This study assessed runoff losses following laboratory rainfall simulation on a grassland soil at two time intervals (48 and 216 h) after a single application of biosolids and meat and bone meal (MBM). The treatments were, a soil-only control, three types of biosolids (lime-stabilised (LS), thermally dried (TD) and anaerobically digested (AD)) and two types of MBM (low ash and high ash content) all applied at two rates (the maximum and double the maximum legal application rate currently permitted in Ireland). Results showed that treatment, time interval and their interactions all had significant effects on dissolved reactive P (DRP), total P (TP) and total dissolved P (TDP) concentrations. Time interval had the greatest effect for DRP and TP concentrations, while treatment was more significant for TDP. All treatments released DRP concentrations in excess of 30 μg DRP L⁻¹. Anaerobically digested biosolids released the least amount of DRP into surface runoff for both application rates at both time intervals. Low ash content MBM, applied at the maximum legal rate, released the most DRP at both time intervals, and the TD biosolids released the most DRP when applied at double the maximum rate. Lime-stabilised biosolids released the most TP in runoff at both application rates. Runoff comprised of >50 % particulate P for all treatments. Besides TD biosolids, all treatments, applied at both rates, released lower concentrations of suspended solids (SS) during the second time interval than the first. Soil-specific effects were also evident, although the soil was non-calcareous and had a low pH and high amounts of available aluminium and iron, high organic matter ensured low levels of P adsorption.

A new solid phase extraction method was developed for the preconcentration and determination of rare earth elements (REEs) (Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, Ce) in water samples. The method is based on the sorption of REE ions onto the 2,6-pyridinedicarboxaldehyde-functionalized Amberlite XAD-4 resin at pH 7.0, followed by the elution with 2 mL of 1.0 mol L⁻¹ HNO₃ solution and determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The main parameters affecting preconcentration, including sample pH, sample and eluent flow rate, and sample volume, have been investigated in detail. Under the optimum conditions (pH 7.0, sample flow rate of 1.0 mL min⁻¹, and eluent flow rate of 4.0 mL min⁻¹), detection limits between 0.011 and 0.298 μg L⁻¹ for a 25 mL sample volume and 0.006 and 0.149 μg L⁻¹ for a 50 mL sample volume were obtained. The sorption capacities for the resin were found to range between 49.0 μmol g⁻¹ (for Lu) and 66.7 μmol g⁻¹ (for Sm). The method was validated by analysis using a surface water certified reference material (SPS-SW2 Batch 127). The proposed method was successfully applied to the determination of REEs in tap water and seawater samples. The recovery values for the spiked water samples were in the range of 90.0–101.7 %.

Ion exchange processes are effective for the removal of arsenic (As) from drinking water. However, the As uptake capacity of ion exchange resins is affected by the presence of other anions such as sulphates and nitrates. As these ions are typically found in groundwater, the design of ion exchange process aimed at removing As from groundwater may be affected by their presence. Therefore, to properly design an ion exchange process for As removal, it is important to characterise the ion exchange equilibria of As in solution in the presence of competing anions. This paper was aimed at obtaining a deeper understanding of the binary equilibria of As(V)Cl⁻ and SO₄ ²⁻/Cl⁻ and of the ternary equilibria of As(V)/SO₄ ²⁻/Cl⁻. To this purpose, a series of batch tests were carried out at different values of the total solution normality. These data were combined with those obtained through continuous flow column tests performed to collect equilibrium data over the entire ionic fraction domain. The equilibrium data were then described using two different models based on the assumption of ideal behaviour of both the liquid and the adsorbed phases: in the first model the resin was considered to have only one type of binding-sites, where two types of binding sites were assumed by the second model, named double-selectivity model. Among these two models, the latter provided the best fitting of binary equilibrium data for both As chlorides and sulphate chlorides systems. However, the same model was unable to fit the experimental data of As in the ternary system As(V)/SO₄ ²⁻/Cl⁻ with a satisfactory agreement probably due to the presence of non-ideality which the model did not account for.

The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower-permeability strata adjacent to sand/gravel units in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for 9 years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection. These results demonstrate successful creation of a long-term, dissolved-phase reactive treatment zone that reduced mass discharge from the source. This project illustrates the application of in situ chemical oxidation as a persistent dissolved-phase reactive treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater.

