The aims of this study were to investigate the presence of mercury (Hg) contamination in shrimp ponds in the south of Thailand and to isolate Hg-resistant purple nonsulfur bacteria (PNSB). Contamination by total mercury (HgT) in water and sediment samples ranged from <0.0002 to 0.037 μg/L and from 30.73 to 398.84 μg/kg dry weight. In all water and sediment samples, the concentration of HgTwas less than the Thai, Hong Kong, and Canadian standard guidelines. Of the Hg-resistant PNSB, six strains detoxified Hg²⁺by volatilization to Hg⁰using their mercuric reductase enzyme. The ability of PNSB to resist Hg²⁺in aerobic dark conditions was better than in microaerobic light, and this corresponded with their Hg reductase activities (dark condition 15.75, 12.62, and 12.16 U/mg protein for strains SSW15-1, SRW1-5, and SSS2-1, respectively). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were the same under both incubating conditions at 2.40 mg/L for SRW1-5 and 1.60 mg/L for SSW15-1. However, both values under light condition of SSS2-1 were 3.20 mg/L while under dark-condition MIC and MBC values were 3.20 and 4.00 mg/L. The half maximal inhibitory concentration (IC₅₀) values of Hg²⁺on strains SSS2-1, SRW1-5, and SSW15-1 under dark and light conditions were 2.16, 1.23, and 0.90; and 1.66, 1.11, and 0.80 mg/L, respectively. They were identified using 16S ribosomal RNA (rRNA) genes establishing that SSS2-1 and SSW15-1 were Afifella marina, while SRW1-5 was Rhodovulum sulfidophilum. These strains can potentially be used to treat Hg-contaminated shrimp ponds.

A wide variety of application of nanoparticles (NPs) in recent years has raised their possible entrance into the environment so that can affect living components of ecosystems. There is no comparative study on the long-term effects of a wide range of concentrations of NPs, related bulk particles (BPs), and corresponding metal ions on different traits of the plants. The present study has investigated comparative effects of zinc oxide (ZnO) NPs, ZnO BPs, and zinc ions (Zn²⁺) on rapeseed (Brassica napus L.) after long-term exposure to a wide range of concentrations. The inhibitory effects of treatments on the growth of B. napus were in the order Zn²⁺ >> ZnO BPs > ZnO NPs. Results showed the significant changes in the antioxidant enzyme activities, total chlorophyll, soluble proteins, proline, and soluble sugars of the leaves in response to the treatments. However, total phenolic compounds were not affected significantly by any treatment. Overall, in the present study, the toxicity of ZnO NPs on B. napus was lower than those of Zn²⁺ or ZnO BPs. Results indicate that adverse effects of ZnO NPs or BPs on B. napus may be due in part to the toxic effects of Zn²⁺ ions dissolution, probably induced by root exudates, or due o the physical interaction of ZnO particles with roots and induction of structural and functional disorders.

The bioactivity of three kinds of multi-walled carbon nanotubes (MWCNT) towards the conidia of entomopathogenic fungus Isaria fumosorosea was examined in an in vitro study. Commercial—raw and functionalized—carboxylated MWCNT were applied. A fungal conidia suspension was placed in contact with dispersed MWCNT over different time-periods. After contact with the nanomaterial, the conidia were cultured on dishes and both the linear vegetative mycelium growth and the sporulation and germination of the spores derived from the culture were investigated. Also, the pathogenicity of the conidia after contact with MWCNT was examined in relation to test larvae. No fungistatic activity of MWCNT relative to I. fumosorosea conidia was demonstrated. Conidia contact with MWCNT resulted in the following changes in vital processes in the subsequent culture compared to the control standard culture: (1) raw MWCNT limited mycelium inoculation, but the growth rate observed later in the log-phase was more intense; (2) after 24-h conidia contact with all MWCNT types, the mycelium sporulated the most intensively; longer contact resulted in sporulation process limitation. Germination of conidia after contact with the MWCNT was not significantly modified. Raw MWCNT potentiated conidia pathogenicity towards test insects. It was observed that carboxylation of MWCNT reduces the bioactivity of this nanomaterial towards the investigated conidia.

