A novel sorbent, chitosan-immobilized pumice, has been prepared for the sorption of As(V) from waters prior to its determination by hydride generation atomic absorption spectrometry. The success of the immobilization has been checked with such characterization techniques as scanning electron microscopy, thermal gravimetric analysis, and elemental analysis. Points of zero charge of the sorbents were determined with potentiometric mass titration. Batch-type equilibration studies have shown that the novel sorbent can be employed at a wide pH range resulting in quantitative sorption (>90 %) at pH 3.0–7.0 and greater than 70 % sorption at pH >8.0. These results demonstrate the advantage of immobilizing chitosan onto pumice, because, under the same conditions, pumice displays <20 % sorption toward As(V), whereas chitosan gives approximately 90 % sorption only at pH 3.0. The validity of the method was verified through the analysis of ultrapure, bottled drinking, and tap water samples spiked with arsenate; the respective sorption percentages of 93.2 (±0.7), 89.0 (±1.0), and 80.9 (±1.3) were obtained by batch-type equilibration. Arsenic sorption was also examined in the presence of common interfering ions resulting in competing effects of PO₄ ³⁻ and NO₃ ⁻ on As(V) adsorption.

An understanding of the effects of land-use activities on atmospherically derived pollutant loadings in stormwater is helpful for determining appropriate treatment strategies for different catchments. Impervious concrete boards (≈1 m²) were deployed for 11 months in different land-use areas (industrial, residential and airside of an airport’s runway) throughout Christchurch, New Zealand, to determine the spatial variability of atmospherically derived pollutants in stormwater runoff. Runoff was analysed for metals (principally Cu, Zn and Pb) and total suspended solids (TSS). All three land-use areas exhibited similar temporal patterns of varying metal and TSS loads, indicating that atmospherically deposited metals and TSS had a homogenous distribution within the Christchurch airshed. However, mean pollutant loadings for all total metals and TSS were significantly higher in the industrial area compared to the residential and airside areas, which had statistically similar mean metal loadings. The signature ratios of specific heavy metals (As, Cr, Mn, Ni, Pb, Sr and Zn) to Cu were relatively homogeneous between the three land-use areas, indicating that the pollutants originate from a similar source and that surrounding land-use was not as an important factor in determining atmospheric pollutant loadings to stormwater runoff as previously thought.

The water retention time (sometimes called residence time) in coastal areas is an indicator of coastal hydrodynamics which can be used to quantify the local transportation of dissolved and suspended pollutants. This study has used dynamic and statistical models to explore what governs the water retention time in non-tidal coastal waters of the Baltic Sea. If freshwater input divided by the cross-section area between the coastal water and the sea was below a certain threshold, freshwater had no notable impact on the retention time. Moreover, statistical models were developed for predicting surface water retention time and total water retention time from coastal water volume, cross-section area and freshwater discharge. This study can be useful for managers who need to determine where abatement measures should be focused in order to be as effective as possibly against coastal water pollution.

In this study, an artificial neural networks (ANN) model was developed to predict the removal of a polycyclic aromatic hydrocarbon (PAH), namely, naphthalene from marine oily wastewater by using UV irradiation. The removal rate was used as model output and simulated as a function of five independent input variables, including fluence rate, salinity, temperature, initial concentration and reaction time. The configuration of the ANN model was optimized as a three-layer feed-forward Levenberg–Marquardt backpropagation network with log-sigmoid and linear transfer functions at the hidden (12 hidden neurons) and output layers, respectively. By considering goodness-of-fit and cross validated predictability, the ANN model was trained to provide good overall agreement with experimental results with a slope of 0.97 and a correlation of determination (R ²) of 0.943. Sensitivity analysis revealed that fluence rate and temperature were the most influential variables, followed by reaction time, salinity and initial concentration. The findings of this study showed that neural network modeling could effectively predict the behavior of the photo-induced PAH degradation process.

The widespread use of alkylphenols in European industry has led to their presence in the environment and the living organisms of the Baltic Sea. The present study (2011–2012) was designed to determine the concentrations of alkylphenols, 4-nonylphenol (NP) and 4-tert-octylphenol (OP), in surface sediments of the Gulf of Gdansk, a section of the Baltic that lies in close proximity to industrial and agricultural areas and borders with an agglomeration of nearly one million inhabitants. It is also where the Vistula, the largest Polish river, ends its course. In spring, large concentrations of 4-nonylphenol and 4-tert-octylphenol were washed off into the coastal zone with meltwater. In summertime, sediments near the beach had the highest alkylphenol concentrations (NP—2.31 ng g⁻¹dw, OP—13.09 ng g⁻¹dw), which was related to tourism and recreational activity. In silt sediments located off the coast, the highest NP (1.46 ng g⁻¹dw) and OP (6.56 ng g⁻¹dw) amounts were observed in autumn. The origin of OP and NP at those test stations was linked to atmospheric transport of black carbon along with adsorbed alkylphenols.

