Search Results (1,170)

This study investigates the intensification of drought in the continental part of the Istrian peninsula using two standardized drought indices: the Standardized Precipitation Evapotranspiration Index (SPEI) and the New Drought Index (NDI). Monthly precipitation and temperature data from the main meteorological station in Pazin, covering the period 1961–2024, were analyzed. Statistical methods, including linear regression, Mann–Kendall test, and Rescaled Adjusted Partial Sums (RAPS) analysis, were applied to detect trends and fluctuations in the time series. Results indicate a significant increase in mean annual air temperatures since the late 1990s, with particularly strong warming in summer months. Precipitation trends, although highly variable, did not show a statistically significant long-term decline. Both drought indices reveal an intensification of drought conditions after 1985, with NDI showing stronger sensitivity to temperature rise than SPEI. Seasonal analyses demonstrate that drought occurrence is most pronounced during the warm part of the year, while cumulative series indicate a shift from predominantly wet to predominantly dry conditions after the mid-1980s. The comparison of the two indices shows a high degree of agreement but also highlights the added value of NDI in detecting temperature-driven drought processes. The findings emphasize the growing risk of more frequent and severe droughts in humid regions of Istria, including the potential for flash drought events. These results may support the development of improved drought early-warning systems and adaptation strategies in the Mediterranean context. Full article

Artemisia frigida (subshrub) communities, which are indicators of grassland degradation, are widespread in overgrazed Eurasian steppes. After 4–6 years of enclosure, the community can recover to an Agropyron cristatum-dominated grass community. Understanding the competitive mechanisms between these two key species provides critical insights for the management of semi-arid steppes, where vegetation dynamics are primarily driven by soil moisture. Nevertheless, how soil moisture distribution mediates above- and belowground competition between A. cristatum and A. frigida remains unclear. To address this, we conducted a pot experiment that simulated natural vertical soil moisture heterogeneity with four soil moisture regimes in two soil layers (0–30 cm and 30–60 cm): uniformly dry (D–D), wet upper/dry lower (W–D), dry upper/wet lower (D–W), and uniformly wet (W–W), using both monoculture and mixed planting methods. Key results showed that (1) A. cristatum was more sensitive to soil moisture regimes than A. frigida. Its above- and belowground biomass were significantly higher under moist treatments (W–W, W–D, D–W) than under drought (D–D), whereas the biomass of A. frigida did not differ significantly among water treatments. (2) Compared with monoculture, mixed planting significantly increased the root–shoot ratio of A. frigida but did not affect that of A. cristatum. (3) Competitive ability differed between aboveground and belowground parts: competitive indices (aggressivity and relative competition intensity) revealed that A. cristatum exhibited stronger aboveground competitiveness under moist treatments, while A. frigida dominated aboveground under drought conditions. However, A. frigida consistently exhibited greater belowground competitive ability than A. cristatum across all water treatments in the mixture. These results emphasize that assessments of grass–shrub competition based solely on aboveground indicators may underestimate the competitive advantage of shrubs. Therefore, integrating belowground competitive processes is essential for accurately predicting grass–shrub competition and succession in semi-arid steppes. Full article

This study analyzed how climate variability affects lactation yield and reproduction in Holstein cows in a continental climate. It specifically compared Wet-Bulb Temperature (T_wb) with the standard Temperature–Humidity Index (THI). We conducted a retrospective study on a dairy farm in Konya, Türkiye, analyzing a total of 144 complete lactation records from a herd of 90 cows calving between 2022 and 2023. To rule out nutritional factors, a consistent TMR diet without pasture access was maintained in both years. Average Daily Milk Yield (ADMY) was calculated to adjust for lactation length. Climatic data showed a distinct contrast. Ambient temperatures and THI were similar between years (p > 0.05). However, 2022 was characterized by “humid heat” (high T_wb), while 2023 presented a “dry heat” profile with significantly lower T_wb (p < 0.001). This difference significantly impacted performance. Cows in the 2023 group produced much higher milk yields (50.55 ± 3.01 kg) than the 2022 group (30.74 ± 0.81 kg) (p < 0.001). Unexpectedly, milk yield peaked during the Autumn and Summer seasons of the low-humidity year. In contrast, fertility declined with thermal load. Poor winter fertility suggested a “carry-over” effect of previous heat stress. These findings show that T_wb is a better indicator of thermal comfort than THI in continental climates. Furthermore, low humidity can significantly reduce the negative impact of heat on milk production. Full article