The paper presents a comprehensive analysis of the most basic features of the air quality of a Mediterranean urban environment area. The impact of meteorology on the air quality is also examined. Observational surface concentrations of the most important air pollutants, recorded at two measuring stations in Patras, Greece, are used. The Weather Research and Forecasting (WRF) meteorological model was employed to produce a series of surface and upper air data and local circulation and ventilation indices. These modeled data along with selected surface meteorological observational data comprise a substantial data set that was used to assess the effect of meteorology on the air quality. Mostly during the summer period, a significant proportion of the particulate matter is transported from sources away from the measuring sites. The synoptic setting of winter and summer seasons represented primarily by the local ventilation and recirculation, the wind, the boundary layer height, and the precipitation has a very strong impact in the overall formation of the air quality status.

Phytoremediation has been proven to be an environmentally sound alternative for the recovery of contaminated soils, and the economic profit that comes along with the process might stimulate its field use. This study investigated cadmium (Cd) transfer and detoxification mechanisms in a soil–mulberry–silkworm system to estimate the suitability of the mulberry and silkworm as an alternative method for the remediation of Cd-polluted soil; it also explored the underlying mechanisms regulating the trophic transfer of Cd. The results show that both the mulberry and silkworm have high Cd tolerance. The transfer factor suggests that the mulberry has high potential for Cd extraction from polluted soil. The subcellular distribution and chemical forms of Cd in mulberry leaves show that cell wall deposition and vacuolar compartmentalization play important role in Cd tolerance. In the presence of increasing Cd concentrations in silkworm food, detoxification mechanisms (excretion and homeostasis) were activated so that excess Cd was excreted in fecal balls, and metallothionein levels in the mid-gut, the posterior of the silk gland, and the fat body of silkworms were enhanced. And, the Cd concentrations in silk are at a low level, ranging from 0.02 to 0.21 mg kg⁻¹. Therefore, these mechanisms of detoxification can regulate Cd trophic transfer, and mulberry planting and silkworm breeding has high phytoremediation potential for Cd-contaminated soil.

River plumes are the major source of nutrients, sediments, and other pollutant into the coastal waters. The predictive capability of a 3D hydrodynamic model (POMGL), a version of the common Princeton Ocean Model (POM), adapted for the Great Lakes, is assessed versus field measurements. The model was applied to simulate the nearshore hydrodynamics as the Grand River plume entering Lake Michigan. A nesting technique was adapted to represent the circulation and thermal structure of the surface river plume with a higher resolution. The model was compared with extensive field studies in the vicinity of Grand Haven. The current predictions showed fairly good agreement with observations, although the thermal structure of the flow especially near the river mouth was not very well represented. The model showed a weak stratification and a mild temperature transition from the plume to the lake water and therefore more diffusion. Application of hydrostatic models in exchange flows (e.g., buoyant river plumes) is recommended with reservations and coupling of these models with near field entrainment or empirical models to consider the nonhydrostatic nature of lake-river interface currents.

