Selenium (Se) is an essential metalloid element for mammals. Nonetheless, both deficiency and excess of Se in the environment are associated with several diseases in animals and humans. Here, we investigated the interaction of Se, supplied as selenate (Se⁺⁶) and selenite (Se⁺⁴), with phosphorus (P) and sulfur (S) in a weathered tropical soil and their effects on growth and Se accumulation in Leucaena leucocephala (Lam.) de Wit. The P-Se interaction effects on L. leucocephala growth differed between the Se forms (selenate and selenite) supplied in the soil. Selenate was prejudicial to plants grown in the soil with low P dose, while selenite was harmful to plants grown in soil with high P dose. The decreasing soil S dose increased the toxic effect of Se in L. leucocephala plants. Se tissue concentration and total Se accumulation in L. leucocephala shoot were higher with selenate supply in the soil when compared with selenite. Therefore, selenite proved to be less phytoavailable in the weathered tropical soil and, at the same time, more toxic to L. leucocephala plants than selenate. Thus, it is expected that L. leucocephala plants are more efficient to phytoextract and accumulate Se as selenate than Se as selenite from weathered tropical soils, for either strategy of phytoremediation (decontamination of Se-polluted soils) or purposes of biofortification for animal feed (fertilization of Se-poor soils).

The single-stage partial nitritation–anammox (PN/A) process is severely limited by a long start-up time and unstable removal efficiency. In this study, PN/A was developed in 67 days in a novel packed bed equipped with porous bio-carriers by gradually increasing the influent nitrogen loading rate (0.15–0.73 kg-N m⁻³·d⁻¹) and controlling the dissolved oxygen (< 1.2 mg L⁻¹). An average ammonium nitrogen removal efficiency (ARE) and total nitrogen removal efficiency (TNR) of 87.01 and 72.41%, respectively, were obtained. This represents a reliable alternative method of achieving rapid PN/A start-up. The results of 16S rRNA sequencing showed that Proteobacteria and Planctomycetes, with which ammonia-oxidizing bacteria and anammox bacteria were affiliated, accounted for 38.8%, representing the dominant phylum in the system after acclimation. The abundance of Nitrosomonas and Candidatus Brocadia increased by 16 and 1.79%, respectively. The results of metagenomics and metatranscriptomics revealed that the nitrite oxidation process was blocked by the transcriptional suppression of nitrite oxidoreductase and the entire nitrogen metabolism process was dominated by the partial nitritation and anammox process. Moreover, a high abundance of heterotrophic bacteria with potential for nitrogen removal was detected. In the nitrogen cycle, a widespread nitrite-accumulated denitrification helps to form a nitrite loop, which promotes the efficiency of total nitrogen removal. This is crucial for further improving the nitrogen removal mechanism in the PN/A system.

Platelet-rich plasma (PRP) composites of various cytokines and growth factors which have the potential to activate and speed the process of wound repair. Sildenafil also is a potent stimulator of angiogenesis which favors its potential effects on wound healing in several models. Existing work planned to examine the effectiveness of topical application of PRP and/or sildenafil citrate hydrogel (SCH) in a non-splinted excision skin wound model. Adult male rats were allocated into control, PRP, SCH, and PRP/SCH groups. On the 7th and 14th days, blood and tissue samples were collected for hematobiochemical, histopathological, and immunohistochemistry analyses. PRP and/or SCH topical treatments caused an enhancement of wound healing parameters, including a rapid switch from inflammatory phase to connective tissue stage evident by less systemic hematological changes and decreased values of proinflammatory cytokines (IL-6, TNF-α, and IL-1β) and C-reactive protein (CRP) on the 7th or 14th days post-wounding. Also, tissue hydroxyproline, collagen, nitrite, and total protein contents were higher in therapeutically handled wounded rats. Histologically, PRP- and/or SCH-treated wounded rats exhibited less necrosis, inflammation, and fibrin with a higher level of granulation tissue formation on the 7th day post-wounding and abundant collagen remodeling, epithelization, and vascularization on the 14th day relative to control. Interestingly, combined PRP and SCH treatment was more efficient in wound healing scoring with less inflammation, more collagen remodeling, and more epithelization. Our findings confirm the effectiveness of PRP and/or SCH as a topical wound healing treatment, with better skin wound healing with their combination.

