The original publication of this paper contains a mistake. The correct name and affiliation of the 3rd Author is presented in this paper.

An appealing technique to prevent and/or minimize pyrite oxidation and subsequent acid generation in mine waste sites is the formation of a protective coating on the surface of sulfide grains. To investigate the conditions for the formation of an efficient coating on pyritic tailings, column tests were performed. These tests involved the treatment with a coating solution, which was continuously recycled through the packed bed of tailings. The coating solution was consisted of SiO₄⁻⁴ oxyanions, an oxidant (H₂O₂), and adjusted to pH 6. The effect of the volume of coating solution per mass of material (L/S ratio), Si concentration and treatment duration on coating formation was studied. Based on the results, a protective coating can be developed on the pyrite particles following treatment with a solution of 0.1 mM Si concentration, which resulted in the reduction of sulfate release by 84% compared to non-treated pyrite samples.

A bioassay battery-integrated index was applied to different soils sampled from a former coke factory, with the aim to evaluate the discriminating capacity of the Ecoscore system (ES) to assess the environmental hazard of PAH-polluted soils. Two soils from a former coke factory, polluted with polycyclic aromatic hydrocarbons (PAHs), were evaluated for their ecotoxicity to terrestrial and aquatic organisms and their genotoxicity. These soils have been already presented in a previous paper but data have been reanalyzed for the present article in an endeavor to standardize the ES. One soil was sampled in the untreated site and the second underwent a windrow treatment. While these soils had a similar total concentrations of US-EPA 16PAHs (around 3000 mg kg⁻¹), different ecoscores were obtained when subjected to a set of solid- and liquid-phase bioassays measuring acute, chronic, and genotoxic effects. The total PAH content of the soil is not a pertinent parameter to assess soil pollution hazards contrary to the ES. ES is a robust method to classify soils according to their toxicity level. Four levels of toxicity have been defined: no (ecoscore = 0), weak (0 < ecoscore ≤33), moderate (33 < ecoscore ≤67), and strong toxicity (67 < ecoscore ≤ 100). The combination of chemical and toxicological data highlights the relationship between three-ring PAHs and acute ecotoxicity. Conversely, chronic effects of water extracts on algal growth could be explained by high molecular weight PAHs, such as five- and six-ring PAHs.

Brassica rapa L. is an annual Brassicaceae species cultivated for oil and food production, whose wild form is a weed of crops worldwide. In temperate regions of South America and especially in the Argentine Pampas region, this species is widely distributed. During 2014, wild B. rapa populations that escaped control with glyphosate applications by farmers were found in this area. These plants were characterized by morphology and seed acidic profile, and all the characters agreed with B. rapa description. The dose-response assays showed that the biotypes were highly resistant to glyphosate. It was also shown that they had multiple resistance to AHAS-inhibiting herbicides. The transgenic origin of the glyphosate resistance in B. rapa biotypes was verified by an immunological test which confirmed the presence of the CP4 EPSPS protein and by an event-specific GT73 molecular marker. The persistence of the transgene in nature was confirmed for at least 4 years, in ruderal and agrestal habitats. This finding suggests that glyphosate resistance might come from GM oilseed rape crops illegally cultivated in the country or as a seed contaminant, and it implies gene flow and introgression between feral populations of GM B. napus and wild B. rapa. The persistence and spread of the resistance in agricultural environments was promoted by the high selection pressure imposed by intensive herbicide usage in the prevalent no-till farming systems.

Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) are anthropogenic contaminants of environmental concern due to their persistence in the environment and capacity to accumulate in biota. Many of these contaminants have been found to have ill effects over wildlife and humans. Birds are known to be particularly affected through endocrine disruption and eggshell thinning. POPs have been banned or restricted through the Stockholm Convention (2001), making monitoring essential for tracking effects of regulation. Seabirds have been used as monitoring tools for being top predators and consuming a diverse array of prey in different trophic levels. Non-destructive sampling has become widely popular using feathers and preen oil, as opposed to carcasses and internal organs. This study aimed to set baseline levels of POP and PAH concentration in a highly pelagic and abundant seabird in Ireland and the Atlantic, the European storm petrel, Hydrobates pelagicus, and to investigate the profiles of contaminant congeners in preen oil and feathers, comparatively. Mean concentrations in preen oil followed: PCB (10.1 ng/g ww) > PAH (7.1 ng/g ww) > OCP (5.4 ng/g ww) > PBDE (3.9 ng/g ww), whilst mean concentrations in feathers followed the order: PAH (38.9 ng/g ww) > PCB (27.2 ng/g ww) > OCP (17.9 ng/g ww) > PBDE (4.5 ng/g ww). Congener profiles highly differed between preen oil and feathers, and little correlation was found between the matrices. These results demonstrate that the sampling of a single matrix alone (preen oil or feathers) might produce confounding results on contamination in seabirds and that more than one matrix is recommended to obtain a full picture of contamination by persistent organic pollutants.

