Tropical Aquatic and Soil Pollution

Land Degradation Detection in Urban Areas Using Spatial Modelling and Semi-Automatic Classification of Satellite Imagery Data

Riska Ayu Purnamasari — 2025-08-29

Urban land degradation poses a growing challenge in rapidly developing countries like Indonesia, where population growth and limited space drive uncontrolled land cover changes. This study aims to detect land degradation in urban areas through spatial modelling and semi-automatic classification of multi-temporal remote sensing imagery. Landsat-5 Thematic Mapper (TM) image from year 2011 and Landsat-9 Operational Land Imager collection 2 (OLI-2) image from year 2023 data were acquired from the The United States Geological Survey (USGS). Image pre-processing included band stacking, subsetting, and enhancement to improve visual interpretation. Semi-automatic supervised classification was applied to map seven land cover classes: agricultural dry land, rice field, forest, plantation, non-agricultural land, water body, and settlement. Training data and validation were supported by Google Earth Pro, official sources, and field surveys using random sampling. Change detection analysis revealed a 1664.65 ha increase in industrial areas, accompanied by significant reductions in rice fields (−1726.92 ha) and dry farmland (−1644.57 ha). The classification accuracy reached 80.24% and 75.11%, with kappa coefficients of 0.76 and 0.65, respectively. Results indicate that urban expansion is a key driver of land degradation, particularly through the loss of productive agricultural land. This research demonstrates the effectiveness of remote sensing-based spatial modelling and classification techniques for monitoring urban land degradation and informing sustainable land use planning.

Microalgae for Palm Oil Mill Effluent (POME) Remediation: Future Trends

Nurlydia Mohd Azmil — 2025-10-26

Microalgae-based remediation of palm oil mill effluent (POME) grew rapidly, yet evidence remained dispersed across methods and outcomes. This study undertook bibliometric mapping to organise research growth, thematic structure, and actionable pathways aligned with SDGs 6, 7, 12, and 14. A Scopus database of 124 articles (2008–2025) was analysed with VOSviewer to produce keyword co-occurrence and temporal overlays, complemented by impact indicators and close reading of highly cited studies. Output increased from a formative phase to a peak in 2021, with 3275 citations overall and influence that was concentrated yet broad (h = 35; g = 51; m = 1.944). The network resolved into a central focal point (POME, microalgae, effluent/wastewater), surrounded by two related fields: pollutant metrics (COD, nitrogen, phosphorus), which supported treatment claims, and valorisation (biomass, lipid, biofuel), which linked remediation to product streams. Temporal overlays showed a progression from feasibility and nutrient polishing to method-rich optimisation (kinetics, immobilisation) and, more recently, to cultivation realism, phycoremediation, and sustainability. These patterns indicated practical levers for mill-scale deployment, including on-site cultivation with boiler CO₂, microalgae–bacteria partnerships for robustness, and combined pond–photobioreactor systems that balanced cost and control. Together, these combinations delivered cleaner effluents (SDG 6), low-carbon energy vectors (SDG 7), circular nutrient and residue reuse (SDG 12), and reduced land-based marine pollution (SDG 14). Remaining priorities included harmonised reporting of removals and yields, techno-economic and life cycle assessments at mill cluster scale, resilient process control and safety for multi-stage systems, and biomass quality assurance to safeguard downstream uses.

Microbial Strategies for the Degradation of Organophosphates: A Sustainable Approach to Pollution Control

Denny Noriel Santiago — 2025-10-31

Organophosphates (OPs) were synthetic chemical compounds that had been applied in household products as well as in agricultural and industrial sectors. Although OPs had proven effective, particularly as pesticide ingredients, their persistence in the environment had raised concerns regarding impacts on ecosystems, the environment, and human health. This study addressed the occurrences and negative impacts of OPs, with a primary focus on microbial degradation as a bioremediation strategy. While various degradation methods had been developed, microbial degradation showed strong potential as a sustainable and cost-effective approach. This review aimed to examine the mechanisms, benefits, and limitations of microbial degradation of OPs, thereby addressing the knowledge gap related to its real-world applications. Microbial degradation involved the use of bacteria capable of breaking down OPs through enzyme production, transforming them into less harmful substances. In comparison with chemical or physical methods, microbial degradation was more environmentally friendly, cost-effective, and adaptable to surrounding conditions. By synthesizing findings from previous studies, the report highlighted both the strengths and shortcomings of microbial degradation in mitigating OPs contamination. The findings underscored its promise as a viable solution, while also pointing to the need for further research and improved frameworks.