Organic amendments, including biochar and compost, are widely recognized for their potential to improve soil health, but their linkage to soil water functions (e.g., storage, infiltration, plant availability) is not clear. Over two years (2024–2025), we investigated soil water infiltration and associated soil health properties in response to soil amendment application under no-tillage conditions in semi-arid agroecosystems of the southwestern USA. Soil water infiltration was measured in biochar, compost, biochar and compost, and control plots using the SATURO dual-head infiltrometer. Soil physical and chemical properties, including bulk density (BD), soil moisture content (SMC), water-filled pore space (WFPS), residue cover, mean weight diameter (MWD) of dry aggregates, water-stable aggregates (WSA), pH, soil organic carbon (SOC), and total nitrogen (TN), were assessed at 0–15 cm soil depth. The results show a 31.5% higher infiltration rate along with, a small but statistically significant (3.7% lower) bulk density, and 119% greater wet aggregate stability in the biochar-amended plots than in the control plots. Compost with biochar also improved soil health, but infiltration responses were variable. Infiltration was positively correlated with residue cover and soil pH, whereas it was negatively correlated or not correlated with other soil properties. This study demonstrates that biochar under no-tillage conditions can enhance soil health and resilience of semi-arid agroecosystems by improving soil water functions. Full article

Slovakia’s biomethane production potential represents up to 10% of Slovakia’s natural gas consumption, which is largely unexploited. The aim of this paper is to develop a model of each available technology (continuous, dry batch, and wet batch) as well as that of a biogas treatment unit and evaluate the energetic, economic, and environmental potential of building a new anaerobic digestion plant in Slovakia, considering four plant locations with feedstock abundance within a 30 km perimeter. Feedstock composition and availability, energy integration, and product usability are evaluated. The applied multi-criteria decision analysis (MCDA) considers four evaluation criteria: return on investment (ROI), CO₂ emissions production, potential industrial biowaste revenue, and municipal density within the operational region. Biogas plant deployment analysis yielded the Levice facility as top-ranked, primarily due to its minimal environmental impact and superior logistical performance, closely followed by the Žilina, Michalovce, and Prešov facilities. When comparing biomethane production facilities, the Levice plant was excluded due to economic infeasibility, and the Žilina facility emerged as the optimal choice, particularly due to its superior ROI performance and the largest biomethane production potential of over 1 million m³ biomethane per year. Thus, biomethane station deployment in Slovakia has proved feasible and can enhance the energy self-sustainability of the country and contribute to meeting the decarbonization goals. Full article

Terminal lakes in arid regions are highly vulnerable to climate variability and human water management, yet their long-term hydrological responses under multi-river regulation remain insufficiently quantified. Using Taitema Lake at the terminus of the Tarim Basin as a case study, this research integrates Landsat and Sentinel observations (2005–2025) with meteorological and river-inflow records to examine lake area dynamics and to identify river-specific hydrological controls. The results show pronounced intra- and interannual variability, with the lake expanding to a maximum of 461.52 km² in October 2017 and shrinking to 0.35 km² in October 2008. High-frequency permanent water (~43 km²) is concentrated in the deep central basin and largely influenced by the Qarqan River, whereas seasonal water (~300 km²) is broadly distributed and strongly affected by ecological releases from the Tarim River. Quantified inflow–area relationships indicate that the lake expands by 7–14 km² for each 0.1 × 10⁸ m³ of inflow. Based on frequency-based hydrological analysis, this study develops joint inflow strategies for wet, normal, and dry years, offering a practical hydrological basis for more precise and adaptive water allocation schemes in arid terminal lakes. Full article

