Heavy Metal Residues Research Articles

The curious case of the Dana platypus and what it can teach us about how lead shotgun pellets behave in fluid preserved museum specimens and may limit their scientific value.

Fluid preserved animal specimens in the collections of natural history museums constitute an invaluable archive of past and present animal diversity. Well-preserved specimens have a shelf-life spanning centuries and are widely used for e.g. anatomical, taxonomical and genetic studies. The way specimens were collected depended on the type of animal and the historical setting. As many small mammals and birds were historically collected by shooting, large quantities of heavy metal residues, primarily lead, may have been introduced into the sample in the form of lead shot pellets. Over time, these pellets may react with tissue fluids and/or the fixation and preservation agents and corrode into lead salts. As these chemicals are toxic, they could constitute a health issue to collection staff. Additionally, heavy element chemicals interfere with several imaging technologies increasingly used for non-invasive studies, and may confound anatomical and pathological investigations on affected specimens. Here we present a case-study based on platypus (Ornithorhynchus anatinus) and other small mammals containing lead pellets from the collection of The Natural History Museum of Denmark.

Overviews of heavy metals residues in some frozen fish and its biocontrol by probiotic

Overviews of heavy metals residues in some frozen fish and its biocontrol by probiotic

The Effect of Heavy Metals in Potato (Solanum tuberosum L.) Genotypes for Some Physiological Parameters

The main aim of this study is to identify physiological characteristics, including Chl a, b, total Chl "a+b" and carotenoids, in potato genotypes under the influence of lead (Pb+2) and cadmium (Cd+2) heavy metals. Two potato genotypes from the Netherlands, Riviera and Agria, were used in the study. Potato tubers were transferred to 2 kg compost pots and placed in a controlled environment with a 12 photoperiod, a day/night temperature of 25/19°C and a relative humidity of 75%. Since Pb+2 and Cd+2 poisoning was greater than in the control and different fractions of heavy metal residues in the substrate were transferred to plant organs, the amounts of these two metals in each treatment (outside the control) were measured. Plant pigments were extracted from fresh leaves in amounts ranging from 60 to 100 mg and these were then extracted into samples containing 80/20% (v/v) acetone/water with 0.5% w/v MgCO3 at room temperature for a full day. Photosynthetic pigments of each sample were extracted three times. The absorbances obtained at 663 nm, 644 nm and 452.5 nm for the maximum absorption of Chl a, Chl b and carotenoids, respectively, were used to measure the amount of chlorophyll and carotenoids. Differences between Pb+2 and Cd+2 and physiological markers were examined with the Duncan Multiple Range test. Information on Pb+2 and Cd+2 content in applications revealed wide variability. When potato genotype seedlings were exposed to varying levels of Pb+2 and Cd+2, the amount of chlorophyll and carotenoids in their leaves was lower than the control group. The results showed that there were significant and statistically significant changes in carotenoid and chlorophyll concentration at the LSD p = 0.01 level. Similar to Pb+2 and Cd+2 inhibiting plant growth, it had a negative effect on photosynthesis as well as chlorophyll and carotenoid contents. Moreover, these effects became more pronounced when the concentrations of two stress factors (Pb+2 and Cd+2) increased.

Seaweed as a feed additive to mitigate enteric methane emissions in ruminants: Opportunities and challenges1

Cutting farming-related methane emissions from ruminants is critical in the battle against climate change. Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions, using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years. Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform. As a type of halogenated methane analogue, bromoform contained in A. taxiformis can specifically inhibit the activity of coenzyme M methyltransferase, thereby blocking the ruminal methanogenesis. However, bromoform is a potential toxin and ozone-depleting substance. In response, current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety, as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment. The current research on seaweed still needs to be improved, especially in developing more species with low bromoform content, such as Bonnemaisonia hamifera, Dictyota bartayresii, and Cystoseira trinodis. Otherwise, seaweed is rich in bioactive substances and exhibits antibacterial, anti-inflammatory, and other physiological properties, but research on the role of these bioactive compounds in methane emissions is lacking. It is worthy of deeper investigation to identify more potential bioactive compounds. As a new focus of attention, seaweed has attracted the interest of many scientists. Nevertheless, seaweed still faces some challenges as a feed additive to ruminants, such as the residues of heavy metals (iodine and bromine) and bromoform in milk or meat, as well as the establishment of a supply chain for seaweed cultivation, preservation, and processing. We have concluded that the methane-reducing efficacy of seaweed is indisputable. However, its application as a commercial feed additive is still influenced by factors such as safety, costs, policy incentives, and regulations.

