Search

This study aims to assess ecological risks from heavy metal atmospheric deposition in the Indus River at Kotri Barrage, Sindh, Pakistan. Monitoring occurred at four locations, yielding 40 air samples analyzed for heavy metals via Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (TQ-ICP-MS). Pollution indicators, including Contaminant Factor (CF), Degree of Contamination (CD), Geo-accumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and Nemerow Integrated Pollution Index (NIPI), quantified contaminant levels. Air monitoring revealed PM2.5 concentrations exceeding regulatory guidelines at all four sites. Heavy metal mean concentrations ranked as follows: Fe > Cr > Pb > Mn > As > Cu > Ni > Cd > Mo > Co, and deposition fluxes followed this order: Fe > Pb > Cr > Mn > As > Cu > Ni > Cd > Mo > Co. Pollution indices indicated moderate to extreme pollution for Fe, Cr, Cd at all sites, and Pb at site D. Emissions from a nearby coal-fired power plant and vehicular sources were identified as primary contributors to high heavy metal deposition. The Ecological Risk Index ranged from 150 to 600, signifying substantial ecological risk linked to Cd. These findings offer crucial insights for governmental agencies and policymakers to address pollution issues arising from heavy metal atmospheric deposition in the Indus River near Kotri Barrage. [ABSTRACT FROM AUTHOR]

Achievement of thermal comfort in air conditioning is a vital issue in the verge of global warming, where it is essential to provide a system that is less harmful to the environment, energy-efficient and economical. In this regard, dehumidification plays an important role in achieving thermal comfort of air conditioning system. Most of the dehumidification systems as of now require high energy and induce negative environmental impacts. Recently a vacuum membrane-based dehumidification has been considered for the alternative air-conditioning system. Development of efficient membranes for the dehumidification operation is indispensable for moisture removal. Typically, the membrane is constructed out of a fine and porous twilled Dutch weave stainless steel wire mesh serving as the support structure laminated with a film of active materials that serve to attract and isolate the moisture from the working air. In this work a combination of nanomaterial and hygroscopic polymer was adopted to improve the film functionality on the wire mesh. In particular, titanium dioxide (TiO2) is coated as intermediate layer on the wire mesh. Further, Polyvinyl alcohol (PVA) and various concentration of potassium formate (KCOOH) were used as the active additive material aiming to increase sensitivity of the membrane towards water vapor. The water vapor and air permeability tests were conducted to investigate the water vapor permeation and air selectivity of the membrane under various air conditions. Morphological and permeance analogy of the produced membrane showed that adding KCOOH enhanced hydrophilicity, which also increased water vapor permeability by 720%. [ABSTRACT FROM AUTHOR]

Fouling is defined as unwanted deposition on the heat exchanger surfaces which retards the heat transfer and declines its performance. In this investigation calcium carbonate (CaCO3) fouling mitigation was achieved by adding clove-treated multiwall carbon nanotubes (C-MWCNT) additive at three variable concentrations (i.e., 0.0143%, 0.0071%, and 0.0036% mass). Water based C-MWCNT nanofluid was selected for its ability to resist the foulant deposition without imposing any corrosion on the heat exchanger surfaces. MWCNT was functionalized with clove extracts for obtaining its suspension in distilled water. After functionalization, thermo-physical properties of all the three different C-MWCNT concentrations of nanofluid and water were investigated with Thermal conductivity meter, density meter, and viscosity meter, which demonstrated the increase in density and thermal conductivity with the increase of C-MWCNT concentration. After that fouling investigation was conducted at a constant heat flux boundary condition where the supersaturated solution of CaCO3 at 300 mg L−1 was used as a fouling liquid. After the fouling experiments, the test coupon was dismantled from the test section for morphological study of the fouling deposits. Field Emission Scanning Electronic Microscopy (FESEM) was used to investigate the morphology of the deposits. The results of CaCO3 mass deposition at variable concentrations of C-MWCNT such as 0%, 0.0143%, 0.00714%, and 0.00357% were 0.1652 g, 0.0993 g, 0.0805 g, and 0.0 584 g respectively, which revealed the inverse relationship between the concentration of water-based C-MWCNT nanofluid and the deposition of CaCO3 foulants on the heat transfer surfaces. [ABSTRACT FROM AUTHOR]

A wide range of industrial processes (i.e., evaporation and condensation in desalination process, steam power plant, solar plant, etc.) involve heat transfer among the fluids. During the process of evaporative and cooling heat transfer, undesirable materials from the fluids accumulate on the surfaces, which critically reduces the performance of heat exchangers and creates one of the biggest challenges in energy transfer. Though the various studies on prediction and removal of fouling was conducted by numerous scientists, this problem is still unresolved in industrial process and is responsible for huge environmental damage and economic losses. This investigation provides a comprehensive overview of crystallization fouling in heat exchangers. Various factors affecting the deposition of crystallization foulaning such as fluid temperature, flow velocity, surface material and roughness, concentration and boiling are systematically reviewed. Accuracy and uncertainty of different equipment and experimental studies are discussed. In addition, fouling modelling is comprehensively discussed from earlier fundamental model to recent computational fluid dynamic and artificial neural networks model. Furthermore, mitigation of fouling with off-line and online approaches are chronologically discussed. Finally, an overview from environmental and economic prospective of fouling in heat exchangers are discussed. The future directions for crystallization fouling in heat exchangers are emphasized, which will support the researchers and industries to retard fouling and achieve economic benefits. [ABSTRACT FROM AUTHOR]

