Levels,distribution profile,and risk assessment of polychlorinated biphenyls (PCBs) in water and sediment from two tributaries of the River Chenab,Pakistan

The first study aimed to investigate the polychlorinated biphenyl (PCB) concentration level, spatial distribution pattern, and ecological risk assessment of water and sediment samples from two tributaries (Nullah Aik and Palkhu) of the River Chenab, Punjab Province, Pakistan. A total of 32 PCB congeners were analyzed, and PCB concentration in sediment and water samples ranged between 0.80 and 60 ng/g and 0.20 and 28 ng/L, respectively, where tetra-CBs and tri-CBs dominated over other studied PCB homologs. Dioxin toxicity equivalency (TEQ) was calculated and PCB-126 and PCB-169 showed the higher TEQ values compared with the WHO guidelines, and sediment samples were more toxic than the water samples. The results of the present study should be considered seriously by government authorities to take a proper action against unchecked discharge of contaminants in ecological integrities; otherwise, there may be drastic results in the near future.     

Aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in peninsular Malaysia

An aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in river water corresponding to five villages situated in three states in peninsular Malaysia was determined. There were 51.3 % (20/39) and 23.1 % (9/39) samples positive for Giardia and Cryptosporidium (oo)cysts, respectively. Overall mean concentration between villages for Giardia cysts ranged from 0.10 to 25.80 cysts/l whilst Cryptosporidium oocysts ranged from 0.10 to 0.90 oocysts/l. Detailed results of the river samples from five villages indicated that Kuala Pangsun 100 % (9/9), Kemensah 77.8 % (7/9), Pos Piah 33.3 % (3/9) and Paya Lebar 33.3 % (1/3) were contaminated with Giardia cysts whilst Cryptosporidium (oo)cysts were only detected in Kemensah (100 %; 9/9) and Kuala Pangsun (66.6 %; 6/9). However, the water samples from Bentong were all negative for these waterborne parasites. Samples were collected from lower point, midpoint and upper point. Midpoint refers to the section of the river where the studied communities are highly populated. Meanwhile, the position of the lower point is at least 2 km southward of the midpoint and upper point is at least 2 km northward of the midpoint. The highest mean concentration for (oo)cysts was found at the lower points [3.15?±?6.09 (oo)cysts/l], followed by midpoints [0.66?±?1.10 (oo)cysts/l] and upper points [0.66?±?0.92 (oo)cysts/l]. The mean concentration of Giardia cysts was highest at Kuala Pangsun (i.e. 5.97?±?7.0 cysts/l), followed by Kemensah (0.83?±?0.81 cysts/l), Pos Piah (0.20?±?0.35 cysts/l) and Paya Lebar (0.10?±?0.19 cysts/l). On the other hand, the mean concentration of Cryptosporidium oocysts was higher at Kemensah (0.31?±?0.19 cysts/l) compared to Kuala Pangsun (0.03?±?0.03cysts/l). All the physical and chemical parameters did not show significant correlation with both protozoa. In future, viability status and molecular characterisation of Giardia and Cryptosporidium should be applied to identify species and genotypes/subgenotypes for better understanding of the epidemiology of these waterborne parasites.     

Hydrogen sulfide ameliorates lead-induced morphological, photosynthetic, oxidative damages and biochemical changes in cotton

Poisonous lead (Pb), among heavy metals, is a potential pollutant that readily accumulates in soils and thus adversely affects physiological processes in plants. We have evaluated how exogenous H₂S affects cotton plant physiological attributes and Pb uptake under Pb stress thereby understanding the role of H₂S in physiological processes in plants. Two concentrations (0 and 200 μM) of H₂S donor sodium hydrosulfide (NaHS) were experimented on cotton plants under Pb stress (0, 50, and 100 μM). Results have shown that Pb stress decreased plant growth, chlorophyll contents, SPAD value, photosynthesis, antioxidant activity. On the other hand, Pb stress increased the level of malondialdehyde (MDA), electrolyte leakage (EL), and production of H₂O₂ and uptake of Pb contents in all three parts of plant, viz. root, stem, and leaf. Application of H₂S slightly increased plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity as compared to control. Hydrogen sulfide supply alleviated the toxic effects of lead on plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity in cotton plants. Hydrogen sulfide also reduced MDA, EL, and production of H₂O₂ and endogenous Pb levels in the three mentioned plant parts. On the basis of our results, we conclude that H₂S has promotive effects which could improve plant survival under Pb stress.     