Fabrication of Raman reporter molecule–embedded magnetic SERS tag for ultrasensitive immunochromatographic monitoring of Cd ions and clenbuterol in complex samples

A rapid, simple but sensitive analytical method for the simultaneous monitoring of heavy metal ions and illegal additives in complex samples remains lacking. We reported a difunctional capture–detection surface-enhanced Raman scattering (SERS) immunochromatographic assay (ICA) for the direct detection of the heavy metal residue Cd ion (Cd2+) and illegal additive clenbuterol (CLE) with high sensitivity and specificity herein. A novel magnetic SERS tag (Fe@RAu) with a Raman reporter molecule–embedded raspberry-like Au shell was fabricated via a one-step reduction reaction that not only simplified the fabrication of common magnetic SERS nanomaterials but also improved SERS activity to increase detection sensitivity. The difunctional SERS–ICA enabled the fast magnetic enrichment of the target small molecules in complex specimens and ultrasensitive and quantitative determination of CLE/Cd2+ on the two test lines of the ICA system. The limits of detection of the developed method for CLE and Cd2+ were as low as 0.48 and 1.88 pg/mL, respectively, and about 2000 and 500 times lower than those of conventional AuNP-based ICA strips. The excellent practicability of Fe@RAu–ICA for real food samples analysis was also demonstrated, revealing the potential of the proposed assay for rapid and on-site screening of small-molecule pollutants.

Simultaneous removal of diclofenac sodium, cadmium and bacterial inactivation from aqueous solutions by activated MgO nanoparticles

This study investigated whether MgO nanoparticles (NPs) produced via the sol–gel process can simultaneously remove the pharmaceutical diclofenac sodium (DCF) and cadmium ions (Cd2+) from water. The UV spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX) were used to confirm the composition, morphology and particle size of the MgO NPs. The adsorption performance of MgO NPs was compared to that of bentonite-nano zero valent iron (B-nZVI) and activated carbon (AC). The impact of contact time, adsorbate concentration, pH, and temperature on the removal efficacy of DCF and Cd2+ via MgO NPs in aqueous solutions were investigated, and the removal data was best described by the kinetic model of pseudo-second-order and the Langmuir isotherm model (R 2 > 0.996). The maximum removal capacity of MgO for DCF and Cd2+ at pH 7 was 66.2 mg.g−1 (%R = 90) and 50.8 mg.g−1 (%R = 80), respectively. The average adsorption enthalpy for DCF and Cd2+ (ΔH° 50 kJ. mol−1) demonstrates the occurrence of physical adsorption process, while the negative value of ΔG° reveals the spontaneous nature of DCF and Cd2+ adsorption on the surface of MgO NPs. The DCF and Cd2+ adsorbed MgO surfaces were reused against various gram-positive bacteria. Finally, it was shown that MgO and sand column were more effective for removal of persistent substances and heavy metal residues than a column packed by a mixture of B-nZVI and sand.

