Ecological risk potentials of petroleum hydrocarbons and heavy metals shape the bacterial communities of marine hydrosphere at Atlantic Ocean, Atlas Cove, Nigeria

Anthropogenic multipollutant input to the offshore South China Sea

The remote region of the South China Sea (SCS), situated far from urban mainland areas, is commonly perceived to experience minimal pollution. However, this may evolve into a considerably polluted region owing to increasing anthropogenic pollutants. In this study, we employ a multidisciplinary approach to analyze the surface sediments collected from the offshore area of the southern SCS. Our aim is to explore potential anthropogenic pollutants, their interactions, and the related controlling factors. This research endeavors to enhance our understanding of the current pollution status in the SCS and help making relevant policy management decisions. Comparison with previous reports reveals that now, the area is more extensively and increasingly contaminated by petroleum hydrocarbons and heavy metals (Cd and As) than before. For the first time, we report the recognition of coprostanol and long-chain alkyl mid-chain ketones, unveiling the noticeable incorporation of sewage fecal matter and biomass burning into offshore sediments. Moreover, sedimentary multipollutants (except ketones) exhibit strong correlations with terrestrial elements and fine-sized particles, displaying a roughly high-west/low-east spatial variability in pollutant accumulation or enrichment. These signatures evidently demonstrate the major impact of river discharges (e.g., the Mekong River to the west and the Pearl and Red Rivers to the north) on the SCS. They have hydrodynamic effects on the subsequent basin-wide dispersal of pollutants, driven by monsoon-induced large- and regional-scale currents. The different behavior of burning-related ketones may be partly due to their aerosol form, leading to atmospheric transportation. Because anthropogenic multipollutants pose compounded threats, exacerbating oceanic warming and acidification to marine ecosystems such as the widespread coral reefs in the southern SCS, scientific management of urban emissions is required to mitigate ecosystem degradation in the Anthropocene era.

Environmental effects from petroleum product transportation spillage in Nigeria: a critical review

Nigeria has struggled to meet sustainable development goals (SDGs) on environmental sustainability, transportation, and petroleum product distribution for decades, endangering human and ecological health. Petroleum product spills contaminate soil, water, and air, harming humans, aquatic life, and biodiversity. The oil and gas industry contributes to environmental sustainability and scientific and technological advancement through its supply chain activities in the transport and logistics sectors. This paper reviewed the effects of petroleum product transportation at three accident hotspots on Nigeria highway, where traffic and accident records are alarming due to the road axis connecting the southern and northern regions of the country. The preliminary data was statistically analysed to optimise the review process and reduce risk factors through ongoing data monitoring. Studies on Nigeria's petroleum product transportation spills and environmental impacts between the years 2013 and 2023 were critically analysed to generate updated information. The searches include Scopus, PubMed, and Google Scholar. Five hundred and forty peer-reviewed studies were analysed, and recommendations were established through the conclusions. The findings show that petroleum product transport causes heavy metal deposition in the environment as heavy metals damage aquatic life and build up in the food chain, posing a health risk to humans. The study revealed that petroleum product spills have far-reaching environmental repercussions and, therefore, recommended that petroleum product spills must be mitigated immediately. Furthermore, the study revealed that better spill response and stricter legislation are needed to reduce spills, while remediation is necessary to lessen the effects of spills on environmental and human health.

Shotgun Metagenomic Analyses of Microbial Assemblages in the Aquatic Ecosystem of Winam Gulf of Lake Victoria, Kenya Reveals Multiclass Pollution