Polychlorinated biphenyls (PCBs), a group of 209 congeners that differ in the number and position of chlorines on the biphenyl ring, are anthropogenic chemicals that belong to the persistent organic pollutants (POPs). For many years, PCBs have been a topic of interest because of their biomagnification in the food chain and their environmental persistence. PCBs with fewer chlorine atoms, however, are less persistent and more susceptible to metabolic attack, giving rise to chemicals characterized by the addition of one or more hydroxyl groups to the chlorinated biphenyl skeleton, collectively known as hydroxylated PCBs (OH-PCBs). In animals and plants, this biotransformation of PCBs to OH-PCBs is primarily carried out by cytochrome P-450-dependent monooxygenases. One of the reasons for infrequent detection of lower chlorinated PCBs in serum and other biological matrices is their shorter half-lives, and their metabolic transformation, resulting in OH-PCBs or their conjugates, such as sulfates and glucuronides, or macromolecule adducts. Recent biomonitoring studies have reported the presence of OH-PCBs in human serum. The occurrence of OH-PCBs, the size of this group (there are 837 mono-hydroxyl PCBs alone), and their wide spectra of physical characteristics (pKa’s and log P’s ranging over 5 to 6 orders of magnitude) give rise to a multiplicity of biological effects. Among those are bioactivation to electrophilic metabolites that can form covalent adducts with DNA and other macromolecules, interference with hormonal signaling, inhibition of enzymes that regulate cellular concentrations of active hormones, and interference with the transport of hormones. This new information creates an urgent need for a new perspective on these often overlooked metabolites.

Studying the influence of topography and litter and soil nutrients on soil enzymes and microbial biomass is important to the understanding of soil nutrient transformation and cycling, but these relationships in heterogeneous soils of karst ecosystem remains poorly understood. We determined environment factors influencing the urease (URS) and alkaline phosphatase (ALP) activity and microbial biomass C and N (MBC and MBN) with advancing vegetation succession. The results showed that ALP increased but URS decreased with the advancing vegetation succession. The MBC and MBN were highest in shrubland, but both were lowest in grassland. The URS was positively correlated with the surface cover of rock outcrops (SRO) but negatively correlated with litter N, and soil available N and pH. Conversely, ALP was positively correlated with litter N, soil organic carbon (SOC), and soil available N and pH, but negatively correlated with soil total N. The MBC was positively related to litter quantities and SOC but negatively related to soil pH; the MBN was positively related to slope gradient (SLG), SOC, and soil total P and available P. Additionally, the trends of the index URS/MBN were grassland > secondary forest > shrubland > primary forest, but the index ALP/MBN increased with advancing vegetation succession. It indicated that soil microorganism mainly exudate extracellular URS and ALP to soils. We also found the interactions of topography (SLG and SRO), litter (nutrients and quantity), and soil (nutrients and pH) explained 42.00, 87.00, and 66.00% of the variations in URS, ALP, and microbial biomass, respectively. Path analysis showed that the topography had a directly positive effect on litter nutrients and quantities, but not on soil nutrients; the litter nutrients and quantities had direct positive effect on soil nutrients, which had direct effect on soil enzymes and microbial biomass; the relationships (R²) between the independent variable and enzymes activities and microbial biomass increased with advancing successions. Thus, it suggested that high SLG and SRO are good for collecting litters back to soils and then the topography, litter, and soil factors increased its controlling effect on soil enzymes activities and microbial biomass with advancing successions in karst ecosystem.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important classes of anthropogenic persistent organic contaminants in the marine environment. This review discusses a whole range of findings that address various aspects of the bioaccumulation of PAHs in two common marine biota (phytoplankton and bivalves) globally and especially for Can Gio coastal wetland, Vietnam. The published information and collected data on the bioconcentration and accumulation mechanisms of PAHs as well as implications for Can Gio coastal wetland are compiled for phytoplankton and bivalves. PAHs are still released to Can Gio coastal environments from various sources and then transported to coastal environments through various physical processes; they may enter marine food chains and be highly accumulated in phytoplankton and bivalves. Thus, PAHs’ bioaccumulation should be considered as one important criterion to assess the water’s quality, directly linked to human health due to seafood consumption. Ecologically, Can Gio coastal wetland plays an important role to the South Vietnam key economic zone. However, it is also an area of potential PAHs inputs. With the abundant phytoplankton and bivalves in Can Gio coastal wetland, the PAHs bioaccumulation in these biota is inevitably detected. Thus, further study on the bioavailability of these contaminants is urgently needed in order to mitigate their negative effects and protect the ecosystems.