Determine the levels of heavy metal residues in different parts of chicken in the Tikrit and Beji cities of Iraq

The aim of this study was to determine the level of heavy metal residues in different parts of local chicken meat (thigh, bone, liver, and breast) obtaining from different houses in the Iraqi cities of Tikrit and Beji. Heavy metal contamination in poultry products is a major concern due to its potential health effects on consumers. Samples were collected from local markets and analyzed for the presence of cadmium (Cd), copper (Cu), cobalt (Co), and lead (Pb) using atomic absorption spectroscopy (AAS). The results indicated that chicken parts all sampled contained detectable level of heavy metals, with concentrations varying between parts. The high level of heavy metals cadmium (Cd) in the liver part in Tikrit was (0.422), also addition the high level of heavy metals copper (Cu) in L the liver part in Beji was (1.923), also the high level of heavy metals cobalt (Co) in the bone part in Tikrit was (1.403) and the high level of heavy metals lead (Pb) in the bone part in Tikrit was (1.045), indicating regional differences in contamination. These results emphasize the importance of monitoring heavy metal levels in different parts of chicken to ensure food safety and public health

Heavy Metal Residues and Bacterial Pathogens of Food Safety Significance in Edible Crustacean from Crude-Oil-Impacted Niger Delta, Nigeria

ABSTRACT The study investigated heavy metal residues and bacterial pathogens in blue crab (Callinectes amnicola), crayfish (Nematopaelemon hastatus), giant tiger prawn (Penaeus monodon), and Indian prawn (Fenneropenaeus indicus) from crude oil impacted Niger Delta waters. Standard methods of analysis were applied in all determinations. Results indicate that chromium, lead, and mercury were within regulatory acceptable levels. Total viable count (TVC) was below threshold, while Vibrio cholerae, Vibrio parahaemolyticus, and Salmonella typhimurium were isolated from all crustacean species. The distribution pattern of pathogens showed blue crab accumulated the highest population of pathogens. Consumption of crustaceans from the location exemplifies conflict of nutrient benefits and risks.

Determination of Heavy Metal Concentrations on some Selected Herbal Medicinal Preparations Marketed in Kano State, Nigeria

Study’s Novelty/Excerpt This study assesses heavy metal concentrations in traditional medicinal herbs consumed in Kano State, Nigeria, providing critical insights into their relative safety and potential health risks. By analyzing ten powdered herbal samples using Atomic Absorption Spectrometry, the research identifies concerning levels of lead, chromium, cadmium, and mercury, with lead concentrations in one sample exceeding the WHO's safety limits. The findings highlight significant variability in heavy metal content among different herbs, underscoring the need for stringent quality control and regulatory measures to ensure consumer safety. Full Abstract Herbs are extensively consumed in Nigeria, for their medicinal properties and availability. This study aimed at determining the concentration of heavy metals residues in some selected traditional medicinal herbs consumed in Kano State, Nigeria. This is to assess their relative safety and potential health risks to local inhabitants based on the World Health Organization standard limit. A total of ten (10) powdered samples of medicinal preparations were purchased from local markets in Kano metropolis and analyzed for the presence of lead, chromium, cadmium, and mercury contents. The samples underwent digestion, and heavy metal concentrations were determined using Atomic Absorption Spectrometry (AAS). The metals found to be present varied in different concentrations in the herbal samples. The presence of heavy metal ranges as follows: 0.6-6.5mg/kg for chromium, 3.10-22.10mg/kg for lead, 0.08-0.60mg/kg for cadmium, and 0.09-0.30mg/kg for mercury. However, mercury content was not detected in some samples. The study's findings conclude that the lead (Pb) values were found to be the highest in concentration, exceeding the W.H.O limits in sample J, which is used as a remedy for cough. This indicates that the sample is highly contaminated compared to others. Mercury was not detected in four of the samples, and when present, it was below the limits set by the World Health Organization, making all the samples free from mercury contamination.

