Search Results (110)

Olive mill wastewaters (OMWWs) are an environmental problem in the Mediterranean region, and it is crucial to explore strategies for their treatment and repurposing. The chemical precipitation technique (CPT) has been presented as a cost-effective wastewater treatment solution that might be applied to OMWW. The CPT-resulting precipitant subproducts (sludge) may be reprocessed (e.g., agricultural fertilizer and/or soil amendment), while the treated wastewater may be repurposed or reused (e.g., irrigation, aquaponic, or industrial processes). This study aimed to evaluate the efficacy of CPT in treating wastewater from the olive oil industry from an ecotoxicological perspective. Additionally, to assess the safe use of the obtained sludge in CPT treatment, its effects on soil biota were assessed. For this, a set of ecotoxicological assays using freshwater (Raphidocelis subcapitata, Daphnia magna and Danio rerio), terrestrial invertebrates (Folsomia candida and Enchytraeus crypticus), and plants (Brassica oleracea and Lolium perenne) were used as model organisms. Results demonstrated that CPT reduced OMWW toxicity to freshwater organisms, offering a favorable outlook on CPT’s potential as a wastewater treatment method. Increasing application rates of sludge in soil reduced the shoot biomass and the hydric content of both plants compared to the control. Survival of F. candida and E. crypticus was not affected by sludge in soil at any tested application rate, yet sludge application negatively affected the reproduction of both species, even at relevant sludge application rates (2%) of sludge in soils. Overall, the applicability of this sludge obtained by the CPT treatment in soils should be carefully evaluated due to the observed adverse effects on soil biota. Although the results of CPT were promising in reducing the toxicity of OMWW for these aquatic species, some adjustments/improvements should be performed to improve this technique and use all the obtained resources (treated water and sludge) in a fully circular perspective. Full article

Limited research has been conducted on the potential and mechanisms of irrigating Suaeda salsa with wastewater and microalgae to improve saline–alkali land. This study used three irrigation treatments (freshwater, saline wastewater, and saline wastewater with microalgae) to irrigate S. salsa, and microalgae promoted the growth of S. salsa and increased soil nutrient content, increasing available nitrogen (4.85%), available phosphorus (44.51%), and organic carbon (24.05%) while alleviating salt stress through reduced soil salinity (13.52%) and electrical conductivity (21.62%). These changes promoted eutrophic bacteria while inhibiting oligotrophic bacteria. Bacterial community composition exhibited significant variations, primarily driven by soil pH, total nitrogen, and organic carbon content. Notably, rhizosphere bacteria showed enhanced functional capabilities, with increased abundance of salt stress resistance and nitrogen metabolism-related genes compared to original soil, particularly under saline irrigation conditions. Furthermore, microalgae addition enriched nitrogen metabolism-related gene abundance. These findings revealed the potential role of key bacteria in enhancing plant growth and the soil environment and highlighted the potential of applying S. salsa, wastewater, and microalgae for the synergistic improvement of saline–alkali land. Full article

Sustainable land management in arid regions such as the Jordan Valley (JV) is essential as climate pressures and water shortages intensify. The extended use of treated wastewater (TWW) for irrigation, while necessary, brings potential risks related to the accumulation of trace elements and their impact on soil health and food safety. This study examined the spatial distribution, variability, and potential sources of five trace elements (Co, Hg, Mo, Mn, and Ni) in agricultural soils across a 305 km² area. A total of 127 surface soil samples were collected from fields irrigated with either TWW or freshwater (FW). Trace element concentrations were consistently higher in TWW-irrigated soils, although all values remained below WHO/FAO recommended thresholds for agricultural use. Spatial modeling was conducted using both ordinary kriging (OK) and empirical Bayesian kriging (EBK), with EBK showing greater prediction accuracy based on cross-validation statistics. To explore potential sources, semivariogram modeling, principal component analysis (PCA), and hierarchical clustering were employed. PCA, spatial distribution patterns, correlation analysis, and comparisons between TWW and FW sources suggest that Co, Mn, Mo, and Ni are primarily influenced by anthropogenic inputs, including TWW irrigation, chemical fertilizers, and organic amendments. Co exhibited a stronger association with TWW, whereas Mn, Mo, and Ni were more closely linked to fertilizer application. In contrast, Hg appears to originate predominantly from geogenic sources. These findings provide a foundation for improved irrigation management and fertilizer application strategies, contributing to long-term soil sustainability in water-limited environments like the JV. Full article

