This review critically examines the use of non-conventional materials, primarily industrial by-products, for phosphorus removal and recovery in WRRFs, with particular attention to their potential implementation within existing treatment processes. Materials assessed include alum sludge, ferric sludge, steel slag, fly ash, red mud, bittern, and magnesium-rich by-products. Their performance is evaluated in terms of removal mechanisms, efficiency across a wide range of operating conditions, operational integration into full-scale WRRFs, potential agronomic value of the resulting products, and regulatory barriers. Evidence shows that many of these materials achieve high phosphorus removal efficiencies (>80%) under diverse conditions, while also offering opportunities for valorization within circular economy frameworks. Nonetheless, gaps remain in large-scale validation, techno-economic assessments, and regulatory harmonization. The review highlights potential pathways for integrating these non-conventional materials into sustainable phosphorus management strategies that can help to reduce reliance on phosphate rock, mitigate eutrophication, and foster the transformation of WWTPs into WRRFs.
Vegetation restoration can enhance soil carbon sequestration but may deplete soil water in drylands. We synthesized 1045 soil organic carbon (SOC) and 875 soil moisture content (SMC) observations from 77 publications on cropland restoration across the Loess Plateau to identify where and when carbon gains coincide with water costs. Overall, restoration increased SOC by 39.2% but reduced SMC by 10.7%. Woody restoration produced larger carbon gains but greater soil-water losses than meadow restoration. SOC accumulation was concentrated in surface soils, whereas marked SMC depletion occurred below 300 cm under forests and shrubs. The imbalance was most evident during the 10-25 yr restoration stage. Nonlinear precipitation responses further showed that greater rainfall did not consistently alleviate soil-water costs. Species-level responses ranged from high-carbon-high-water-cost patterns to more balanced SOC-SMC responses. These findings identify the vertical, temporal, and biological contexts of restoration-induced carbon-water imbalance and provide a risk-based basis for carbon-water-balanced restoration.
Despite advances in rice water and nitrogen (N) management, previous studies still fail to quantitatively balance economic benefit and environmental cost on the basis of high yield, and lack robust N diagnostic thresholds for rice production. In a three-year field experiment, treatments comprised two irrigation regimes, conventional irrigation (CI) and alternate wetting and drying (AWD), and four N rates (0, 180, 270, and 360 kg N ha-1). Results suggest that AWD significantly outperformed CI, enhancing grain yield (12.39%-16.02%), agronomic N efficiency (12.27%-22.30%), and economic benefits (27.36%-38.07%), while mitigating global warming potential (GWP) by 25.90%-29.59%. Distinctively, this is the first study to incorporate an inverse normalization-based trade-off model between yield, economic benefit, and GWP under AWD in the lower reaches of the Yangtze River, identifying 235.37-273.09 kg N ha-1 as the optimal N range in this region. Compared to the rate for maximum yield (311.12 kg N ha-1), this optimized N range maximized economic profitability and N use efficiency while reducing GWP, with a negligible yield penalty of only 0.60%-2.38%. Furthermore, we establish quantitative diagnostic thresholds for dry matter and N accumulation at key growth stages, providing a robust tool for in-season N management in this region. Unlike traditional leaf color diagnostics, these thresholds are quantitative field indicators that can directly guide in-season topdressing decisions. This integrated water-N management strategy based on multi-objective optimization provides a viable pathway for the sustainable intensification of rice systems.
The European rabbit is a key species in Mediterranean ecosystems, yet its populations show contrasting trends: despite broad declines, some areas now sustain very high densities that cause crop damage. Conventional control methods, including hunting, have proven insufficient. As a complementary strategy, cultivating less palatable cereals may reduce crop losses while limiting food availability for rabbits, and, in turn, curbing further population growth. Triticale (x Triticosecale) has been proposed as resistant to rabbit herbivory, but its effectiveness remains unquantified. To quantify its relative resistance under conditions where alternative crops are available, we experimentally compared the yield outcomes of triticale and commonly cultivated cereals under staggered durations of rabbit exposure. Triticale exhibited significantly greater resistance, retaining ∼50% of its yield after six months of rabbit browsing, whereas commonly cultivated cereals dropped to ∼10% of their yield remaining. This difference reflects lower relative herbivory on triticale when alternative cereal crops are available. Responses to herbivory were consistent across triticale varieties, suggesting a general trait rather than a cultivar-specific effect. Under full protection from rabbits, both crop types achieved comparable yields, indicating no major productivity cost associated with triticale. Our findings highlight triticale as a promising tool to mitigate rabbit-induced damage in cereal-based agroecosystems without compromising productivity. Further research should assess the long-term effectiveness for controlling rabbit populations and the broader agroeconomic implications of adopting triticale as an alternative crop to commonly cultivated cereals.