Water pollution in Pakistan and its impact on public health--a review

Water pollution is one of the major threats to public health in Pakistan. Drinking water quality is poorly managed and monitored. Pakistan ranks at number 80 among 122 nations regarding drinking water quality. Drinking water sources, both surface and groundwater are contaminated with coliforms, toxic metals and pesticides throughout the country. Various drinking water quality parameters set by WHO are frequently violated. Human activities like improper disposal of municipal and industrial effluents and indiscriminate applications of agrochemicals in agriculture are the main factors contributing to the deterioration of water quality. Microbial and chemical pollutants are the main factors responsible exclusively or in combination for various public health problems. This review discusses a detailed layout of drinking water quality in Pakistan with special emphasis on major pollutants, sources of pollution and the consequent health problems. The data presented in this review are extracted from various studies published in national and international journals. Also reports released by the government and non-governmental organizations are included.     

Hydrocarbon degradation, plant colonization and gene expression of alkane degradation genes by endophytic Enterobacter ludwigii strains

The genus Enterobacter comprises a range of beneficial plant-associated bacteria showing plant growth promotion. Enterobacter ludwigii belongs to the Enterobacter cloacae complex and has been reported to include human pathogens but also plant-associated strains with plant beneficial capacities. To assess the role of Enterobacter endophytes in hydrocarbon degradation, plant colonization, abundance and expression of CYP153 genes in different plant compartments, three plant species (Italian ryegrass, birdsfoot trefoil and alfalfa) were grown in sterile soil spiked with 1% diesel and inoculated with three endophytic E. ludwigii strains. Results showed that all strains were capable of hydrocarbon degradation and efficiently colonized the rhizosphere and plant interior. Two strains, ISI10-3 and BRI10-9, showed highest degradation rates of diesel fuel up to 68% and performed best in combination with Italian ryegrass and alfalfa. All strains expressed the CYP153 gene in all plant compartments, indicating an active role in degradation of diesel in association with plants.     

Molecular characterization of conjugative plasmids in pesticide tolerant and multi-resistant bacterial isolates from contaminated alluvial soil

A total of 35 bacteria from contaminated soil (cultivated fields) near pesticide industry from Chinhat, Lucknow, (India) were isolated and tested for their tolerance/resistance to pesticides, heavy metals and antibiotics. Bacterial isolates were identified by 16S rDNA sequencing. Gas Chromatography analysis of the soil samples revealed the presence of lindane at a concentration of 547 ng g⁻¹ and α-endosulfan and β-endosulfan of 422 ng g⁻¹ and 421 ng g⁻¹ respectively. Atomic Absorption Spectrophotometry analysis of the test sample was done and Cr, Zn, Ni, Fe, Cu and Cd were detected at concentrations of 36.2, 42.5, 43.2, 241, 13.3 and 11.20 mg kg⁻¹ respectively. Minimum inhibitory concentrations of all the isolates were determined for pesticides and heavy metals. All the multi-resistant/tolerant bacterial isolates were also tested for the presence of incompatibility (Inc) group IncP, IncN, IncW, IncQ plasmids and for rolling circle plasmids of the pMV158-family by PCR. Total community DNA was extracted from pesticide contaminated soil. PCR amplification of the bacterial isolates and soil DNA revealed the presence of IncP-specific sequences (trfA2 and oriT) which was confirmed by dot blot hybridization with RP4-derived DIG-labelled probes. Plasmids belonging to IncN, IncW and IncQ group were neither detected in the bacterial isolates nor in total soil DNA. The presence of conjugative or mobilizable IncP plasmids in the isolates indicate that these bacteria have gene transfer capacity with implications for dissemination of heavy metal and antibiotic resistance genes. We propose that IncP plasmids are mainly responsible for the spread of multi-resistant bacteria in the contaminated soils.     

