Total Heavy Metal Concentrations Research Articles

Assessment of the risks of impacts of heavy metals and arsenic entering the human body with herbal medicines

Introduction. Liquid dosage forms based on medicinal plant raw materials are very convenient to use and must meet safety requirements. In the context of harmonization of pharmacopoeial requirements, determining the total content of heavy metals in tinctures is not enough. Risk assessment is necessary to calculate the permissible concentrations of heavy metals in tinctures.Aim. To assess the safety of using tinctures in terms of the content of heavy metals and arsenic within the framework of a risk-oriented strategy.Materials and methods. The objects of the study were 20 samples of valerian and motherwort tinctures manufactured by various enterprises. The quantitative content of 15 elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sr, Tl, V, Zn) was determined by inductively coupled plasma mass spectrometry.Results and discussion. The concentrations of elements in tinctures varied in the range of 0–1.84 μg/g. Manganese and zinc were found in maximum quantities, while cadmium, molybdenum and vanadium were found in minimum quantities. Mercury was not detected in any of the samples. The content of toxic elements in the tinctures did not exceed the levels of permissible concentrations regulated by the normative documentation of the Russian Federation. Total hazard indices (HI) were calculated at the levels of the median and 90th percentile of the content of elemental toxicants. In the tinctures, they were, respectively: valerian – 0.016 · 10–5 and 0.027 · 10–5, motherwort – 0.022 · 10–5 and 0.028 · 10–5. The obtained values were significantly lower than 1.0. Calculation of individual carcinogenic risk (CR) of elemental carcinogens (Cd, As, Cr, Pb) entering the body with tinctures of valerian and motherwort showed that the CR values were in the range of 4.9 · 10–9–6.84 · 10–7, which did not exceed the permissible threshold value (1 · 10–6).Conclusions. The actual content of toxic elements (Pb, Cd, As, Hg) in tinctures of valerian and motherwort was 0–0.006 μg/g, which did not exceed the levels of permissible concentrations. Calculations of non-carcinogenic risks when using tinctures of valerian and motherwort showed that the total impact of 15 studied elements on human health when consuming a daily dose of tinctures is characterized as permissible, periodic monitoring of the content of non-standardized elements in samples of herbal medicines is not required. It was established that the studied tinctures of valerian and motherwort are not oncogenic factors and do not require risk reduction measures.

Immobilization of Heavy Metals in Biochar Derived from Biosolids: Effect of Temperature and Carrier Gas

Slow pyrolysis was carried out in biosolids under three different temperatures (400, 500 and 600 °C) and two different carrier gases (CO2 and N2) on a fluidized bed reactor. The total concentration, chemical fractionation, and plant availability of the heavy metals in biochar were assessed by standard methods. The total concentration of Fe, Zn, Cu, Mn, Cr, Ni and Pb increased with the conversion of biosolids to biochar and with increasing pyrolysis temperature. The community’s Bureau of Reference (BCR) sequential extraction identified the migration of metals from toxic and bioavailable to potentially stable available or non-available forms at higher pyrolysis temperatures. Diethylenetriamine penta-acetic acid (DTPA)-extractable metals (Cu, Zn, Cd, Cu, Fe and Pb) were significantly lower in biochar compared to biosolids. By replacing N2 with CO2, the total metal concentration of heavy metals was significantly different for Mn, Ni, Cd, Pb and As. There were larger amounts of metals in the residual and oxidizable fractions compared to when N2 was used as a carrier gas. Consequently, the biochar produced at higher temperatures (500 and 600 °C) in the N2 environment exhibited lower potential ecological risks than in CO2 environments (69.94 and 52.16, respectively, compared to values from 75.95 to 151.38 for biochars prepared in N2). Overall, the results suggest that the higher temperature biochar can support obtaining environmentally safe biochar and can be effective in attenuating the ecological risks of biosolids.

