Concentrations, input prediction and probabilistic biological risk assessment of polycyclic aromatic hydrocarbons (PAHs) along Gujarat coastline.

A comprehensive investigation was conducted in order to assess the levels of PAHs, their input prediction and potential risks to bacterial abundance and human health along Gujarat coastline. A total of 40 sediment samples were collected at quarterly intervals within a year from two contaminated sites-Alang-Sosiya Shipbreaking Yard (ASSBRY) and Navlakhi Port (NAV), situated at Gulf of Khambhat and Gulf of Kutch, respectively. The concentration of ΣPAHs ranged from 408.00 to 54240.45 ng g-1 dw, indicating heavy pollution of PAHs at both the contaminated sites. Furthermore, isomeric ratios and principal component analysis have revealed that inputs of PAHs at both contaminated sites were mixed-pyrogenic and petrogenic. Pearson co-relation test and regression analysis have disclosed Nap, Acel and Phe as major predictors for bacterial abundance at both contaminated sites. Significantly, cancer risk assessment of the PAHs has been exercised based on incremental lifetime cancer risks. Overall, index of cancer risk of PAHs for ASSBRY and NAV ranged from 4.11 × 10-6-2.11 × 10-5 and 9.08 × 10-6-4.50 × 10-3 indicating higher cancer risk at NAV compared to ASSBRY. The present findings provide baseline information that may help in developing advanced bioremediation and bioleaching strategies to minimize biological risk.

Polycyclic aromatic hydrocarbons (PAHs) at the Gulf of Kutch, Gujarat, India: Occurrence, source apportionment, and toxicity of PAHs as an emerging issue.

The present study extrapolates the assessment and characterization of a barely studied region, the Gulf of Kutch, (near Jamnagar), Gujarat, India, in terms of PAH exposure, adverse effects caused by them, and various toxicological indices showing the catastrophic effects of their elevated concentrations. ΣPAH concentration in the site ranged from 118,280 to 1,099,410ngg-1 dw, with a predominance of 2-3-ring PAHs (79.09%) as compared to 4-5- and 6-ring PAHs (20.91%). The concentrations of carcinogenic PAHs were found to be between 8120 and 160,000ngg-1 dw, with a mean of 63,810ngg-1 dw, which is much higher than normal acceptable values. The toxic equivalent quotient for 6CPAHs ranged from 150.47 to 26,330ngg-1 BaPeq, encompassing 50.63% of ΣPAH toxicity. This toxicological profile of the present study site would be of paramount importance as it offers fresh information regarding the load of legacy pollutants such as PAHs and the inputs and methods to cope with their extremely high concentrations in less explored marine habitats.

Distribution, sources and ecological risk assessment of PAHs in historically contaminated surface sediments at Bhavnagar coast, Gujarat, India.

The concentration, distribution and ecological risk of polycyclic aromatic hydrocarbons (PAHs) have been investigated in surface sediments near Bhavnagar coast. The concentration of ∑PAHs ranged from 5.02 to 981.18 µg g(-1) dry weight, indicating heavy pollution compared to other historically polluted study sites. It was found to be introduced via mixed origins such as burning of gas, oil, coal, production of petrochemicals, cement, and rubber tires. Domestic fuel burning and motor vehicles are also culprits for air pollution. Industrial effluents and accidental oil spillage can also be considered. PAHs can be exposed through air, water, soil and food sources including ingestion, inhalation, and dermal content in both occupational and non-occupational levels by single or sometimes multiple exposures routes concomitantly. Furthermore, diagnostic ratios, statistical principal component analysis (PCA) and hierarchical cluster analysis (HCA) models have confirmed that the sources of PAHs were both - petrogenic and pyrogenic. For both the sites, assessment of ecological risk of the elevated levels of these pollutants has been exercised based on toxic equivalency factors (TEFs) and risk quotient (RQ) methods. The composite results indicated accurately that both the sites, bears potentially acute and chronic health hazards such as decreased immune functionality, genotoxicity, malignancy and developmental malfunctions in humans. The sites studied here and the workers have been exposed to hazardous pollutants for a longer period of time. Evidences indicate that mixtures of PAHs are carcinogenic to humans, based on occupational studies on workers, exposed to these pollutants. Hence, the present study and statistical approaches applied herein clearly indicate the historic mix routes of PAHs that resulted in magnified concentrations leading to high ecosystem risk. Thus, the scientific communities are urged to develop strategies to minimize the concentrations of PAHs from the historically impacted coastlines, thereby concerning for the future investigations and restoration of these sites.

