Challenges and opportunities for low-carbon remediation in the Niger Delta: Towards sustainable environmental management.

There is increasing demand for low-carbon remediation strategies for reducing greenhouse gas emissions and promoting sustainable development in the management of environmental contamination. This trend is within the broader context of sustainable remediation strategies that balance environmental, economic, and social aspects. This article critically reviewed existing literature to evaluate and compare various low-carbon remediation methods, such as bioremediation, phytoremediation, in situ chemical oxidation, soil vapour extraction, and electrokinetic remediation, to identify suitable techniques for the remediation of oil-contaminated sites in the Niger Delta region of Nigeria. We analysed the UK sustainable remediation frameworks (SuRF-UK) to glean lessons for the Nigerian context. Our findings indicate that bioremediation and phytoremediation are particularly promising low-carbon remediation technologies for the Niger Delta region due to their cost-effectiveness and adaptability to local conditions. We proposed a framework that deeply considers opportunities for achieving multiple goals including effective remediation and limited greenhouse gas emissions while returning net social and economic benefit to local communities. The proposed framework will help decision makers to implement effective remediation technologies that meet sustainability indices, integrates emissions considerations return net environmental benefit to local communities. There is a need for policymakers to establish and enforce policies and regulations that support sustainable remediation practises, build the capacity of stakeholders, invest in research and development, and promote collaboration among stakeholders to create a regulatory environment that supports sustainable remediation practises and promotes environmental sustainability in the region. This study provides insights for achieving low-carbon remediation in regions addressing land contamination by different contaminants and facilitates the adoption of remediation technologies that consider contextual socio-economic and environmental indices for sustainable development.

Efficacy of bioadmendments in reducing the influence of salinity on the bioremediation of oil-contaminated soil.

This study aimed to investigate the potential of three bioamendments (rice husk biochar, wheat straw biochar, and spent mushroom compost) to enhance microbial degradation of crude oil in saline soil. A soil microcosm experiment was conducted, comparing the response of soil microorganisms to crude oil under saline (1 % NaCl) and non-saline conditions. The soils were amended with different bioamendments at varying concentrations (2.5 % or 5 %), and degradation rates were monitored over a 120-day period at 20 °C. The results showed that the bioamendments significantly influenced the degradation of total petroleum hydrocarbons (TPH) in both non-saline and saline soils by 67 % and 18 % respectively. Non-saline soils exhibited approximately four times higher TPH biodegradation compared to saline soils. Among the bioamendments, rice husk biochar and spent mushroom compost had the greatest impact on biodegradation in saline soil, while wheat straw and rice husk biochar combined with spent mushroom compost showed the most significant effects in non-saline soil. The study also revealed that the bioamendments facilitated changes in the microbial community structure, particularly in the treatments with rice husk biochar and wheat straw biochar. Actinomycetes and fungi were found to be more tolerant to soil salinity, especially in the treatments with rice husk biochar and wheat straw biochar. Additionally, the production of CO2, indicating microbial activity, was highest (56 % and 60 %) in the treatments combining rice husk biochar or wheat straw biochar with spent mushroom compost in non-saline soil, while in saline soil rice husk biochar treatment (50 %) was the highest. Overall, this research demonstrates that the application of bioamendments, particularly rice husk biochar and wheat straw biochar combined with spent mushroom compost, can effectively enhance the biodegradation of crude oil in saline soil. These findings highlight the potential of such bioamendments as green and sustainable solutions for soil pollution, especially in the context of climate change-induced impacts on high-salinity soils, including coastal soils.

Assessment of the effectiveness of onsite exsitu remediation by enhanced natural attenuation in the Niger Delta region, Nigeria.

This study was conducted to quantify and rank the effectiveness of onsite exsitu remediation by enhanced natural attenuation using soil quality index. The investigation was conducted at three oil spill sites in the Niger Delta (5.317°N, 6.467°E), Nigeria with a predominance of Oxisols. Baseline assessment and a two-step post-remediation monitoring of the sites were conducted. Target contaminants including total petroleum hydrocarbon (TPH) and BTEX (benzene, toluene, ethylbenzene, and xylene) were analyzed by gas chromatography-mass spectrometry. Results of the baseline assessment showed that TPH concentrations across the study sites averaged between 5113 and 7640 mg/kg at 0- to 1-m depth, which was higher than the local regulatory value of 5000 mg/kg. The soil quality index across the sites ranged between 68 and 45, suggesting medium to high potential ecological health risks with medium to high priority for remediation. BTEX concentrations followed a similar trend. However, after remediation TPH degraded rapidly initially and then slowly but asymptotically during the post-remediation monitoring period. Then, soil quality index across the study sites ranged between 100 and 58, indicating very low to medium potential ecological health risks. This demonstrates the effectiveness of onsite exsitu remediation by enhanced natural attenuation as a remediation strategy for petroleum-contaminated soils, which holds great promise for the Niger Delta province.