This study aims to produce and apply a biosurfactant from Gordonia westfalica GY40 for enhancing fuel oil solubilization and degradation in seawater. The immobilization of G. westfalica GY40 cells on chitosan flakes increased biosurfactant yield, and we achieved a biosurfactant concentration as high as 1.85 g L⁻¹ when using 2 % soybean oil as the carbon source. The critical micelle dilution (CMD) value of cell-free broth was 25 % and the lowest surface tension was 35 mN m⁻¹. The cell-free broth was able to solubilize and disperse fuel oil, at efficiencies corresponding to biosurfactant concentrations and CMD values. The surface activity of cell-free broth was stable under wide ranges of salinity, temperature, and pH. For the oil degradation test, cell-free broth at 0.5× CMD was added along with polyurethane foam-immobilized Gordonia sp. JC11, an efficient oil-degrading bacterial inoculum, to fuel oil spiked seawater. The system removed 81 % of 1 g L⁻¹ fuel oil in nutrient seawater medium within 6 days. When tested with three seawater samples collected along the Thai coastal area, the addition of both biosurfactant and immobilized Gordonia sp. JC11 was able to remove 60–70 % of 1 g L⁻¹ fuel oil, while the natural attenuation (control) removed only 26–35 % of fuel oil. The application of cell-free broth reduced the extraction and purification steps. In addition, the simple production of G. westfalica GY40 biosurfactant and Gordonia sp. JC11 inoculum suggested that they are suitable for cleaning-up oil spills in seawater.

Main aim of the work assumed recognition of physicochemical changes in snowpack occurring during the melting period. Properties of snow cover had been identified at two sites in Western Sudetes mountains (860 and 1228 m asl) in SW Poland since the end of January, and monitored until the disappearance of snow in late Spring. Snow pit measurements and sample collection at both sites were made followed by chemical analyses with the use of ionic chromatography. The results were compared for subsequent stages of snowpack evolution. Thermometers installed above the ground during summer in one site (860 m asl) helped to identify the thermal gradient existing inside snow during winter. During studies, special attention was paid to the pollutant elution with determination the different release rates of individual ions from the snow cover. Results of chemical analysis showed that during the thaw, the first portions of meltwater were responsible for drainage into the ground a substantial part of the impurities. During the first two weeks of thaw at higher elevated site, pollutants released from the snow cover load amounted to 123.5 mMol·m⁻². In those days, there was a release to the ground of approximately 74, 74, and 57 %, respectively of H⁺, NO³⁻, and SO₄ ²⁻ ions contained in the snow cover, while only 14 % of snow mass in the form of meltwater was released.

Traffic-based pollution causes accumulation of some elements in plant tissues and damages anatomical and physiological processes of plants. Nutrient use proficiency and litter decomposition are two basic processes of nutrient dynamics. This study aimed to determine the effects of traffic-based pollution on N and P use proficiency and litter decomposition in Malus domestica Borkh. (Rosaceae) which is a commonly cultivated fruit tree worldwide. The study was carried out in Amasya, Turkey, where the apple is the symbol of the city. Leaf samples were collected from apple trees at 0-, 100-, and 200-meter distances from the highway. N, P, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn concentrations were measured in the collected samples. All of the element concentrations varied according to the distance from the road. Traffic-based heavy metal pollution increased N and P use proficiency. It may be said that M. domestica reabsorb more N and P from senescent leaves due to the high heavy metal concentrations in their leaves. The decomposition rate was highest at 0 m and lowest at 100 m. The variations in the remaining dry weight, mass loss (%), and k value due to traffic-based pollution were not statistically significant. A significant negative relationship was determined between the initial N concentration and the litter decomposition rate. It was thought that this negative relationship resulted from recalcitrant condensation products that are formed by lignin and N.

Samples were collected from the middle and lower reaches of the Yangtze River, China, to study the concentrations, distributions, and compositions of 16 US-EPA priority polycyclic aromatic hydrocarbons (PAHs) in water and suspended particulate matter (SPM). We also evaluated sources of the PAHs and their potential toxicity. Total concentrations of the PAHs (ΣPAHs) in water ranged from 17.33 to 77.12 ng L⁻¹, and in SPM, the levels ranged from 595.91 to 2473.74 ng g⁻¹. Total concentrations of seven carcinogenic PAHs (ΣCPAHs) ranged from 7.63 to 13.02 ng L⁻¹ in water and 276.55 to 1216.89 ng g⁻¹ in SPM. PAH levels in water samples were relatively low, and those in the lower reaches were higher than in the middle reaches. SPM samples had higher levels of PAHs, especially in the lower reaches and in Dongting Lake and Poyang Lake. Principal component analysis (PCA) with multiple linear regression analysis (MLR) was performed to quantitatively characterize the PAH sources. Two factors and their contributions were identified from water samples. Coal and wood combustion accounted for 74.1 % of the PAHs, and petroleum emissions explained 25.9 % of the PAHs. Three source factors were identified from SPM samples: these were vehicular emissions (46.3 % of PAHs), wood and coal combustion (40.4 % of PAHs), and petrogenic sources (13.3 %). Ecological risk assessment indicated that a moderate undesirable impact will be caused by PAHs, and some control measures and remedial actions should be conducted.

