Solidification is a very effective way to alleviate heavy metal impacts to the environment. In this paper, an improved method was adopted herein for the solidification/stabilization (S/S) of sediments with cement-based additives and low content of cement in S/S materials. Sediments in Xiangjiang River, containing high concentrations of Cu, Cd, and Pb, were solidified/stabilized by binders of cement, fly ash, and bentonite. Admixtures such as sodium lignosulfonate, sodium lauryl sulfate, and triethanolamine were used to improve the bonding properties of S/S, which had never been investigated before. Results demonstrated that the addition of concrete admixtures had significant effects on the S/S of sediments. Sequential extraction method indicates that the concentrations of heavy metals changed significantly after solidification and were more stable over time, with the exception of Pb. In addition, SEM images indicated that the main hydrated product was ettringite. Large quantities of calcium silicate hydrates (CSH) formed and filled the solidified sediment in 60 days. The results provide further insights into the transformation of heavy metals during S/S.

Data from the National Health and Nutrition Examination Survey for 1999–2012 were used to evaluate factors that affect observed levels of urine cadmium (UCd) among children aged 6–11 years and nonsmoker adolescents aged 12–19 years. Adjusted UCd levels were found to be statistically significantly higher for female nonsmoker adolescents than male nonsmoker adolescents (p < 0.01). Non-Hispanic white (NHW) participants had statistically significantly lower adjusted levels of UCd (<0.01) than non-Hispanic black (NHB) participants for both children (p < 0.01) and adolescents (p < 0.01). Dietary intake of cadmium was not found to affect the levels of UCd. While unadjusted levels of UCd for nonsmoker adolescents declined (p < 0.01) over 1999–2012 by 28.3%, no statistically significant trend was observed for adjusted levels.

It has been shown previously that, under acidic conditions, 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4-dinitroanisole (DNAN) degrade in the presence of iron/copper bimetal particles; the reactions can be modeled by pseudo-first-order kinetics. This study investigates the reaction mechanisms of the degradation processes under different conditions. Batch studies were conducted using laboratory-prepared solutions and an industrial insensitive munition-laden (IMX) wastewater. The influence of parameters such as initial pH of the solution, copper/iron (Fe-Cu) contact, and solid/liquid ratio were systematically investigated to assess their impact on the reaction kinetics. These parameters were subsequently incorporated into pseudo-first-order decomposition models for NTO and DNAN. The activation energies for the degradation reactions were 27.40 and 30.57 kJ mol⁻¹, respectively. Degradation intermediates and products were identified. A nitro-to-amino pathway, which ultimately may lead to partial mineralization, is postulated. The amino intermediate, aminonitroanisole, was detected during DNAN degradation, but for NTO, aminotiazolone is suggested. Additionally, urea was identified as a degradation product of NTO.

The improper disposal of used frying oil (UFO) presents numerous ecological, environmental and municipal problems. Of great concern is the resultant blockage of municipal drainage systems and water treatment facilities, harm to wildlife when they become coated in it and detriment to aquatic life and ecosystems due to the depletion of the oxygen content in water bodies such as rivers and lakes that have become contaminated. Statistics show that in Trinidad and Tobago, in excess of one million liters of used cooking oil is collected annually from various restaurant chains. This paper investigated the potential of using UFO as a performance enhancing additive for road paving applications utilizing Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB) as a mitigation strategy for improper UFO disposal. Modified blends containing various additions of UFO (2–10% wt) were prepared for the TLA and TPB asphaltic binders. Results demonstrated in terms of stiffness, increasing the dosage of UFO in TLA and TPB base binders resulted in a gradual decrease in stiffness (G* value decreased). In terms of elasticity, increasing the dosage of the UFO additive in TLA resulted in a general decrease in the elasticity of the blends indicated by an increase in phase angle or phase lag (δ). Increasing dosages of the UFO additive in TPB resulted in a significant decrease in δ where the most elastic blend was at the 6% UFO level. TLA and UFO-TLA modified blends exhibited significantly lower values of δ and higher values of G* confirming the superiority of the TLA material. Incorporation of the UFO in the blends led to a decrease in the rutting resistance and increase in the fatigue cracking resistance (decrease in G*/sinδ and G*sinδ, respectively). This study highlighted the potential for the reuse of UFO as an asphalt modifier capable of producing customized UFO modified asphaltic blends for special applications and confirms its feasibility as an environmentally attractive means of reusing the waste/hazardous UFO material locally.

