Search Results (490)

Optimizing organic fertilizer substitution is essential for enhancing the sustainability of agriculture and achieving a balance between crop productivity, nutritional quality, and environmental safety. Here, we conducted an 11-year field experiment to evaluate the effects of substituting 50% of mineral fertilizers with pig manure (PM) or cattle manure (CM) on the nutritional quality of wheat grain, heavy metal (HM) accumulation, and associated human health risks. The yield and protein content were highest in the mineral fertilizer (MF) treatment, and grain micronutrients (Fe, Mn, Cu, Zn) were 6.7–13.8% higher under organic substitution (PM/CM) than in the MF treatment. The Ni, Pb, and As contents were 35.4–43.0% higher in the PM treatment than in the MF treatment, which stems from the higher HM content in pig manure. Health risk assessments indicated that the Hazard Index (HI) for children exceeded 1 in the PM treatment, primarily due to As, which accounted for 69.6% of the HI. All treatments remained within safe thresholds, although As and Pb posed detectable carcinogenic health risks. The higher levels of Ni and As in pig manure likewise led to a significant increase in the health risk associated with the PM treatment compared to the MF treatment. We developed a novel Grain Quality Index (GQI) that combined nutrient and HM data, which indicated that the nutritional quality of wheat grain was similar in the CM and MF treatments. The GQI was 9.1% lower in the PM treatment than in the MF treatment. These findings suggest that the substitution of mineral fertilizer with cow manure can help achieve a balance between yield, nutrition, and safety, and more stringent regulation of HMs is required for the use of pig manure. Our findings provide actionable insights with implications for sustainable wheat production policies. Full article

Urban community gardens are valued for promoting sustainable food production, yet the accumulation of toxic heavy metals in city soils can present both ecological and public health risks. Therefore, this study was aimed at assessing the environmental and health risks of toxic heavy metals in community gardens soil contaminated by an industrial fire hazard in New Brunswick, Canada. Both top and subsoil soil samples were collected at Carleton community garden. The collected samples were examined for toxic heavy metals using inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry. Ecological risks were evaluated through the ecological risk factor and the potential ecological risk index, while human health risks were determined using a standard human health risk assessment approach. The mean concentration of Pb, Zn, Cu, and Sn exceeded permissible limits when compared to the Canadian soil quality guidelines and upper continental crust values. Findings from the ecological risk assessment showed that all metals were associated with low risk, except for nickel, which posed a high ecological risk across both soil layers. PERI results revealed a low overall ecological threat. The human health risk analysis indicated that children could face non-carcinogenic and carcinogenic risks from As exposure, while adults were not at risk from any of the studied metals. These findings identify arsenic as the primary contaminant of concern, with children representing the most vulnerable population, emphasizing the necessity for targeted mitigation strategies and protective measures to reduce their exposure. The results of this study can inform interventions aimed at safeguarding both environmental and public health, while also raising awareness about the presence and risks of toxic heavy metals, ultimately contributing to the protection of human health and the broader ecosystem. Full article

Sustainable manure recycling in cold climates faces low efficiency and nutrient loss. This study evaluated housefly larva-pretreated manure (HL) for winter swine manure composting in East China, comparing it to sawdust-conditioned (CK2) and untreated manure (CK1). Larval pretreatment converted 12.71% of manure weight into biomass, assimilating 10.69% C, 30.55% N, 8.54% P, and 11.53% K. Harvested larvae contained 53.35% crude protein, with amino acids matching/exceeding fishmeal and soybean meal, while heavy metals were below safety limits. Theoretical annual larval protein yield per unit area (29,530 kg·mu⁻¹·year⁻¹) was 206.5 times higher than soybean crops. During composting, the HL treatment promoted early protease and catalase activation. This enzymatic synergy accelerated organic matter degradation and maturation, achieving a germination index of 147.67% by day 51. Coordinated nitrate and nitrite reductase activity in HL facilitated efficient denitrification, minimizing NO₂⁻ accumulation and N₂O emissions. Consequently, HL composting achieved faster stabilization, enhanced nutrient retention, and greater protein recovery compared to controls. These findings demonstrate that housefly larval pretreatment offers a climate-resilient and scalable strategy for winter manure management and protein valorization, with strong potential for applications in cold and resource-limited agricultural systems worldwide. Full article

