fruticosa) was assessed for cleaning metal (Mn, Zn, Pb and Cr) polluted soils of the Karachi coast. Seasonal (winters, pre and post-monsoon summers) and spatial (three littoral zones: viz., site – I: Sandspit, site – II: Do-Dariya/Clifton and site – III: Korangi creek) variations in soil and plant metals of the Karachi coast were studied. Soil Zn, Pb and Cr were generally higher in winters, Mn and organic matter in summers (7–11%) while pH values ranged between 7.15 and 7.5 in all seasons at site – III. All tested species had potential for cleaning Pb through their harvestable part (shoots) with A. stocksii as prominent candidate (16 mg kg−1) at site – I. Cressa cretica emerged as exclusive candidate for Zn phytoremediation (96 mg kg−1) at site – I, while S. fruticosa, A. macrostachyum and A. lagopoides showed bioaccumulation in pre-monsoon summers at site II. Aeluropus lagopoides with higher Mn in post monsoon summers (62 at site – III and 53 mg kg−1 at site – II) and Cr (7.1 mg kg−1 at site – II and 14 mg kg−1 at site – III) appeared exclusive bioindicator with potential of for cleaning all metals (Mn, Zn, Pb and Cr) at different sites. Metal bioaccumulation at study sites appeared species specific and varied seasonally among tested halophytes.

Yellow finned sea bream (Acanthopagrus arabicus) is a commercially important fish of coastal water of Pakistan. It is widely consumed by the people within and outside the country. Therefore, the paper investigates the concentration of macro-minerals (Ca, K, Mg and Na) in its meat and gills. The concentrations of different elements demonstrated statistically significant difference (P < 0.01) between meat and gills of the fish. Significantly higher concentrations of calcium and lower concentrations of potassium and sodium were recorded in gills compared to those in meat. In meat, mean concentrations were found in the order Na (5.41%) > K (3.44%) > Ca (2.16%) > Mg (0.24%), while in gills, the mean concentrations were Ca (57.72%) > Na (3.43%) > K (1.19%) > Mg (0.31%). Statistically significant correlations (P < 0.05) were noted between the body weight and the concentrations of calcium and magnesium in the meat of fish. The results are also compared with estimated daily intake and dietary reference intake values. The present study suggests that Acanthopagrus arabicus is an important source of macro-minerals for human consumption.

This study aimed at assessing heavy metals (Fe, Mn, Zn, Cu, Cr and Pb) in four perennial halophytes (viz. Heliotropium bacciferum, Halopyrum mucronatum, Ipomoea pes-caprae and Salsola imbricata) growing at two sites on the Karachi coast. Site - II, closer to the Industrial area had higher bioavailability as well as translocation factor (TF) for most of the heavy metals and Na+ where soil sediments had lower pH (approximately 7.5), higher salinity (EC) and organic matter (OM). Site - I which was far from Industrial area had comparatively higher bio-concentration factor (BCF) and lower TF for metal ions and soil pH of 8.1-9. Metal accumulation in plants was both site and species specific. Extractable concentration of shoot Pb in all tested halophytes was above normal of the threshold values (i.e., >0.3 mg kg-1) while Mn (<50 mg kg-1) and Cu (<40 mg kg-1) were within permissible limits. Salsola imbricata had highest Na+ at both sites (site - I = 73; site - II = 98 mg kg-1) with and 10 mg kg-1 extractable shoot Pb at site - I. Ipomea pes-caprae also accumulated shoot Pb higher than normal (site - I = 3.3; site - II = 0.8 mg kg-1) with lowest Na+ content. Heliotropium bacciferum had higher extractable Pb (site - I = 10.5; II = 2.75) with >20 mg kg-1 Na+ in shoot while maintaining > 1 TF for Pb, Cu, Mn and Zn at site - I and all tested metals at site - II. Halopyrum mucronatum had highest shoot Fe (644 mg kg-1), Zn (63 mg kg-1) and Cr (9.2 mg kg-1) at site - II and above threshold values of Pb at both sites (site - I = 8.2; site - II = 2.5 mg kg-1) which makes this species an ideal bio-indicator candidate while other species could be potentially used for Pb phytoremediation.

This study assesses the fluoride adsorption characteristics of red brick paving blocks or red pavers which is locally available and a cheap potential adsorbent for defluoridation. Batch experiments were conducted to evaluate basic parameters such as pH, contact time, dosage, and adsorbent capacity. The adsorption data were incorporated with kinetics (Lagergren pseudo-orders) and isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich [DR], and Temkin) to comprehend the mechanism and types of adsorption. The data recorded in the study agreed with the applied models. The mechanism of interaction between red paver and fluoride was of complex nature as Freundlich and DR isotherm models suggest that adsorption is physisorption with little ion exchange mechanism while Lagergren's pseudo-second order kinetics and Langmuir isotherm model outlined that adsorption could be chemisorption. The highest percentage of fluoride removal was achieved at pH range of 6-7 with 62% removal. Elemental and mineral phases on red paver before adsorption were characterized by X-ray diffraction and wavelength dispersive X-ray fluorescence and WD-XRF, major elemental and mineral components were CaO, Fe2O3, SiO2 and Al2O3 and ankerite, dolomite, calcite, and lime, respectively.