Gender-specific responses in gene expression of Nile tilapia (Oreochromis niloticus) to heavy metal pollution in different aquatic habitats

Monitoring heavy metal accumulation is essential for assessing the viability of aquatic ecosystems. Our methodology involved integrating analysis of immunological, stress, inflammatory, and growth-related gene expression in male and female Nile tilapia with on-site recordings of physicochemical parameters. Additionally, we assessed the effect of different physicochemical parameters on heavy metal bioavailability and residual concentration in fish and water. Samples of fish and water were gathered from three different localities: Lake Brullus, a brackish lake sited in northern Egypt; Lake Nasser, an artificial freshwater reservoir located in southern Egypt; and El-Qanater El-Khayria, a middle-freshwater location belonging to the Rashid branch of the river Nile. The assessment of heavy metal residues (Fe, Cu, Zn, Mn, and Ni) revealed that their concentrations were higher in fish specimens compared to their counterparts in water (except for Ni). In addition, Lake Brullus emerges as the most polluted area, exhibiting elevated levels of heavy metals concentrations in water and fish specimens. In contrast, Lake Nasser showed the least degree of heavy metals pollution. Gene expression analysis revealed gender-specific responses to heavy metal exposure at the three investigated water bodies. The expression of hepatic antioxidant genes (GST and MT) and inflammatory-related genes (CC-chemokine and TNFα) increased in males compared to females. In females, the immune and pro-inflammatory-related genes (IgM and CXC2-chemokine) transcripts were upregulated. Additionally, growth-related genes were downregulated in both Lake Brullus and El-Qanater; on the contrary, fish samples from Lake Nasser exhibited a normal expression pattern of growth-related genes. Stress-related genes (HSP70 and HSP27) showed significant downregulation in gills of both genders from Lake Brullus. The minimal presence of heavy metal contaminants in Lake Nasser seems to endorse the normal patterns of gene expression across all gene categories. A potential gender-specific gene expression response towards pollution was noticed in genes associated with inflammation and antioxidant activities. This highlights the importance of considering gender-related responses in future environmental assessments.

Volcanic eruption-inspired co-melting treatment of municipal solid waste incineration fly ash

The resourceful disposal of municipal solid waste incineration fly ash (MSWI FA) is a major global challenge. Inspired by volcanic eruptions, a method to lower the melting point of MSWI FA and to promote heavy metal chlorination volatilization was proposed. The introduction of river mud transformed melting products from crystalline to amorphous, obtaining glass products with low heavy metal residues. The volatilization efficiencies of Cu, Zn, Pb, and Cd reached 82.67 %, 100 %, 100 %, and 100 %, respectively, the heavy metal and salts were enriched in secondary ash. Alkali metal oxide induced the transformation of bridging oxygen to non-bridging oxygen, providing binding site for Cl in the form of Ca-Cl coordination and increasing the chlorine content. Then chlorine reacted with CuO converted from Cu2S and promoted the Cu volatilization. The outcomes fundamentally solved the problem of heavy metal residues in MSWI FA melting treatment, supporting resourceful and harmless treatment of MSWI FA.

Comparison of heavy metal residue in selected processed canned tomato paste and bottled tomato sauce using atomic absorption spectrometry

Heavy metals are used to manufacture various types of packaging materials such as cans and glass bottle containers. Determination of heavy metal concentration presence in processed food products is crucial to identify specific possibly hazard metal contaminants and create public awareness upon consumption. A total of ten samples consisting of five different brands of canned tomato paste and bottled tomato sauce sold in Malaysia were analysed for the concentration of lead (Pb), cadmium (Cd), iron (Fe), zinc (Zn), chromium (Cr) and nickel (Ni) metals residues by Atomic Absorption Spectrometry (AAS). The average heavy metals concentration of all samples was arranged in increasing order, Cd > Ni > Cr > Pb > Zn > Fe. The highest level of metal was Fe (69.93 mg/kg) while the lowest was Cd (0.01 mg/kg). The concentration of Pb, Cr and Ni in all samples exceed the permissible limit set by the World Health Organisation 2011, the European Commission 2006 and the Malaysia Food Act and Regulation 1985 except Zn. There is a significant difference between heavy metal concentrations in canned tomato paste and bottled tomato sauce (p˂0.05). Therefore, this study suggests efficient monitoring and inspection of both agricultural environment quality and industrial processing procedures.