Characterization of beach debris is crucial to assess the strategy to answer questions such as recycling. With the aim to assess its use in a recycling scheme, in this note, we carried out a physical and chemical characterization of plastic litter from a pilot beach in Central Italy, using the FT-IR spectroscopy and thermoanalysis. Fourteen polymers, having mainly thermoplastic origin, were identified; among them, the most represented are polyethylene (41.7%) and polypropylene (36.9%). Chemical and mechanical degradation were clearly observed by an IR spectrum. The thermogravimetric analysis curve of the plastic blend shows the melting point at 120–140 °C, and degradation occurs almost totally in a one-step process within 300–500 °C. The high heating value of the plastic debris is 43.9 MJ kg⁻¹. Polymer blends obtained by beach debris show mechanical properties similar to the virgin high-density polyethylene polymer. Following the beach plastic debris characterization, a recycling scheme was suggested.

Biodegradable chelant-enhanced phytoremediation offers an alternative treatment technique for metal contaminated soils, but most studies to date have addressed on phytoextraction efficiency rather than comprehensive understanding of the interactions among plant, soil microbes, and biodegradable chelants. In the present study, we investigated the impacts of biodegradable chelants, including nitrilotriacetate, S,S-ethylenediaminedisuccinic acid (EDDS), and citric acid on soil microbes, nitrogen transformation, and metal removal from contaminated soils. The EDDS addition to soil showed the strongest ability to promote the nitrogen cycling in soil, ryegrass tissue, and microbial metabolism in comparison with other chelants. Both bacterial community-level physiological profiles and soil mass specific heat rates demonstrated that soil microbial activity was inhibited after the EDDS application (between day 2 and 10), but this effect completely vanished on day 30, indicating the revitalization of microbial activity and community structure in the soil system. The results of quantitative real-time PCR revealed that the EDDS application stimulated denitrification in soil by increasing nitrite reductase genes, especially nirS. These new findings demonstrated that the nitrogen release capacity of biodegradable chelants plays an important role in accelerating nitrogen transformation, enhancing soil microbial structure and activity, and improving phytoextraction efficiency in contaminated soil.

The toxicity of nickel and three of its main collectors, sodium isopropyl xanthate (SIPX), sodium ethyl xanthate (SEX), and potassium ethyl xanthate (PEX) to soil microbial activity, was analyzed, individually and as a binary combination of nickel and each of the collectors. The investigation was performed through the microcalorimetric analysis method. For the single chemicals, all power-time curves exhibited lag, exponential, stationary, and death phases of microbial growth. Different parameters exhibited a significant adverse effect of the analyzed chemicals on soil microbial activity, with a positive relationship between the inhibitory ratio and the chemical dose (p < 0.05 or p < 0.01). A peak power reduction level of 24.23% was noted for 50 μg g⁻¹ soil in the case of Ni while for the mineral collectors, only 5 μg g⁻¹ soil and 50 μg g⁻¹ soil induced a peak power reduction level of over 35 and 50%, respectively, in general. The inhibitory ratio ranged in the following order: PEX > SEX > SIPX > Ni. Similar behavior was observed with the mixture toxicity whose inhibitory ratio substantially decreased (maximum decrease of 38.35%) and slightly increased (maximum increase of 15.34%), in comparison with the single toxicity of mineral collectors and nickel, respectively. The inhibitory ratio of the mixture toxicity was positively correlated (p < 0.05 or p < 0.01) with the total dose of the mixture. In general, the lesser and higher toxic effects are those of mixtures containing SIPX and PEX, respectively.

The aim of this study was to determine the effect of the supplementation of slow release bolus of selenium (Se), copper (Cu), zinc (Zn), cobalt (Co), phosphorous (P), manganese (Mn), and iodine (I) at late gestation (60 day prepartum) on performance of Najdi ewes and their newborn. Twenty Najdi ewes at late gestation were randomly selected from a herd raised under an intensive system and equally divided into two groups (control and treated). Blood samples were collected from ewes and newborns at parturition. Body weights of newborns were taken at birth, 30 and 60 days. A significant (P < 0.05) increase in Cu and Co in blood of dams treated with boluses with an increase (P < 0.05) in blood P, Zn, Cu, Co, and Se of their newborn lambs were observed. Creatinine and triglyceride were significantly (P < 0.05) low in treated newborn while urea was significantly (P < 0.05) high in the same group. In dams, significantly (P < 0.05) low concentration of triglyceride was observed. Body weight of lambs from treated group at 30 days was significantly (P < 0.05) higher when compared with the control. In conclusion, bolus of trace minerals at late gestation improved some mineral status of ewes and the newborns with higher body weight.