The rheology of digested sludge affects the flow hydrodynamics, dewaterability, and the polymer consumption in wastewater treatment plants. The rheological characteristics of digested sludge are highly dependent on changes in total solid concentration, temperature, and polymer dose. Hence, this study aims at investigating the impacts of total solid concentration, temperature, and polymer dose on the rheological characteristics and the dewaterability of digested sludge. Investigating the relationship between rheological and physicochemical characteristics of sludge can also serve as a tool to optimize essential process parameters. Different homogenized digested sludge samples were subjected to rheological measurement on rotational stress-controlled rheometer equipped with Peltier concentric cylinder system. The shear stress–shear rate and viscosity–shear rate curves were then developed before and after polymer conditioning at various temperatures and solid concentrations. Different rheological model were fitted to the shear stress–shear rate and viscosity–shear rate rheograms, and the model with the best fitting and more practical significance was selected to determine key rheological parameters. The relationship between dewaterability and digested sludge rheology was also developed. The rheological characteristics of digested sludge during polymer conditioning and flocculation process was significantly affected by temperature and solid concentration; hence, polymer dose can be reduced by operating the dewatering process at optimum temperature condition and varying the polydose as a function of the total solid concentration and viscosity of the digested sludge. The dewaterability as measured in capillary suction time (CST) improved with increasing polymer dose up to 12 kg/t DS but further increase in polymer dose resulted in the deterioration of the dewaterability due to overdosing.

Trimethylamine (TMA) is a volatile organic compound which causes not only unpleasant odor but also health concerns to humans. The average emission of TMA from food and fishery industries is 20.60 parts per billion (ppb) and emission from the gas exhausters is even higher which reaches 370 parts per million (ppm). In order to select the best plant TMA removal agent, in this study, 13 plants were exposed to 100 ppm of TMA and the remaining TMA concentration in their system was analyzed by gas chromatography (GC). Furthermore, plant metabolites from the selected plant were identified by gas chromatography-mass spectrometry (GC-MS). The result showed that Euphorbia milii was the most superior plant for TMA removal and could absorb up to 90 % of TMA within 12 h. E. milii absorbed TMA via leaf and stem with 55 and 45 % uptake efficiency, respectively. Based on its stomatal movement during the exposure to TMA, it was implied that the plant switched the photosynthetic mode from crassulacean acid metabolism (CAM)-cycling to CAM and CAM-idling. The switching of photosynthetic mode might reduce the stomata role in TMA absorption. Fatty acids, alkanes, and fatty alcohols in the plant leaf wax were also found to contribute to TMA adsorption. Leaf wax, stomata, and other leaf constituents contributed 58, 6, and 36 %, respectively, of the total TMA absorption by the leaf. The analysis and identification of plant metabolites confirmed that TMA was degraded and mineralized by E. milii.

Natural organic matter (NOM) in groundwater is a factor of concern in long-term operation of Fe⁰ permeable reactive barrier (PRB). In this study, humic acid, a major component of NOM, showed dual effects in trichloroethylene (TCE) removal from simulated groundwater by Fe⁰ in batch and column experiments. In the initial stage of contacting with Fe⁰, humic acid promoted TCE removal due to its hydrophobic partitioning towards TCE and the subsequent fast adsorption onto Fe⁰ surfaces. In a long run, humic acid inhibited TCE removal because the buildup of adsorbed humic acid on Fe⁰ surfaces passivated Fe⁰ reactivity and limited TCE mass transfer. Ca²⁺ enhanced the co-aggregation of humic acid with Fe⁰ corrosion products and led to a faster depletion of TCE removal capacity by diminishing Fe⁰ matrix porosity. Revealed by FTIR analysis, part of TCE removed through hydrophobic partitioning was retained in humic acid accumulated on Fe⁰ surfaces rather than reductively degraded by Fe⁰. It raises a concern of using Fe⁰ PRB to treat organic contaminants in NOM-rich groundwater. Releasing back of NOM retained organic contaminants might take place once the accumulated NOM is desorbed or detached from Fe⁰ surfaces, resulting in a rebound of organic contaminants in the groundwater beyond the confine of PRB.

