Tropical Aquatic and Soil Pollution

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

2025-11-13T05:16:24+00:00

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.

Toxicological and Haematological Effects of Senna alata Extract on Clarias gariepinus Fingerlings

2025-11-13T05:16:21+00:00

The study evaluated the acute and sub-lethal effects of ethanol extract of Senna alata stem bark on physicochemical parameters and haematological indices of Clarias gariepinus fingerlings. A 96-hour acute toxicity bioassay established an LC₅₀ of 11.54 mg/l (95% CI: 10.92–12.16 mg/l) and an LC₉₉ of 23.30 mg/l (95% CI: 21.75–24.85 mg/l), with mortality increasing from 0% in the control to 85% at 12.6 mg/l. Sub-lethal concentrations (0.61, 0.71, and 0.81 mg/l, corresponding to 1/20th, 1/16th, and 1/14th of LC₅₀, respectively) were applied for eight weeks. Physicochemical parameters (pH, temperature, total dissolved solids, electrical conductivity, and dissolved oxygen) were monitored before and after extract application. Electrical conductivity differed significantly at 0.61 mg/l (p = 0.0351), while other parameters remained statistically unchanged, although dissolved oxygen declined progressively with increasing concentration. Haematological analysis revealed no significant changes (p > 0.05) in haemoglobin, mean corpuscular haemoglobin, mean corpuscular volume, packed cell volume, platelet, red blood cell, and white blood cell counts, except for a significant alteration in mean corpuscular haemoglobin concentration (p = 0.0479). These findings demonstrate that S. alata exhibits moderate piscicidal toxicity under acute exposure and induces mild physiological stress under sub-lethal conditions, which could have long-term implications for fish health and aquaculture productivity. The use of S. alata as a piscicide should therefore be approached cautiously to prevent unintended ecological consequences. Future studies should evaluate histopathological and biochemical stress responses to establish environmental safety limits for S. alata in aquaculture systems.

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

2025-11-13T05:16:23+00:00

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 Biodegradation of Sunscreen Agents: Mechanisms, Enzymatic Pathways, and Environmental Implications

2025-11-13T05:16:21+00:00

Environmental contamination from sunscreen ingredients such as oxybenzone and octinoxate has become an increasing concern due to their persistence and toxicity, even at trace concentrations. Continuous sunscreen usage leads to the constant release of these pollutants into the environment, where they can bioaccumulate and resist degradation. The novelty of this review lies in its focused synthesis of recent studies on the microbial and enzymatic degradation mechanisms of sunscreen contaminants, particularly oxybenzone and octinoxate, which exhibit high persistence and bioaccumulative potential. Microbial degradation offers a promising biological approach for the breakdown of these organic pollutants, as microorganisms have demonstrated strong biodegradative capabilities toward various environmental contaminants. This process relies on microbial enzymes that transform or mineralize pollutants into less toxic and simpler compounds. Key enzymes involved include laccase, cytochrome P450, and monooxygenase, which catalyze oxidation, reduction, and hydroxylation reactions. The article further examines these organic pollutants in terms of their persistence, environmental occurrence, degradation mechanisms, and pathways, while also addressing their ecological and health impacts. Moreover, different microbial-based treatment technologies are evaluated, highlighting their respective strengths and limitations. Finally, the review emphasizes the need for continued research into organic pollutant behavior and bioremediation technologies to deepen understanding and mitigate the adverse effects of these contaminants on the environment.

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

2025-10-24T00:41:56+00:00

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.