Leuser Journal of Environmental Studies

Influence of Elevational and Environmental Factors on Parasitic Nematode Distribution in Arabica Coffee in the Gayo Highlands, Indonesia

Fri, 23 May 2025 00:00:00 +0700

Highland agricultural landscapes are sensitive to environmental variation, particularly in regions like the Gayo Highlands of Aceh, Indonesia, where Arabica coffee (Coffea arabica L.) is a major crop. While parasitic nematodes are known to affect crop health and soil ecosystems, little is known about how their abundance and distribution vary with elevation in tropical coffee systems. The Gayo Highlands, despite their significant contribution to national coffee production, have been understudied in terms of soil biodiversity and nematode-related threats. To address this knowledge gap, we assessed the composition and abundance of parasitic nematodes in coffee plantations across three elevation zones: 800–1000 m, 1001–1200 m, and 1201–1400 m above sea level. We collected soil and root samples from symptomatic coffee plants, extracted nematodes using the Baermann funnel method, and identified them to the genus level. The study found three genera: Pratylenchus, Meloidogyne, and Rotylenchus. Pratylenchus was the most abundant, particularly at 800–1,000 m (34 individuals/10 ml), while the highest total nematode abundance occurred at 1,001–1,200 m (7.2 ± 1.44 individuals/10 ml). Statistical analysis showed significant differences in nematode abundance between elevation zones. These results indicate that elevation influences nematode populations, likely through environmental factors such as temperature, soil moisture, and pH. Understanding these patterns is important for developing site-specific strategies for pest management and maintaining soil health in highland coffee systems.

Optimizing Palm Oil Biodiesel Purity for a Cleaner Environment: Urea Complexation and RSM Approach

Zohera Zohera, Zuchra Helwani, Sunarno Sunarno — Sun, 27 Jul 2025 00:00:00 +0700

The performance and stability of biodiesel are strongly influenced by its fatty acid composition, particularly the balance between saturated (SFA) and unsaturated fatty acids (UFA). This study employed the urea inclusion compound (UIC) method to fractionate biodiesel and optimize conditions for obtaining a high-yield, high-quality saturated fraction (UCF). A central composite design (CCD) under response surface methodology (RSM) was used to evaluate the effects of urea-to-methanol ratio, crystallization temperature, and crystallization time on UCF and NUCF yields and iodine values. Experiments were conducted using a range of crystallization temperatures (18–22 °C), times (3–5 h), and urea-to-methanol ratios (1:1.5–1:2.5). The response variables were analyzed and optimized using desirability functions. The results showed that all three factors significantly influenced both the yield and iodine value of the fractions. The optimal condition, urea-to-methanol ratio of 1:1.73, temperature of 19.99 °C, and time of 5 h, yielded 81.59% UCF with an iodine value of 36.65 g I₂/100 g, falling within the desired range for high-performance saturated biodiesel. In contrast, the NUCF fraction was minimized to 1.76% and enriched in PUFA. These findings demonstrate the potential of UIC-based fractionation for producing biodiesel with improved oxidative stability and combustion properties, aligning with international quality standards and contributing to more sustainable fuel formulations.

Environmental Influence of Altitude on Coffee Leaf Rust Severity in Arabica Coffee of Aceh Tengah, Indonesia

Fri, 17 Oct 2025 00:00:00 +0700

Coffee leaf rust (CLR), caused by Hemileia vastatrix, remains one of the most damaging diseases affecting Arabica coffee worldwide. Understanding how environmental gradients influence CLR development is critical for sustainable management in tropical highland systems. This study examined the influence of altitude on CLR incidence and severity across five elevation ranges (800–1800 masl) in Arabica coffee plantations of Aceh Tengah, Indonesia. Field assessments were conducted on 25 farms using a standardized sampling layout and severity scoring scale. Analysis of variance (ANOVA) revealed that altitude had no significant effect on disease incidence (F = 0.14 < F_0.05= 3.01), which remained uniformly high across all sites (>75%), but significantly affected disease severity (F = 3.34 > F_0.05 = 3.01). The highest mean severity (51.88%) occurred at 1600–1800 masl, differing significantly from lower elevations. These findings suggest that while CLR infection frequency is widespread, environmental conditions at higher altitudes favor greater lesion expansion and disease development. The results highlight the importance of considering local microclimatic variability in disease risk assessment and adaptive management. Further studies integrating microclimatic and agronomic measurements are needed to strengthen causal understanding and support environmentally based strategies for sustainable Arabica coffee production.

Geochemical Evidence from Major and Trace Elements in Geothermal Waters of Empat Lawang, Southern Sumatra: Clues to Mineralization and Hydrothermal Sources

Rofiqul Umam, Suharno Suharno, Rahmad Junaidi — Mon, 20 Oct 2025 00:00:00 +0700

This study explores the major and trace element geochemistry of geothermal waters from Empat Lawang, Southern Sumatra, Indonesia, to assess hydrothermal origins and mineral prospecting potential. Five water samples were analyzed using ternary plots, ion correlation diagrams, and geothermometric equations. A strong Na–Cl correlation (R² = 0.9694) suggests evaporite dissolution or mixing with connate water, while the Ca–SO₄ relationship (R² = 0.9555) indicates gypsum or anhydrite dissolution. The Ca + Mg vs. HCO₃ pattern reflects carbonate and silicate weathering influenced by lithological variability. Diagnostic ion plots reveal active ion exchange and halite dissolution across sample sites. Reservoir temperatures estimated using Giggenbach and Fournier Truesdell equations range from 190°C to 404°C, with an outlier of 1593.75°C in PN3, likely due to fluid disequilibrium. Depths span 4.22 to 16.39 km, indicating deep-seated hydrothermal systems with intense fluid–rock interaction. The Cl/Li vs. B plot identifies hydrothermal signatures, with most samples below the Cl/Li < 1000 threshold and elevated boron levels, suggesting active leaching and mineral transport. These findings highlight the potential for borate and metal mineralization. By integrating classical geochemical approaches with modern trace element indicators, this study provides a novel framework for geothermal exploration in Indonesia’s volcanic regions. These findings suggest potential for borate and metal mineralization and offer a geochemical framework for geothermal exploration in Indonesia’s volcanic regions.

From Waste to Resource: Sustainable Recycling Strategies for Monocrystalline Solar Panels in Indonesia

Thu, 23 Oct 2025 00:00:00 +0700

The rapid growth of photovoltaic (PV) installations in Indonesia, projected to exceed 8.5 GW by 2030, is expected to generate over 1 million tons of solar panel waste by 2050, highlighting the urgent need for end-of-life (EoL) management. This study evaluates the environmental impacts of monocrystalline PV panels and examines suitable recycling strategies for Indonesia. A Life Cycle Assessment (LCA) framework compares landfill and recycling scenarios using Global Warming Potential (GWP) and Cumulative Energy Demand (CED), supported by sensitivity analysis. Results show that aluminum recycling can reduce GWP by up to 83% and CED by 95% compared to primary production. Mechanical recycling and direct reuse are the most feasible options given local market conditions and technological readiness, while advanced recycling requires additional support. Extending panel lifespan and further improving efficiency further reduce emissions and accelerate carbon payback. The study emphasizes the need for a national PV waste management framework that integrates recycling with circular economic strategies. Policy measures such as Extended Producer Responsibility and fiscal incentives, combined with cross-sector collaboration, are crucial to ensuring a sustainable, low-carbon solar energy transition in Indonesia.