Ecological Risk of Heavy Metals in an Eco-Industrial Park in China

ABSTRACT To ascertain whether rapid industrialization has affected the accumulation of heavy metals (HMs) in Suzhou Industrial Park (SIP), China, the occurrence and ecological risk of HMs, including Cu, Zn, Pb, Cr, Cd, Ni, As and Hg in sediments were analyzed. The results indicated that total concentrations of HMs (mg kg−1) were in the descending sequence of Zn (235.28) > Cr (95.71) > Cu (78.91) > Ni (55.51) > Pb (23.96) > As (22.12) > Cd (0.38) > Hg (0.14). The concentrations of HMs, except for Ni and Cd, were found to be below the probable effect level (PEL). Correlation analysis (CA) and principal component analysis (PCA) showed that HMs in SIP mainly originated from anthropogenic activities. HMs were mainly in residual fractions (55.5 ~ 95.1%), and the exchangeable fractions of Zn and Cd were relatively high. The risk assessment results indicated that Hg and Cd significantly contributed to ecological risks, whereas Cr and Pb made relatively minor contributions. Our findings indicated that intense anthropogenic activities promote HMs accumulations in streams in SIP during rapid industrialization.

Impact of Flooding on Lands with Emerging Contaminants on the Quality of Receiving Water Bodies

Among crucial factors that control flooding events are extreme climate, urban growth, and mismanagement. Islands in the Nile River have experienced successive cycles of flooding and drying due to recent rainy years in the Nile Basin countries. This paper focuses on the impact of floods on the amounts of ammonium-N released, total concentrations of heavy metals, enzyme activities, and microbial biomass (C and N) in flood soils of 11 Nile River islands. Field moist soils and their airdried counterparts were collected from the outskirts of the island and incubated for 15 days at 30 °C to be analyzed. Results reflected that the amounts of released NH4-N were higher in airdried than in wet soils. The average hydrolysis rates of the studied six enzyme substrates were correlated significantly with organic C, organic N, microbial bio-mass C and N in the field moist soils. The highest correlation coefficients (r) were with rates of hydrolysis of substrates of asparaginase, amidase, and β-glycosaminidase. A significant intercorrelation between rates of hydrolysis of the six studied enzyme substrates and r values which range from 0.81 to 0.98. At 10 mmol kg−1 soil, Co+2, Cd+2, Pb+2, Cu+2, Cr+3, and Ni+2 inhibited the release of NH4-N. Arginine hydrolysis was inhibited by the six heavy metals at 5 mmol kg−1 soil; the most effective inhibitors were Pb+2, Ni+2, and Cr+3. Due to the complex soil enzymatic and organic nitrogen hydrolase activities that occur during floods, fertile fields on the Nile River islands should not be fertilized before the summer flood seasons, which will prevent contamination of the Nile River water and loss of its island soil fertility.

Exploring the traits and possible ecological risks of heavy metals in biochars derived from rice husk and sugar beet pulp.

This research investigated the properties and potential environmental hazards associated with biochars derived from rice husk (RH) and sugar beet pulp (SBP), both of which are rich in heavy metals (HMs). The results indicated that the concentration of various HM fractions is significantly affected by the type of feedstock and the pyrolysis temperature. Specifically, the total concentrations of HMs in biochars produced at 600°C were found to be 10-140% higher than those in the original biomasses, a phenomenon attributed to the precipitation of HMs. Cd was a notable exception, exhibiting a reduction of 3-7% in the resultant biochars when compared to biomass, likely attributable to its volatilization. The results also revealed that the F1 + F2 fraction of HMs were largely transformed into F3 + F4 fraction during combustion, indicating that pyrolysis may reduce the ecotoxicity of HMs present in contaminated biomass. However, the process did not effectively diminish the F1 and F2 fractions of Cr and Cd. Elevated pyrolysis temperature significantly enhanced the reduction of HMs phytoavailability. Specifically, the phytoavailability of HMs in biochars produced at 600°C exhibited a decrease ranging from 10 to 92% when compared to the original biomass. Conversely, an unexpected rise in the phytoavailable fractions of Cr and Cd was noted in both RH and SBP biochars as the pyrolytic temperature increased, which correspondingly raised the potential ecological risk index (PERI). All materials analyzed exhibited a very high risk level, with PERI values exceeding 800, primarily due to the significant toxicity of Cd. Excluding Cd from consideration, the biomasses and their resultant biochars displayed PERI values ranging from 7 to 13. It is important to acknowledge that pyrolysis may not effectively diminish the environmental toxicity associated with HMs present in contaminated biomass, thereby limiting its safe application.

