Health risk assessment for heavy metal accumulation in leafy vegetables grown on tannery effluent contaminated soil

Recent advances in alginate-based composite gel spheres for removal of heavy metals

The discharge of heavy metal ions from industrial wastewater into natural water bodies is a consequence of global industrialisation. Due to their high toxicity and resistance to degradation, these heavy metal ions pose a substantial threat to human health as they accumulate and amplify. Alginate-based composite gels exhibit good adsorption and mechanical properties, excellent biodegradability, and non-toxicity, making them environmentally friendly heavy metal ion adsorbents for water with promising development prospects. This paper introduces the basic properties, cross-linking methods, synthetic approaches, modification methods, and manufacturing techniques of alginate-based composite gels. The adsorption properties and mechanical strength of these gels can be enhanced through surface modification, multi-component mixing, and embedding. The main production processes involved are sol-gel and cross-linking methods. Additionally, this paper reviews various applications of alginate composite gels for common heavy metals, rare earth elements, and radionuclides and elucidates the adsorption mechanism of alginate composite gels. This study aimed to provide a reference for synthesising new, efficient, and environmentally friendly alginate-based adsorbents and to contribute new ideas and directions for addressing the issue of heavy metal pollution.

Heavy metals contamination in vegetables irrigated with wastewater: a case study of underdeveloping regions of Pakistan

Irrigation of food crops with untreated wastewater leads to the accumulation of heavy metals in their edible parts. Exposure to toxic elements through consumption of contaminated vegetables even at very low concentration is becoming a serious problem for human health in many countries. This issue of heavy metals contamination needs great attention especially in Pakistan where irrigation by wastewater has become a common practice in urban and periurban areas. The present study was conducted to assess the contamination of different heavy metals including nickel (Ni), cadmium (Cd), lead (Pb) and chromium (Cr) in vegetables irrigated with wastewater in different districts of Punjab (Pakistan) like, Faisalabad, Lahore, Gujranwala, Sargodha, Sahiwal, Multan, Rawalpindi and Bahawalpur during years 2016-2019. The maximum contamination factor (Ni, 1.39; Cd, 5.86; Pb, 3.99; Cr, 2.24), pollution load index (2.92) and degree of contamination (13.48) were observed in wastewater irrigated agricultural soils of district Gujranwala as compared to other districts. Mean metal concentration in vegetables grown with untreated wastewater and transfer factor varied with plant type, frequency of irrigation and soils types/series of different districts of Punjab. The highest metal contamination was observed in Gujranwala where 44% vegetable samples were contaminated with Ni, 87% with Cd, 97% with Pb and 88% with Cr. Radar analysis and hierarchical cluster analysis showed that mustard leaves, spinach and lettuce were more contaminated vegetables compared to other vegetables. This study contributes to the evidence-based conclusion that cultivation of vegetable with untreated wastewater should be prohibited and required treatment of wastewater is needed.

A review on heavy metal biosorption utilizing modified chitosan

Heavy metal pollution in water bodies is a global concern. The prominent source of metal contamination in aqueous streams and groundwater is wastewater containing heavy metal ions. Elevated concentrations of heavy metals in water bodies can have a negative impact on water quality and public health. The most effective way to remove metal contaminants from drinking water is thought to be adsorption. A deacetylated derivative of chitin, chitosan, has a wide range of commercial uses since it is biocompatible, nontoxic, and biodegradable. Due to its exceptional adsorption behavior toward numerous hazardous heavy metals from aqueous solutions, chitosan and its modifications have drawn a lot of interest in recent years. Due to its remarkable adsorption behavior toward a range of dangerous heavy metals, chitosan is a possible agent for eliminating metals from aqueous solutions. The review has focused on the ideas of biosorption, its kinds, architectures, and characteristics, as well as using modified (physically and chemically modified) chitosan, blends, and composites to remove heavy metals from water. The main objective of the review is to describe the most important aspects of chitosan-based adsorbents that might be beneficial for enhancing the adsorption capabilities of modified chitosan and promoting the usage of this material in the removal of heavy metal pollutants.