Nature-based Solutions (NbS) such as rolled cover crops are increasingly adopted in rainfed vineyards to reduce soil degradation and drought risk, but their effectiveness depends on local soil physical conditions. We compared spontaneous inter-row vegetation managed by mowing (Control) with a cereal-based rolled cover crop (C-R) in two vineyards of the Oltrepò Pavese (Northern Italy) with contrasting texture, structure, and slope: Canevino (CNV) and Santa Maria della Versa (SMV). From 2021 to 2025, continuous soil moisture monitoring was combined with field measurements of saturated hydraulic conductivity (K_s) and bulk density, interpreted using temporal indicators (MRD, ITS) and a drought index (SWDI) calibrated to field moisture thresholds. During wet phases, average saturation at 50 cm was consistently higher at SMV (about 78 to 84 percent) than at CNV (about 68 to 75 percent). Under water-limited conditions, management contrasts were most evident at SMV: at 50 cm during the post-termination dry phase, saturation remained around 70 percent under C-R versus about 64 percent under the Control, and K_s was higher under C-R (8.32 × 10⁻⁶ m/s in topsoil) than under the Control (7.39 × 10⁻⁶ m/s). At CNV, SWDI at 50 cm indicated a moderate improvement in one agronomic year (median −1.2 under C-R versus −5.3 under the Control in 2021 to 2022), while a full tillage operation in 2024 defined a disturbed phase that was interpreted separately. SWDI occasionally suggested severe drought levels not fully matching field evidence, highlighting the need for site-calibrated reference thresholds in structured fine-textured soils. Overall, soil physical properties set the hydrological envelope, while rolled cover management can enhance buffering and preserve conductive pathways during dry phases; therefore, NbS performance should be evaluated with site-adapted monitoring and cautious inference from temporally autocorrelated time series. Full article

Wetlands play a significant role in the climate system due to their ability to store large amounts of carbon, while remaining highly sensitive to hydrometeorological variability. Droughts can profoundly alter these ecosystems, causing them to become significant sources of CO₂ and reducing CH₄ emissions. However, long-term observational evidence quantifying this response remains scarce. Here, we analyze a 12-year dataset (2013–2024) of CO₂ and CH₄ fluxes measured using the eddy-covariance method at a site in the Biebrza wetlands of northeastern Poland. The study period included both cool, wet years and hot, dry years characterized by extremely low water table levels. In the warmest and driest year, 2024, the mire acted as a substantial CO₂ source with a net emission of 1260 ± 400 g CO₂ m⁻² y⁻¹. Other drought-affected years, 2019 and 2023, also showed high net emissions of 1020 ± 230 and 840 ± 300 g CO₂ m⁻² y⁻¹, respectively. Conversely, the wettest year, 2013, exhibited a considerable net uptake of CO₂ of −990 ± 250 g CO₂ m⁻² y⁻¹. During dry years, CH₄ emissions declined markedly to values close to measurement uncertainty (1–3 g CH₄ m⁻² y⁻¹). When expressed as CO₂ equivalents, drought conditions consistently transformed the mire into a strong net greenhouse gas source. Full article

The construction of reservoirs has undeniably provided numerous conveniences and benefits to human societies. However, it has also markedly altered downstream flow regimes, leading to essential fish habitat loss that directly undermines the ecosystem services provided by fish populations, thereby jeopardizing the long-term sustainability of fishery resources. Existing assessments of spawning suitability largely concentrate on static characteristics of available spawning grounds, while the dynamics of habitat suitability migration and contraction in response to changing environmental flows remain poorly understood. To address this gap, we classified hydrological years into wet, flat, and dry categories to reflect the varying environmental flow requirements during the fish-spawning period. Using the Mike21 hydraulic model together with a spatial suitability analysis for spawning habitats, we quantified spawning ground suitability from both temporal and spatial perspectives. Taking the four major Chinese carps (FMCC) and the Dongta spawning ground in the Pearl River as a case study, our findings reveal that the proportion of highly suitable habitats closely tracks the environmental-flow trajectories. Throughout the FMCC spawning period, the spatial pattern of high suitability zones undergoes a marked migration in response to flow variations across wet, flat, and dry years, consistently shifting upstream. Specifically, as discharge rises from low-flow to high-flow events, the most suitable areas move from downstream deep-pool sections toward upstream shallow riffle zones, which is crucial for the sustainable development of fishery resources. Full article