Urban meadows are an important component of urban green spaces and have substantial potential for biodiversity conservation. Conventional mowing can enhance plant diversity by altering the niches of dominant herbaceous species, yet it often adversely affects insect communities. Developing appropriate mowing strategies is therefore critical for conserving insects and maintaining multi-trophic biodiversity. In this study, we used a controlled experiment to assess the short-term effects of retaining flowering plants during mowing on plant and insect diversity. Four treatments were established: the Mowing group (M), the Medicago sativa L. retained group (MS), the Carduus nutans retained group (CN), and the Control group (CK). Cluster analysis was used to compare plant and insect community composition among the four treatments. Linear regression and redundancy analysis (RDA) were further performed to examine the effects of plant diversity and plant functional groups on insect diversity. Compared with CK, all three mowing treatments significantly increased plant diversity. Conversely, these treatments significantly reduced insect Shannon-Wiener diversity, driven largely by declines in the abundances of Diptera, Coleoptera, and Orthoptera. The cover and height of Fabaceae plants were positively correlated with insect Shannon-Wiener diversity. Partial least squares structural equation modeling (PLS-SEM) revealed that the effect of mowing on insect diversity was mediated by altering the community structure of Fabaceae plants. These findings suggest that retaining dominant flowering plants during mowing can mitigate short-term losses in insect diversity while simultaneously enhancing plant diversity.
Soil quality plays critical roles in supporting the sustainable development of agriculture and forestry. In agroforestry ecosystems, soil multifunctionality refers to soil quality and further affects forest management practices. However, it still remains obscure how soil microbial communities and their functional genes affect soil multifunctionality. This study quantitatively evaluated the soil multifunctionality in a poultry-farming agroforestry ecosystem to reveal its relation to functional bacterial community. At seven years after a three-year experiment of poultry farming, soil samples were collected from poplar plantation (Populus × euramericana 'Neva') across three soil layers (topsoil: 0-30 cm, middle: 30-60 cm, deepsoil: 60-90 cm). Further, soil properties, soil bacterial community composition and structure, bacterial functional genes related to nitrogen and phosphorus cycling were fully examined. The results showed that soil multifunctionality was significantly increased in poultry-farming plantation of poplar, with notable improvements observed in the topsoil and deepsoil. Soil microbial diversity in the poultry farming plots was significantly higher than in the non-poultry farming plots, and diversity indices showed positive correlations with soil multifunctionality. Meanwhile, in the poultry farming plots, bacterial community transitioned from oligotrophic (e.g., Acidobacteria, Chloroflexi) to copiotrophic taxa (e.g., Actinobacteria, Proteobacteria). Additionally, bacterial functional genes related to nitrification (e.g., amoA2) and organic phosphorus mineralization (e.g., CPhy) were significantly enriched in the topsoil. Some specific microbial taxa (e.g., Gaiella) were indicated to play crucial roles in driving soil nitrogen and phosphorus cycling, and soil multifunctionality was significantly regulated by these key functional microbial taxa. The study revealed deeper microbial mechanisms improving soil productivity in a poultry-farming agroforestry ecosystem, proposing a possible countermeasure for sustainable management of the plantation forest.
Urbanisation and population growth have significantly increased waste generation, intensifying the need for efficient urban cleaning and waste management. Despite technological progress in other sectors, waste collection and street cleaning practices remain largely reactive, resource-intensive, and insufficiently supported by live information. In this context, smart and data-driven technologies offer new opportunities to improve operational efficiency, environmental performance, and urban quality of life. This study presents a structured overview of emerging digital technologies applied to municipal waste management, with a particular focus on street cleanliness assessment and Artificial Intelligence-based monitoring.The paper examines key technological domains, including Internet of Things systems, street-level imagery, mobile mapping, and machine learning methods for waste detection, classification, and decision support. Beyond summarising current solutions, the analysis identifies critical limitations in the field, notably the lack of standardised urban cleanliness indicators, limited availability of representative datasets for real-world conditions, and insufficient integration between objective measurements and citizen perception. Building on these insights, the paper proposes an integrated conceptual framework to address these gaps. The suggested methodology combines unmanned aerial vehicle-based image acquisition, computer vision techniques, and citizen perception surveys to support the development of a digitalised urban cleanliness index. This integrative approach enables scalable, data-driven, and citizen-informed urban cleanliness assessment, supporting more transparent and efficient decision-making in municipal waste management.