Toxic Elements in Beans from Zhejiang, Southeast China: Distribution and Probabilistic Health Risk Assessment

This study described the distribution of As, Cd, Cr, Hg, and Pb in 692 bean samples from Zhejiang province, southeast China, and estimated the health risk using Monte Carlo simulation. The average levels of As, Cd, Cr, Hg, and Pb were 0.0349, 0.0379, 0.246, 0.0019, and 0.0246 mg kg-1. Correlation analyses showed very strong positive correlations for Cd-Pb in kidney beans and mung beans, Cd-As in black beans, and Pb-As in red beans. The target hazard quotients (THQs) were adopted for non-carcinogenic risk assessment, and THQs at the 50th percentile were all less than 1, indicating that there are no deleterious effects from rice exposure to these elements. When evaluating THQ for multiple elements, the certainty with a hazard index (HI) greater than 1 for children was 12.64%, for teens 11.54%, and for adults 1.01%. The sensitivity analysis reveals that the concentration of Cd in beans and ED (exposure duration) are the main principal factors that contributed to the total risk. The mean carcinogenic risks for children, teens, and adults were all less than 1 × 10-4, indicating no potential carcinogenic risk. Despite that, the routine monitoring of these elements, especially for Cd should be continued.

Does eating fish cause cancer? A case study metal(loid)s accumulation in mackerel and sardine tissues from İskenderun Bay, Türkiye

Due to the increasing harmful effects of metal(loid)s over time, it has become important in environmental studies carried out to increase environmental awareness. It is important to investigate the cumulative presence of metal(loid)s in nature, their interactions with each other and risks posed by fish consumption for human health. Total concentrations of As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn were determined in muscle and gill tissues of horse mackerel (Trachurus trachurus) and sardine (Sardina pilchardus). Metal analyses were carried out using Inductively Coupled Plasma-Mass Spectroscopic (ICP-MS) methods. In both tissues, Fe and Zn concentrations were the highest and Cd, Cu and Pb concentrations were the lowest. The target hazard coefficient, estimated daily intake, target cancer risk, total target hazard coefficient, and hazard indices were calculated to assess the risks to an individual's health from consuming fish. Hazard index and total target hazard coefficient values calculated for each fish exceeded 1 but were very close to 1. Target cancer risk values of As and Ni were found to be 10-6 and 10-4 for Pb. These limit values indicate the need for regular monitoring of the region. In addition, the interactions between the metal(loid)s accumulated in the tissues were analyzed and a high correlation was found between As-Ni, which poses a risk to public health.

Investigation of the incidence of heavy metals contamination in commonly used fertilizers applied to vegetables, fish ponds, and human health risk assessments

Overuse of fertilizers on agricultural lands and fish ponds may result in serious pollution problems, such as heavy metals that can enter the food chain and pose serious health problems. Due to this, the present study investigates the incidence of heavy metals in commonly used fertilizers and its association with heavy metals in vegetables, soil, fish species, and pond water. Samples were collected from different sites (fields and ponds) in district Kohat, where the application of fertilizers was common and control groups (no fertilizers used). Heavy metal analysis was carried out through a spectrophotometer. Results showed higher Cd and Cr concentrations in triple superphosphate (TSP), Cu and Pb in nitrogen, phosphorus, and potassium (NPK), while lower concentrations were found in gypsum. In vegetables (onion, tomato, brinjal, and potato) and associated soil, most of the heavy metals concentrations were significantly higher (P < 0.05) in fertilizer-applied sites than in the control. Also, the Cd concentration in potatoes and Pb level in all vegetables obtained from sites were greater than the WHO/FAO standard limit. In the case of fish species (Hypophthalmichthys molitrix and Cyprinus carpio) muscles and their habitat (water), all the understudy heavy metals were notably higher (P < 0.05) in fertilizer-applied sites (ponds) than the control group. Collectively, in all vegetables and muscles of fish species, the bioaccumulation factor was higher in sites compared to the control. The estimated daily intake (EDI) and target hazard quotient (THQ) values were also higher in fertilizer-applied sites (fields and ponds) than control. The health index (HI) value was > 1 in vegetables (onion, tomato, and potato) and fish muscles collected from different sites compared to the control. Thus, there is the possibility of severe health risks. The use of fertilizers must be carefully monitored in order to ensure that humans and animals are safe from exposure to heavy metals.