Comprehensive investigation of undesired substances and microbial contamination in plant-based drinks

There is a growing market relevance of non-dairy alternatives mainly driven by issues concerning an increasing prevalence of vegetarianism, awareness of animal welfare and ecological impact of food production. Among the most popular plant-based drinks (PBDs) are almond-, oat- and soy-based products. As the likeliness of contamination of PBDs varies markedly depending on their plant origin, in a survey of selected most common organic-products from the German market mycotoxins, residues of plant protection products, heavy metals, and microbial contamination have been monitored. The results showed that, with one exception, all products were commercially sterile, free of pathogenic microorganisms and contained at most trace amounts of plant protection agent residues. For nickel especially, soy-based drinks showed elevated levels of up to 315 μg/kg and these products also had the highest cadmium levels of up to 7.2 μg/kg. Oat and almond based drinks contained up to 159 and 54 μg/kg Ni and 1.4 and 0.6 μg/kg Cd respectively. By contrast, for mycotoxins, the soy-based drinks showed almost no detectable contamination, while up to 2.1 μg/L T2+HT2-toxin and 5.5 μg/L deoxynivalenol were quantified in oat-based drinks and up to 130 ng/L aflatoxin B1 (AFB1) were found in almond-based drinks. Additionally, oat- as well as almond-based drinks frequently contained up to 263 ng/L and 70 ng/L of the emerging mycotoxin and AFB1 precursor sterigmatocystin.In particular, the mycotoxins in oat- and almond-based drinks and heavy metals in soy-based drinks should be further investigated and minimized, as PBDs represent a novel and additional source of the overall human exposure to these contaminants.

Occurrence and Risk Assessment of Pesticides, Phthalates, and Heavy Metal Residues in Vegetables from Hydroponic and Conventional Cultivation.

Hydroponic cultivation of fresh produce is gaining popularity worldwide, but few studies have provided a comparative assessment of hydroponic and conventional soil-based vegetables. In this study, we analyzed a series of hazardous chemicals, including 120 pesticides, 18 phthalates (PAEs), and 2 heavy metals (lead and cadmium) in four vegetable commodities (lettuces, celeries, tomatoes, and cucumbers) from hydroponic and conventional soil-based cultivation. Our study showed that at least one pesticide was present in 84% of the conventionally grown samples, whereas only 30% of the hydroponic samples contained detectable pesticide residues. Regarding the total PAE concentrations, there was no significant difference between conventional and hydroponic vegetables. The lead and cadmium residues in conventionally cultivated vegetables were significantly higher than in those produced from hydroponic cultivation. Lead is the primary heavy metal pollutant across all vegetable samples. The hazard index (HI) values of the hydroponic and conventional vegetables were 0.22 and 0.64, respectively. Since both values are below one, the exposure to these hazardous chemicals through consumption of the studied vegetables may not pose a significant health risk. The HI values also suggested that the health risks of eating hydroponic vegetables are lower than for conventional soil-based vegetables.

Combined effects of biochar and biodegradable mulch film on chromium bioavailability and the agronomic characteristics of tobacco

Biochar (BC) and biodegradable mulch film (BMF) are both commonly used means of production in agriculture. In recent years, most studies have focused on the effects of BC or BMF on soil heavy metal pollution, while they have neglected the combined effects. In this study, a pot experiment was conducted to examine the impacts of BMF, BC, and combined BMF and BC (CMB) on the mobility of chromium (Cr) and the agronomic characteristics of flue-cured tobacco. Compared with the control, BMF, BC, and CMB significantly reduced the concentrations of diethylenetriamine pentaacetic acid (DTPA) extractable Cr in soils by 29.07–29.75%, 45.35–48.54%, and 34.21–37.92%, respectively. In comparison to the application of BMF and BC alone, co-application reduced the availability of Cr in soil via increasing the adsorption of soil Cr and soil enzyme activity, which resulted in the decrease of Cr content and bioconcentration factor and in plants. Moreover, the combined application increased the plant height, stem diameter, leaf area, total root area, root tip number, and root activity of tobacco, which leaded to increase in leaf and root biomass by 11.40–67.01% and 23.91–50.74%, respectively. Therefore, the application of CMB can reduce the heavy metal residues in tobacco leaves and improve tobacco yield and quality.