Phytoplankton and bacterioplankton perform important ecological functions in lake ecosystem. In this paper, the abundance and composition of phytoplankton and bacterioplankton at 13 sites of Dianchi lake during the wet and dry seasons were monitored, and the relationship between phytoplankton and bacterioplankton in this plateau lake was studied. Phytoplankton community structure analysis was carried out by ocular method, and bacterioplankton was investigated by high-throughput 16S rRNA gene Illumina sequencing. The relationship between phytoplankton and bacterioplankton was observed using redundancy analysis. The results showed that 87 species of phytoplankton belonging to 5 phyla and 29 genera were identified in Dianchi lake. Phytoplankton diversity and richness were higher in the wet season than those in the dry season. In the wet season, Cyanophyta was the dominant phylum whose density was 2.01 × 10⁸ cells/L, accounting for more than 90% of the total algae, then followed by Chlorophyta, Bacillariophyta, Chrysophyta, and Cryptophyta. The spatial distribution of phytoplankton in the wet season and dry seasons showed significant differences. In the dry season, the north-central part of Dianchi lake was dominated by Limnothrix redekei and Microcystis minutissima of Cyanophyta, while Pseudanabaena moniliformis and Coelosphaerium nagelianum of Cyanophyta mainly was dominated in the south of Dianchi lake. In the wet season, Microcystis minutissima of Cyanophyta was the dominant species all the area, while Limnothrix redekei of Cyanophyta was second dominant. Proteobacteria and Bacteroidetes were the dominant phyla among bacterioplankton. The community structure of bacterioplankton was influenced by Cyanophyta and Bacillariophyta. Cyanophyta had a major influence on Pseudomonas, Acinetobacter of Proteobacteria, and Flavobacterium of Bacteroidetes. Bacillariophyta showed a strong correlation with Gemmobacter, Stenotrophomonas, and Aeromonas of Proteobacteria. Cyanophyta and Bacillariophyta produced the most significant impact on predicted functional genes of bacterioplankton, and the predicted functional genes of the samples were different in different seasons. Cell densities of Cyanophyta were positively related to metabolism-predicted functional genes of bacterioplankton. Bacillariophyta and Cryptophyta had an impact on most of the cellular processes and signaling predicted functional genes. Bacterioplankton-predicted functional gene information storage and processing were significantly affected by cell densities of Chlorophyta. Therefore, the analysis of the phytoplankton community and the bacterioplankton-predicted functional gene in Dianchi lake exerts a great significance in revealing the ecosystem function of plateau lakes and harmful algal bloom control.

Due to the rapid growth in the heavy metal-based industries, their effluent and local dumping have created significant environmental issues. In the past, typically, removal of heavy metals was handled by reverse osmosis and ion exchange techniques, but these methods have many disadvantages. Therefore, extensive work into the development of improved techniques has increased, especially for heavy metal removal. Many countries are currently researching new materials and techniques based on nanotechnology for various applications that involve extracting heavy metals from different water sources such as wastewater, groundwater, drinking water and surface water. Nanotechnology provides the possibility of enhancing existing techniques to tackle problems more efficiently. The development in nanotechnology has led to the discovery of many new materials such as magnetic nanoparticles. These nanoparticles demonstrate excellent properties such as surface-volume ratio, higher surface area, low toxicity and easy separation. Besides, magnetic nanoparticles can be easily and efficiently recovered after adsorption compared with other typical adsorbents. This review mainly emphasises on the efficiency of heavy metal removal using magnetic nanoadsorbent from aqueous solution. In addition, an in-depth analysis of the synthesis, characterisation and modification approaches of magnetic nanoparticles is systematically presented. Furthermore, future opportunities and challenges of using magnetic particles as an adsorbent for the removal of heavy metals are also discussed.