Ratios of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) have been used extensively for predicting bioavailability of divalent metals (i.e., Cd, Cu, Pb, Ni, Zn) in sediments of aquatic environments. However, the role of sulfides (as AVS) as a toxicant has been largely ignored. The aim of this research was to measure relationships of AVS (as sodium sulfide [Na₂S]-amended sediment) and toxicity to a sensitive benthic amphipod Hyalella azteca to evaluate the exposure-response relationships among a series of sulfide exposures. The specific objectives were to (1) measure SEM/AVS ratios in a series of sodium sulfide (Na₂S·9H₂O)-amended sediments producing a range of sulfide concentrations and (2) measure responses of H. azteca (as mortality) in 96-h static sediment toxicity tests to exposures of Na₂S-amended sediments. Amended sediments had a predictable increase in AVS concentrations and a concomitant decrease in ∑SEM/AVS ratios. Increasing concentrations of AVS resulted in a range of ∑SEM/AVS ratios that varied over more than an order of magnitude from 0.185 to 0.006. H. azteca survival decreased with increasing concentrations of “excess” AVS, with 96-h no observable effect concentration (NOEC) and LC₅₀ of 0.041 and 0.019 ∑SEM/AVS, respectively. Clearly, the SEM/AVS model provides a useful tool for evaluating potential bioavailability of divalent metals and predicting ecological risk; however, this study demonstrates the need to consider sulfide (as AVS) as a potential source of toxicity in situations with low [<<1] ∑SEM/AVS ratios.

In order to clarify how cadmium (Cd) chemical forms in planta relate to the genotype difference in Cd accumulation of spinach (Spinacia oleracea L.), two low-Cd and two high-Cd cultivars were compared under a hydroponic experiment with two concentrations of Cd (8.98 or 44.71 μmol Cd L⁻¹). The concentrations of phosphorus in the hydroponic system were also adjusted to two levels (0.5 and 1.0 mmol L⁻¹) to investigate the influence of phosphorus on the forms and accumulation of Cd in the tested cultivars. Average Cd concentrations in shoots were 8.50−10.06 mg kg⁻¹ for high-Cd cultivars and 6.11–6.64 mg kg⁻¹ for low-Cd cultivars a under lower Cd treatment and were as high as 24.41–31.35 mg kg⁻¹ and 19.65–25.76 mg kg⁻¹, respectively, under a higher treatment. Phosphorus significantly decreased Cd accumulation in the tested cultivars, and the effect had superiority over the cultivar alternation under higher Cd stress. Cadmium in the NaCl-extractable fraction of the plant tissues showed the greatest relationship to genotype difference of Cd accumulation. The difference in the capacity to binding Cd into F HAc, F HCₗ, or F Rₑₛᵢdᵤₑ was another important mechanism involving in the genotype difference in Cd accumulation of spinach. Among them, average proportion of Cd in F HAc in low-Cd cultivars was higher than that in high-Cd cultivars in association with the effect of phosphorus.

The stress tolerance of wetland plants is crucial for their appropriate application in constructed wetland (CW). Ammonia, one of the major pollutants in wastewater, is nutrition for plants at low concentrations but could be toxic at excess concentrations. This study aimed to investigate the effect of external ammonia at different concentrations (0, 1, 2, 4, 8, 10 mg L⁻¹) to a specific submerged plant Potamogeton crispus (P. crispus), which has been used widely in CW. Results showed that the threshold value of ammonia for P. crispus was 4 mg L⁻¹, under which no obvious variations from the control group were detected in all associated observations. When ammonia concentration exceeded 4 mg L⁻¹, plants displayed significant increase in lipid peroxidation product contents (MDA, O₂ ⁻ and H₂O₂), antioxidant enzyme activities (T-SOD, POD, and CAT), and a corresponding increase in the percentages of electrolyte leakage. However, external ammonia only had slight effect on the chlorophyll synthesis of P. crispus under the studied concentration range. Excess ammonia exposure (≥4 mg L⁻¹) could affect the physiological responses of P. crispus, by inducing oxidative stress and by limitedly altering permeability of cell membrane and plant photosynthesis. The results of this study supplied useful information for the aquatic vegetation collocation in CW design, and it is suggested to take proper application of P. crispus in CW when treating eutrophication or other relatively heavily polluted water.