Heavy metal pollutants and organic contaminants often co-exist in the environment, posing significant ecological risks due to their combined toxicity. Phytoremediation, a plant-based biotechnology, offers a promising solution for pollutant removal. This study investigated the potential cadmium (Cd) removal capacity of Narrow Crown Black-Cathay poplar (Populus × canadensis Moench × Populus simonii Carr. f. fastigiata Schneid.) under combined Cd-phenol stress. The results showed that the combined stress synergistically inhibited the photosynthetic physiological characteristics, with an inhibition rate up to 54.0%, significantly higher than that under single stress (p < 0.05). Cd accumulation varied markedly among plant organs, following the order: root (ranging from 4000.2 to 9277.0 mg/kg) > stems (ranging from 96.0 to 383.6 mg/kg) > leaf (ranging from 10.3 to 40.1 mg/kg). Phenol enhanced Cd absorption and enrichment in the roots by up to 1.8 times but reduced its translocation to aboveground parts by 37.8–40.0%. Notably, at low Cd concentrations, the Cd removal efficiency under combined stress (26.0%) was substantially higher than under single Cd stress (6.6%). In contrast, biomass, tolerance index, and root–shoot ratio were slightly affected in all treatments (p > 0.05). These findings demonstrate that Narrow Crown Black-Cathay poplar is a suitable candidate for the short-term remediation of Cd in environments co-contaminated with cadmium and phenol. Full article

The Three Gorges Reservoir, serving as a crucial ecological barrier for the middle-lower Yangtze River basin, faces substantial threats to watershed ecosystems from sediment-associated heavy metal, threatening aquatic ecosystems and human health via bioaccumulation. Leveraging the legislative framework of the Yangtze River Protection Law, this study analyzed sediment cores (0–65 cm) collected from 12 representative sites in the Three Gorges Reservoir using 2020 Air–Space–Ground integrated monitoring data from the Changjiang Water Resources Commission. Concentrations of nine heavy metals (Cd, Cu, Pb, Fe, Mn, Cr, As, Hg, and Zn) were quantified to characterize spatial and vertical distribution patterns. Source apportionment was conducted through correlation analysis and principal component analysis (PCA). Contamination severity and ecological risks were assessed via geo-accumulation index (I_geo), potential ecological risk index (RI), and acute toxicity metrics. The findings indicated substantial spatial heterogeneity in sediment heavy-metal concentrations, with the coefficients of variation (CV) for Hg and Cd reaching 214.46% and 116.76%, respectively. Cu and Pb showed surface enrichment, while Cd exhibited distinct vertical accumulation. Source apportionment indicated geogenic dominance for most metals, with anthropogenic contributions specifically linked to Cd and Hg enrichment. Among the metals assessed, Cd emerged as the primary ecological risk driver, with localized strong risk levels (E_i > 320), particularly at FP and SS sites. These findings establish a scientific foundation for precision pollution control and ecological restoration strategies targeting reservoir sediments. Full article