Characterization of polychlorinated biphenyls and brominated flame retardants in surface soils from Surabaya, Indonesia

In this study, soil contamination by PCBs, PBDEs, HBCDs and two novel BFRs such as 1,2-bis-(2,4,6-tribromopenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE) in various locations such as industrial, urban, rural, dumping site and agricultural areas of Surabaya, Indonesia has been characterized in order to evaluate their contamination status, profiles, potential sources, fate and behavior. Range and median concentrations of PCBs, PBDEs, HBCDs, BTBPE and DBDPE were ND - 9.6 (1.2), 0.069 - 24 (7.4), ND - 1.8 (0.48), ND - 1.7 (0.14) and ND - 7.6 (2.2) ng g⁻¹ dw, respectively. Industrial, urban and dumping areas were inventoried as the main sources of these pollutants. Decreasing gradient levels were observed for these contaminants from industrial district, urban, dumping site, rural and agricultural areas, in that order. Furthermore, organic carbon contents and proximity to the point sources were found as the major controlling factors. Contaminant profiles were characterized by the predominance of hexa-, hepta- and penta-homologues for PCBs; deca-, nona- and octa- for PBDEs and α-isomer for HBCDs. Product mixtures such as Ar1260/KC600 and Ar1254/KC500 for PCBs, deca- and octa-BDEs for PBDEs were the possible common formulations used in study area. To our knowledge, this is a first comprehensive study on characterization of soil contamination by PCBs, PBDEs and HBCDs together with two novel BFRs in a highly industrialized city located in tropical region. This study provides baseline information for establishing national monitoring programs in Indonesia.     

Optimal deployment of emissions reduction technologies for construction equipment

The objective of this research was to develop a multiobjective optimization model to deploy emissions reduction technologies for nonroad construction equipment to reduce emissions in a cost-effective and optimal manner. Given a fleet of construction equipment emitting different pollutants in the nonattainment (NA) and near -nonattainment (NNA) counties of a state and a set of emissions reduction technologies available for installation on equipment to control pollution/emissions, the model assists in determining the mix of technologies to be deployed so that maximum emissions reduction and fuel savings are achieved within a given budget. Three technologies considered for emissions reduction were designated as X, Y, and Z to keep the model formulation general so that it can be applied for any other set of technologies. Two alternative methods of deploying these technologies on a fleet of equipment were investigated with the methods differing in the technology deployment preference in the NA and NNA counties. The model having a weighted objective function containing emissions reduction benefits and fuel-saving benefits was programmed with C++ and ILOG-CPLEX. For demonstration purposes, the model was applied for a selected construction equipment fleet owned by the Texas Department of Transportation, located in NA and NNA counties of Texas, assuming the three emissions reduction technologies X, Y, and Z to represent, respectively, hydrogen enrichment, selective catalytic reduction, and fuel additive technologies. Model solutions were obtained for varying budget amounts to test the sensitivity of emissions reductions and fuel-savings benefits with increasing the budget. Different mixes of technologies producing maximum oxides of nitrogen (NO(x)) reductions and total combined benefits (emissions reductions plus fuel savings) were indicated at different budget ranges. The initial steep portion of the plots for NO(x) reductions and total combined benefits against budgets for different combinations of emissions reduction technologies indicated a high benefit-cost ratio at lower budget amounts. The rate of NO(x) reductions and the increase of combined benefits decreased with increasing the budget, and with the budget exceeding certain limits neither further NO(x) reductions nor increased combined benefits were observed. Finally, the Pareto front obtained would enable the decision-maker to achieve a noninferior optimal combination of total NO(x) reductions and fuel-savings benefits for a given budget.     

Removal of selected endocrine disrupting chemicals and personal care products in surface waters and secondary wastewater by ozonation

This study investigated the removal of parabens, N,N-diethyl-m-toluamide (DEET), and phthalates by ozonation. The second-order rate constants for the reaction between selected compounds with ozone at pH 7 were of (2.2 +/-0.2) X 10(6) to (2.9 +/-0.3) X 10(6) M 1/s for parabens, (2.1+/- 0.3) to (3.9 +/-0.5) M-1/s for phthalates, and (5.2 +/-0.3) M-1/s for DEET. The rate constants for the reaction between selected compounds with hydroxyl radical ranged from (2.49 +/-0.06) x 10(9) to (8.5 +/-0.2) x 10(9) M-1/s. Ozonation of selected compounds in secondary wastewater and surface waters revealed that ozone dose of 1 and 3 mg/L yielded greater than 99% depletion of parabens and greater than 92% DEET and phthalates, respectively. In addition, parabens were found to transform almost exclusively through the reaction with ozone, while DEET and phthalates were transformed almost entirely by hydroxyl radicals (.OH).     

Comparative effect of organic amendments on physio-biochemical traits of young and old bean leaves grown under cadmium stress: a multivariate analysis

Environmental Science and Pollution Research - The current study investigated the influence of organic amendments on cadmium (Cd) uptake and its effects on biochemical attributes of young and old...