The kinetics and mechanism of methylene blue adsorption onto raw pine cone biomass (Pinus radiata) was investigated under various physicochemical parameters. The extent of the methylene blue dye adsorption increased with increases in initial dye concentration, contact time and solution pH but decreases with the amount of adsorbent, salt concentration and temperature of the system. Overall the kinetic studies showed that the methylene blue adsorption process followed pseudo-second-order kinetics among various kinetic models tested. The different kinetic parameters including rate constant, half-adsorption time and diffusion coefficient are determined at different physicochemical conditions. Equilibrium data were best represented by Langmuir isotherm among Langmuir and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine cone biomass was 109.89 mg/g at 30°C. The value of separation factor, R L, from Langmuir equation and Freundlich constant, n, both give an indication of favourable adsorption. Thermodynamic parameters such as standard Gibbs free energy (∆G 0), standard enthalpy (∆H 0), standard entropy (∆S 0) and the activation energy (A) were calculated. A single-stage batch absorber design for the methylene blue adsorption onto pine cone biomass has been presented based on the Langmuir isotherm model equation.

Polycyclic aromatic hydrocarbons and heavy metal (Pb, Cd, Cu, Zn, Hg, Fe, Co, Cr, Mo) contents were established in soil and plant samples collected in different areas of the railway junction Iława Główna, Poland. Soil and plant samples were collected in four functional parts of the junction, i.e. the loading ramp, main track within platform area, rolling stock cleaning bay and the railway siding. It was found that all the investigated areas were strongly contaminated with polycyclic aromatic hydrocarbons (PAHs). The PAH contamination of the soil was the highest in the railway siding and in the platform area (59,508 and 49,670 μg kg−1, respectively). In the loading ramp and cleaning bay, the PAH concentration in soil was lower but still relatively very high (17,948 and 15,376 μg kg−1, respectively). The contamination in the railway siding exceeded the average control level up to about 80 times. In the soil of all the investigated areas, four- and five-ring PAHs prevailed. The concentrations of PAHs were determined in four dominating species of plants found at the junction. The highest concentration was found in the aerial parts of Taraxacum officinale (22,492 μg kg−1) growing in the cleaning bay. The comparison of the soil contamination with PAHs in the investigated railway junction showed a very significant increase of the PAHs level since 1995. It was found that the heavy metal contamination was also very high. Pb, Zn, Hg and Cd were established at the highest levels in the railway siding area, whereas Fe concentration was the highest in the platform area. A significant increase in mercury content was observed in the cleaning bay area. The investigations proved very significant increase of contamination with PAHs and similar heavy metals contamination in comparison with the concentration determined in the same areas 13 years ago.

This study investigated the storage of nitrogen (N) and phosphorus (P) in the biomass, bed sediments and water column of representative reaches of a sub-tropical river, the upper Brisbane River (UBR), Queensland, Australia, and contrasted instream storage with total wet season exports. In reaches which contained accumulated fine sediments, more than 87% of total P and between 50% and 92% of total N were stored in the surface sediments. The lower proportion of N in sediment at some sites was attributed to substantial differences in the N/P ratios of sediments and macrophytes. At one site, the riverbed was dominated by cobbles and boulders and total nutrient stocks were comparatively low and dominated by the biomass. In reaches with a narrow channel and intact riparian cover, biomass N and P were stored predominately in leaf litter, while in wider unshaded reaches, macrophytes dominated. Total instream storage in the mid to lower reaches of the UBR was ∼50.9 T for N and ∼18.1 T for P. This was considerably higher than total wet season N (∼15.6 T) and P (∼2.7 T) exports from the UBR. The first flow event in the river after a prolonged period of no flow resulted in the export of free-floating, emergent species Azolla. The estimated biomass of Azolla in the mid to lower reaches of the river was equivalent to approximately 24% and 9% of the total N and P flux, indicating that this may be a significant, previously unaccounted for, source at peak flow.

A constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH ₄ ⁺ ) decreased from 4.6 to 1.7 mg L⁻¹, nitrate (NO ₃ ⁻ ) decreased from 6.8 to 5.3 mg L⁻¹, total N (TN) decreased from 14.6 to 10.1 mg L⁻¹, and total P (TP) decreased from 1.6 to 1.1 mg L⁻¹. Average removal efficiencies (loading basis) for NO ₃ ⁻ , NH ₄ ⁺ , TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH ₄ ⁺ . Results from mesocosm experiments indicated that NH ₄ ⁺ was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO ₃ ⁻ was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2-4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH ₄ ⁺ and P can be maximized in the pond while NO ₃ ⁻ requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant.

Due to the inherent differences in bioavailability and transport properties of particulate and dissolved mercury (HgP and HgD), it is important to understand the processes by which each is mobilized from soil to stream. Currently, there is a paucity of HgP data in the literature despite the fact that it can be the dominant fraction in some systems. We analyzed HgP in conjunction with volatile solids (VS, an estimate of organic content) and total suspended solids (TSS) and investigated the viability of using turbidity as a surrogate measure of HgP. Samples were collected for flow conditions ranging from 72 to 8,223 L s−1 during October 2009 through March 2010 in a 10.5-km2 forested headwater catchment. Total Hg concentrations ranged from 0.28 to 49.60 ng L−1, with the relative amount of HgP increasing with discharge from approximately 40% to 97%. Storm dynamics of HgP and HgD were not consistent, indicating unique controls on the export of each fraction. During high-flow events, HgP was consistently higher on the rising limb of the hydrograph compared with the receding limb for a range of discharge events, with this hysteresis contributing to a degraded relationship between HgP and streamflow. Overall, HgP was strongly positively correlated with VS (r 2 = 0.97), confirming the known association with organic carbon. Due to a consistent organic fraction of the suspended solids (34 ± 6%), HgP was also well correlated with TSS (r 2 = 0.95), with an average of 0.10 ng of HgP per milligram of TSS in this system. Stream turbidity measured with an in situ sonde also had a strong correlation with TSS (r 2 = 0.91), enabling commutative association with VS (r 2 = 0.86) and HgP (r 2 = 0.76). Turbidity can explain more than twice the temporal variance in HgP concentrations (n = 50) compared with discharge (r 2 = 0.76 versus 0.36), which leads to improved monitoring of HgP dynamics and quantification of mass fluxes.