Lake Victoria, the second-largest freshwater lake in the world, provides an important source of food and income, particularly fish for both domestic consumption and for export market. In recent years, Lake Victoria has suffered massive pollution from both industrial and wastewater discharge. Microplastic biomes, pharmaceutical residues, drugs of abuse, heavy metals, agrochemicals, and personal care products are ubiquitous in the aquatic ecosystem of Winam Gulf. These pollutants are known to alter microbial assemblages in aquatic ecosystems with far-reaching ramification including a calamitous consequence to human health. Indeed, some of these pollutants have been associated with human cancers and antimicrobial resistance. There is a paucity of data on the microbial profiles of this important but heavily polluted aquatic ecosystem. The current study sought to investigate the metagenomic profiles of microbial assemblages in the Winam Gulf ecosystem. Water and sediment samples were collected from several locations within the study sites. Total genomic DNA pooled from all sampling sites was extracted and analyzed by whole-genome shotgun sequencing. Analyses revealed three major kingdoms: bacteria, archaea and eukaryotes belonging to 3 phyla, 13 classes, 14 families, 9 orders, 14 genera, and 10 species. Proteobacteria, Betaproteobacteria, Comamonadaceae, Burkholdariales, and Arcobacter were the dominated phyla, class, family, order, genera, and species, respectively. The Kyoto Encyclopedia of Genes and Genomes indicated the highest number of genes involved in metabolism. The presence of carbohydrate metabolism genes and enzymes was used to infer organic pollutions from sewage and agricultural runoffs. Similarly, the presence of xylene and nutrotoluene degradation genes and enzyme was used to infer industrial pollution into the lake. Drug metabolism genes lend credence to the possibility of pharmaceutical pollutants in water. Taken together, there is a clear indication of massive pollution. In addition, carbohydrate-active enzymes were the most abundant and included genes in glycoside hydrolases. Shotgun metagenomic analyses conveyed an understanding of the microbial communities of the massively polluted aquatic ecosystem of Winam Gulf, Lake Vicoria, Kenya. The current study documents the presence of multiclass pollutants in Lake Victoria and reveals information that might be useful for a potential bioremediation strategy using the native microbial communities.

Heavy metals assessment of ecosystem polluted with wastewaters and taxonomic profiling of multi-resistant bacteria with potential for petroleum hydrocarbon catabolism in nitrogen-limiting medium

The coexistence of heavy metals (HMs) and petroleum hydrocarbons (PHs) exacerbates ecotoxicity and impair the drivers of eco-functionalities that stimulate essential nutrients for the productivity of the impacted environment. Profiling the bacteria that stem the ecological impact via HMs sequestration and PHs catabolism with nitrogen fixation is imperative to bioremediation of the polluted sites. The sediment of site that was consistently contaminated with industrial wastewaters was analysed for ecological toxicants and the bacterial strains that combined HMs resistance with PHs catabolism in a nitrogen-limiting system were isolated from the sediment and characterized. The geochemistry of the samples revealed the co-occurrence of the above-benchmark concentrations of HMs with the derivatives of hydrocarbons. Notwithstanding, nickel and mercury (with 5% each of the total metal concentrations in the polluted site) exhibited probable effect concentrations on the biota and thus hazardous to the ecosystem. Approx. 31% of the bacterial community, comprising unclassified Planococcaceae, unclassified Bradyrhizobiaceae, Rhodococcus, and Bacillus species, resisted 160 µmol Hg²⁺ in the nitrogen-limiting system within 24 h post-inoculation. The bacterial strains adopt volatilization, and sometimes in combination with adsorption/bioaccumulation strategies to sequester Hg²⁺ toxicity while utilizing PHs as sources of carbon and energy. Efficient metabolism of petroleum biomarkers (> 87%) and Hg²⁺ sequestration (≥ 75% of 40 µmol Hg²⁺) displayed by the selected bacterial strains portend the potential applicability of the bacilli for biotechnological restoration of the polluted site.

