Composting is considered as one of the main sustainable methods for the treatment of livestock manure. In this study we investigated the effects of additives (urea and rice straw) on methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂) emissions using a traditional Chinese pig slurry composting method over an 81-day period, as well as examining total organic carbon and total nitrogen loss. Four common treatment strategies were examined in this study: a control (MC), urea nitrogen addition (MN), composting using rice straw cover (MScₒᵥₑᵣ), and compost mixed with rice straw (MSₘᵢₓ). Our results indicate that the addition of urea resulted in the lowest total CH₄ emissions and the highest N₂O emissions. MScₒᵥₑᵣ treatment had the highest and most significant effect on CH₄ emissions, while MSₘᵢₓ treatment had the lowest CO₂ emissions. Carbon lost through CH₄ and CO₂ released during the experiment was 0.1–0.9 and 2.4–3.9% of total carbon loss, respectively, and nitrogen lost through N₂O release was 11.1–17.9% of total nitrogen. In general, although MSₘᵢₓ, MScₒᵥₑᵣ, and MN treatments increased global warming potential by 21.4, 41.6, and 50.9% per kg of pig slurry, respectively, no statistical differences between the four treatments were recorded. By considering carbon and nitrogen conservation, as well as the improvement of the quality of compost and the mitigation of greenhouse gases (GHGs), the small-scale composting method of pig slurry alone is an acceptable environmentally friendly strategy for use in China.

Mercury is a metal which is potentially toxic for the environment. Many factors control its retention in the soil, such as cation exchange capacity, pH, clay content, organic matter, and redox potential. It is important to know the phytotoxic effects of soil Hg to prevent environmental contamination and its entry into the food chain. Several analytical methods are used to measure metal phytoavailability in soils, but none has been reported for Hg in Oxisols, the most common soil class in Brazil and a very important soil class throughout the tropics. The aim of this study was to select the chemical extractor that best correlated the Hg levels in plants and the Oxisols. The soils used were classified as Dystrophic Red-Yellow Oxisol (LVAd) and Dystroferric Red Oxisol (LVdf), which were collected in the 0–0.2-m soil layer. The species selected for cultivation were a monocotyledon, oat (Avena sativa L. cv. São Carlos) and a eudicotyledon, common bean (Phaseolus vulgaris L. cv. Madrepérola). Each test plot was composed of a 500 cm³ pot filled with soil samples contaminated with HgCl₂. Treatments were arranged in a completely randomized design, with four replications. The experiment was conducted for 30 days. Mercury contents were separately extracted with the following extractors: USEPA 3051A, Mehlich-1, Mehlich-3, DTPA, and water. Mercury was determined by hydride generation atomic absorption spectroscopy. The extracted contents were correlated with the contents in the tissues of the plants’ aerial part by the Pearson correlation. Although it is not considered a standard procedure to evaluate metal phytoavailable contents, the method that presented the best correlations between soil Hg and plant Hg was USEPA 3051A (r = 0.75*). As expected, the worst correlation was with water (r = 0.57* for common bean and r = 0,05ⁿˢ for oat).

Antarctic pristine environment is threatened by the presence of microplastics that occur in a variety of shapes and sizes, from fibers to irregular fragments. The aim of this study is to assess the abundance, distribution, and the characterization of the microfibers in zooplankton samples found in ocean waters in Admiralty Bay, Antarctica. The samples were collected at five points in Admiralty Bay during the XXIX Brazilian Antarctic Expedition in the austral summer of 2010–2011. A total of 603 microfibers were collected in 60 samples, with an average abundance of 2.40 (± 4.57) microfibers 100 m⁻³. Microfiber size ranging from ca. 10 to 22 μm in diameter of various lengths and colors (blue, red, black, and clear) was collected and characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Most of these microfibers were entangled in various different zooplankton species and were identified as polymers composed mostly by polyethyleneglycols, polyurethanes, polyethylene terephthalates, and polyamides. The presence of such microfibers may cause the loss of biodiversity in the Antarctic continent, and the results presented herein can contribute to a better understanding of the impact caused by them within the food chain and human health. Graphical Abstract ᅟ

