Metal pollution and ecological risk assessment in marine sediments of Karachi Coast, Pakistan

Concentrations of 12 metals (Fe, Mn, Cr, Mo, Ni, Pb, Se, Sr, U, V, Zn, and Zr) in surface sediments of Karachi Coast, Pakistan were determined to evaluate their distribution and pollution assessment. The measured metals in the sediments were found to be in the range of Fe, 0.84–6.96 %; Mn, 300–1,300 μg/g; Cr, 12.0–319.84 μg/g; Mo, 0.49–2.03 μg/g; Ni, 1.53–58.86 μg/g; Pb, 9.0–49.46 μg/g; Se, 0.25–.86 μg/g; Sr, 192–1185 μg/g; U, 0.19–1.66 μg/g; V, 15.80–118.20 μg/g; Zn, 15.60–666.28 μg/g; and Zr, 44.02–175.26 μg/g. The mean contents of the metal studied were: Fe, 3.07 %, Mn, 0.05 %; Cr, 96.75 μg/g; Mo, 1.34 μg/g; Ni, 31.39 μg/g; Pb, 23.24 μg/g; Se, 0.61 μg/g; Sr, 374.83 μg/g; U, 0.64 μg/g; V, 61.75 μg/g; Zn, 204.75 μg/g; and Zr:76.27 μg/g, and arrangement of the metals from higher to lower mean content in this area is: Fe?>?Zn?>?Mn?>?Sr?>?Zn?>?Cr?>?Zr?>?V?>?Ni?>?Pb?>?Mo?>?U?>?Se. There is no significant correlation among most of these metals, indicating different anthropogenic and natural sources. To assess ecotoxic potential of marine sediments, Numerical Sediment Quality Guidelines were also applied. The concentration of Pb in all the sediments except one was lower than the threshold effect concentration (TECs) showing that there are no harmful effects to marine life from Pb. On the other hand, the concentrations of Cr, Ni, and Zn exceeded TEC in three stations, indicating their potential risk. The degree of pollution in sediments for metals was assessed by calculating enrichment factor (EF) and pollution load index (PLI). The results indicated that sediments of Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are highly enriched with Cr and Zn (EF?>?5). Sediments of Layari River Outfall Zone were moderately enriched with Ni and Pb (EF?>?2). The pollution load index was found in the range of 0.98 to 1.34. Lower values of PLI (≤1) at most of sampling locations imply no appreciable input from anthropogenic sources. However, relatively higher PLI values (>1) at Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are attributed to increased human activity in the area.     

Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements

The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid contents. Plants were treated with a combination of As, Pb, Cu, Cd, and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48–120 h. The pH and organic acids were detected in the mucilage dissolved from root surface, reflecting the rhizospheric solution. Also the pH of root–cell apoplasm was investigated. Both apoplasmic and mucilage pH increased and the concentrations of organic acids enhanced in the mucilage with slightly elevated levels of toxic elements. When organic acids concentration was high, also the pH was high. Thus, efflux of organic acids from the roots of E. angustifolium may induce rhizosphere basification.     

Health risk assessment of hexachlorocyclohexane in soil,water and plants in the agricultural area of Potohar region,Punjab, Pakistan

Environmental Geochemistry and Health - As the largest organ of the human body, the skin is the major exposure route of NO2. However, the evidence for a relationship between NO2 exposure and...     

Do transportation taxes promote pro-environmental behaviour? An empirical investigation

The transportation sector is a crucial driver of energy intensity and environmental degradation. Therefore, we aim to explore the nexus of transportation taxes, energy intensity, and CO₂ emissions for the BICS economies. The econometric approaches, CS-ARDL and PMG-ARDL, have been employed to compute the estimates. The long-run estimates of the green transportation tax variable are negatively significant in both energy intensity and CO₂ emissions models irrespective of the estimation technique. These findings imply that green transportation taxes help reduce energy intensity and CO₂ emissions in BICS economies. Conversely, in the short-run, the effects of transportation taxes on energy intensity and CO₂ emissions are mixed and inconclusive. Hence, transportation taxes are necessary to keep the polluters under control not only from the transport sector but also serve as a deterrent for other sectors as well.