A meta-analysis on the heavy metal uptake in Amaranthus species

Metals can accumulate in different parts of plant species in high concentrations, which gives the basis for the plant-based technology called phytoremediation. Among annual species, Amaranthus is a well-studied, potential metal accumulator genus; however, some conflicts are found among published results. Thus, we studied the metal (Cd, Cu, Fe, Ni, Pb, and Zn) accumulation potential of Amaranthus plant parts (root, stem, and leaf) by meta-analysis, furthermore, by calculation of bioaccumulation factor (BAF) values. After the extensive literature search and the calculation of relative interaction intensity (RII) values, we found significant accumulation for each metal by Amaranthus individuals growing on contaminated soils compared to plants collected from uncontaminated ones. Differences among plant parts were significant for Cu and Fe, minor for Ni, Pb, and Zn, and negligible for Cd. The BAF values indicated high accumulation in the leaf, moderate in root and stem for Cd, moderate in each plant part for Pb, and very low in each plant part for Fe, Ni, and Zn. We highlight that Amaranthus species are good prospects for metal phytoremediation projects, although, due to specific plant part-metal patterns, special attention should be paid to the harvesting practice.

Health Risk and Quality Assessment of Vegetables Cultivated on Soils from a Heavily Polluted Old Mining Area

Three garden vegetables-radish, carrot and lettuce-were cultivated in a pot experiment using two soils from the Příbram area polluted mainly by cadmium (Cd), zinc (Zn), lead (Pb) and chromium (Cr). The soils of the Příbram district, Czech Republic, are heavily polluted as a result of the atmospheric deposition of toxic elements originating from historic lead-silver mining and smelting activities. The results showed that lettuce absorbed the highest amounts of toxic elements (Cd 28 and 30, Cr 12 and 13, Zn 92 and 205 mg·kg^-1 DW), except Pb, which was higher in radish (30 and 49 mg·kg^-1 DW). Changes in macronutrient contents in edible parts were not found, except for sulfur. A higher total free amino acids (fAAs) accumulation was shown in all vegetables in more contaminated soil, with the highest fAA content being in radish. A group of essential fAAs reached 7-24% of total fAAs in vegetables. The risk to human health was characterized using the target hazard quotient and total hazard index (HI). The cumulative effect of the consumption of vegetables with HI > 1 showed possible non-carcinogenic health effects for lettuce and carrot. HI decreased in the order Cd > Pb > Cr > Zn. The carcinogenic risk of toxic elements decreased in the order Cd > Cr > Pb (0.00054, 0.00026, 0.00003). These values showed a carcinogenic risk from the consumption of lettuce and carrot and confirmed that the adult population of the studied area is at high risk if lettuce and carrot cultivated in this area are consumed daily.

Evaluation of heavy metals contamination in cereals, vegetables and fruits with probabilistic health hazard in a highly polluted megacity

Heavy metals (HMs) contamination in foodstuffs could pose serious health issues for public health and humans are continually exposed to HMs through the consumption of cereals, fruits, and vegetables. The present study was conducted to assess 11 HMs in foodstuffs to investigate pollution levels and health risks to children and adults. The mean contents of Cd, Cr, Cu, Ni, Zn, Fe, Pb, Co, As, Mn and Ba in foodstuffs were 0.69, 2.73, 10.56, 6.60, 14.50, 9.63, 2.75, 0.50, 0.94, 15.39 and 0.43 mg/kg, respectively and the concentration of Cd, Cr, Cu, Ni and Pb were higher than maximum permissible concentrations (MPCs) showing that these foods may be contaminated with metals and constitute a danger to consumers. Vegetables had relatively higher metal contents followed by cereals and fruits. The average value of the Nemerrow composite pollution index (NCPI) for cereals, fruits, and vegetables were 3.99, 6.53, and 11.34, respectively indicating cereal and fruits were moderately contaminated whereas vegetables were heavily contaminated by the studied metals. The total estimated daily and weekly intakes for all studied metals were higher than the maximum tolerable daily intake (MTDI) and provisional tolerance weekly intake (PTWI) recommended by FAO/WHO. The target hazard quotients and hazard index of all studied metals exceeded the standard limit for adults and children suggesting significant non-carcinogenic health hazards. The total cancer risk value of Cd, Cr, Ni, Pb, and As from food intake exceeded the threshold range (1.0E-04), suggesting potential carcinogenic risks. Based on practical and sensible evaluation techniques, the current work will assist policymakers in controlling metal contamination in foodstuffs.