Manchar Lake, Pakistan’s biggest lake in the arid zone, faces human-induced salinity issues. This study investigated its effects on the multifaceted ecosystem services, including serving as a source of drinking and irrigation water and aquatic health through assessing fish diversity and characteristics. Analyses of 189 water samples from 21 sites revealed spatiotemporal variations in major ions contributing to lake water salinity. The study assessed water suitability for drinking and agriculture using the water quality index (WQI), sodium adsorption ratio (SAR), magnesium hazard (MH), sodium percent (Na%), and Kelly’s ratio (KR). The WQI, ranging from 141 to 408, indicated that the lake water was unfit for drinking. In some seasons, such as the pre-monsoon period, the lake water was deemed unsuitable for irrigation due to high SAR values (18 ± 4 g/L, average ± standard deviation), consistently rising MH values exceeding 66 in all seasons and elevated sodium percentages surpassing 66% in both the pre-monsoon and monsoon seasons. The KR remained acceptable (averaging 0.8 to 2.5) in all seasons. Fish health in highly saline conditions was assessed using data from interviews, focus group discussions, and fish sampling (1684 fish from 10 sites). Results depicted that high salt contamination severely impacted fish length and weight. The study found low richness (Simpson’s biodiversity: 0.697 and Shannon Weaver: 1.51) and evenness (Pielou’s index: 0.48) among the fish populations. Since 1998, Manchar Lake has seen a decline in fish varieties from 32 to 23, with changes in fish species’ feeding habits. To improve lake water quality, the study recommends diverting saline water to the sea before and after the monsoon season while utilizing freshwater from alternative sources to fill any water deficit. [ABSTRACT FROM AUTHOR]

Preserving the ecological health of wetlands has enormous importance in an arid climate. Manchar Lake, located in the arid part of Pakistan, is one of the most vulnerable freshwater lakes and has continuously been exposed to direct pollutants influx. Its vulnerability demands an assessment of pollution loads of trace elements in bed sediments. This study was carried out with sediment samples from 21 locations. Nine trace elements (As, Pb, Fe, Cr, Hg, Cu, Ni, Mn, and Zn) were detected using Inductively Coupled Plasma Mass Spectrometry. Pollution load-related analytical approaches were applied to estimate the contamination loads of individual elements and the aggregated ecological risks. Overall, the mean concentrations of all trace elements in lakebed sediments were detected as: As 5.4, Pb 2.2, Cr 17, Cu 1.5, Fe 165.1, Hg 0.028, Mn 2.6, Ni 7.5, and Zn 64.9 in mg/kg. Results revealed that the lakebed sediment is significantly polluted, primarily with Fe, Zn, Hg, Cr, and As. The spread of these trace elements also varies across locations as many locations do not receive polluted water during dry seasons due to the low water level in the lake. The ecological risk assessment and multivariate analysis findings establish that the Main Nara Valley Drain comprising drainage water from agricultural fields and in part from municipalities is the greatest pollution source to the lake. This dangerous pollution problem calls for action to restore the purity of the natural lake ecosystem. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effectiveness and safety of suprachoroidal versus intravitreal Triamcinolone Acetonide in cases of resistant diabetic macular edema. Study Design: Quasi experimental study. Place and Duration of Study: This research was executed at Retina Department of Al-Ibrahim Eye Hospital, Karachi, Pakistan, from January 2022 to June 2022. Methods: Thirty-four patients with resistant diabetic macular edema were selected through convenient sampling and divided equally into two groups. All patients underwent ocular examination. Group I was given single Intravitreal injection (IVI) of 0.1 mL Triamcinolone Acetonide at 4 mg per 0.1 mL concentration. Group II received same dosage of drug via Suprachoroidal injection (SCI). After 24 hours, they were assessed for side effects. After 6 weeks, second dose of same drug was administered. Patients were followed at 3 and 6 months. Results: No serious side effect was observed in any patient within 24 hours. At 1 month follow-up period, comparison between the two groups for BCVA, CMT and IOP was not significant (p > 0.05). When the two groups were compared at 3 months, both routes were equally effective but IOP remained more stable via SCI route. At 6 months, IOP remained elevated in group I but decreased in group II (p = 0.003). Conclusion: Triamcinolone Acetonide was effective by both routes in resistant diabetic macular edema in terms of improved BCVA and CMT but SCI was better in terms of IOP and cataract progression. [ABSTRACT FROM AUTHOR]

Keenjhar Lake in Pakistan provides several ecosystems services including drinking water to millions of people. The seasonal variation (pre-, during, and post-monsoon) in Keenjhar Lake water quality was investigated during nine sampling rounds at ten locations. Water samples (n = 270) were analyzed for As, Cd, Cr(III), Cu, Fe, Hg, Mn, Ni, and Pb using atomic absorption spectrophotometry, Cr(VI) with a UV spectrophotometer, and water quality parameters (solids, oxygen, conductivity, and pH). Several elements exceeded WHO or Pakistan safe limits for unrestricted use including As (0.038 mg·L−1, 95th upper confidence limit), Cr(III) (0.15 mg·L−1), Cd (0.11 mg·L−1), Fe (0.42 mg·L−1), Ni (0.037 mg·L−1), and Pb (0.04 mg·L−1). Monsoon levels of chromium, Cu, Fe, Mn, and Pb were higher than other seasons, while As was highest during post-monsoon, and Ni was highest during pre and post-monsoon. There were significant spatial differences in metals concentrations in the lake. As, Cu, and Fe significantly declined in concentration with distance from the lake inlet. Using the lake as a source of drinking water presented unacceptable carcinogenic risk and non-carcinogenic hazards. This study suggests measures should be taken to limit discharge of pollution to the lake and future monitoring should consider seasonal monsoon effects on lake quality. [ABSTRACT FROM AUTHOR]