Water scarcity is a critical challenge in arid and semi-arid regions, where agricultural water consumption accounts for a significant portion of freshwater use. Conventional agriculture (CA) methods with high reliance on chemical and mechanical inputs often exacerbate this issue through soil degradation and water loss. This review aims to examine how different organic practices, such as mulching, cover cropping, composting, crop rotation, and no-till (NT) in combination with precision technologies, can contribute to water optimization, and it discusses the opportunities and challenges for the adoption and implementation of those practices. Previous findings show that organic agriculture (OA) may outperform CA in drought conditions. However, the problems of weed management in organic NT, trade-offs in cover crop biomass and moisture conservation, limited access to irrigation technologies, lack of awareness, and certification barriers challenge agricultural resilience and sustainability. Since the outcomes of OA practices depend on the crop type, local environment, and accessibility of knowledge and inputs, further context-specific research is needed to refine a scalable solution that maintains both productivity and resilience. Full article

To investigate the changes in the composition and structure of the dissolved organic matter (DOM) of the lysate solutions of different types of soil after green manure tilling treatment, we set up two types of soil materials (fluvo-aquic soil; coastal saline soil) and three green manure tilling treatments (T1: CK—without green manure, T2: tilling Dongmu70 rye, and T3: tilling rapeseed green manure); then, the soil leachate was obtained with a soil column simulation test and its DOM spectral properties were determined. The rapeseed green manure leachate demonstrated a significantly higher humic macromolecule content and aromaticity compared to Dongmu70 rye leachate. Fluorescence Index (FI) values (1.5–2.2) suggest a mixed origin of dissolved organic matter (DOM) from both terrestrial and microbial-derived sources. All Humification Index (HIX) values remained below 1, indicating low humification levels and limited stabilization of DOM within the leachate system, and Biological Index (BIX) values exceeding 1 across all soil layers highlight the predominance of a recent biological metabolism in shaping DOM autochthonous origins. The SUVA₂₆₀ values in Dongmu70 rye–moist soils and rapeseed green manure–coastal saline soil exhibited reductions of 0.020–2.573 L·(mg·m)⁻¹ relative to pre-drenching levels. After tilling rapeseed green manure, the SUVA₂₅₄ value of coastal saline soil at the 60–90 cm layer decreased by 1.941 L·(mg·m)⁻¹. This study shows that differences in green manure and soil type affect DOM sources and composition, reducing DOM leaching, with coastal saline soil + rapeseed green manure and fluvo-aquic soil + Dongmu70 rye being the advantageous combinations. The study results provide theoretical guidance for applying green manure coupled with freshwater leaching technology in the context of saline and alkaline land with multiple soil types. Full article

Although plastic has many desirable properties and numerous social benefits, it is a serious ecological problem due to massive application and difficult decomposing. Various environmental and anthropogenic impacts indicate that plastic breaks down into small particles that are ubiquitous in the environment. Microplastics (MPs) are detected in oceans and seas, freshwater, wastewater, glaciers, soils, air, sediments, precipitation, plants, animals, humans, food and drinking water worldwide. Traces of MPs have been found even in remote and sparsely populated areas, indicating far-reaching movement through environmental compartments. Inadequate waste management and wastewater treatment is considered the major source of MP pollution. MPs are persistent contaminants that can adversely affect the ecological balance of the environment and may damage the health of living organisms, including humans. This review emphasizes the current global problems of MP pollution. It covers different areas of MPs, which include basic characteristics, interactions with other pollutants, occurrence and impacts in the environment, toxic effects on living organisms, sampling, sample pre-treatment and analytical methodology for the identification and quantification of MPs in different matrices as well as potential reduction and remediation strategies and the possibilities for effective control of MPs in the environment. Various interesting and useful previously published knowledge collected in this review can serve as a valuable foundation for further MP research. Full article