State of Innovation in Alginate-Based Materials

This review article presents past and current alginate-based materials in each application, showing the widest range of alginate's usage and development in the past and in recent years. The first segment emphasizes the unique characteristics of alginates and their origin. The second segment sets alginates according to their application based on their features and limitations. Alginate is a polysaccharide and generally occurs as water-soluble sodium alginate. It constitutes hydrophilic and anionic polysaccharides originally extracted from natural brown algae and bacteria. Due to its promising properties, such as gelling, moisture retention, and film-forming, it can be used in environmental protection, cosmetics, medicine, tissue engineering, and the food industry. The comparison of publications with alginate-based products in the field of environmental protection, medicine, food, and cosmetics in scientific articles showed that the greatest number was assigned to the environmental field (30,767) and medicine (24,279), whereas fewer publications were available in cosmetic (5692) and food industries (24,334). Data are provided from the Google Scholar database (including abstract, title, and keywords), accessed in May 2023. In this review, various materials based on alginate are described, showing detailed information on modified composites and their possible usage. Alginate's application in water remediation and its significant value are highlighted. In this study, existing knowledge is compared, and this paper concludes with its future prospects.

Zero waste discharge in tannery industries - An achievable reality? A recent review

In the recent times, more attention is on industrial waste management due to the unaffordable space for dump yards and landfills and the increased charges for waste dumping. Even though the vegan revolution and plant-based meat products are booming, the traditional slaughterhouses and the wastes produced by them continue to be a concern. Waste valorisation is an established procedure striving to create a closed chain process in industries where there is no refuse. Although a highly polluting industry, slaughterhouse industry wastes have been recycled to economically viable leather since ancient times. However, the tannery industry is causing pollution in par with or even more than the slaughterhouses. Effective management of the liquid and solid wastes from the tannery is of utmost concern because of its toxicity. The hazardous wastes generated enter the food chain, causing long term impacts in the ecosystem. Several leather waste transformation processes are widely used in the industries, and they are yielding good products of economic value. However careful exploration into the processes and products of waste valorisation are often ignored as long as the transformed waste product is of higher value than the waste. The most efficient and environmentally friendly waste management technique should convert the refuse into a value-added utilization without any toxic leftovers. Zero waste concept is an extension of the zero liquid discharge concept, where the solid waste is also treated and reused to such an extent that there is no residue to be sent to the landfill. This review initially presents the existing methods for the de-toxification of tannery wastes and examines the possibility of solid waste management within the tannery industry to attain zero waste discharge.

Activity and potential mechanisms of action of persimmon tannins according to their structures: A review

One distinguishing feature of the persimmon, that differentiates it from other fruits, is its high proanthocyanidins content, known as persimmon tannin (PT). Despite the poor absorption of PT in the small intestine, results from animal studies demonstrate that PT has many health benefits. Our goal in this review is to summarize the literature that elucidates the relationship between PT structure and activity. In addition, we also summarize the potential mechanisms underlying the health benefits that result from PT consumption; this includes the hypolipidemic, hypoglycemic, antioxidant, anti-inflammatory, antiradiation, antibacterial and antiviral, detoxification effects on snake venom, and the absorption of heavy metals and dyes. Studies show that PT is a structurally distinct proanthocyanidins that exhibits a high degree of polymerization. It is galloylation-rich and possesses unique A-type interflavan linkages in addition to the more common B-type interflavan bonds. Thus, PT is converted into oligomeric proanthocyanidins by depolymerization strategies, including the nucleophilic substitution reaction, acid hydrolysis, and hydrogenolysis. In addition, multiple health benefits exerted by PT mainly involve the inactivation of lipogenic and intracellular inflammatory signaling pathways, activation of the fatty acid oxidation signaling pathway, regulation of gut microbiota, and highly absorptive properties.