Fe (hydr)oxides have significant impacts on the fate of molybdenum (Mo) via the adsorption of molybdate (MoO42-) onto their surfaces. However, these materials always interact with natural organic matter (NOM) in the natural environment, and the role of NOM in mediating the geochemical behavior of Mo(VI) at mineral surfaces remains poorly understood. Using humic acid (HA) as a model organic compound, the adsorption behavior, influencing factors, and underlying mechanism of Mo(VI) onto ferrihydrite (Fh)-HA co-precipitates were investigated via batch experiments, combined with XPS and FTIR analyses. The results revealed that HA exhibited dual effects on Mo(VI) retention, with a pronounced dependence on the C/Fe molar ratio. It inhibited Mo(VI) uptake at a higher C/Fe molar ratio (0.5), while promoting adsorption at a lower C/Fe molar ratio (0.1) under acidic-to-neutral conditions (pH 4.0-7.5). The presence of various coexisting anions exerted distinct effects on Mo(VI) adsorption. Specifically, H2PO4-/SO42- inhibited Mo(VI) adsorption, whereas Cl-/NO3- promoted its uptake. The results of XPS, FTIR characterization, and chemical extraction consistently indicated that the binding modes of Mo consisted of a mixture of outer-sphere complexes, inner-sphere complexes with both ferric hydroxyl and carboxyl groups, and ferric molybdate-like precipitates in the presence of HA, with no significant reduction of Mo(VI) occurring. These findings highlight the critical role of NOM in governing Mo speciation and mobility at Fe (hydr)oxide-water interfaces, providing essential insights for predicting Mo fate and developing remediation strategies for contaminated soils.
Yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis) are among the most heavily exploited pelagic species, with combined annual catches exceeding 4.6 million tons. However, how regional environmental conditions affect tuna growth across different areas remains poorly understood. Here, we develop a bioenergetic model for epipelagic tuna based on the Von Bertalanffy Growth Function to explain the divergent responses of the Length-Weight Relationship (LWR) in Yellowfin and Skipjack tunas to varying sea surface temperature (SST) and chlorophyll-a (SSChl). We found the LWR scaling factor (b) decreased with rising SSChl in the South China Sea (SCS), the Eastern Indian Ocean (EIO), and the South Atlantic near Brazil (SAB) but increased in the North Bone Bay (NBB), the South Bone Bay (SBB), and the Indonesian Sea (IS). We also found a positive response of b to SST across most of our study regions, yet showed a significant negative response in the SBB. A bioenergetic model analysis revealed that these patterns are driven by ontogeny and prey composition. The anomalous positive SST effect in the SBB is explained by the region's much larger Yellowfins (with asymptotic maximal length of L∞ = 207 cm and asymptotic maximal weight W∞ = 176 kg) compared to the average size (L∞ = 144.7 cm, W∞ = 53.89 kg) over various study sites. The SSChl dichotomy reflects the diversity in the dominant prey of the study sites, with a negative correlation indicating bottom-up control via planktonic prey, while a positive correlation, as seen in the NBB/SBB, signals a trophic cascade where tuna prey on intermediate trophic levels, decoupling their condition from direct primary production. This framework enables robust projections of tuna populations under future climate change.