This study focused on the Wugong coal fire area in the Zhunnan coalfield of Xinjiang, analyzing 41 soil samples extending from the fire center outward. The key parameters included pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available potassium (AK), various ions (Ca²⁺, Na⁺, Mg²⁺, SO₄²⁻, CO₃²⁻, HCO₃⁻, and Cl⁻), and heavy metal concentrations (As, Cr, Hg, Ni, Cd, Cu, Zn, and Pb). The primary objectives were to evaluate heavy metal pollution levels and potential ecological risks using the single factor pollution index (P_i), the Geo-accumulation index (I_Geo), Nemero’s pollution index (P_n), the pollution load index (PLI), and the ecological risk factor (E_rⁱ) and risk index (RI). Spatial distribution analysis indicated higher heavy metal concentrations in the southwestern and central regions. The heavy metals Cr, Ni, Cd, Cu, and Zn reached mild pollution levels, while Hg exhibited high pollution, with P_i, I_Geo, and P_n values of 3.27, 0.61, and 9.68, respectively. Hg (E_rⁱ = 111.07) and Cd (E_rⁱ = 45.91) emerged as the primary ecological risk factors. The overall ecological risk index (RI) of 184.98 indicated a moderate ecological risk. The results demonstrate that soils surrounding the coal fire zone are significantly impacted by coal fire, characterized by severe heavy metal contamination and nutrient deficiency. Full article

Excess Cd in soils can be accumulated in rice, presenting a serious human health risk. The effect of foliar transpiration inhibitors (TIs) on the Cd content and the endophytic bacterial community in rice plants was unclear. We evaluated the key part of the rice plant to control the Cd translocation and the profile of the endophytic bacterium structure after spraying with foliar reagents; some possible typical endophytes were induced by the TIs to inhibit the Cd translocation in the rice plant. The rice plants in three sites with different available Cd content were sprayed with foliar TIs. We assessed the Cd, N, P, K and water-soluble saccharide (WSS) in different parts of the rice plant and the endophytic bacteria community in the stem. Foliar application of TIs reduced Cd translocation factor (TF_Cd) by ~20% from the root to the grain compared with that of CK. The TI can increase the adsorptive site concentration of stem nodes from 5.10 to 6.83 mmol/g. The diversity of the endophytic bacteria community was enhanced after application of TI, and the Shannon index increased from 3.29 to 3.92. The endophytic bacterial community induced by TI showed higher potentiality on the biofilm and stress-tolerant and metal-transport functions than that of CK, respectively. The relative abundances of Burkholderiaceae and Bacterium_g_Anaeromyxobacter were significantly negatively correlated (p < 0.05), with TF_Cd and positively correlated (p < 0.05), with water-solution saccharide content, simultaneously. The TI enhanced the endophytic diversity and amount. A high abundance of special endophytic bacteria induced by TI might decrease the TF_Cd. Full article

This study aims to evaluate the feasibility of using the mussel as a bioindicator for the rapid detection of heavy metal (such as Cd, Pb, Hg, Ni, Cr, Cu, As, and Zn) fluctuations in aquatic environments and the sensitivity of the bioaccumulation of heavy metals in muscle tissues over time. The seasonal bioaccumulation patterns of heavy metals within Asian green mussels (Perna viridis), from Vietnamese coastal waters of Hai Phong were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Additionally, the health risks from the consumption of P. viridis by local people were assessed. Mussels of varying sizes were sampled on a monthly basis between March (dry season) and July 2024 (wet season). The results revealed that the hepatopancreas had substantially higher concentrations of metals at all times relative to their corresponding muscle tissues, confirming its appropriateness as a bioindicator organ. The concentrations of heavy metals in mussels were recorded as significantly lower than the guideline levels, except for arsenic (As). Zinc (Zn) showed the highest concentrations, while mercury (Hg) had the lowest concentrations. There were strong seasonal and monthly differences, with peak levels of Pb, Cr, and As during the dry season, and high levels of Cs and Cu during the rainy season. It was found that the condition index, physiological factors, and shell size all had major impacts on the absorption of specific heavy metals. It was indicated that Pb, Cr, As, Cs, and Cu bioaccumulation are both biologically and environmentally responsive and can be used as proxies for environmental contamination, while the accumulation of these metals correlated with biological traits (shell length, weight, and CI), which is useful in modeling efforts. Health risk assessments using target hazard quotients (THQs) and the total hazard index (THI) identified Pb in the hepatopancreas as a primary contributor to the non-carcinogenic risk (THQ > 1), particularly during the dry season. The findings revealed the suitability of P. viridis, particularly hepatopancreatic tissue, as a short-term biomonitoring tool for detecting spikes and rapid fluctuations of certain heavy metals and assessing related human health risks in coastal aquatic systems. Full article