The ground impedance (insulation resistance R_isol) of photovoltaic (PV) modules is usually measured only in the dry state, even though arrays frequently operate under dew-wet or rain-wet conditions, when leakage paths can change. We measured dry insulation resistance R_dry and IEC 61215 MQT 15 wet leakage resistance R_wet for N = 37 field-aged crystalline-silicon modules from utility-scale plants and related the results to the IEC 40 MΩ·m² criterion (R_wet × A ≥ 40). The measurements used 1000 V DC and a 2 min dwell; R_wet was obtained in a salted bath with a solution resistivity < 3500 Ω·cm. The median R_dry was 42.4 GΩ, whereas the median R_wet was 462.5 MΩ, resulting in a median R_dry/R_wet ratio of ~110×. Three modules (8.1%) failed the 40 MΩ·m² limit already in the dry state, whereas eight modules (21.6%) failed under IEC-wet conditions; five were dry-pass/wet-fail cases that would have passed dry screening. For a representative area A = 1.8 m², a practical conservative dry triage threshold of approximately 55.5 GΩ identifies modules needing IEC-wet verification rather than serving as a stand-alone limit. Overall, combining dry and IEC-wet measurements improves safety and supports sustainability through resource-efficient repowering/revamping and end-of-life decisions in large PV fleets, particularly in hot climates. Full article

Dryland coastal–mountain systems stand at the frontline of climate change, where steep topographic gradients amplify the balance between resilience and collapse. Mount Elba—Egypt’s hyper-arid coastal–mountain reserve—embodies this fragile equilibrium, preserving a seventy-year climatic record across a landscape poised between sea and desert. Here, we present the first multi-decadal, spatio-temporal assessment (1950–2021) integrating the Standardized Precipitation–Evapotranspiration Index (SPEI-6) with satellite-derived vegetation responses (NDVI) along a ten-grid coastal–highland transect. Results reveal a pervasive drying trajectory of −0.42 SPEI units per decade, with vegetation–climate coherence (r ≈ 0.3, p < 0.05) intensifying inland, where orographic uplift magnifies hydroclimatic stress. The southern highlands emerge as an “internal drought belt,” while maritime humidity grants the coast partial refuge. These trends are not mere numerical abstractions; they trace the slow desiccation of ecosystems that once anchored biodiversity and pastoral livelihoods. A post-1990 regime shift marks the breakdown of wet-season recovery and the rise in persistent droughts, modulated by ENSO teleconnections—the first quantitative attribution of Pacific climate signals to Egypt’s coastal mountains. By coupling climatic diagnostics with ecological response, this study reframes drought as a living ecological process rather than a statistical anomaly, positioning Mount Elba as a sentinel landscape for resilience and adaptation in northeast Africa’s rapidly warming drylands. Full article

Rational nitrogen applications can not only improve nutrient use efficiency, but also reduce environmental pollution caused by nitrogen leaching. To explore reasonable nitrogen application strategies for synergistically enhancing alfalfa production and ecological benefits, this study calibrated and validated the APSIM–Lucerne model based on field experiments conducted from 2021 to 2023. The effects of nitrogen application levels of 0, 80, 120, 140, 160, 180, 200, and 240 kg/ha on alfalfa yield, soil NO₃⁻–N and NH₄⁺–N residues, and nitrogen use efficiency under dry, normal, and wet years were simulated. The results indicate: (1) The calibrated APSIM–Lucerne model effectively simulates alfalfa yield and soil nitrogen residuals (R² ranging from 0.67 to 0.91, NRMSE between 6.55% and 24.03%). (2) Increased nitrogen application significantly elevates soil nitrogen residue, yet alfalfa yield follows a pattern of initial increase followed by decline, with nitrogen fertilizer use efficiency continuously decreasing. Under identical nitrogen application rates, the wet year type proves more advantageous for achieving high yields, low nitrogen residue, and high nitrogen fertilizer use efficiency. (3) The nitrogen application thresholds for achieving increased alfalfa yields and high efficiency during dry years, normal years, and wet years are 107–140 kg/ha, 135–160 kg/ha, and 150–183 kg/ha, respectively. Full article