When sewage sludge is incorrectly applied, it may adversely impact agro-system productivity. Thus, this study addresses the reaction of Cucumis sativus L. (cucumber) to different amendment rates (0, 10, 20, 30, 40 and 50 g kg⁻¹) of sewage sludge in a greenhouse pot experiment, in which the plant growth, heavy metal uptake and biomass were evaluated. A randomized complete block design with six treatments and six replications was used as the experimental design. The soil electrical conductivity, organic matter and Cr, Fe, Zn and Ni concentrations increased, but the soil pH decreased in response to the sewage sludge applications. As approved by the Council of European Communities, all of the heavy metal concentrations in the sewage sludge were less than the permitted limit for applying sewage sludge to land. Generally, applications of sewage sludge of up to 40 g kg⁻¹ resulted in a considerable increase in all of the morphometric parameters and biomass of cucumbers in contrast to plants grown on the control soil. Nevertheless, the cucumber shoot height; root length; number of leaves, internodes and fruits; leaf area; absolute growth rate and biomass decreased in response to 50 g kg⁻¹ of sewage sludge. All of the heavy metal concentrations (except the Cu, Zn and Ni in the roots, Mn in the fruits and Pb in the stems) in different cucumber tissues increased with increasing sewage sludge application rates. However, all of the heavy metal concentrations (except the Cr and Fe in the roots, Fe in the leaves and Cu in the fruits) were within the normal range and did not reach phytotoxic levels. A characteristic of these cucumbers was that all of the heavy metals had a bioaccumulation factor <1.0. All of the heavy metals (except Cd, Cu and Zn) had translocation factors that were <1.0. As a result, the sewage sludge used in this study could be considered for use as a fertilizer in cucumber production systems in Saudi Arabia and can also serve as a substitute method of sewage sludge disposal. Graphical Abstract The effects of different sewage sludge amendment rates on the heavy metal bioaccumulation, growth and biomass of cucumbers

The excessive enrichment of trace elements, such as Pb and Cd, from food may contribute to the decline of migratory red-crowned cranes (Grus japonensis) in China. To test this prediction, we determined the concentrations of Pb and Cd, as well as further macro and trace elements (Ca, Mg, Cu, Zn) in the target species and their prey (sediment, reed root, mollusk, arthropods, and common fish species) in both the wintering (Yancheng wetland) and breeding sites (Zhalong wetland) of cranes in China. The maximum concentrations of Pb (130 mg kg⁻¹ dry weight (dw)) and Cd (10.60 mg kg⁻¹ dw) in the sediments of breeding site and the maximum concentration of Cd (4.50 mg kg⁻¹ dw) in the sediments of wintering site exceeded the probable effect level values (91.30 mg kg⁻¹ for Pb and 3.53 mg kg⁻¹for Cd), suggesting the potential exposure risk of the examined species. Indeed, Pb and Cd contents of essential foods, i.e., aquatic animals, sampled in two sites were above the limit of allowable concentration recommended by the Joint Food and Agriculture Organization of the United Nations/World Health Organization food standards program. Approximately 80, 31.4, and 60.3 mg kg⁻¹ dw of Pb were detected in the eggshells, liver, and kidney, respectively, of the target species, and the values are above the levels of concern (1.7 mg kg⁻¹ for eggshell and 30 mg kg⁻¹ for liver and kidney) in common birds. Nevertheless, the increased Pb and Cd levels in the prey and bodies of the red-crowned cranes did not induce the levels of Ca and Mg depletion. Average contents of the macronutrients, Ca (1.38 g kg⁻¹ dw) and Mg (1.32 g kg⁻¹ dw), in the liver of the examined species exceeded the background concentrations (0.2–0.4 g kg⁻¹ for Ca and 0.4–0.8 g kg⁻¹ for Mg) in the liver of birds. Consumption of Ca-rich foods, e.g., grits and exoskeleton species, may aid in compensating the possible loss caused by the increased Pb and Cd concentrations in the bodies of the cranes.