Ecological restoration of soda saline-alkali soils is critical for synergizing food security with climate change mitigation; however, the coupling mechanisms between soil carbon cycling and carbonaceous greenhouse gas dynamics during amelioration remain obscure. This study conducted a field experiment in the soda saline-alkali region of Northeast China to investigate the responses of the soil-plant-microbe system and carbonaceous greenhouse gas driving mechanisms under uncultivated wasteland (WL), conventional paddy (CK), and organically amended paddy field (PF). The results throughout the entire 2023 growing season indicated that the amendment significantly reduced soil pH by 3.66% (down to 8.68) and electrical conductivity by 77.28% (down to 0.333 mS cm-1) relative to CK via a "Ca-Na displacement" mechanism, alleviating osmotic stress and boosting soil organic carbon (SOC) accumulation (an increase of 49%-135%, peaking at 10.132 g kg-1) and carbon cycling enzyme activities. The PF treatment reduced CO2 emissions (averaging 27.55% lower than WL, with the peak limited to 1097.26 mg m-3), but conversely resulted in elevated CH4 concentrations (an average increase of 30.98% relative to WL, peaking at 996 mg m-3). Furthermore, multivariate explanation and variance decomposition analysis suggested a potential transition in carbonaceous greenhouse gas regulation: the ecosystem transitioned from a plant-dependent transport pathway under saline constraints (CK, dominated by plant biomass transport) to a substrate-enzyme coupled regulation pathway following amelioration (PF, dominated by carbon fractions and enzyme activities). Consequently, a preliminary stratified low-carbon management strategy is proposed: prioritizing salt-tolerant varieties with developed aerenchyma for unameliorated soils, while implementing precision regulation of carbon substrates and water for reclaimed fertile soils to balance productivity with environmental footprints.
The gut microbiome is a reservoir for antibiotic resistance genes (ARGs) and is sensitive to environmental pollutants. ARGs in environmental and host-associated microbiomes can be enriched by metal(loid)s through co-selection with metal resistance genes (MRGs). However, as a ubiquitous toxic metalloid, antimony (Sb) induced alterations of ARGs in the gut microbiome and the underlying mechanisms remain unclear. Here, by integrating genome-resolved metagenomics and metatranscriptomics, we characterized the genomic potential and transcriptional activity of ARGs and MRGs in the gut microbiome of mice exposed to Sb(III)- and Sb(V)-contaminated drinking water. We found that both Sb(III) and Sb(V) significantly increased ARGs abundance, whereas only Sb(III) enhanced ARGs transcription (288.40 ± 41.67 TPM, P < 0.05). Co-selection of ARGs and MRGs was observed through metagenome-assembled genomes (MAGs) analysis, and key taxa driving this process were identified (e.g., Eubacterium_J and Lachnospiraceae_COE1). Sb(III), but not Sb(V), induced co-regulation of macrolide-lincosamide-streptogramin resistance genes and arsRABC operon. A potentially higher risk of ARG dissemination under Sb(III) stress was suggested by the increased abundance and transcription of mobile genetic elements (MGEs). This study advances our understanding of the interactions between Sb and ARGs in the gut microbiome and highlights the potential chemical species-dependent enrichment and transcriptional activation of ARGs.
Antimony (Sb) mobility in acid mine drainage (AMD) is strongly regulated by interactions with secondary Fe minerals and dissolved organic matter (DOM), yet how mineralogical heterogeneity modifies DOM-induced Sb redistribution remains poorly understood. Here, we investigated how DOM concentration and composition regulate Sb(V) retention and mobilization in a naturally derived multicomponent secondary iron mineral assemblage (nmSIM) and representative single Fe minerals, using humic acid (HA), fulvic acid (FA) and L-tryptophan (L-Trp) as representative DOM types. By integrating Sb retention/release measurements with Fe dissolution, mineralogical characterization and surface spectroscopic analyses, we identified a concentration-dependent shift in the relative importance of retention and mobilization processes. At relatively low DOM concentrations, HA and FA generally enhanced Sb(V) retention, whereas at higher concentrations they promoted Fe dissolution and Sb mobilization; L-Trp exerted substantially weaker and less systematic effects. Notably, nmSIM did not consistently exhibit lower initial Sb release than individual minerals. Instead, under HA and FA perturbation, it displayed a distinct temporal response, with relatively high initial Sb mobilization followed by attenuation or stabilization of dissolved Sb, whereas several single-mineral systems showed more sustained release. Mineralogical and surface-chemical evidence indicates that DOM-promoted dissolution of relatively reactive Fe-bearing phases was accompanied by phase evolution toward more crystalline Fe-(oxyhydr)oxide-rich surfaces. The concurrent decline or stabilization of dissolved Sb despite continued Fe release supports the involvement of newly generated Fe-bearing interfaces in subsequent partial Sb re-immobilization, although their mineral-specific contribution cannot be quantitatively resolved by the present data. Overall, the results reveal a two-level regulatory framework in which DOM concentration and composition govern the initial balance between Sb retention and mobilization, whereas mineralogical heterogeneity modulates the subsequent fate of mobilized Sb through coupled dissolution, phase transformation and partial re-immobilization. This framework cautions against directly extrapolating single-mineral behavior to heterogeneous AMD systems and provides a mechanistic basis for assessing Sb mobility and retention under DOM perturbation.