Assessment of Heavy Metal Contamination in Combretum micranthum Leaves and Decoctions: Implications for Human Health

Combretum micranthum is a well-known medicinal plant in Africa and the decoction of its leaves is used as a drink or to treat various diseases such as malaria, high blood pressure and liver disorders, among others. Due to its high consumption by all sections of the Senegalese population, we felt that its heavy metal intake should be examined to see its impact on health. Leaves of two species of Combretum micranthum produced in the central (I) and southern (II) regions of Senegal and their decoctions in ultrapure water (Ii) and (IIi) were analyzed for 12 elements (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Ag, Cd, Pb, Bi) by inductively coupled plasma optical emission spectrometer (ICP-OES). The concentrations of heavy metals (μg/g) are in the ranges 2.55 – 84.19 for Cr, 5.21 – 379.72 for Mn, 0.00 – 317.80 for Fe, 0.08 – 1.08 for Co, 1.54 – 8.88 for Ni, 1.75 – 8.08 for Cu, 0.91 – 9.70 for Zn, 0.00 – 0.16 for Cd, 0.46 – 0.84 for Pb. As, Ag and Bi are below detectable limits in any of the samples by ICP-OES analysis. Among all samples, manganese content was highest and represented 46.85% for I , 64.18% for II , 86.88% for Ii and 46.27% for IIi , of the total heavy metal concentrations. The results showed that the leaves of both varieties of Combretum micranthum and decoctions made from these leaves contain heavy metal levels lower than the values recommended by the WHO for consumed medicinal plants. Overall, Variety I harvested from peri-urban areas contains more metals than Variety II harvested from forest.

Smartphone-assisted colorimetric sensor arrays based on nanozymes for high throughput identification of heavy metal ions in salmon

The rapid, precise, and high-throughput identification of multiple heavy metals ions holds immense importance in ensuring food safety and promoting public health. This study presents a novel smartphone-assisted colorimetric sensor array for the rapid and precise detection of multiple heavy metals ions. The sensor array is based on three signal recognition elements (AuPt@Fe-N-C, AuPt@N-C, and Fe-N-C) and the presence of different heavy metal ions affects the nanozymes-chromogenic substrate (TMB) catalytic color production, enabling the differentiation and quantification of various heavy metal ions. Combined with a smartphone-based RGB mode, the colorimetric sensor array can successfully identify five different heavy metal ions (Hg2+, Pb2+, Co2+, Cr6+, and Fe3+) as low as 0.5 μM and different ratios of binary and ternary mixed heavy metal ions in just 5 min. The sensor array successfully tested seawater and salmon samples with a total heavy metal content of 10 μM in the South China Sea (Haikou and Wenchang). Overall, this study highlights the potential of smartphone-assisted colorimetric sensor arrays for the rapid and precise detection of multiple heavy metal ions, which could significantly contribute to food safety and public health monitoring.

Sources Analysis and Health Risk Assessment of Heavy Metals in Street Dust from Urban Core of Zhengzhou, China

Fifty-one street dust samples were systematically collected from the urban core of Zhengzhou, China, and analyzed for potentially toxic metals. The concentrations of vanadium (V), manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), lead (Pb), and nickel (Ni) in the samples surpassed the background values of the local soil, indicating a notable potential for contamination. Spatially, the traffic area was the most polluted with a total heavy metal concentration of Cu, Zn, As, Pb, and Ni, while the pollution levels were lower in the culture and education area and commercial area with total concentrations of V and Mn. Seasonal variations were discerned in the concentrations of heavy metals, with V, Cu, Zn, and As exhibiting heightened levels during the fall and winter, while Mn, Ni, and Pb reached peaks in the spring season. Zn exhibited the highest mean geo-accumulation index (Igeo) value at 2.247, followed by Cu at 2.019, Pb at 0.961, As at 0.590, Ni at 0.126, Mn at −0.178, and V at −0.359. The potential ecological risk index (RI) in the traffic-intensive area markedly exceeded other functional areas. Health risk assessments showed that children were more vulnerable to heavy metal exposure than adults, particularly through the ingestion pathway. Correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were applied in conjunction with the spatial–temporal concentration patterns across various functional areas to ascertain the plausible sources of heavy metal pollutants. The results indicated that heavy metals in the urban street dust of Zhengzhou were multifaceted, stemming from natural processes and diverse anthropogenic activities such as coal burning, industrial emissions, traffic, and construction operations.