Exploring the pollution characteristics and ecological risks of urbanization on lakes in urban fringe areas has guiding significance for the control and scientific management of heavy metal pollution in lakes in urban fringe areas. Taking the West Lake in Kaifeng city as an example, the samples of the sediments and surface water of the lake were collected, and the contents of heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were measured, assessing the degree and ecological risk of heavy metal pollution using the Geo-Accumulation Index (I_geo) and Potential Ecological Risk Index methods (RI); and the sources of pollution were identified. The results show that the heavy metal concentrations in the surface water of the West Lake in Kaifeng city are generally low; average concentrations of Cd, Cu, Zn, Cr, Ni, Pb, and As in sediments are 3.120, 1.810, 1.700, 1.540, 1.000, 0.990, and 0.430 times higher than the background value of fluvo-aquic soil, respectively. The sequence of the average I_geo from high to low is Cd (1.020) > Cu (0.220) > Zn (0.160) > Cr (0.000) > Pb (−0.610) > Ni (−0.640) > As (−1.850). Among them, contaminations with Pb are classed as moderately polluted; As pollution is relatively light, while other heavy metals are unpolluted. The average Potential Ecological Risk Coefficient (E) values for seven heavy metals are Cd (93.500) > Cu (9.040) > Ni (4.990) > Pb (4.950) > As (4.290) > Cr (3.080) > Zn (1.700). Cd is at a considerable potential ecological risk, while other heavy metals are at low ecological risks. Heavy metal pollution in sediment of West Lake in Kaifeng mainly comes from traffic activities such as yacht machinery wear and gasoline burning. The research findings provide a scientific foundation for developing effective mitigation strategies against heavy metal contamination in peri-urban lacustrine ecosystems. Full article

Municipal sewage sludge is a potential soil amendment rich in organic matter and nutrients, yet its reuse is often constrained by heavy metal contamination. This study evaluated six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in sludge collected from seven centralized wastewater treatment plants in Bangkok, Thailand, by analyzing physicochemical properties, total metal concentrations, and chemical speciation. Three ecological risk indices, the geo-accumulation index (I_geo), risk assessment code (RAC), and potential ecological risk index (PERI), were applied to assess contamination status, mobility, and ecological threat. The sludge exhibited high levels of organic matter and essential nutrients, indicating potential for agricultural reuse; however, elevated electrical conductivity at some sites may pose salinity risks if unmanaged. Speciation analysis revealed that Cd and Zn were largely present in mobile and redox-sensitive fractions, Cr and Pb were primarily in stable residual forms, and Cu and Ni occurred in moderately mobile forms influenced by environmental conditions. Across all indices, Cd consistently posed the highest ecological risk, followed by Zn, in a site-dependent manner, while Cr and Pb represented low risk. These findings provide a clearer understanding of metal behavior in sewage sludge and underscore the importance of integrating chemical speciation with multi-index risk assessment in sludge management. Incorporating such approaches into national guidelines, particularly in countries lacking established heavy metal limits, can strengthen monitoring frameworks, guide safe and sustainable reuse, and support regulatory development in contexts with limited monitoring data. Full article