Studying the toxic risk of pesticide exposure to ladybird beetles is important from an agronomical and ecological perspective since larval and adult ladybirds are dominant predators of herbivorous pest insects (e.g., aphids) in various crops in China. This article mainly deals with the long-term effects of a single application of the insect growth regulator hexaflumuron on Coccinella septempunctata. A 72- h and a 33-day toxicity test with hexaflumuron (single application) were performed, starting with the second instar larvae of C. septempunctata. Exposure doses in the long-term experiment were based on the estimated 72-h acute LR50 (application rate causing 50 % mortality) value of 304 g active ingredient (a.i.) ha-1 for second instar larvae of C. septempunctata. The long-term test used five hexaflumuron doses as treatment levels (1/50, 1/100, 1/200, 1/400, and 1/800 of the 72-h acute LR50), as well as a solvent control and blank control treatment. The measurement endpoints used to calculate no observed effect application rates (NOERs) included development time, hatching, pupation, adult emergence, survival, and number of eggs produced. Analyzing the experimental data with one-way analysis of variance showed that the single hexaflumuron application had significant effects on C. septempunctata endpoints in the 33-day test, including effects on development duration (NOER 1.52 g a.i. ha-1), hatching (NOER 3.04 g a.i. ha-1), pupation (NOER 3.04 g a.i. ha-1), and survival (NOER 1.52 g a.i. ha-1). These NOERs are lower than the reported maximum field application rate of hexaflumuron (135 g a.i. ha-1) in cotton cultivation, suggesting potential risks to beneficial arthropods.

In this study, dissolved air flotation (DAF) was examined as a possible treatment method for the removal of chromium from aqueous solution and plating wastewater. Two coagulants, ferric chloride and poly aluminum chloride (PAC), were used for pretreatment of wastewater. Maximum removal of chromium was achieved for poly aluminum chloride (98 %). Artificial neural network was used for the prediction of the DAF system. The best neuron used for the prediction of chromium removal percentage of interpolated wastewater was 6 %. The mean score error and the coefficient correlation were 0.0007542 and 0.997, respectively.

The present study reports the remediation of radiocesium-137 (¹³⁷Cs) using napiergrass in Cs-contaminated soils of Fukushima Prefecture. Two field experiments were performed to examine the remediation effects in two different land-use soils (lowland and upland soils) using two different cutting frequencies (cut once or twice a year). Plant growth in the upland soil was significantly greater than that in the lowland soil. The¹³⁷Cs concentration (Bq kg⁻¹dry weight basis) in the aboveground parts and total Cs-removal ratio (CR) in the upland soil were also significantly higher than those in the lowland soil. In the lowland soil, cutting twice a year [at 12 and 24 weeks after transplanting (WAT)] was more effective for CR (P < 0.01) than cutting once a year (18 WAT); however, there was no significant difference of CR related to cutting difference in the upland soil as a result of the shading effect on the plants at second cutting. In the present study, aboveground dry matter weight was highly correlated with CR in both fields. Given the possibility to increase plant number per unit of land to increase aboveground biomass per unit of land, the potential Cs remediation effect could be much greater in a wide range of Cs-contaminated soils than the potential of napiergrass for Cs uptake demonstrated in the present study.

An on-line preconcentration system using solid-phase extraction with polytetrafluoroethylene was used for the determination of mercury by cold vapor atomic absorption spectrometry. The system uses electronically controlled valves and operates in two simple steps using sorption and elution. The Hg(II) ammonium pyrrolidinedithiocarbamate complexes are retained in a minicolumn packed with the sorbent. The elution, transportation, and reduction of the analyte ions are promoted by a solution of sodium tetrahydroborate(III). After optimization, the developed method showed the following analytical characteristics: a limit of detection of 0.02 μg L⁻¹, linearity of 0.07 to 2.00 μg L⁻¹, enrichment factor of 35, and sampling frequency of 27 h⁻¹. The accuracy of the method was tested by analyzing the certified reference material BCR-060 Lagarosiphon major (aquatic plant). The proposed method was applied to the determination of mercury in water samples.

Recycling irrigation water is a common practice at ornamental plant nurseries for conserving water; however, it poses the risk of sourcing and dispersing waterborne plant pathogens, especially species of Phytophthora. Slow sand filtration is a water treatment process that can remove pathogens from water, but the slow rate of water treatment may limit its application at nursery operations. In this study, four novel substrates (crushed brick, calcined clay, polyethylene beads, and Kaldnes® medium) in addition to sand were examined to determine how effective each substrate was at removing zoospores of Phytophthora nicotianae from water. The effects of substrate physical parameters, substrate depths (0, 5, 10, 20, 40, and 60 cm), and microbe density (after nursery effluent was recirculated through each substrate for 21 days) on zoospore removal by each substrate were quantified. Sand was the most effective physical filter and supported development of the best biological filter for removing zoospores. Sand columns 40 and 60 cm deep removed zoospores completely using physical filtration alone, and zoospore removal by sand at 10- and 20-cm depths was increased with the addition of biological filtration. Kaldnes® medium and polyethylene beads were the least effective filtration substrates under all conditions tested. After 21 days of recirculating nursery effluent through substrate columns, microbe density in and zoospore removal by all substrates increased. With further optimization, crushed brick may have potential to be utilized as a recycled material for a slow filtration system focused on removing plant pathogens from irrigation water.