Bisphenol A (BPA) is an endocrine disruptor. To evaluate the effect of canned food consumption on internal BPA dose, urinary BPA concentrations were measured before and after intake of canned foods. This study applied a randomized crossover design, recruited 20 healthy volunteers, and divided them into two groups. One group consumed canned food; the other group consumed fresh food. After a 1-day washout, the dietary interventions were reversed. In each period, urine samples were collected immediately before meals and then 2 h, 4 h, and 6 h after meals. A mixed-effects model was used to assess BPA changes over time. Our results showed urinary BPA concentrations increased after consumption of canned food. Specifically, urinary BPA concentrations significantly differed between consumption of canned food and fresh food at 2 h, 4 h, and 6 h after intake (p values of 0.001, < 0.001, and < 0.001, respectively). Mean BPA concentrations at 2 h, 4 h, and 6 h after meals were 152%, 206%, and 79% higher, respectively, than mean BPA concentrations before meals. Urine concentration profiles of canned food intake showed that peaks were at 4 h, the increase diminished at 6 h, and returned to baseline levels at 24 h after intake. Therefore, dietary intervention and a 1-day washout period are effective for limiting internal BPA burden. This study provides convincing evidence of a human exposure route to BPA and a basis for designing interventions to mitigate exposure.

NZVI has long been used for the remediation of different groundwater contaminants but their tendency to get oxidized easily has always been a barrier to their reductive ability. In this work, we have made an attempt to enhance the aerobic stability of the nanoparticles by synthesizing them in a medium consisting of a viscous solvent, glycerol, and water. The XRD analysis of the nanoparticles reveals that the particles prepared in the presence of glycerol have a very thin coating of iron oxides on the outer surface of the nanoparticles in comparison with those prepared in the aqueous medium. These nanoparticles were applied for the simultaneous reduction of two groundwater contaminants, nitrate ions, and alachlor, which is an herbicide. Stock solutions of these two contaminants were prepared and then they were mixed in varying amounts and were treated by different doses of the nanoparticle. The optimized dose of the nanoparticles obtained for almost 97% removal of both the contaminants is 2.05 g/L. The studies showed that increasing the concentration of either of the contaminants while the other one was kept fixed led to a decrease in the removal efficiency. The studies conducted to see the effect of pH variation showed that the best removal can be achieved when the pH is 3 or even less than it, showing that acidic pH leads to higher removal values. Such nanoparticles which can be prepared easily at low-cost and can simultaneously act upon different contaminants are highly desired.

Styrene is one of the essential components in making thousands of everyday products. Occupational exposure to styrene causes pulmonary, neurological, genetic and ocular complications, and leukemia and affects reproduction. The aim of this study was to assess the health risks of exposure to styrene in the electronics industry of Neyshabur, Iran. This descriptive and analytical cross-sectional study was carried out in three electronics industries, in Neyshabur city, in 2017–2018. Occupational exposure to styrene was measured according to the NIOSH1501 method, using a low-flow rate sampling pump (0.2 L/min) and an active charcoal absorber tube. Health risk assessment was done according to the Singapore semi-quantitative method and the United States Environmental Protection Agency (OEHHA) method. The average occupational exposure to styrene in men employed in the compact plastic parts production halls was 79.61 mg m⁻³ (range 28–208.33). 45.8% of exposed subjects (27 people) encountered exposure above the permitted limit. The average lifetime carcinogenic risk of styrene was 1.4 × 10⁻³; therefore, 100% (59 people) had a definite risk of getting cancer. The highest lifetime risk of getting cancer was observed in plastic injection device users (1.9 × 10⁻³) and then in shift managers (1.6 × 10⁻³). The results of this study indicate a definite risk of getting cancer for all workers. Strategies to reduce workers exposure to styrene through engineering controls and routine measurements are necessary.