This study examined the temporal dynamics of metal(loid) concentrations in agricultural soils, fern Amauropelta rivularioides, and surface waters in a peri-urban region on the Brazil–Paraguay border during 2019–2020. Elevated levels of As, Se, Co, Mn, Cu, and Zn raised concerns about environmental and human health risks, especially when compared to international guidelines. Post-harvest and pre-harvest periods, particularly during corn cultivation, revealed higher concentrations of toxic metals, suggesting cumulative effects of agrochemical use. Principal Component Analysis indicated significant geochemical variation, with particular emphasis on the Collection 1 period (1 June 2019). The fern A. rivularioides demonstrated metal accumulation, especially for As, Pb, Cr, and Ba, reflecting the influence of agrochemical residues and seasonal runoff. Surface waters displayed metal concentrations below detection limits, but phosphorus levels surpassed USEPA thresholds for eutrophication risk. Risk assessments indicated moderate to high contamination in soils, particularly for P, As, Mg, and Se. Hazard Quotient and Hazard Index values suggested chronic health risks, and Incremental Lifetime Cancer Risk values for dermal exposure to As, Pb, and Cr indicated an elevated cancer risk. Full article

This study aimed to evaluate the impact of vineyard cultivation time and the use of metal-based fungicides on the chemical fractions of soil organic matter (SOM) as well as their interactions with Cu, Zn, and Mn in vineyard soils from Southern Brazil with varying histories of fungicide application. Soil samples were collected in 2017 from vineyards aged 35, 37, and 39 years in the Serra Gaúcha region and 13, 19, and 36 years in the Campanha Gaúcha. In each region, samples were also collected from a non-anthropized reference area. In the oldest vineyards, sampling was conducted both within and between the rows of planting. Chemical fractionation of SOM was performed: non-humic substances (nHSs), particulate organic matter (POM), fulvic acid (FA), humic acid (HA), and humin (Hu). Fourier-transform infrared (FTIR) spectra were obtained for the HA, from which the aromaticity index (AI) and relative intensities (RIs) were calculated. In each SOM fraction, total organic carbon and the concentrations of Cu, Zn, and Mn were determined. Changes in land use alter the forms and distribution of soil organic carbon (SOC) and, consequently, of metals. Elemental and spectroscopic analyses of HS revealed that HA in the reference areas (forest and native grassland) was more aliphatic and had higher concentrations of polysaccharides, indicating fractions with a lower degree of stabilization. However, in vineyard areas, HA exhibited greater humification and aromaticity. Increasing cultivation time gradually increased soil carbon content, indicating that viticultural agroecosystems can sequester carbon in the soil over time, reaching levels similar to those observed in the reference areas. When comparing vineyard areas alone, with row collections and inter-row collections, we observed an increase in SOC levels in areas managed with cover crops, demonstrating the importance of conservation management in these areas. When evaluating the distribution of metals in these soils, we could observe the high affinity of Cu for the functional groups of SOM, with FA and HA responsible for the complexation of these elements in the soil. For Zn and Mn, the greatest accumulations were observed in the Hu fraction due to their greater affinity for soil clay minerals. This shows that soil organic matter is a key component in the complexation of metals in soils, reducing their availability and potential toxicity to cultivated plants. Full article

Accumulation of copper (Cu) in soils devoted to intensive agriculture due to anthropogenic additions is becoming a significant threat to plant productivity. Biological inoculants may play an important role in alleviating toxic effects of heavy metals on plants. The plant-growth-promoting rhizobacteria (PGPR) Bacillus subtilis subsp. spizizenii has demonstrated the ability to reduce harmful impacts of heavy metals on crops. This study aimed to evaluate the suitability of seed inoculation with biofilm produced by this bacterium to mitigate the severity of Cu toxicity on tomato. In the laboratory, first, B. subtilis was cultivated under increased Cu concentrations. Then, germination of inoculated and non-inoculated tomato seeds was tested for Cu concentrations of 0, 50, 100, 150, and 200 ppm. Next, a greenhouse experiment was conducted for four months to assess the effects of both inoculation and excess 150 ppm Cu in the substrate. The studied treatments included control, no inoculation and Cu surplus, inoculation and no Cu surplus, and inoculation plus Cu surplus. In the laboratory, first, the bacterium’s ability to grow in a liquid medium containing Cu was confirmed. Thereafter, we verified that the germination of non-inoculated seeds was negatively affected by Cu, with higher concentrations leading to a more detrimental effect. However, seed inoculation with biofilm mitigated the adverse impact of Cu on germination. Under greenhouse conditions, excess Cu significantly reduced root dry weight, tomato number, and tomato yield compared with the control, whereas shoot dry weight, plant height, leaf area, and soluble solid concentration (Brix index) did not experience significant changes (p < 0.05). However, seed inoculation mitigated the toxic effects of excess Cu, significantly enhancing all the aforementioned plant parameters, except plant height. Seed inoculation also significantly reduced the Cu contents in the fruits of tomato plants growing in the metal contaminated substrate. The biofilm of the B. subtilis strain used demonstrated its effectiveness as a bioinoculant, attenuating the detrimental effects induced by a substrate with excess Cu. Full article