Biosorption has potential to be an economical colour removal technology. As such, the colour removal potential of inactivated Aspergillus niger biomass was investigated for the treatment of activated sludge-treated pulp mill effluent from a northern bleached softwood kraft mill. Biomass pretreatment methods, effects of initial pH of the effluent and preparative biomass washing methods were examined. The most effective pretreatment method was found to be simple autoclaving of the biomass and this approach was applied in subsequent kinetic and isotherm batch studies. It was also found that the pH of the wastewater prior to addition of the biomass affected the biosorption rate and the solubility of chromophores in pulp mill effluent. The results also indicated that biomass washing methods reduced the quantity of organic matter leached from the fungal biomass during application. The kinetic study revealed that colour removal by biosorption occurred most readily in the first 8 h and could be described adequately by both the Lagergren and Ho et al. models. The maximum colour removal was over 900 TCU, with a biomass dose of about 20 g/L. The isotherm study data were fitted with the BET isotherm model. The results indicated that adsorption occurred in a multi-layer fashion and that physical adsorption was the main mechanism contributing to the biosorption. Therefore, dead A. niger biomass was concluded to be a promising alternative for colour removal from pulp mill effluent.

Application of one-dimensional transport considering multiple member of decay chain in a single rock fracture has been studied. Input sources for constant, pulse, impulse, Heaviside, and exponential decay have been used to demonstrate the suitability of relevant solutions. It shows that the breakthrough curves of dimensionless concentration for the three-member decay chain for Np-237 and the seven-member chain for Cm-246 can be well presented in the temporal and spatial domains. The analytical solutions of this study can clearly demonstrate the general form of contaminant transport with complete multiple-member decay chain in one-dimensional fractured or porous media of arbitrary analytical input sources without considering the matrix diffusion, which the conceptual model provides an alternative type to demonstrate the fate of radionuclide transport in the geosphere. The solutions are conservatively used to support the performance assessment for disposal site of radioactive waste. An application to a hybrid test site for the final disposal of spent nuclear fuel is newly demonstrated. Proposed solution to simulate the transport of nuclides in the one-dimensional pathway of host rock becomes feasible, so that the simulation and prediction of radionuclide transport of fractured media existing in geosphere can be conservatively performed in the future.

Leaching column tests were conducted to determine the mobility of polybrominated diphenyl ethers (PBDEs) in biosolids-amended soils. Deionized water was introduced from the bottom of a glass leaching column containing a 14-mm layer of biosolids-amended soils (210 g) under 42 mm of agricultural soil (600 g). After 4 weeks of leaching, 3.75 L of deionized water had passed through the 210-g biosolids–soil layer and 600 g soil, corresponding to 34 volumes of the leachate per volume of solid. The agricultural soil was divided into three 14-mm layers to determine the PBDE distribution along the flow path of the infiltrating water. PBDEs were found to leach from the biosolids-amended soils layer and migrate through the soil. The predominant congeners BDE47, 85, 99, 100, 153, 154, 183, and 209 decreased to 3–98% of their initial concentrations in the biosolids-amended soil, whereas the total concentration of these eight congeners decreased by 38%. PBDE concentrations in the first 14-mm soil layer increased from not detected (nd) to up to 234 × 103 pg/g dry weight basis (dw). Concentrations in the second and third soil layers increased from nd to 20 and 25 pg/g dw. PBDE in the leachate increased from nd to 310 × 103 pg/L. Mobilization of PBDEs is likely associated with dissolved organic matter and colloids in the infiltrating water.

Synthetic musks are used in many consumer products for their pleasant odor and their binding affinity for fabrics. In the early 1990s, polycyclic musks were reported to occur in air, water, sediment, wildlife, and humans from many European countries. Concentrations of polycyclic musks, particularly 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-[γ]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronapthalene (AHTN), have been reported to increase over time in the environment. In this study, concentrations of musks in water, sediment, fish, and mussel were determined from three locations along the upper Hudson River. HHCB and AHTN were detected in water (n = 5; 3.95-25.8 and 5.09-22.8 ng/L, respectively), sediment (n = 3; 72.8-388 and 113-544 ng/g, dry weight), fish (n = 30; <1-125 and <1-32.8 ng/g, lipid weight), and zebra mussel (n = 4; 10.3-19.3 and 42.2-65.9 ng/g, lipid weight) samples. Bioaccumulation factors of HHCB calculated for white perch, catfish, smallmouth bass, and largemouth bass were in the range of 18 to 371, when the concentrations in fish were expressed on a wet weight basis; the factors were in the range of 261 to 12,900, when the concentrations in fish were expressed on a lipid weight basis.