In global drought-prone cotton-growing (Gossypium hirsutum L.) areas, saline water irrigation has become a key strategy to alleviate the shortage of freshwater resources. Against this backdrop, the synergistic effect of mineralization degree (MD) and sodium adsorption ratio (SAR) on the rhizosphere microecological regulation mechanism remains unclear. To address this issue, this study constructed an experimental framework of the interaction between MD and SAR, aiming to explore their effects on the bacterial community structure in the rhizosphere of cotton and the soil environment. The soil type in the study area is saline–sodic sandy loam. In the experimental design, three MD levels (3 g/L, 5 g/L, 7 g/L) were set, and under each mineralization condition, three SAR levels (10 (mmol/L)^1/2, 15 (mmol/L)^1/2, 20 (mmol/L)^1/2) were arranged. In addition, local freshwater irrigation was used as the control group (CG), resulting in a total of 10 treatment schemes. The aim of this study was to investigate the effects of varying levels of irrigation water MD and SAR on the structure of bacterial communities in cotton rhizosphere soil and the soil environment. The results indicated that saline water irrigation could enhance the diversity and richness of the bacterial community in the rhizosphere soil of cotton and alter its community structure. Under treatment with the MD of 3 g/L and the SAR of 10 (mmol/L)^1/2, the diversity and richness of the bacterial community in the cotton rhizosphere reached their peak levels. Compared with the CG, the Chao1 index significantly increased by 260 units, while the Shannon index increased by 0.464. When the MD does not exceed 5 g/L, reducing SAR can enhance the diversity and network stability of the rhizosphere bacterial community, thereby synergistically promoting the accumulation of soil nutrients. The key soil environmental factors driving changes in the rhizosphere bacterial community structure mainly include soil moisture content, total nitrogen, nitrate nitrogen, and total organic carbon. The concentrations of total nitrogen, nitrate nitrogen, available phosphorus, and available potassium significantly increased by 19.66%, 26.10%, 89.41%, and 49.76% respectively (p < 0.05). This study provides a theoretical basis for sustainable irrigation and microbial regulation strategies in saline–alkali cotton fields at the theoretical level, and offers a new perspective for revealing the mutual feedback mechanism between bacterial community assembly and soil environment under saline conditions. From a practical perspective, this research offers valuable hands-on experience for optimizing agricultural ecological management in saline–alkali sandy loam soils, thereby contributing to the sustainable development of agriculture on such lands. Full article

Microbial communities in wastewater treatment plants (WWTPs) play a crucial role in the decontamination of polluted water. An uncultured order-level lineage AKYH767 of the phylum Bacteroidota has been consistently detected in microbial consortia of activated sludge at WWTPs worldwide, but its functional role remains elusive. Representatives of AKYH767 were also detected in soils and freshwater bodies, which may be their natural reservoirs. Here, we obtained ten high-quality metagenome-assembled genomes, including one closed circular genome, of AKYH767 bacteria from metagenomes of the wastewater and activated sludge and used genomic data to uncover the metabolic potential of these bacteria and to predict their functional role. The cells of the AKYH767 bacteria were inferred to be rod-shaped and non-motile. Genome-based metabolic reconstruction predicted the Embden–Meyerhof pathway, the non-oxidative stage of the pentose phosphate pathway, and the complete tricarboxylic acid cycle. A facultatively anaerobic chemoheterotrophic lifestyle with the capacity to oxidize low organic substrates through aerobic respiration was suggested. Under anaerobic conditions AKYH767 bacteria can perform different steps of denitrification. They have limited capacities to hydrolyze carbohydrates and proteinaceous substrates but can utilize fatty acids. A peculiar property of AKYH767 bacteria is the presence of the phenylacetyl-CoA pathway for the utilization of phenylacetate, and about half of the genomes encoded the benzoate degradation pathway. Apparently, in bioreactors at WWTPs, the AKYH767 bacteria could be involved in the denitrification and biodegradation of aromatic compounds. Based on phylogenetic and genomic analyses, the novel AKYH767 bacterium is proposed to be classified as Candidatus Pollutiaquabacter aromativorans, within the candidate order Pollutiaquabacterales. Full article

Global challenges such as soil degradation and water scarcity necessitate sustainable agricultural practices, particularly in regions where saline water is increasingly used for irrigation. This study investigates the effects of four compost treatments, including surface-applied mulch compost (MC), Johnson–Su biologically active compost incorporated into soil (JCI), mulch compost incorporated into soil (MCI), and no compost as control (NC), on soil fertility, microbial activity, and Capsicum annuum (chili pepper) growth. Greenhouse experiments were conducted using soil from two different sites (New Mexico State University’s (NMSU) agricultural research plots and agricultural field-testing site at the Brackish Groundwater National Desalination Research Facility (BGNDRF) in Alamogordo, New Mexico) and two irrigation water salinities (brackish at ~3000 µS/cm and agricultural at ~800 µS/cm). The Johnson–Su compost treatment demonstrated superior performance, due to its high soil organic matter (41.5%), nitrate (NO₃⁻) content (82.5 mg/kg), and phosphorus availability (193.1 mg/kg). In the JCI-treated soils, microbial biomass increased by 40%, and total microbial carbon reached 64.69 g/m² as compared to 64.7 g/m² in the NC. Plant growth parameters, including chlorophyll content, root length, and wet biomass, improved substantially with JCI. For instance, JCI increased plant height by 20% and wet biomass by 30% compared to NC treatments. The JCI treatment also effectively mitigated soil salinity, reducing Na⁺ accumulation by 60% and Cl⁻ by 70% while enhancing water retention and soil structure. Principal Component Analysis (PCA) revealed a distinct clustering of JCI treatments, demonstrating its ability to increase nutrient retention and minimize salinity stress. These results indicate that biologically active properties, such as fungi-rich compost, are critical to providing an effective, environmentally resilient approach for enhancing soil fertility and supporting sustainable crop production under brackish groundwater irrigation, particularly in regions facing freshwater scarcity. Full article