The adsorption of microcystin-LR (MCLR) by biochar has never been well understood. For the first time, the unconventional adsorption of hydrophilic MCLR on wood-based biochars was comprehensively investigated as a function of biochar properties, environmental temperature, solution pH, coexisting dissolved organic matter (DOM), and polar organic competitors. High-temperature-prepared biochar from 700 °C (BC-700) and low-temperature-prepared biochar from 300 °C (BC-300) were characterized with significantly different surface areas but similar alkaline nature. Despite a very low surface area, BC-300 exhibited very high adsorption capacity, which implies the important contribution of surface groups to biochar. MCLR adsorption on biochars was pH dependent and was strongly reduced by macromolecular DOM. Polycarboxylic aliphatic acids and 2-(2-hydroxyethyl) guanidinium cation, which are similar to specific structural groups in MCLR, exhibited an evident competitive effect. The results indicated that both carboxylic and guanidino groups of MCLR serve significant functions in MCLR adsorption to biochar. The adsorption mechanisms may be primarily related to the columbic attractions and the hydrogen bonding interactions between MCLR and biochar surface. In particular, the irreversible adsorption enhancement of MCLR was observed on BC-700, which suggests that biochar amendment can aid in immobilizing MCLR from water to sediment, thereby prolonging MCLR environmental fate in biochar-amended sediment.

Effects of the combined application of ferrihydrite-modified diatomite (FHMD) and gypsum on phosphorus control were investigated in a laboratory-scale artificial aquarium under anoxic and agitation conditions over 120 days. Daily oscillation of a metal grid to simulate agitating effects by wind did not yield the sediment resuspension in the 120-day treatment aquarium (120-day aquarium) due to the gypsum stabilization, while significant sediment resuspension was observed in the control aquarium. The combined application of FHMD and gypsum did not affect the total kjeldahl nitrogen (TKN) concentrations in both the control aquarium and the 120-day aquarium. Under anoxic conditions and sediment resuspension conditions, a large increase in total phosphorus (TP) concentrations was observed in the control aquarium. However, the TP concentrations in the 120-day aquarium stayed relatively stable, within a range of 9.1–13.3 μg/L. After the 120 days’ incubation, translocation from mobile labile-P and organic-P to P adsorbed by FHMD occurred. The combined application of FHMD and gypsum effectively maintained TP levels within the oligotrophic range under anoxic and agitation conditions in the laboratory-scale artificial aquarium by removing phosphorus from lake water and reducing sedimentary phosphorus release via gypsum sediment stabilization and FHMD phosphorus immobilization.

This study was undertaken to synthesise a novel biomass-based chemically activated carbon from Australian pine cone and to investigate its effectiveness in the removal of anionic dye Congo red from aqueous solution. The effect of activation parameters such as the concentration of phosphoric acid and temperature were identified as the most efficient parameters for activation in the Congo red removal. The synthesised activated carbon was characterised by Fourier transform infrared and different physical properties, such as bulk density, CHNS analysis, carbon yield, particle size, zeta potential and Brunauer–Emmett–Teller surface area were also determined. Batch adsorption study showed that the amount of adsorption depends on various physico-chemical process parameters, such as solution pH, dye concentration, temperature and adsorbent dose. It was observed that Langmuir maximum adsorption capacity was 500 mg/g at a pH of 3.5. Furthermore, pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models were fitted to examine the adsorption kinetic and mechanism of adsorption. Equilibrium data were fitted with Langmuir, Freundlich and Tempkin adsorption isotherm models. Thermodynamic parameters such as ΔG⁰, ΔH⁰, and ΔS⁰were also calculated. Finally, a single-stage batch adsorber design for the Congo red adsorption onto activated carbon particles was presented based on the Freundlich isotherm model equation. These results indicated pine cone biomass is a good and cheap precursor for the production of an effective activated carbon adsorbent and alternative to commercial-activated carbon.

We determined basal levels of cholinesterase (ChE) and carboxylesterase (CbEs; two substrates: α-naphthyl acetate and 4-nitrophenylvalerate) in different tissues of tadpoles and adults of the frog Pseudis paradoxa and evaluated their use as complementary biomarkers of anti-cholinesterase pesticide exposure. ChE and CbEs sensitivity to malaoxon was also evaluated. Adults and tadpoles were collected with sweep net from temporary ponds located in natural riparian forests along the Paraná River (Garay Department, Santa Fe province, Argentina). We found significant differences in B-esterase activities between adults and tadpoles and among different tissues. The in vitro inhibition tests indicated that ChE is more sensitive to inhibition than CbEs. Our results suggest that basal ChE and CbE (α-NA and 4-NPV) activities in different tissues of adult and tadpoles P. paradoxa would be suitable biomarkers of pesticide exposure, and this amphibian species could be used as sentinel in field monitoring.

A pot experiment was conducted to investigate the effect of nitrogen fertilizer on CH₄ emission from a paddy soil under greenhouse conditions. The experiment was designed with two fertilizer types, i.e., controlled-release nitrogen fertilizer (CRNF) and urea (U), and two rice cultivars, i.e., herbicide-resistant transgenic rice (japonica line B2) and its parent conventional rice (japonica cv Xiushui 63). Compared with control (urea), one-time basal application of CRNF increased tiller number, plant height, biomass, and yield in rice and significantly decreased total CH₄ emission from the paddy soil. The total CH₄ emission was significantly lower from the transgenic cultivar than that from the conventional cultivar. It is suggested that CRNF and herbicide-resistant transgenic rice are helpful in mitigating CH₄ emission from the paddy soil.