Comprehensive evaluation of the distribution, transport and ecological risk of heavy metals in intra-urban river sediments using high-resolution techniques

Determining the distribution trends, transport mechanisms, and ecological risks of heavy metals (HMs) in urban river sediments is essential for the government to conduct appropriate remediation work. In this study, we collected sediment cores from the Yayao Waterway in Foshan City, China. The vertical distribution profiles of dissolved and labile Fe, Mn, Cd, Zn, Cu, Cr, Ni, Pb, As, and Co in the sediments were obtained using the thin-film diffusive gradient (DGT) and high-resolution peeper (HR-Peeper) techniques. In addition, the transport rates, contamination levels, and ecological concerns of the HMs were evaluated using the European Community Bureau of Reference (BCR) sequential extraction technique, the DGT-induced sediment fluxes (DIFS) model, and multiple contamination evaluation metrics. The results showed that most of the DGT-labile HMs were associated with Fe/Mn (hydrogen) oxides, and in particular, Zn, Ni, and Cr showed a significant negative correlation with Fe/Mn (p < 0.001). Additionally, Cd had the highest bioavailability (89.17%), and its net diffusive flux at the sediment–water interface (SWI) was positive, which indicated a high release risk from the sediment. However, the R-value of Cd based on the DGT-induced sediment fluxes (DIFS) operation was extremely low, suggesting that although Cd had the biggest supply pool of releases, its release rate was slow. The majority of sampling sites had significantly higher total HM contents in the surface sediments than the background values. The HM contamination in the sediments originated from human activities, primarily from industrial enterprises and with a large contribution from both agricultural and domestic sources. The most polluted HM with the highest ecological danger was Cd, followed by Cu, Zn, Ni, and As when the results of the four pollution evaluation indicators were combined. Consequently, the risk of contamination by HMs in inner-city river sediments should receive more attention.

Assessing heavy metal contamination and health risks in playground dust near cement factory: exposure levels in children

Heavy metals pose significant threats to human health, particularly children. This study aimed to assess heavy metal pollution in children's playgrounds using surface dust as an indicator and to ascertain the associated exposure levels and health risks. A total of one hundred twenty dust samples were collected from the surface of playground toys in areas surrounding the cement factory in Bursa, Türkiye, on precipitation-free days. The heavy metal content of the samples was analyzed using ICP-MS. The average total concentration of heavy metals ranged from 2401 to 6832 mg/kg across the sampling sites, with the highest values observed at PG4, PG3, PG2, and PG1, respectively. The most commonly detected heavy metals in the samples included Cr, Mn, Fe, Co, Cu, Zn, Pb, Cd, As, and Ni. Statistical analysis revealed significant positive correlations (p < 0.01) among Cr, Mn, Fe, Co, Cu, Pb, As, and Ni, with Cu and Pb also showing correlation (p < 0.05). PCA analysis identified three principal components explaining 79.905% of the total variance. The Hazard Quotient (HQ) and Hazard Index values for heavy metals were found to be below the safe threshold (HQ < 1). Quantitative techniques such as the geoaccumulation index and enrichment factor are used to determine pollution levels at the sampling sites. Overall, the results indicate that cement factories significantly contribute to heavy metal pollution, with observed values varying based on proximity to the emission source.

Heavy Metals in the Cultivated Soils of Central and Western Serbia

Concern over the harmful impacts of heavy metal pollution in soil has increased dramatically on a global scale. For the sake of environmental preservation, accurate estimates of the heavy metal concentrations in soil are essential. This study provides valuable data regarding heavy metal concentrations in soil collected from field crops production area in Central and Western Serbia. Five wider localities in the zones of Central and Western Serbia were selected for the collection of soil samples. Based on our research, focused on determining the total contents of heavy metals in the soil and the degree of pollution in the environment caused by their behavior, distribution, and origin, it can be concluded that there is pronounced variability in relation to localities. Heavy metal contents were mostly within the same ranges as those in similar soils from Europe and around the world. Any pollution control system must include heavy metal monitoring, including the methodical collection of data on the concentrations of heavy metals in a particular environment. Before environmental degradation occurs, it is crucial to set pollution limits and implement efficient monitoring procedures.