Phytoremediation capacity of hybrid aspen at sites affected by industry and agriculture.

Fast-growing Populus spp. are well-acknowledged to restore contaminated soils from heavy metals in industrial areas. Thus far, there is no knowledge about the phytoremediation capacity of Populus spp. plantations in hemiboreal Estonia conditions to restore industrially polluted areas. The objective of this study was to assess the soil contamination rate of heavy metals (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) and their uptake by mature hybrid aspen (Populus tremula × Populus tremuloides Michx.) in plantations in different industrial pollution areas (e.g. cement factory, oil shale mining). For the reference, industrially polluted plantations were compared with the low pollution area hybrid aspen plantation on former agricultural soil, which was influenced by fertilization and liming before afforestation. Twenty-one years after afforestation, soil samples were collected from the 0-10cm topsoil layer. Aboveground biomass sampling was performed for bark and stem wood by ingrowth cores to separate wood formed during early (1-10years) and late (11-21years) stand development. Two decades after the afforestation of industrially polluted areas, the heavy metal concentrations in the soil were higher than the reference plantation and the standard reference for unpolluted soils in most cases. The highest concentrations of heavy metals in woody biomass were in the oil shale quarry spoil; because of poor growth, the accumulated pools in aboveground biomass were low. Cd differed from other metals and accumulated less in wood and more in bark. The concentration of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni and Zn) was higher in the first decade of stand formation (1-10years) than in the last 10years (11-21years). High pools of heavy metals were accumulated in aboveground biomass in the reference plantation, indicating the considerable removal of heavy metal residues from the previous fertilization and liming source with harvest. Two decades of afforestation with hybrid aspen is too short for complete ecosystem restoration from heavy metals in industrially polluted areas.

Effect of blast furnace slag substitution for cement in carbon-reduced and low-cost solidified/stabilized cementitious materials

The development of low-carbon cementitious materials involves the selection of the appropriate raw materials and the transformation of the hydration mechanism. In this study, low-carbon and low-cost cementitious materials were prepared using municipal solid waste incineration fly ash (MSWI FA), blast furnace slag (BFS), and desulfurization gypsum (DFG) as raw materials to reduce clinker usage. Results showed that the compressive strength of K5 (mass ratio of BFS: DFG: MSWI FA = 7:1:2) after 360 d of curing was 41.49 MPa, with a low leaching concentration of heavy metal residues that meet groundwater Class II standards, a dioxin content of only 25 ngTEG/kg, and a stable pH value ranging between 11 and 11.5. Microscopic analysis revealed a continuous decrease in the Ca/Si atomic ratios of K4 (mass ratio of BFS: DFG: MSWI FA: P·I 42.5 = 42:10:20:28) and K5, i.e., 1.18–1.54 and 1.04–1.23, respectively, with the increase in the hydration age. The highest Al/Si atomic ratio of K5, i.e., 0.26–0.31, was observed with the strongest conversion trend of calcium–silicate–hydrate gel into calcium–aluminum–silicate–hydrate gel, and the network structure of sodium–(calcium)–aluminum–silicate–hydrate gel zeolite-like phase was generated. The water-to-binder (WTB) mass ratio of 0.35 was determined to be more suitable for the K4 and K5 systems and resulted in a 56.83% and 90.82% reduction in half-life t∂ compared with the WTB ratio of 0.5, respectively. Notably, the value of the reaction velocity constant K in the induction period was 10 times that of K1, and the autocatalytic reaction controlled the value of N to < 1. The X-ray absorption near-edge structure indicated that Zn solidification produced Zn2SiO4 with a small solubility product. The production of 1 t of K5 emitted only 10.83 kg/t of CO2, which was 40 times less than that of K1. Overall, K5 provides the highest economic benefit at 40.08 USD/t, and the clinker-free cementitious system with multisolid waste synergy has significant advantages in terms of solidifying harmful substances, reducing carbon emissions, and lowering costs.