Distribution of Cadmium in Fresh Vegetables Marketed in Southeast China and Its Dietary Exposure Assessment

This study investigated concentrations of cadmium (Cd) in 2465 vegetable samples (52 species) from 2018 to 2022 and estimated the associated health risk for local consumers. The average concentration of Cd was 0.035 mg kg−1, and the percentage of samples exceeding the Chinese maximum allowed concentration was 3.89% (96/2465). The top five species with highest Cd levels were Lilium brownii F (0.182 mg kg−1), Allium chinense G (0.117 mg kg−1), Allium macrostemon Bunge (0.105 mg kg−1), Colocasia esculenta (0.064 mg kg−1), and Amaranthus tricolor L (0.054 mg kg−1). Bulb vegetables had a higher relative accumulation of Cd compared to other vegetables. The levels of Cd in vegetables varied significantly across sampling areas and years. The mean estimated daily intake (EDI) of cadmium through consumption of vegetables was 0.519 μg kg−1 bw per day for adults and 0.217 μg kg−1 bw per day for children. The target hazard quotients (THQs) were all less than the threshold of 1 for both adults and children. This indicates that there is low health risk for Cd through vegetable consumption. However, routine monitoring of Cd levels in food is still crucial to ensure food safety and protect public health.

Mixing tannery effluent had fertilizing effect on growth, nutrient accumulation, and photosynthetic capacity of some cucurbitaceous vegetables: A little help from foe

Tannery effluent contains a number of organic and inorganic elements as pollutants which reduce plant growth. To overcome shortage of water, use of diluted industrial wastewater such as tannery effluent can be a viable strategy for improving crop growth and yield. A pot experiment was conducted to determine the effects of tannery effluent and its various dilutions on physiological and biochemical characteristics of five cucurbitaceous vegetables. Tannery effluent was applied 0, 25, 50, 75 and 100% to 3-week-old plants of five cucurbitaceous vegetables (Cucurbita maxima, Luffa cylindrica, Citrullus vulgaris, Cucumis melo, and Praecitrullus fistulosus) for 4 weeks. Tannery effluent reduced the growth of all five cucrbitaceous vegetables. Diluted tannery effluent (25%) improved the growth of Cucurbita maxima, Citrullus vulgaris, and Cucumis melo. Moderately diluted (50%) did not affect the growth of Citrullus vulgaris and Cucumis melo. Toxic effects of tannery effluent were associated with high accumulation of heavy metals Cr, Cd, Mn, and Fe in leaves and roots. High accumulation of heavy metals in leaves reduced the accumulation of nutrients in leaves (N, P, K) and reduced photosynthetic pigments and photosynthetic rate. Changes in photosynthetic rates of all vegetable species due to tannery effluent were not associated with stomatal limitations (stomatal conductance, transpiration rate, internal CO₂). Toxic effects of tannery effluent on plants also include changes in N-metabolism (amino acid and protein). However, extent of these adverse effects of tannery effluent on vegetables was species specific. It is suggested that Cucurbita maxima can be grown by supplying 25% tannery effluent, whereas Citrullus vulgaris and Cucumis melo can be grown with moderately diluted (50%) tannery effluent.

Heavy Metal Contamination in Leafy Vegetables Grown in Jazan Region of Saudi Arabia: Assessment of Possible Human Health Hazards

The food chain, through vegetable consumption, is considered to be an important route of heavy metal exposure. Therefore, in this study, heavy metal concentrations in leafy vegetables grown in the Jazan region of Saudi Arabia were assessed using an ICP-MS. Lettuce, radish, mint, parsley and jarjir (Arugula) were selected for study and subjected to digestion using HCl. The results indicated that the Fe level was highest in all vegetables, while jarjir was the most contaminated vegetable. However, no tested metal exceeded the maximum permissible limits set by the FAO/WHO and European Committee. The possible health hazards associated with the exposure to metal contaminants via vegetable consumption were evaluated by estimating target hazard quotient (THQ) values, and the results revealed that the vegetables grown in close proximity of Jazan city were the most contaminated and those in Darb the least. However, the daily intakes of all the tested metals were well below the corresponding oral reference doses (RfDs), and the THQ values were less than unity, suggesting that the vegetables grown in the studied region were safe and the heavy metal exposure via vegetable consumption was unlikely to cause adverse effects to the local inhabitants of the region.

