Spatiotemporal characterization of petroleum hydrocarbons and polychlorinated biphenyls in small craft harbour sediments in Nova Scotia, Canada

Risk assessment of sediment PAH, BTEX, and emerging contaminants in Chanomi Creek Niger Delta, Nigeria

This study assessed the levels of polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, and xylene (BTEX), and emerging contaminants in Chanomi Creek. Sediment samples were collected between March 2019 and July 2020 to evaluate the concentrations of PAH, BTEX, and emerging contaminants using GC-MS and GC-FID with Headspace extraction. Results indicated mean PAH concentrations were 22.691 ± 15.09 µg/kg. The highest individual PAH concentrations were fluorene (7.085 µg/kg), naphthalene (4.517 µg/kg), and phenanthrene (3.081 µg/kg). Carbazole (0.828 µg/kg) was discovered as a novel environmental toxin with dioxin-like toxicity and widespread prevalence in sediments. The most common congener (25%) was ethylbenzene, followed by toluene and ortho- and meta-xylene (21%) and benzene (13%). The analysis of diagnostic ratios revealed that the main factors responsible for the presence of PAHs in the study area are the residential use of firewood, emissions from industrial activities, bush burning, and petroleum slicks. The risk assessment indicated that most PAHs exceeded the permissible risk quotient values, suggesting a moderate to high ecological risk. However, cutaneous exposure to PAHs and BTEX was found to have minimal impact on human health, with no significant hazards identified in adults and children. Nevertheless, the study revealed low cancer risks associated with PAH and BTEX compounds for both age groups. The continued discharge of PAHs and BTEX compounds into Chanomi Creek could have significant long-term negative effects on human and aquatic health. Thus, contamination risk awareness programs and the development of stringent contextual thresholds for identified contaminants could enhance environmental and public health protection.

Multiple contaminant ecological risk evaluation in small craft harbour sediments in Nova Scotia, Canada

Small craft harbours are vital for the fishing industry and have high socioeconomic and cultural importance for surrounding communities. Presence of potential contaminants of concern in small craft harbour sediments can have significant impacts in biota and humans, including fishing activities and the local economy. While single contaminant sediment concentrations may be below sediment quality guidelines, the interaction of multiple contaminants in sediments may potentially exacerbate chemical ecological risk. An ecological risk evaluation for four classes of contaminants (i.e., petroleum hydrocarbons, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and metals) was conducted in 31 small craft harbours in Nova Scotia, Canada, using two approaches (i.e., mean probable effect level quotient and number and frequency of sediment quality guideline exceedances). Most small craft harbours showed a low ecological risk to marine biota, with only two small craft harbours suggesting high risk. While urgent action is not needed, monitoring is recommended for these small craft harbours to confirm that pollution is not increasing, and to potentially identify and control contamination sources.

Genotoxicity Set Up in Artemia franciscana Nauplii and Adults Exposed to Phenanthrene, Naphthalene, Fluoranthene, and Benzo(k)fluoranthene

Polycyclic aromatic hydrocarbons (PAHs) consist of a group of over 100 different organic compounds mainly generated by anthropogenic activities. Because of their low water solubility, they tend to be accumulated in sediment, where their degradation rate is very low. Few studies have been carried out so far to investigate the effects of PAHs on Artemia franciscana. Artemia is easy to manage at laboratory scale, but it is not a sensitive biological model considering the traditional endpoints (i.e., mortality). In addition to evaluating the lethality on nauplii and adults of A. franciscana after 24 and 48 h, we focused on the genotoxicity to investigate the potential effects of phenanthrene (PHE), naphthalene (NAP), fluoranthene (FLT), and benzo(k)fluoranthene (BkF). Results showed that FLT was the most toxic both for nauplii and adults after 48 h of exposure. Real-time qPCR showed that all toxicants, including BkF, which had no negative effects on the survival of the crustacean, were able to switch the gene expression of all nine genes. This work has important ecological implications, especially on contaminated sediment assessment considering that PAHs represent the most abundant organic group of compounds in marine environment, opening new perspectives in understanding the molecular pathways activated by crustaceans.

Baseline occurrence, distribution and sources of PAHs, TPH, and OCPs in surface sediments in Gorgan Bay, Iran

Baseline polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPH) and organochlorine pesticides (OCPs) in surface sediments were measured in Gorgan Bay, Iran. Total PAHs, TPH, and OCPs concentrations ranged between 13.70 and 23.68 ng g^-1, 2.97 to 11.51 μg g^-1 dry weight, and below detection to 1.41 ng g^-1, respectively. Benzo [k] fluoranthene and anthracene had the highest (BkF; 19.77 ± 0.08 ng g^-1), and lowest (Ant; 4.38 ± 1.72 ng g^-1) individual PAH concentrations, respectively. The most abundant OCPs were β-Endosulfan, followed by methoxychlor and endrin. PAH isomeric ratios in sediments revealed that contamination originated from mixed sources, with a strong indication of pyrogenic sources. Ecological risk assessments based on sediment quality guidelines (SQGs) suggested that individual PAHs and OCPs posed low ecological risks in Gorgan Bay.