Enhanced chrysene degradation by a mixed culture Biorem-CGBD using response surface design.

Degradation of chrysene, a four ringed highly carcinogenic polycyclic aromatic hydrocarbon (PAH) has been demonstrated by bacterial mixed culture Biorem-CGBD comprising Achromobacter xylosoxidans, Pseudomonas sp. and Sphingomonas sp., isolated from crude oil polluted saline sites at Bhavnagar coast, Gujarat, India. A full factorial Central Composite Design (CCD) using Response Surface Methodology (RSM) was applied to construct response surfaces, predicting 41.93% of maximum chrysene degradation with an experimental validation of 66.45% chrysene degradation on 15th day, using a combination of 0.175, 0.175 and 0.385 mL of OD600 = 1 inoculum of A. xylosoxidans, Pseudomonas sp. and Sphingomonas sp., respectively and a regression coefficient (R2) of 0.9485 indicating reproducibility of the experiment. It was observed that chrysene degradation can be successfully enhanced using RSM, making mixed culture Biorem-CGBD a potential bioremediation target for PAH contaminated saline sites.

Application of response surface methodology for rapid chrysene biodegradation by newly isolated marine-derived fungus Cochliobolus lunatus strain CHR4D.

For the first time, Cochliobolus lunatus strain CHR4D, a marine-derived ascomycete fungus isolated from historically contaminated crude oil polluted shoreline of Alang-Sosiya ship-breaking yard, at Bhavnagar coast, Gujarat has been reported showing the rapid and enhanced biodegradation of chrysene, a four ringed high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH). Mineral Salt Broth (MSB) components such as ammonium tartrate and glucose along with chrysene, pH and trace metal solution have been successfully optimized by Response Surface Methodology (RSM) using central composite design (CCD). A validated, two-step optimization protocol has yielded a substantial 93.10% chrysene degradation on the 4(th) day, against unoptimized 56.37% degradation on the 14(th) day. The results depict 1.65 fold increase in chrysene degradation and 1.40 fold increase in biomass with a considerable decrement in time. Based on the successful laboratory experiments, C. lunatus strain CHR4D can thus be predicted as a potential candidate for mycoremediation of HMW PAHs impacted environments.

Enhanced biodegradation of total polycyclic aromatic hydrocarbons (TPAHs) by marine halotolerant Achromobacter xylosoxidans using Triton X-100 and ß-cyclodextrin--a microcosm approach.

Ability of Achromobacter xylosoxidans, a chrysene degrading marine halotolerant bacterium to degrade polycyclic aromatic hydrocarbons (PAHs) using a cost effective laboratory microcosm approach, was investigated. Effect of variables as chrysene, glucose as a co-substrate, Triton X-100 as a non-ionic surfactant and ß-cyclodextrin as a PAHs solubilizer was examined on degradation of low molecular weight (LMW) and high molecular weight (HMW) PAHs. A total of eleven PAHs detected from polluted saline soil were found to be degraded. Glucose, in combination with Triton X-100 and ß-cyclodextrin resulted in 2.8 and 1.4-fold increase in degradation of LMW PAHs and 7.59 and 2.23-fold increase in degradation of HMW PAHs, respectively. Enhanced biodegradation of total PAHs (TPAHs) by amendments with Triton X-100 and ß-cyclodextrin using Achromobacter xylosoxidans can prove to be promising approach for in situ bioremediation of marine sites contaminated with PAHs.