This study demonstrated that application of the particular plant growth-promoting rhizobacteria (PGPR) strains Erwinia sp. and Serratia sp. (named C15 and C20, respectively) significantly enhanced tea plant resilience in Zn (zinc)-, Pb (lead)-, and Zn + Pb-contaminated soils by the improving survival rates (over 60%) and chlorophyll content of tea plants, and by reducing the accumulation of these metals in tea plants’ tissues (by 19–37%). The PGPRs elevated key soil nutrients organic carbon (OC), total nitrogen (TH), hydrolysable nitrogen (HN), and available potassium (APO) and phosphorus (APH) contents. Compared to non-PGPR controls, both strains consistently increased microbial α-diversity (Chao1 index: +28–42% in Zn/Pb soils; Shannon index: +19–33%) across all contamination regimes. PCoA/UniFrac analyses confirmed distinct clustering of PGPR-treated communities, with strain-specific enrichment of metal-adapted taxa, including Pseudomonas (LDA = 6) and Bacillus (LDA = 4) under Zn stress; Rhodanobacter (LDA = 4) under Pb stress; and Lysobacter (LDA = 5) in Zn + Pb co-contamination. Fungal restructuring featured elevated Mortierella (LDA = 6) in Zn soils and stress-tolerant Ascomycota dominance in co-contaminated soils. Multivariate correlations revealed that the PGPR-produced auxin was positively correlated with soil carbon dynamics and Mortierellomycota abundance (r = 0.729), while the chlorophyll content in leaves was closely associated with Cyanobacteria and reduced by Pb accumulation. These findings highlighted that PGPR could mediate and improve in tea plant physiology, soil fertility, and stress-adapted microbiome recruitment under heavy metal contaminated soil and stress. Full article

The Ichubamba Yasepan wetlands, in the Andean páramos of Ecuador, suffer heavy metal contamination due to anthropogenic activities and volcanic ash from Sangay, impacting biodiversity and ecosystem services. This quasi-experimental study evaluated the bioaccumulation and tolerance of metals in high Andean species through stratified random sampling and linear transects in two altitudinal ranges. Concentrations of Cr, Pb, Hg, As, and Fe in water and the tissues of eight dominant plant species were analyzed using atomic absorption spectrophotometry, calculating bioaccumulation indices (BAIs) and applying principal component analysis (PCA), clustering, and linear discriminant analysis (LDA). Twenty-five species from 14 families were identified, predominantly Poaceae and Cyperaceae, with Calamagrostis intermedia as the most relevant (IVI = 12.74). The water exceeded regulatory limits for As, Cr, Fe, and Pb, indicating severe contamination. Carex bonplandii showed a high BAI for Cr (47.8), Taraxacum officinale and Plantago australis for Pb, and Lachemilla orbiculata for Hg, while Fe was widely accumulated. The LDA highlighted differences based on As and Pb, suggesting physiological adaptations. Pollution threatens biodiversity and human health, but C. bonplandii and L. orbiculata have phytoremediation potential. Full article