The contents of total arsenic (tAs), inorganic arsenic (iAs), Cd, Cr, Cu, Mn, Ni, Pb, Sb, and Zn in 135 rice grain samples from Zijiang River basin were determined, and the probabilistic distribution of noncarcinogenic and carcinogenic risks associated with ingesting locally produced rice was determined by Monte Carlo simulation. Further, multivariate statistical analysis was used to analyze the potential sources of the heavy metals in rice grains. The average concentrations of the heavy metals in rice grains were ranked as follows: Mn (17.314 mg/kg) > Zn (16.043 mg/kg) > Cu (2.013 mg/kg) > Ni (1.332 mg/kg) > Cr (0.571 mg/kg) > Cd (0.283 mg/kg) > tAs (0.241 mg/kg) > Pb (0.145 mg/kg) > Sb (0.027 mg/kg). These heavy metals were significantly enriched in some rice grain samples. The analysis of potential sources indicated that As, Pb, Sb, and Zn were mainly derived from mining and smelting and agricultural activities; Cd, Cu, Mn, and Ni were mainly derived from the agricultural activities; Cr were mainly derived from the natural source. The results of Monte Carlo simulation indicated that ingestion of rice grown in the area may pose health risks for children, adult males, and adult females. The noncarcinogenic risks were mainly from As, Cd, Mn, Ni, and Sb, and the carcinogenic risk was mainly from As, Cd, and Ni. This study could provide basic information for land management and rice intake in the study area.

Accumulation of transitory starch in leaves is an environment-dependent multifaceted process affected through stress caused by nutrient deficiency or excess of heavy metals in growing medium. On the other hand, textile effluent is one of the major pollution causing industrial waste due to the presence of heavy metal and organic contaminants. Besides the presence of higher pollution load, this effluent also contains some minerals essential for plant growth and metabolism and can serve as source of nutrients to plants. In presented experiment, a mesocosm study was conducted to evaluate the phenotypic, biochemical performance and trace element status of Triticum aestivum (cv. LOK-101 and GW-496) cultivars in response to transitory starch activity grown under textile effluent fertilization. Improved activity of transitory starch under textile effluent fertilization deals with plant growth by providing carbon in the form of soluble sugar. Study also finds a strong correlation of photosynthetic pigments, carbohydrates and plant biomass to transitory starch. As expected, the elemental concentration (Zn, Cu, Mn, Fe, Co, Pb, Cd, and As) in plants increased with increasing dose of textile effluent. The study concluded that the transitory starch is one of the key components in plant leaves that regulate plant growth under stress condition. Furthermore, the study also concluded that the lower dose of textile effluent significantly favours growth and nutrient status of plants without any negative impact. Therefore, the application of lower concentration of textile effluent as basal dose in agriculture may serve as source of nutrient/micronutrient to plants and also can be a sustainable way for effluent management.

Several regions of the world suffer from water quality degradation caused mainly by anthropogenic interference, domestic sewage discharge, industrial discharges, and contaminants from agricultural activities, which increase the amount of nutrients into water such as nitrogen and phosphorus intensifying the process of eutrophication. Considered as one of the main problems faced by supply water sources in the world, eutrophication represents a global phenomenon that also affects the socioeconomic and environmental sector. In the present study, a bacterial pool formed by the Nitrosomonas europae, Nitrobacter winogradskyi, and Paracoccus denitrificans strains was used to remove the compounds NH₃, NO₂⁻, NO₃⁻, P, and PO₄³⁻, real water samples from human supply at time 0 to 24 h. At the final time (24 h), the bacterial pool obtained total removal (100%) of all compounds analyzed. With the removal of nutrients from water, there was also reduction in the amount cyanobacteria and saxitoxins of water. Thus, the bacterial pool can be applied as a remediators of micropollutants such as compounds N and P, since their performance in removel the compounds was satisfactory. The removal of micropollutants from water bodies aims to decrease the nutrients responsible for cyanobacteria blooms, eutrophication, as well as improve water quality, optimize, and reduce water treatment costs, benefiting both the aquatic ecosystem and human health.