Microbial community succession in soils under long-term heavy metal stress from community diversity-structure to KEGG function pathways

Currently, understanding the structure and function of the microbial community is the key step in artificially constructing microbial communities to control soil heavy metal pollution. Abundant/rare microbial communities play different roles in different levels of concentrations. However, the correlation between heavy metals and rare/abundant subgroups is poorly understood. In this study, we used a metagenomics approach to comprehensively investigate the evolutionary changes in microbial diversity, structure, and function under different heavy metal concentration stress in soils surrounding gold tailings. The results show that the main pollutants were Pb, As, and Zn. Indigenous microorganisms have different responses to heavy metal concentrations. Bacteria are the main components of indigenous microorganisms, mainly including Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. With the increase of heavy metal pollution, the relative abundance of Proteobacteria increased, and that of Actinobacteria decreased. Archaea was significantly inhibited by heavy metal stress and was more sensitive to heavy metal concentration. The response of fungi to heavy metal concentration was not obvious. The results of KEGG pathways showed that carbon fixation was inhibited with increasing heavy metal concentrations, while nitrogen metabolism was in contrast. Abundant subcommunity had a greater correlation mainly with metal resistance mechanisms, and rare subcommunity plays a key role for soil nutrient cycling such as N, S cycling in soils contaminated. Overall, this study provides a comprehensive analysis of the effects of heavy metal stress at different concentrations on microorganisms in farmland around gold tailings and reveals the relationship between heavy metals on KEGG pathways.

Degradation potential of alkanes by diverse oil-degrading bacteria from deep-sea sediments of Haima cold seep areas, South China Sea

Marine oil spills are a significant concern worldwide, destroying the ecological environment and threatening the survival of marine life. Various oil-degrading bacteria have been widely reported in marine environments in response to marine oil pollution. However, little information is known about culturable oil-degrading bacteria in cold seep of the deep-sea environments, which are rich in hydrocarbons. This study enriched five oil-degrading consortia from sediments collected from the Haima cold seep areas of the South China Sea. Parvibaculum, Erythrobacter, Acinetobacter, Alcanivorax, Pseudomonas, Marinobacter, Halomonas, and Idiomarina were the dominant genera. Further results of bacterial growth and degradation ability tests indicated seven efficient alkane-degrading bacteria belonging to Acinetobacter, Alcanivorax, Kangiella, Limimaricola, Marinobacter, Flavobacterium, and Paracoccus, whose degradation rates were higher in crude oil (70.3–78.0%) than that in diesel oil (62.7–66.3%). From the view of carbon chain length, alkane degradation rates were medium chains > long chains > short chains. In addition, Kangiella aquimarina F7, Acinetobacter venetianus F1, Limimaricola variabilis F8, Marinobacter nauticus J5, Flavobacterium sediminis N3, and Paracoccus sediminilitoris N6 were first identified as oil-degrading bacteria from deep-sea environments. This study will provide insight into the bacterial community structures and oil-degrading bacterial diversity in the Haima cold seep areas, South China Sea, and offer bacterial resources to oil bioremediation applications.

Heavy metals research in Nigeria: a review of studies and prioritization of research needs

Nigeria is experiencing continuous economic and industrial transformations, typical of many developing nations. In addition to its well-established oil industry, which is infamous for exuding various kinds of pollutants, there are increased mining operations, indiscriminate disposal and burning of wastes, illegal oil refinery and terroristic insurgency, all poised to increase the levels of heavy metal contaminants in the Nigerian environment. A recent revelation indicates that about 2 million people in South-western Nigeria alone could potentially be poisoned by lead (Pb) and mercury (Hg), emanating from illegal mining operations. This further underscores the importance of investigations of toxic trace metal levels in the country. The current review of 148 research articles was conducted to provide an understanding of the scope of heavy metals research in Nigeria and to prioritize needed research. The review recognized that the scope of heavy metals studies has been wide, covering matrices such as cosmetics, human blood, hair, medicines, foods, beverages, water, air, soil and crude oil. However, important toxic metals, especially mercury (Hg), arsenic (As) and antimony (Sb), are largely under-investigated. Also, there is a need for more studies to be conducted in the northern part of the country. Furthermore, studies need to focus on marine environments rather than the freshwater ecosystems alone. Techniques such as the inductively coupled plasma-optical emission spectrometry (ICP-OES) and particle-induced X-ray emission (PIXE) analyses are herein recommended to bridge the data gap and to overcome limitations in trace metals analyses in the Nigerian total environment.