A novel magnetic silica gel adsorbent (Fe₃O₄-Si-COOH) was successfully prepared by introducing carboxyl group in situ to improve the performance for Pb(II), Zn(II), and Cd(II) adsorption. Infrared spectroscopy (IR), scanning electron microscope (SEM), transmission electron microscope (TEM), thermo-gravimetric analyzer (TGA), the Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) characterizations suggested that Fe₃O₄-Si-COOH has been successfully prepared. The adsorption performance was evaluated by batch experiments with different initial concentrations, ionic strength, contact time, and pH. The adsorption kinetics data followed pseudo-second-order model and exhibited a three-stage intraparticle diffusion mode. Isothermal adsorption equilibrium data were best fitted by the Freundlich model and the adsorption capacity were 155, 110, and 93 mg/g (initial concentration 210 mg/L) for Pb(II), Zn(II), and Cd(II), respectively. The result of X-ray photoelectron spectroscopy (XPS) survey spectrum suggested that the main adsorption mechanism is that the H⁺ of carboxyl groups exchanged with heavy metal ions in the adsorption processes. In addition, the adsorbed Fe₃O₄-Si-COOH could be regenerated and the adsorption capacity of reused Fe₃O₄-Si-COOH could maintain 80.3% after five cycles. Hence, the Fe₃O₄-Si-COOH could be a kind of potential material for removing Pb(II), Zn(II), and Cd(II) from wastewater. Graphical abstract

Barium (Ba) is a toxic element and can cause serious health effects. Humans have experienced increased exposure to Ba due to its intensive usage in industrial areas and daily life. Anthropogenic activities of Ba mining and the manufacture of Ba containing products introduce the element into surrounding areas, posing environmental concerns. Concentrations of total Ba (TBa) and dissolved Ba (DBa) in water samples collected from active Ba mines in Tianzhu, east Guizhou Province, southwestern China were measured to show the regional dispersion of Ba contamination. Aqueous Ba species in water were calculated using the PHREEQC program. The results showed that TBa and DBa concentrations ranged from 6.7 to 483.1 μg/L and from 7.5 to 222.7 μg/L, respectively. TBa concentrations presented a high average value of 126.6 μg/L and greatly exceeded the reported common value of 10 μg/L Ba in surface water set by the Ministry of Environment Protection of China. PHREEQC results indicated that Ba species in water were present as Ba²⁺, BaSO₄, BaHCO₃, BaCO₃, and BaOH⁺. The distribution of Ba species in water is controlled by pH and total organic carbon (TOC), and the lower pH (pH < 7) the higher the dissolved fractions. The log K d values (K d , dissolved-particulate distribution coefficients) varied from 2.41 to 6.32. Significant correlations were observed among Ba²⁺ and K⁺, Na⁺, Cl⁻, NO₃⁻, with Pearson correlation coefficients of 0.425, 0.531, 0.853, 0.612, and 0.329, respectively (p < 0.01). Elevated Ba concentrations in water indicated that the Ba contamination and its distribution pattern in local aquatic ecosystems are derived from Ba mining sites in the Tianzhu area.