Mechanical coffee drying is an energy-intensive stage of postharvest processing that directly affects product quality and production costs. This study evaluated the technical and economic feasibility of using expanded polystyrene (EPS) as a thermal insulation material to improve the performance of a mechanical coffee dryer and to demonstrate its potential for sustainable reuse. Experiments were conducted using a total of 210 kg of wet parchment coffee (Coffea arabica L. var. Cenicafé 1) per treatment, corresponding to three experimental replicates of 70 kg each, dried at 50 ± 2 °C, comparing an EPS-insulated dryer (0.02 m thickness) with a non-insulated control. A theoretical model based on steady-state heat transfer through series resistances estimated energy losses and system efficiency for different insulating materials. Theoretical results indicated that EPS, polyethylene foam, and cork reduced heat losses by 58.1%, 54.3%, and 50.9%, respectively. Experimentally, EPS reduced drying time by 7.82%, fuel consumption by 13.9%, and energy demand by 9.5%, while increasing overall efficiency by 6.7% and reducing wall heat losses by 37.7%. Improved temperature stability enhanced heat retention and moisture migration behavior. Economically, EPS reduced operating costs, yielding annual savings of USD 81.5, a 0.45-year payback period, and an annual return on investment (ROI) of 10.86, confirming its viability as a cost-effective and sustainable solution for improving energy efficiency in mechanical coffee drying. Full article

To reconcile the intensifying trade-off between chronic water scarcity and escalating forage demand in the Yellow River Basin, this study optimized integrated irrigation and fertilization regimes for silage maize. Leveraging the AquaCrop model, validated by 2023–2024 field experiments and a 35-year (1990–2024) meteorological dataset, we systematically quantified the impacts of multi-factorial water–fertilizer–heat stress under drip irrigation with mulch (DIM) and shallow-buried drip irrigation (SBDI). Model performance was robust, yielding high simulation accuracy for soil moisture (RMSE < 3.3%), canopy cover (RMSE < 3.95%), and aboveground biomass (RMSE < 4.5 t·ha⁻¹), with EF > 0.7 and R² ≥ 0.85. Results revealed distinct stress dynamics across hydrological scenarios: mild temperature stress predominated in wet years, whereas severe water and fertilizer stresses emerged as the primary constraints during dry years. To mitigate these stresses, a medium fertilizer rate (555 kg·ha⁻¹) was identified as the stable optimum, while dynamic irrigation requirements were determined as 90, 135, and 180 mm for wet, normal, and dry years, respectively. Comparative evaluation indicated that DIM achieved maximum productivity in wet years (aboveground biomass yield 70.4 t·ha⁻¹), whereas SBDI exhibited superior “stable yield–water saving” performance in normal and dry years. The established “hydrological year–irrigation method–threshold” framework provides a robust decision-making tool for precision management, offering critical scientific support for the sustainable, high-quality development of livestock farming in arid regions. Full article

The Yangtze-to-Huaihe Water Diversion (YHWD) project has raised concerns about balancing economic benefits and ecological impacts in Lake Caizi, a nationally protected wetland recognized by the World Wildlife Fund. To assess post-diversion contamination and ecological risks, seasonal variation in polycyclic aromatic hydrocarbons (PAHs) was investigated in surface sediments from Lake Caizi. Total PAH concentrations were 103–565 ng/g dw in the wet season, marginally exceeding the 97.1–526 ng/g dw observed in the dry season. The lowest levels occurred in the western sub-lake (Lake Xizi), showing marked declines relative to a decade ago, attributable to enhanced wastewater treatment, farmland-to-lake restoration, and a 10-year fishing ban. Conversely, PAH concentrations in the main lake, particularly the southeastern and northern sectors of the Caizi route, have increased, reflecting pollutant inflows from Zongyang County via the Yangtze River and accumulation driven by the diversion flows. The diagnostic ratio and positive matrix factorization model indicated biomass burning as the dominant PAH source in Lake Xizi across seasons. In contrast, PAH in the main lake were primarily derived from petroleum combustion and leakage, with coal combustion during the wet season shifting to coal combustion dominance in the dry season due to the seasonal halt of shipping activity. Although overall ecological risk remains low in Lake Caizi, localized hotspots near the Caizi routes and industrial zones pose moderate-to-high risks, necessitating continuous monitoring in the future. Full article