Heavy metal pollution in watercourses is a major environmental problem throughout the world due to rapid population growth, industrialization, and economic development. Considering this, the present study aimed to develop a new adsorbent from pumpkin husk (PH) by KOH modification to remove copper (Cu²⁺) ions and to explore its adsorptive potential. The sorption studies of Cu²⁺ on KOH-modified PH were carried out as functions of particle size, solution pH, adsorbent dose, temperature, initial metal concentration, and contact time. The sorption capacity of KOH-modified PH was found to be higher than that of raw PH, as 19.4 and 10.2 mg g⁻¹, respectively. Morphology and surface structures of adsorbents were characterized by determination of zero point charge, a Fourier transform infrared spectrometer (FTIR–ATR) spectra, and a scanning electron microscopy (SEM) of PH powders before and after the sorption of Cu²⁺. The pHzₚc of PH was found to be 5.0. FTIR–ATR analyses indicated that amino, amide, hydroxyl, carboxyl, and oxygenated groups of PH play an important role in the sorption process. Sorption isotherm, kinetic, and thermodynamic parameters of Cu²⁺ on KOH-modified PH were studied. The kinetic process was well represented by the Logistic model. The maximum sorption was found as 73.16 mg g⁻¹ according to the well-fitting of Langmuir isotherm. Results of sorption and thermodynamic studies indicated that the process was exothermic, being feasible, and spontaneous. KOH-modified PH as an eco-friendly adsorbent had great potential to remove Cu²⁺ ions from aquatic system.

The issue of contaminated sites has been highlighted as an immediate priority in the 13th Five-Year Plan of China. Identification and prioritization of contaminated sites are of key importance for proposing effective strategies for the regional management of contaminated sites. In this study, three advanced multi-attribute methodologies, the risk-based priority methodology, the regional risk assessment methodology, and the dominance-based rough set approach (DRSA), were comparatively employed to screen contaminated sites in, Guangxi, Southwest of China. The results of the three prioritizations show that the highest ranking site identified by the three methods had great agreement. In regard to the screening attributers, while the risk-based prioritization methodology and regional risk assessment methodology allowed a high discrimination in the screening of contaminated sites associated with different attributes, such as farmland, residential areas, contaminant level, number of people, area, storage quality, site service life, and surrounding communities, the DRSA allowed the identification of contamination strength (CS) and contamination potential (CP).

This study aims to illustrate the preparation of a new nanobiocomposite by incorporating copper oxide nanoparticles into cuttlebone matrix (CB/CuO NPs), and it was tested to define how effective it was to adsorb and remove arsenate from aqueous systems. CB is the bone tissue of cuttlefish with high porosity, permeability, and low cost. CuO NPs have been introduced as an effective arsenate adsorbent. Producing nanocomposite by introducing of CuO NPs in the structure of CB enhanced their stability and facilitated their separation from solution. Incorporation of CuO NPs in the structure of CB enhanced the adsorption capacity of CB. The adsorption data were fitted with both Langmuir and Freundlich isotherms, but Langmuir isotherm exhibited better matching rather than Freundlich isotherm. The maximum adsorption capacity (qₘₐₓ) was calculated from Langmuir adsorption isotherm which was around 25.13 mg g⁻¹. Kinetic data fitted well to the pseudo-second-order reaction model. The results indicate that the possible mechanism of arsenate adsorption on CB/CuO is through development of inner sphere complex. Simple preparation and abundant and good adsorption capacity in the presence of calcium ions indicate that the CB/CuO is suitable for removal of arsenate from contaminated drinking water.

Water quality models are important tools used in the management of water resources. The models are usually developed for specific regions, with particular climates and physical characteristics. Thus, applying these models in regions other than those they were designed for can generate large simulation errors. With consideration to these discrepancies, the goal of this study is to identify the models employed in different countries and assist researchers in the selection of the most appropriate models for management purposes. Published studies from the last 21 years (1997–2017) that discuss the application of water quality models were selected from three engineering databases: SpringerLink, Web of Science, and Scopus. Seven models for water quality simulations have been widely applied around the world: AQUATOX, CE-QUAL-W2, EFDC, QUALs, SWAT, SPARROW, and WASP. The countries most frequently applying water quality models are the USA, followed by China, and South Korea. SWAT was the most used model, followed by the QUAL group and CE-QUAL-W2. This study provides the opportunity for researchers, who wish to study countries with fewer cases of applied water quality models, to easily identify the work from that region. Furthermore, this work collated central themes of interest and the most simulated parameters for the seven countries that most frequently employed the water quality models.