Digestate from an Agricultural Biogas Plant as a Factor Shaping Soil Properties

In the context of a circular economy, special attention should be paid to the rational management of biodegradable waste. Currently, a potentially valuable waste material, rich in ingredients available to plants, is digestate, obtained as a by-product in agricultural biogas plants. The presented study aimed to determine the impact of digestate (DIG) from an agricultural biogas plant on soil reaction (pH), electrical conductivity (EC), sorption properties (SBC, HAC, CEC, BS), and chemical composition of soil. The research was based on a pot experiment in which increasing doses of liquid (LD) and solid (SD) forms of DIG were used in corn cultivation, balanced in terms of the amount of N introduced into the soil. The composition of DIG varied and depended on the LD or SD form. The LD was characterized by a lower pH value and higher EC compared to the SD form. The LD contained much less TC, fewer macroelements, and fewer trace elements. The application of LD significantly increased in the soil the content of TC, Ntot, available K, P, Fe, and Mn, and exchangeable cations K+. The SD significantly increased the content of available P, Mg, and Mn and exchangeable cations Ca2+ and Mg2+ in the soil. Both forms of digestate increased the total content of heavy metals (Cu, Cr, Pb, and Ni) in the soil. However, they did not pose a threat to the environment concerning their legally permissible levels.

Determination of potentially toxic heavy metals in selected wood treatment sites in Uasin Gishu County and their associated health concerns

One of the monumental environmental and public health concerns of our time lies in the use of toxic preservatives in wood treatment plants. In this investigation, we report the results of potentially toxic heavy metals from wood treatment plants in Uasin Gishu County. A 20 g ground and sieved soil sample from each sampling site Cheplaskei (CK), Outspan (OS) and Sukunanga (SK) was weighed and treated with 0.5 M nitric acid for 2 h. The sample was then analyzed for potentially toxic metals using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The statistical treatment of the data was done using Principal component analysis (PCA) and Pearson’s correlation. The highest concentration of copper was observed at SK, which contributed approximately 37% of all the potentially toxic heavy metal content analyzed, whereas the concentration of lead was found to be about 33% of the total heavy metal content analyzed at the same sampling site. Furthermore, the most abundant metal in the sampled sites is manganese, which was found to be 390.0 ± 8.63, 279.0 ± 8.05and 44.5 ± 2.95 ppm in OS, CK, and SK, respectively. PCA showed that the heavy metals in the sample sites originated from two independent sources—natural and anthropogenic. Evidently from the concentration profile data, all the potentially toxic heavy metals had concentrations above the World Health Organization (WHO) acceptable limits, although, based on the contamination factors determined, the wood treatment sites are less polluted; however, there is need for regular monitoring to ensure adherence to proper public and environmental health practices.

Seasonal variation of heavy metals in water and Cyprinus carpio L. from Umiam Lake reservoir of Meghalaya, India: Potential health risk assessment for human consumption.

The purpose of this study is to assess the seasonal variation of heavy metal concentration in water and fish tissues of common carp (Cyprinus carpio L.) from the Umiam Lake reservoir located in the Ri bhoi district of Meghalaya, India, and to elucidate the possible human health risk of ingesting fish captured from the contaminated lake. Results show significant (p < 0.05) seasonal differences of heavy metal concentrations in the water and different tissues of fish Cyprinus carpio L.. The total concentration of heavy metals in the water exceeds the WHO and BIS standards and thus poses a significant threat to the aquatic flora and fauna of the reservoir. The heavy metal concentrations in fish tissues were tissue-dependent, where the average concentration of heavy metals in all the tissues of Cyprinus carpio L. was in the order of Cr > Pb > Cu > Cd. In addition, the health risk assessment suggests that the heavy metals in the fish muscle from the Umiam Lake reservoir might have adverse effects on human. Therefore, the overall results of the study provide an understanding on the seasonal distribution of heavy metals in water, provide insight on their bioaccumulation in the fish tissues, and highlights the potential health risk for the local population of long-term fish consumption from Umiam Lake reservoir.