Mesoplastics are emerging environmental pollutants that can pose a threat to the environment. Researching mesoplastics is crucial as they bridge the gap between macroplastics and microplastics by determining their role in plastic fragmentation and pathways, as well as their ecological impact. Investigating mesoplastic sources will help develop targeted policies and mitigation strategies to address plastic pollution. These pollutants are found across aquatic, terrestrial, and agricultural ecosystems. Unlike microplastics, mesoplastics are reviewed in the scientific literature. This paper focuses on existing published research on mesoplastics, determining the trends and synthesizing key findings related to mesoplastic pollution. Research primarily focused on marine and freshwater ecosystems, with surface water and beach sediments being the most studied compartments. Mesoplastics research often offers baseline data, with increased publications from 2014 to 2024, particularly in East Asia. However, certain ecosystems and regions remain underrepresented. Also, mesoplastics can disrupt ecosystems by degrading biodiversity, contaminating soils and waters, and affecting food chains. Mesoplastics can also become vectors for additives and pathogenic microorganisms, highlighting their environmental risks. Various factors influence mesoplastics’ prevalence, including anthropogenic and non-anthropogenic activities. With this, future research should expand into less-studied ecosystems and regions, explore mesoplastic interactions with pollutants and organisms, and promote public awareness, education, and policy measures to reduce plastic use and mitigate pollution globally. Full article

In recent years, microplastic pollution has become one of the major global concerns and represents a complex, multidimensional, and multisectoral reality. The considerable existing data relating to microplastic pollution in matrices such as water and soil suggests that microplastics are widespread globally, but there are several knowledge gaps regarding their actual distribution mostly in remote locations far from sources. In this review we examine current knowledge on microplastic pollution in the Antarctic continent. Antarctica, the unique continent not permanently anthropized, is the southernmost part of the planet but its geographic isolation does not protect against the harmful impact of human activities. This continent is characterized by limited internal pollution sources but high-burden external routes of contaminants and represents a unique natural laboratory to analyze how pollution can reach every part of the biosphere. This review reports the presence of microplastics in organic and inorganic matrices not only at marine level (water, sediments, benthic organisms, krill, and fish) but also in freshwater (lakes, rivers, snow, and glaciers) highlighting that microplastic contamination is endemic in the Antarctic environment. Microplastic pollution is of great environmental concern everywhere, but the characteristics of remote ecosystems suggest that they could be more sensitive to harm from this pollution. Full article

Water resources are essential for human survival and sustainable development. However, the global freshwater scarcity, exacerbated by climate change, presents significant sustainability challenges. Using the SWAT model, we simulated the spatiotemporal distribution of total nitrogen (TN) in the Hangjiang River Basin from 2005 to 2020. The average TN concentration was 2.16 mg/L, with the soil nitrogen pool contributing 92.78% of emissions, highlighting the need to address the soil nitrogen legacy. Sampling showed average concentrations of TN, nitrate, ammonium, nitrite, and dissolved organic nitrogen at 3.01 mg/L, 1.66 mg/L, 0.21 mg/L, 0.02 mg/L, and 1.11 mg/L, respectively. Precipitation accounted for 61.4% of nitrogen emission variability, indicating that water resource sustainability will be significantly influenced by climate change. Projections indicated that from 2020 to 2050, climate change will increase runoff by 6.19 m³/s and reduce TN concentration by 0.004 mg/L annually, potentially enhancing the overall sustainability of water resources. It’s necessary to continue strengthening the prevention and control of agricultural non-point source pollution and reduce nitrogen discharge to further enhance water resource security for the Beijing–Tianjin–Hebei development. The findings provide critical insights to inform policies aimed at protecting water sources and ensuring public water safety. Full article