The Nevado de Toluca Natural Protected Area (Zona de Protección de Flora y Fauna Nevado de Toluca, ZPFFNT), Central Mexico, encompasses one of the four highest (> 4000 m a.s.l.) volcanoes in Mexico, Nevado de Toluca; an extended area of woodland surrounds this volcano. Although identified as a remote area based on its high altitude, the ZPFFNT is not far from the urban and industrial zones of Toluca (~20 km) and Mexico (~72 km) cities, which potentially threatens the environmental health of the ZPFFNT by emitting SO₂ and NOX. Acid precipitation falling on areas with low alkaline reserve leads to environmental acidification and land degradation. To provide reliable data on the air pollution reaching the ZPFFNT and the related potential risks, our study analyzed the bulk atmospheric deposition chemistry and its temporal dynamics throughout an annual cycle. There are two well-defined seasons: (a) cold/dry with SW–NE wind direction and (b) warm/rainy with NE–SW wind direction. The pH, electric conductivity (K₂₅), cations, Cl⁻, and HCO₃⁻ were statistically higher in the cold/dry period. Differently, NO₃⁻ and SO₄²⁻ showed steadier behavior. Bulk deposition pH remained acidic at all times but reached extreme low values from July to September during the warm/rainy season. In the cold/dry season, alkaline cations were important in partially neutralizing the acidic compounds from the urban and industrial zones of Toluca and Mexico cities. Previously assumed to be safe based on its remoteness, the ZPFFNT is threatened by acid precipitation, which demand the implementation of preventative and mitigating actions as part of a management plan to avoid environmental deterioration.

In this paper, RE-CHAR® biochar, produced by a wood biomass pyrolysis process, which is usually applied as a soil fertilizer, was investigated for a novel use, that was as adsorbent for remediating a lead-contaminated solution. Firstly, a deep physical and chemical characterization of RE-CHAR® biochar was carried out. Then, the adsorption capacity of lead from 50 to 100 mg/L solutions was determined under batch and continuous flow conditions. Kinetics of the batch adsorption process were very rapid and complete removal was achieved within 4-h contact time at both Pb concentrations, using a biochar dosage of 5 g/L. These data were best fitted by the pseudo-second-order model, with the rate constant and the equilibrium capacity equal to kₛ = 0.0091 g/min and qₑ = 9.9957 mg/g at 50 mg/L Pb and kₛ = 0.0128 g/min and qₑ = 20.1462 mg/g at 100 mg/L Pb, respectively. The Langmuir isotherm model best fitted the equilibrium data at both Pb concentrations, with the Langmuir constant and maximum adsorption capacity equal to b = 11.5804 L/mg and qₘₐₓ = 4.6116 mg/g at 50 mg/L Pb and b = 2.8933 L/mg and qₘₐₓ = 9.5895 mg/g at 100 mg/L Pb. Continuous flow column tests showed that adding biochar to the soil of the adsorbent bed significantly extended the breakthrough and exhaustion times, with respect to the column filled with soil only. The Thomas model best fitted the experimental data of the breakthrough curves, with the constant kTH = 5.28 × 10⁻⁵ mL/min/mg and the maximum adsorption capacity q₀ = 334.57 mg/g which was comparable to the values reported for commercial adsorbents. Based on these results, it can be assessed that RE-CHAR® biochar can be used as an effective adsorbent for lead removal from water solutions even at high concentrations.