Assessment of water quality and heavy metal contamination in ballast water: Implications for marine ecosystems and human health

The global menace of non-compliance with ballast water management poses a pressing environmental threat, as it facilitates the transfer of harmful organisms and sediment contaminants. This study investigates the environmental impact of ballast water discharged by ships, focusing on water quality and heavy metal concentrations. The release of ballast water, often containing elevated levels of heavy metals like mercury, lead, and cadmium, poses a significant threat to marine ecosystems. The research, involving water sample collection from ten different vessels across various countries, assesses physicochemical parameters and heavy metal concentrations. Results indicate variations in temperature, turbidity, conductivity, dissolved oxygen, and pH levels among samples. Turbidity values surpassing WHO limits suggest potential anthropogenic pollution. The study identifies significant differences in pH values, potentially influencing microbial populations. Total dissolved solids and total suspended solids values vary, affecting the distribution of potential pathogens. The results reveal varying total concentrations of heavy metals (mg/L) in the following decreasing order: SA&gt;SE&gt;SF&gt;SB&gt;SC&gt;SD&gt;SH&gt;SI&gt;SG&gt;SJ(6.07 &gt;4.95 &gt; 2.07 &gt; 1.59&gt;0.24&gt;1.22&gt;0.09&gt;0.04&gt;0.03&gt;0.01). The highest concentration of heavy metals is recorded for iron (SA= 5.78), zinc (mg/L) (SB = 1.36, SE = 1.30, and SF = 1.35) and lead (Pb) (SE = 2.39). The elevated iron levels in vessels from SA are potentially linked to corrosion processes. Cadmium, lead, and nickel were not detected, except for lead in the sample from SE. Copper concentrations were aligned with EU standards in the vessels. Proper ballast water management is vital for monitoring water qualities, preventing environmental spread of heavy metals, ensuring marine ecosystem health, and developing compliance strategies for ships docking in ports. Highlights Global shipping causes heavy metal pollution, affecting human and ecosystem health Physicochemical parameters variations suggest potential pollution and microbial impact Mercury, lead, and cadmium in ballast water (BW) pose threats to marine ecosystems Increased iron levels could be associated with corrosion processes Effective BW management is crucial for environmental conservation

Driving factors for distribution and transformation of heavy metals speciation in a zinc smelting site

Heavy metal pollution at an abandoned smelter pose a significant risk to environmental health. However, remediation strategies are constrained by inadequate knowledge of the polymetallic distribution, speciation patterns, and transformation factors at these sites. This study investigates the influence of soil minerals, heavy metal occurrence forms, and environmental factors on heavy metal migration behaviors and speciation transformations. X-ray diffraction analysis revealed that the minerals associated with heavy metals are mainly hematite, franklinite, sphalerite, and galena. Sequential extraction results suggest that lead and zinc are primarily present in the organic-sulfide fractions (F4) and residual form (F5) in the soil, accounting for over 70% of the total heavy metal content. Zinc displayed greater instability in carbonate-bound (16%) and exchangeable (2%) forms. The migration and diffusion patterns of heavy metals in the subsurface environment were visualized through the simulation of labile state heavy metals, demonstrating high congruence with groundwater pollution distribution patterns. The key environmental factors influencing heavy metal stable states (F4 and F5) were assessed by integrating random forest models and redundancy analysis. Primary factors facilitating Pb transformation into stable states were available phosphorus, clay content, depth, and soil organic matter. For Zn, the principal drivers were Mn oxides, soil organic matter, clay content, and inorganic sulfur ions. These findings enhance understanding of the distribution and transformation of heavy metal speciation and can provide valuable insights into controlling heavy metal pollution at non-ferrous smelting sites.

Prediction models for bioavailability of Cu and Zn during composting: Insights into machine learning

Bioavailability assessment of heavy metals in compost products is crucial for evaluating associated environmental risks. However, existing experimental methods are time-consuming and inefficient. The machine learning (ML) method has demonstrated excellent performance in predicting heavy metal fractions. In this study, based on the conventional physicochemical properties of 260 compost samples, including compost time, temperature, electrical conductivity (EC), pH, organic matter (OM), total phosphorus (TP), total nitrogen, and total heavy metal contents, back propagation neural network, gradient boosting regression, and random forest (RF) models were used to predict the dynamic changes in bioavailable fractions of Cu and Zn during composting. All three models could be used for effective prediction of the variation trend in bioavailable fractions of Cu and Zn; the RF model showed the best prediction performance, with the prediction level higher than that reported in related studies. Although the key factors affecting changes among fractions were different, OM, EC, and TP were important for the accurate prediction of bioavailable fractions of Cu and Zn. This study provides simple and efficient ML models for predicting bioavailable fractions of Cu and Zn during composting, and offers a rapid evaluation method for the safe application of compost products.