Assessment of health risks associated with pesticide and heavy metal contents in Fritillaria thunbergii Miq. (Zhe Beimu)

Fritillaria thunbergii Miq. (Zhe Beimu, F. thunbergii) is widely cultivated in China's Zhejiang province, and pesticides and heavy metals are two major factors affecting its quality and safety. A total of 106 F. thunbergii samples from six main production areas were analyzed for 76 pesticides and four heavy metal content (As, Cd, Hg, and Pb). The pesticide detection rate of the samples was 66.98%; overall, the pesticide residues were very low, and residue levels ranged from 0.010 to 0.231 mg kg^-1. The detection rates of As, Cd, Hg, and Pb were 95.3%, 100%, 76.4%, and 100%, respectively. A risk assessment of human exposure to pesticides and heavy metals via intake of F. thunbergii was performed, and the results revealed that the pesticide residues and heavy metal content detected in F. thunbergii does not pose a potential risk to human health, either in the long or short term. The exposure assessment showed that the levels of pesticides and heavy metals in F. thunbergii were safe for human consumption. These results provide useful information on F. thunbergii consumption.

Heavy metal accumulation efficiency and subsequent of cytogenotoxicity evaluation in the medicinal plant Equisetum hyemale

Heavy metals in soils represent a threat to the environment, food safety, as well as human and animal health. The bioaccumulation of these elements in plants might enhance medium- and long-term adverse health risk promoting genetic alterations that lead to dermal, gastrointestinal, circulatory, renal, and brain disorders. The present study aimed to determine the bioaccumulation potential and cytogenotoxic effect of Equisetum hyemale extracts. E. hyemale seedlings were divided into two groups: exposed group (plants cultivated in soil with heavy metals solution) and control (plants cultivated in soil with distilled water). Heavy metals were quantified in the cultivation soils (control and exposed) and extracts (ethanolic and infusion) of vegetative parts from E. hyemale cultivated in both soils. Root length and cytogenotoxic effect were determined utilizing Allium cepa bioassay. Data demonstrated that Equisetum hyemale present the ability to absorb and bioaccumulate different heavy metals including lead, copper, cobalt manganese, zinc, iron and chromium. Given this property E. hyemale may be considered a reliable bioindicator to assess cytogenotoxicity of certain substances that exert adverse risks to environment and human and animal health.

A censorious review on the role of natural lignocellulosic fiber waste as a low-cost adsorbent for removal of diverse textile industrial pollutants

BACKGROUND

Textile industries produce fabricated colored products using toxic dyes and other harsh chemicals. It is the responsibility of the textile industries to treat and eliminate these hazardous pollutants. However, due to the growing population demand, the treatment of these hazardous effluents is ineffective and imposes the treatment cost over the end users. The release of partially treated effluents in the environment may cause a severe threat to the ecology and its biota. The critical objective is to treat textile effluents efficiently using agricultural natural fiber waste. Generation of agricultural lignocellulosic fibrous waste increases every year due to growing population demand. Its use in the modern world is limited due to synthetic products. An alternative has enumerated to avoid wastage of fibrous resources and its clean disposal.

OBJECTIVE

The main objective of this review paper discussed the feasibility of lignocellulosic fibers and other lignocellulosic materials as natural low-cost adsorbent.

METHODS

The literature study was performed using Web of Science and Scopus indexed journals. The main factors considered to increase the adsorption ability, including the types of lignocellulosic surface modification techniques were searched with utmost importance for quality results. Intending to summarize the literature survey and provide persuasive content, systematic review process was considered for this novel article.