Large-scale climate modes such as ENSO influence crop production, yet the pathways linking remote variability to local losses remain unclear. Here, we link the El Niño-Southern Oscillation to winter wheat risk across China using heading-harvest hot-dry-windy hours from hourly ERA5-Land and 1981-2020 county-level yields. ENSO does not shift exposure uniformly; it redistributes probability mass along the HDW-hour distribution in a region-dependent way, changing the likelihood of high-exposure seasons. This imprint widens and left-shifts the yield-anomaly distribution and thickens the negative tail, consistent with thresholded, convex damage under late-season compound stress. Mediation decomposition indicates spatial asymmetry: HDW-mediated effects are clearest in southern latitude bands, whereas northern ENSO-yield variation is more strongly associated with competing non-HDW pathways. A targeted northern diagnosis identifies late frost as the strongest adverse non-HDW pathway, counterbalanced by a spring-precipitation pathway of comparable magnitude but opposite sign. A structural equation model supports a layered cascade in which ENSO intensifies extreme heat, the dominant proximal driver of HDW exposure, while irrigation intensity and soil organic carbon primarily damp exposure-to-loss translation.
Microwave treatment can alleviate mass-transfer limitations in soils containing aged polycyclic aromatic hydrocarbons (PAHs), but its efficiency is often constrained by weak and spatially heterogeneous soil-microwave coupling. Coal gasification fine slag (CGS) was upcycled into FeN-CGS, a porous Fe3O4-anchored N-doped carbon magnetodielectric susceptor with multiscale heterointerfaces. Phenanthrene (PHE) was used as a model three-ring PAH. Under closed-loop 2.45 GHz irradiation at a probe-monitored setpoint of 80 °C, 10 g kg-1 FeN-CGS achieved 85.8 ± 1.7% and 90.9 ± 2.0% apparent depletion of extractable PHE after 5- and 10-min nominal holding periods, respectively, substantially exceeding the microwave-only and FeN-CGS-only controls. The operational apparent rate coefficient was 0.631 min-1, with a rate-coefficient-based synergy index of 3.71. Density functional theory calculations, electromagnetic measurements, and blank-controlled heating tests supported the proposed coupling between favorable PHE adsorption at the graphene-N/Fe3O4 (111) interface (Eads = -1.13 eV) and microwave dissipation through dielectric and magnetic losses. Non-target gas chromatography-mass spectrometry showed no prominent accumulation of new extractable aromatic products, while integrated off-gas trapping showed that the PHE-related C14H10 marker was not a major component of the recovered semivolatile fraction. FeN-CGS retained its thermal and magnetic response after material-only microwave aging. Comparative water extraction showed analyte-dependent changes, including lower Fe, Cu, and As concentrations in coupled-system extracts than in microwave-only extracts. Overall, this study demonstrates a waste-derived magnetodielectric strategy for rapid microwave treatment of PHE-contaminated soil without added oxidants, integrating treatment performance with interfacial affinity-dissipation analysis and pathway-oriented environmental screening.
Determining the optimal chemical dosing in drinking water treatment plants is a complex process due to the variability of hydro-meteorological parameters and the nonlinear dynamics of water chemistry. Conventional machine learning approaches typically rely on a behavioral cloning paradigm, thereby replicating suboptimal or inefficient operator decisions. In this study, a novel strategy is proposed to transform artificial intelligence from a purely predictive tool into a prescriptive decision support system. World Health Organization (WHO) and Turkish Standards Institute (TS-266) water quality standards are applied as a pre-filter, and the models are trained exclusively on data from optimal operational conditions. Tree-based ensemble algorithms are employed to predict the dosing of pre-chlorination, post-chlorination, ferric chloride, and potassium permanganate. To improve model transparency, the explainable artificial intelligence (XAI) method SHAP (SHapley Additive exPlanations) is integrated. Rather than establishing physical causality, SHAP is utilized to identify the most influential variables contributing to the model's predictions. Consequently, SHAP dependence plots are used to derive actionable, site-specific operational rules for plant operators. While the proposed framework demonstrates high predictive accuracy, the current study is limited to a single-site dataset, highlighting the need for future external validation to fully assess model generalizability and associated uncertainties. Ultimately, this framework integrates explainable machine learning with operational principles, offering a reliable foundation to reduce chemical consumption and minimize human error.