. This study reveals chemical and physical properties of soils collected from a remote site at Karachi, Pakistan. Altogether 23 parameters were determined. Out of 12 soil samples 11 were categorised as sand or sandy loams, pH varied between 7.35-8.49, density ranged between 1.61-2.39 gm/cm 3 , the conductivity of 1:2 water extracts varied up to a great extent i.e., between 0.437-16.47 mS/m 3 . Sodium (Na) contents were higher in ammonium acetate extract when compared with 1:2 water extract. The bicarbonate (HCO 3 ) contents were ranged between 0.17-1.73 ppm. The organic matter contents were low (0.81-2.21%); these soils were also deficient in their macronutrient contents. Specifically, the ranges of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S) were 0.04-1.16%, 0.25-15.99 ppm, 4.40-135.89 ppm, 0.001-0.199%, 0.001-0.019% and 0.01-0.143%, respectively. Heavy metals were determined in diethylene-triamine-pentaacetic acid (DTPA) extracts and the levels of iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn) in these samples were 1.86-32.80 ppm, 1.68-7.69 ppm, 16.51-75.28 and 0.25-20.75 ppm, respectively. Toxic heavy metals, lead (Pb) and nickel (Ni) contents were also estimated and their concentration was found low ranging between 0.91-5.63 ppm and 0.32-1.26 ppm, respectively.

This study reveals the water quality of Hab River which is the primary source of water supply for Hab City of Baluchistan Province, Pakistan and is also one of the major sources providing water to the mega city of Karachi. The quality of Hab River water is continuously declining owing to the accumulation of industrial effluents of Hab Trading Estate (HTE) and other domestic and agricultural waste. Altogether, 17 samples of water were collected from the study area in pre monsoon and post monsoon seasons and the Physico-chemical parameters like PH, TDS, Turbidity, Salinity, Ca, Mg, Na, K, Cl and SO4 were evaluated. Spatial analysis of PH, TDS, Salinity and Turbidity has also been carried out by conducting interpolation technique in GIS. This analysis spatially explains the differences in different parameters in pre and post-monsoon period. According to Quantitative Indicator (QI), most of the water bodies have crossed the maximum threshold limits defined by WHO guidelines and have entered in to impaired water category.

We report data from a yearlong (2006–2007) study of black carbon concentrations ([BC]) measured at 5-min intervals with an Aethalometer in Karachi, Pakistan. Daily mean [BC] varied from about 1 to 15μgm−3. However, short-term spikes exceeding 40μgm−3 were common, occurring primarily during the morning and evening rush-hour periods. The [BC] values were highest during November through February, ∼10μgm−3, and lowest during June through September, ∼2μgm−3. Diurnal, seasonal, and day-of-the-week trends are discussed. It is demonstrated that these trends are strongly affected by meteorological patterns. A simple expression is applied to the concentration profiles to separate the effects of meteorological conditions and elucidate the underlying emissions patterns. Daily emissions varied from 14,000 to 22,000kg of BC per day. When integrated over the year emissions for Karachi Proper were estimated at 6.7 kilometric tons per year and emissions for greater Karachi were 17.5 kilometric tons per year. Folding in the populations of each area yields BC emissions of 0.74 and 1.1kg per person per year, respectively. Applying the model to previously collected data at Lahore, Pakistan yields emissions during November–January that are around a factor of two higher than those in Karachi, but because the BC measurements in Lahore covered only three months, no estimates of annual emissions were attempted. Given the large populations of these cities the local health impact from PM alone is expected to be severe but because of the high [BC] emissions the impact on the global climate may be equally significant.

The concentration of fluoride (F) in groundwater samples of district Tharparkar was determined, which is the largest arid region of Sind province. Various other water quality parameters such as pH, EC, TDS, Ca, Mg, Na, K, Cl, SO4, HCO3, were also measured. On the basis of these results, the groundwater of dist. Tharparkar can be characterized according to Rabinove, et al., classification of salinity as moderately to highly saline and according to Durfor, Beaker's classification of total hardness, these samples may be characterized as hard to very hard. A systematic calculation of correlation coefficient among fluoride and other physicochemical parameters was performed, a significant -ve correlation was observed for F and Ca, Ca/F ratio, Mg, HCO3, & Cl contents of district Tharparkar. The fluoride concentration in the groundwater samples of this region varied from (0.93-11.8) mg/L. 27 samples out of 33 were found to have higher fluoride contents as compared to WHO Guideline value of 1.5 ppm. These elevated levels of fluoride are putting the population at a high risk of dental and skeletal fluorosis and other severe problems associated with fluoride.