Dedicated microwave extraction allows uniform energy distribution to efficiently solubilize Ascophyllum nodosum

Considering the current transition to biobased carbon sources and the search for viable extraction procedures, the microwave-assisted solubilization of seaweed biomass was explored. Hereto, the brown North Sea native species Ascophyllum nodosum was processed using water as green extraction solvent. Response surface methodology was used to determine the best solubilization conditions towards maximizing the solubilization efficiency and minimizing the applied energy per mass of solubilized seaweed by varying (i) temperature, (ii) time and (iii) solid to liquid ratio (S/L). It was found that a temperature of 120 °C, a processing time of 15 min and a 1.03 w:v S/L are most suitable to achieve the pre-set criteria. Concurrently, mass balances were developed with respect to total lipid, polysaccharide, protein, mineral and heavy metal contents. Moreover, zeta potential measurements were performed to link the obtained values and the antimicrobial characteristics of the extracts. Finally, antimicrobial tests on S. aureus and E. coli were conducted and with results indicating up to 97 % inhibition of bacterial growth after 8 h, antimicrobial characteristics were indeed observed.

Unlocking critical nutritional potential: A comprehensive analysis of small indigenous fishes in Bangladesh and the development of ready-to-use fish products as balanced food

The study aimed to develop fish powder as a promising dietary supplement to combat inadequate nutrition. To achieve this goal, the study assessed the nutritional aspects, including proximate composition, mineral content, amino acid profile, and fatty acid profile, as well as the microbiological quality and heavy metal contents, of six small indigenous fish species. The protein content ranged from 57.73 % to 65.26 %, with G. chapra exhibiting the highest protein content (p < 0.001). In all fish powders, the mineral composition was found in the following order: Na > P > Ca > K> Mg > Fe > Mn > Zn. The results revealed significantly elevated levels of total essential amino acids in A. mola (227.20 mg/g, p < 0.001). The PUFA/SFA ratio (> 0.45) and ω-6/ω-3 fatty acids ratio (< 4.00) were generally optimal. The quality and safety of the fish products for human consumption were confirmed, as both the total colony count and heavy metal concentrations remained below the recommended threshold. All ready-to-use fish products, except A. mola, meet over 20 % of the daily nutritional needs for PLW, infants, and adults. Hence, these findings advocate the utilization of the studied fish species as a dietary supplement to address malnutrition.

Enrichment Characteristics and Ecological Risk Assessment of Heavy Metals in a Farmland System with High Geochemical Background in the Black Shale Region of Zhejiang, China

Soils derived from black shale enriched in heavy metals pose risks to the environment and human health. Eighty sets of soil–rice samples were collected in northwest Zhejiang, China. The results showed significant enrichment of As, Cd, Pb, and Zn in the studied soil. Sequential extraction data indicated that Cd had relatively high bioavailability. Thirty-four percent of the rice samples exceeded the heavy metal pollution thresholds of national food safety standards. A comprehensive evaluation of soil heavy metals using the potential ecological risk index (RI) revealed low-to-moderate-grade risk. Risk assessment code (RAC) levels decreased as follows: Cd &gt; Ni &gt; Zn &gt; Cr &gt; Cu &gt; Pb &gt; As &gt; Hg. The RAC of Cd was high and very high risk, whereas those of others were no or low risk. Cd was the major contributor to the environmental risk based on the total heavy metal concentration, toxicity, and chemical fractions. The health risk to the local populace was assessed using the method recommended by the USEPA. Local people may experience both non-carcinogenic and carcinogenic health risks, and children face greater health risks than adults. As, Cd, and Pb are the most significant contributors to non-carcinogenic health risks, and Cd is the main carcinogenic risk. In conclusion, special attention should be given to heavy metal pollution in black shale-derived soils.