Anthropogenic use of rare earth elements (REEs) in modern technologies has increased their occurrence in wastewater streams and aquatic environments. This study evaluated floating treatment wetlands (FTWs) planted with Juncus inflexus for removal, biomass accumulation, and phyto-ash enrichment of selected REEs (La, Ce, Y, Sc, Gd) from synthetic high-strength wastewater. Three REE systems were tested: MIX1 (La + Ce), MIX2 (Y + Sc), and MIX3 (Gd), at 1-20 mg L-1 per element. Removal efficiency, plant responses, uptake kinetics, mass distribution, short-term remobilization, and phyto-ash enrichment were assessed. After 14 days, total REE removal exceeded 54.9% across all treatments, reaching up to 95.5% for La/Ce and >91% for Gd. Bioconcentration factors exceeded 100 at lower exposure levels, consistent with relatively high plant-associated accumulation. Time-course measurements showed a rapid initial decrease in aqueous REE concentrations within the first 1-3 days, followed by slower stabilization. Mass-balance analysis at 5 mg L-1 showed that 40.6-68.1% of the initial REE mass was quantified in plant tissues after 14 days, predominantly in roots. Release experiments showed limited short-term REE remobilization from harvested biomass, while plant responses included descriptive variations in root anatomy and mainly transient changes in chlorophyll fluorescence. Root-derived ash showed clear REE enrichment, with AEF values of 16-22 for La/Ce and calculated REO-equivalent concentrations of 0.19-2.63 wt%. Overall, FTWs planted with Juncus inflexus reduced aqueous REE concentrations and concentrated REEs in harvestable biomass, supporting further evaluation of this system as a potentially low-input polishing and pre-concentration step for selected REE-containing wastewater streams.
This research looked into the catalytic impact of diatomite (DE) on the pyrolysis of oil-based drilling cuttings (OBDC) to achieve the high-value use and safe handling of OBDC. Thermogravimetric kinetic analysis revealed that the 20 wt% DE addition reduced the apparent energy of activation (Ea) of OBDC pyrolysis from 172.06 kJ/mol to 119.63 kJ/mol and transformed the reaction mechanism model from a 4th-order reaction model (F4) to a 2.5th-order reaction model (F2.5). Combined thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), gas chromatography-mass spectrometry (GC-MS), and density functional theory (DFT) analyses verified that DE narrowed the frontier orbital energy gap. The surface active sites of DE facilitated decarboxylation and olefin hydrogenation reactions, raising the alkane content by 28.81%. Furthermore, DE promoted the conversion of sulfur into gaseous H2S and solid sulfates/sulfones, while nitrogen-rich heterocycles were stably retained in solid coke. Environmental and ecological risk assessment demonstrates that DE exerted a prominent microscopic passivation effect on heavy metals. The proportions of acid-soluble fraction (F1) of Mn and Zn decreased from 68% and 30% to 1% and 14%, respectively. The final potential ecological risk index (RI) of pyrolytic solid residue was only 12.07, far below the threshold for slight ecological risk. This work provided detailed multi-scale theoretical guidance for the green thermal conversion of OBDC, directional upgrading of target products, and safe industrial disposal of residues.
Overgrazing and uneven spatial use of forage continue to constrain pasture management in the grasslands of northern China. In the context of a family run pasture, livestock repeatedly graze easily accessible areas, while high quality forage in more distant areas remains underutilized. This makes grazing route planning a practical need for improving forage use distribution. To address this issue, we propose a multi objective Improved Grazing Ant Colony Optimizer (IGACO) for constraint aware grazing route planning. IGACO extends classical Ant Colony Optimization (ACO) with grazing specific improvements, including progress based loop guidance, herd aware obstacle avoidance, a nonlinear walking efficiency index and a multi objective pheromone update rule. The algorithm combines UAV multispectral imagery with GIS data to build a high resolution, constraint annotated pasture graph, in which forage patches, watering points and danger points are encoded as route planning elements. In experiments on a representative pasture in northern China, IGACO achieved the lowest composite objective value and shortest mean path length among ACO, GA and PSO under AHP derived weights. Additional 5 x 6 and 7 x 7 grid-based scenarios showed that the method can also support coarse grained rotational grazing unit sequencing. Ablation analysis further confirmed the contribution of the proposed grazing specific components. These results suggest that IGACO can provide a practical spatial decision support tool for precision grazing route planning.