RESULTS

Out of 230 valuable publications, 159 published articles were considered for the present study until March 2022. The articles surplus with factors affecting adsorption (pH, adsorption dosage, surface area, temperature, initial concentration, contact time, physical and chemical properties of pollutants) and surface modification techniques (physical, chemical, and biological) were considered for this manuscript.

CONCLUSION

Overall, the physical and chemical modification methods are widely used instead of biological methods due to various factors as discussed briefly. Furthermore, the finding of this article supports the fact that the fibrous by-product resources are wasted in various occasions due to the modern lifestyle. Even though there is evidential possibility to implement the low-cost adsorbents, the industries limit their application prospects due to existing technology and financial compromises.

Spatial Analysis of Cultivated Land Productivity, Site Condition and Cultivated Land Health at County Scale

Cultivated land is a fundamental factor related to the social stability and sustainable development of the whole country. However, the safety of quantity and quality of cultivated land has decreased year by year, resulting in great challenges to the sustainable development of cultivated land. Cultivated land productivity, site conditions, and soil health jointly determine the sustainable development potential of cultivated land. Analyzing and calculating the coupling and cooperative relationship between these three subsystems can provide a theoretical and methodological reference for protecting and zoning cultivated land resources. Using Jiangyou City as a case study, this paper constructs a coupling coordination degree model of cultivated land productivity, site conditions, and soil health assessment systems in different geomorphic regions, and comprehensively analyzes the level of sustainable development of cultivated land in the study area. The results show that there are differences in the development potential of cultivated land resources in the mountainous regions in the north, the hilly regions in the center, and the plain regions in the south of Jiangyou City. The coupling coordination index of the three regions were calculated as 0.34, 0.51, and 0.63, respectively, for which the overall average coupling coordination index is 0.57; notably, it only reaches the "barely coordination" level. Based on our analysis results, the cultivated lands in Jiangyou City are classified into the following zones: core protection zone, dominant remediation zone, and key regulation zone. The cultivated land located in the core protection zone has a high coupling coordination index, which can be used as the preferred area for the delimitation of high standard basic farmland and permanent basic farmland. For the cultivated land located in the dominant remediation zone, the development of its subsystems is unbalanced. Comprehensive land improvement projects can be carried out in this zone to improve the overall quality. For the cultivated land located in the key regulation zone, it is recommended to implement projects such as returning farmland to forests to improve land use efficiency. In particular, the evaluation index system constructed in this paper is sufficiently representative, as it can support the classification, quality improvement, and sustainable use of cultivated land. Thus, other similar countries and regions can learn from the evaluation system constructed in this paper.

Risk assessment and early warning of the presence of heavy metal pollution in strawberries

Heavy metal pollution is a major threat to agricultural produce and it can pose potential ecological risks which subsequently impacts on human health. Strawberries are an economically important produce of China. The intrinsic link of heavy metal pollution risk in the soil-strawberry ecosystem is of concern. In this study, the pollution index of heavy metal pollutants in farmlands of different provinces were evaluated, and the results showed significantly high levels of cadmium. In addition, Nemerow integrated pollution index analysis showed that low-pollution farmlands only accounted for 14.07% of the total arable land area. Then, the transfer factors were used to calculate the migration of heavy metals from the soil into strawberries. The results showed that cadmium and nickel were relatively high in strawberries from the Guangxi province. Similar results were found for mercury in Jiangxi Province. The pollution index of single food pollution also showed that mercury in strawberries from Jiangxi Province was at a moderate pollution level. The comprehensive pollution index indicated that heavy metal pollution in strawberries in Central China may be severe. In addition, spatial clustering analysis showed that cadmium, chromium, lead, arsenic and zinc in strawberries had significant hotspot clustering in central, south and southwest China. Finally, our studies also suggested that the risk of carcinogenic and non-carcinogenic diseases was higher in the (2, 4] years age group than in other age groups. People in Yunnan Province were also found to have a higher non-carcinogenic risk than those in other provinces and cities in China. This study provides a comprehensive view of the potential risks of heavy metal contamination in strawberries, which could provide assistance in the design of regulatory and risk management programs for chemical pollutants in strawberries, thus ensuring the safety of consumption of these edible fruits.