Arsenic (As) is a ubiquitous metalloid known for its adverse effects to human health. Microorganisms are also impacted by As toxicity, including methanogenic archaea, which can affect the performance of a process in which biological activity is required (i.e., stabilization of activated sludge in wastewater treatment plants). The novel ability of a mixed methanogenic granular sludge consortium to adapt to the inhibitory effect of arsenic As was investigated by exposing the culture to approximately 0.92 mM of arsenite (Asᴵᴵᴵ) for 160 days in an arsenate (Asⱽ)-reducing bioreactor using ethanol as the electron donor. The results of shaken batch bioassays indicated that the original, unexposed sludge was severely inhibited by Asᴵᴵᴵ as evidenced by the low 50 % inhibition concentrations (IC₅₀) determined, i.e., 19 and 90 μM Asᴵᴵᴵ for acetoclastic and hydrogenotrophic methanogenesis, respectively. The tolerance of the acetoclastic and hydrogenotrophic methanogens in the sludge to Asᴵᴵᴵ increased 47-fold (IC₅₀ = 910 μM) and 12-fold (IC₅₀ = 1100 μM), respectively, upon long-term exposure to As. In conclusion, the methanogenic community in the granular sludge demonstrated a considerable ability to adapt to the severe inhibitory effects of As after a prolonged exposure period.

This paper analyzes the mathematical modeling procedure to describe the decomposition of adsorbed phenanthrene in prototypical and real soil samples (sand and agricultural soil, respectively) by ozone. The modeling scheme considered a set of ordinary differential equations with time varying coefficients. This model used the adsorbed ozone in the soil, the ozone reacting with the contaminant and the phenanthrene concentration in the soil sample. The main parameters involved in the mathematical model included a time varying ozone saturation function (k ₛₐₜ (t)) and reaction constants (k ᵣ). These parameters were calculated using the ozone concentration variation at the reactor output, named as ozonogram, and the measurements of phenanthrene decomposition through ozonation. The model was validated using two series of experiments: (1) soil saturated with ozone in the absence of the contaminant and (2) soil artificially contaminated with phenanthrene. In both cases, the proposed parametric identification method yields to validate the mathematical model. This fact was confirmed by the correspondence between numerical simulations and experimental data. In particular, total decomposition of phenanthrene adsorbed in two different systems (ozone-sand and ozone-agricultural soil) was obtained after 15 and 30 min of reaction, respectively. This difference was obtained as a consequence of soil physicochemical characteristics: specific surface area and pore volume. The ozonation reaction rate constants of phenanthrene in the sand and agricultural soil were calculated using the same parameter identification scheme.

Benzotriazoles (BTs) are an emerging class of environmental pollutants used in a wide range of industrial applications. Benzotriazole (BTri) and 5-methylbenzotriazole (5-MeBT) have recently been detected in water supplies around the world, and are thus attracting the attention of many environmental researchers. The focus of this review is on assessing contemporary methods to detect BTs using high-performance liquid chromatography (HPLC), and providing information regarding their occurrence, degradation and toxicity within the environment.

Photosynthetic process is a good approach to discriminate cadmium-tolerant species, because it is reported as one of the most sensitive processes. Our goal was to measure Elephantopus mollis Kunth (Asteraceae) tolerance, determining the interference of Cd on the photosynthetic process. For this, a hydroponic experiment design was conducted in nutrition solution with concentrations of 0 (control), 10, 50, and 100 μM of cadmium (Cd). Measures of photosynthesis performance were obtained, for example, gas exchange, photosystem integrity, chlorophyll content, leaf growth rate, root length, and dry weight. In addition, cadmium and zinc concentrations were measured. Furthermore, results were linked to phytoremediation potential. Our specific questions were as follows: (1) Can the photosynthetic apparatus of E. mollis deal with cadmium stress? (2) Is E. mollis able to accumulate cadmium and maintain zinc level? (3) Is E. mollis a tolerant or sensitive species? (4) Can any phytoremediation practice be suggested from these results? Our results showed that E. mollis can deal with cadmium toxicity up to 10 μM Cd. Moreover, this plant is a potential hyperaccumulator, which can accumulate 248 mg Cd kg⁻¹ dry weight. However, at concentrations of 50 and 100 μM Cd, this species was sensitive and cadmium toxicity affected both biochemistry and photochemistry phases of photosynthesis on account of negative changes on gas exchange, fluorescence chlorophyll, and chlorophyll content. Nevertheless, these results did not compromise the research about its tolerance at lower concentrations of cadmium.