Heavy Metals Contaminants in Honey and Dry-Cured Meat Sold in Northern Nigeria Markets

Honey and dry-cured meat are common products for consumption and export in Nigeria but with a paucity of reports on their chemical contamination status. The occurrence of heavy metal residue in honey and dry-cured meat (Kilishi) for export in Kano and the Federal Capital Territory (FCT), Abuja, Nigeria and their safety status were investigated. The toxic metals profile in ninety samples of each animal product was established by Atomic Absorption Spectrometry (AAS, M5 Thermo Fisher Scientific, USA). The mean prevalence of Copper (Cu) in the honey samples from Kano Central was statistically higher than from other locations. Cadmium (Cd) contaminants occurred in the products at a range of 0.001-0.041 mg kg-1. Lead (Pb) and Cobalt (Co) were below detectable levels in all the samples. Due to the relatively high profile of Cu in both products, Cr in honey and Cd in the dry-cured meat, which was slightly higher than the permissible level in humans by the World Health Organization, there is a health risk concern. The Nigerian regulatory entities should always routinely monitor and enforce the set legislative laws to ensure a safe animal product for local consumption or export in Nigeria.

Data-driven approach for sustainable geopolymer mortar production with treated sewage sludge

ABSTRACT This paper highlights an innovative approach to address the environmental challenges associated with waste management and construction materials. The study presents a new technique for utilising treated sewage sludge in the production of eco-friendly geopolymer mortar. Sewage sludge is a byproduct generated from wastewater treatment plants that poses significant environmental issues due to its disposal problems. Geopolymer mortar, on the other hand, is a sustainable construction material that can be produced by activating industrial waste materials, such as fly ash, using alkaline activators. By integrating machine learning algorithms and data visualisation techniques, this study optimises the mix parameters of geopolymer mortar while simultaneously reducing the negative impact of sewage sludge disposal. The experimental results show that sewage sludge ash can replace fly ash and fine aggregate in 1:3 geopolymer mortar by up to 30% and 20%, respectively, without any toxic or heavy metal residues. The compressive and flexural strength of the sludge-based mortar were comparable to ordinary geopolymer mortar, while water absorption and drying shrinkage were similar to control specimens. This research offers a unique solution to promote sustainability in waste management and construction industry by utilising waste materials, including fly ash and treated sewage sludge, for geopolymer production.

Environmental factors dominate microbial community puppet-like driving the distribution of antibiotic resistance genes in different utilization lands

Excessive use of antibiotics has caused the accumulation of antibiotic resistance genes (ARGs) in the soil environment, posing a great challenge to environmental safety and public health. However, there is a lack of comprehensive investigations of soil ARGs profiles under different land utilization patterns, and the drivers that affect the distribution of ARGs remain poorly defined. Herein, we investigated the ARGs profiles of eight different land uses and explored the critical factors influencing the distribution of ARGs. The results showed that ARGs abundance in soil of parks, residential areas, farmland, and vegetable cultivation was significantly higher than that in other lands, with an average of 2.08 × 103 copies/g dry soil. The structural equation model demonstrated that the environmental variables were the pivotal drivers that dominated the differences in ARG distribution across land utilization types (path coefficient=0.934), in which the physicochemical factors exhibited the greatest contribution with an explanatory rate of 20.27%, which was markedly higher than that of antibiotics and heavy metal residues. Importantly, these physicochemical factors manipulate the succession of microbial communities by altering the connections between microorganisms, which in turn indirectly affects the distribution of ARGs. Moreover, ARG exposure was strongly correlated with fertilizer application, precipitation, and per capita water resources (p < 0.01). Overall, this study provides a well-rounded understanding of ARG exposure under different land-use patterns, which helps to develop management strategies for curbing ARGs dissemination in the environment.