The use of treated wastewater (TWW) in agriculture is an important technological alternative for decreasing freshwater consumption and improving soil physicochemical and biological properties. The aim of this study was to investigate how the quality of soil and olive plants was affected by irrigation with TWW, surface water (SW), and blended water (BW), using tap water as the control. Several plant growth, chemical, and microbial parameters, namely plant height, trunk diameter, chlorophyll content, pH, total organic carbon (TOC), total nitrogen (TN), metals, salinity, and microbial population were selected for this purpose. The short-term irrigation of olive plants for 3 years with TWW, BW, and SW increased the electrical conductivity, TOC, TN, phosphorus, and potassium in the soil. There were notable differences in plant height and chlorophyll content observed in the third year of the experiment, with the greatest values found for the TWW-irrigated plants. These differences were attributed to the rise in the TOC and TN in the soil, which promoted rapid plant growth. The reduction in microbial contamination during the cold seasons may indicate the natural control of these harmful pathogens. Accordingly, it can be concluded that the blending of TWW with SW can reduce the negative effects of TWW resulting from the accumulation of TOC, TN, and metals. Full article

Current studies have paid extensive attention to the occurrence of brominated flame retardants (BFRs) in aquatic environments; however, there is a lack of exploration of BFRs in ice media in freshwater environments, and there are fewer studies on the distribution patterns and ecological risks of BFRs in different media. In order to fill this gap in the current research status, this study conducted four seasonal samplings in the Songhua River wetland in Northeast China. The distribution and risk of 14 polybrominated diphenyl ethers (PBDEs) and 22 new brominated flame retardants (NBFRs) in water, ice, sediment, and soil were analyzed using liquid–liquid extraction sample pretreatment and gas chromatography–mass spectrometry instrumentation. A total of 18, 5, 8, 19, and 18 BFRs were detected in non-ice-covered water, ice-covered water, ice, sediment, and soil, respectively. NBFRs dominated contaminant concentrations in each medium. Significant correlations were found between BFRs in ice and subglacial water, suggesting that the sources of BFRs in these two media are similar and there is an exchange between them. The ice enrichment factor (IEF) revealed the water–ice distribution mechanism of BFRs, indicating that wetland ice acts as a temporary sink for 2-(Allyloxy)-1,3,5-tribromobenzene (ATE), 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (α-TBECH), 1,2,5,6-Tetrabromocyclooctane (TBCO), and 2-Bromoallyl 2,4,6-tribromophenyl ether (BATE). In order to achieve dynamic equilibrium, the exchange profile of BFRs between water and sediment requires the release of BFRs into water. The risk quotient (RQ) indicated that TBCO in water and ice poses a moderate risk to aquatic organisms, and its potential impact on wetland ecology cannot be ignored. Full article

Mangrove swamp rice (MSR) production is critical for the diet of small farmers of coastal Guinea-Bissau. In mangrove swamp agroecosystems, rice is grown during the rainy season when freshwater and nutrients are abundant. However, small-scale farmers face challenges like unpredictable rainfall and rising sea levels, which increase soil salinity and acidity. This study aims to assess soil physical–chemical properties, paired with farmers’ local practices, to evaluate fertility constraints, and to support sustainable soil–plant management practices. This co-designed research contributes to filling a gap concerning the adoption of sustainable agricultural practices adapted to specific contexts in West Africa. In two regions, Oio (center) and Tombali (south), rice yields were measured in semi-controlled trials both in two agroecological settings: Tidal Mangrove (TM) and Associated Mangrove (AM) fields. 380 soil samples were collected, and rice growing parameters were assessed during the 2021 and 2022 rice sowing, transplanting, and flowering periods. Principal Component Analyses (PCA) and Multivariate Regression Analysis (MRA) were applied to understand trends and build fertility proxies in predicting yields. Significant spatial and temporal variability in the soil properties between agroecologies was found. Salinity constraints in Oio TMs limit production to an average of 110 g/m², compared to 250 g/m² in Tombali. Yield predictions account for 81% and 56.9% of the variance in TMs and AMs, respectively. Variables such as organic matter (OM), nitrogen (N), potassium (K), and precipitation positively influence yields, whereas sand content, pH, and iron oxides show a negative effect. This study advances the understanding of MSR production in Guinea-Bissau and underscores the importance of incorporating farmers’ knowledge of their diverse and complex production systems to effectively address these challenges. Full article