     

Adsorption of pesticides by salorthids and camborthids of Punjab,Pakistan

This study was conducted to examine adsorption of pesticides bifenthrin, carbosulfan, λ-cyhalothrin, cypermethrin, endosulfan, parathion methyl, monocrotophos and 4-nitrophenol by sandy clay loam (S.C.L) and sandy loam (S.L) soils (with varying organic content). There was no significant difference between the observed soil water partitioning coefficient values (K _d) derived from linear and nonlinear Freundlich isotherms. Adsorption of pesticides on S.C.L soils was higher than those on S.L soils. K _d values showed significant correlations (r ²?=?0.8???0.99 and 0.65???0.97) with soil organic carbon content (OC) and weak correlations (r ²?=?0.2???0.29 and 0.1???0.18) with clay contents of S.C.L and S.L soil at p?≤?0.05, respectively for all pesticides (except monocrotophos). Observed K _oc values (soil-water partitioning constants based on the organic C fraction of the soil) were in accordance with the literature values of Wauchope and Tomlin with a maximum deviation of less than 0.5 log units. Ten Quantitative Property-Property Relationships (QPPR) among water solubility, n-octanol water coefficient (K _ow) and K _oc were proposed for studied pesticides except monocrotophos. The models were considered acceptable when predicted-observed difference for log?K _ow and log?K _oc were ≤?0.3 and ≤?0.5?log units, respectively, during the validation procedure. This work indicates that the log?K _oc derived from the log K_ow, from some of existing relationships, may be a fair predictor where observed values (i.e., K _d and K _oc) are not available. Furthermore, predicted leaching potential by groundwater ubiquity scores (GUS) equation was solved by using observed K _oc values and literature reported half lives of pesticides. GUS ranked the mobility of nonvolatile compounds i.e., bifenthrin, λ-cyhalothrin, cypermethrin and endosulfan extremely low; methyl parathion very low; 4-nitrophenol low; carbofuran and monocrotophos very high in S.C.L and S.L soils, respectively. Results discussed in this paper provide background to prioritize pesticides or chemical groups that should be evaluated under field conditions with regard to their leaching potential to groundwater in arid climates.     

Recent Progress in Silane Coupling Agent with Its Emerging Applications

Journal of Polymers and the Environment - This paper presents the effects of silane coupling agent, which includes interfacial adhesive strength, water treatment, polymer composites and coatings...     

Transforming an open dump into a sanitary landfill: a development effort in waste management

Upgrading a crude dump site into a sanitary landfill is a very challenging task; Matuail landfill site in Dhaka posed just such a challenge. From the very beginning, the existing disposal site had been used for the crude dumping of solid wastes. All types of solid wastes were haphazardly disposed of all over the site. The existing drainage channels of the dumping ground were not operational due to blockage by indiscriminate waste dumping. A large amount of leachate oozing out from the waste mixed with storm water and made the site esthetically very displeasing and environmentally unsound. This adverse situation sometimes caused disruption of the waste vehicular movement. Step-by-step improvement measures have been taken in the open dump to make it controlled and sanitary by adopting simple and locally available materials, technical guidelines, and construction techniques.     

Inulin–Niacin Conjugates: Preparation,Characterization, Kinetic and In Vitro Release Studies

Journal of Polymers and the Environment - Niacin, an essential B-complex vitamin, used in the treatment of nonalcoholic fatty liver disease is the first perceived lipid regulating medication,...     

Impact of population dynamics on Margalla Hills Ecosystem:a community-level case study

Margalla Hills National Park(MHNP) is a declared natural reserve of Pakistan,and Saidpur village is located at its foothills.To sustain livelihood,Saidpur community relies on natural resources and has established an intriguing relationship with the surrounding ecosystem.Human intrusion and related impacts were investigated through self-structured questionnaire from village community to gather information about demography,life practices,natural resource use,and their perception about the environment.Quadrat analysis revealed that the overall plant density was<4 plants/m~2,whereas ordination biplot has indicated significant reduction in plant cover and sparse distribution of species in areas close to human settlement.Survey results show that more than 50%families rely on forest wood as fuel source.Logistic regression has identified education paucity(odds ratio,OR=2.6,95%confidence interval,CI=1.0-6.7),large family size(OR= 5.0,95%CI=1.5-16.6),and fuel type(OR=3.5,95%CI=1.2-9.9)as significant predictors of accelerated forest cutting in MHNP.Male members were mostly illiterate and in favor to promote construction activities which reflects their low concern and casual attitude toward resource conservation.In this study,lack of awareness and peoples’ dependency on natural resources emerged as priority challenges,and hence,we suggest provision of alternate fuel sources,better education and sustained income resources as incentives to bring behavioral change.It is pivotal to involve local community before the adoption of any conservation plan as intervention strategy to protect MHNP ecosystem.