A post-harvest experiment was conducted further to our previous greenhouse pot study on upland kangkong (Ipomoea aquatica Forsk.) and Alfred stonecrop (Sedum alfredii Hance) intercropping system in Cd-contaminated soil inoculated with arbuscular mycorrhizal (AM) fungi. Previously, four treatments were established in the intercropping experiment, including monoculture of kangkong (control), intercropping with stonecrop (IS), and IS plus inoculation with Glomus caledonium (IS+Gc) or Glomus versiforme (IS+Gv). Both kangkong and stonecrop plants were harvested after growing for 8 weeks. Then, the tested soils were reclaimed for growing post-harvest kangkong for 6 weeks. In the post-harvest experiment, there were no significant differences between the IS and control treatments, except for a significantly decreased (p<0.05) soil available P concentration with IS treatment. Compared with IS, both IS+Gc and IS+Gv significantly decreased (p<0.05) soil DTPA-extractable (phytoavailable) Cd concentrations, but not total Cd, by elevating soil pH, causing significantly lower (p<0.05) Cd concentrations in both the root and shoot of kangkong. In addition, both Gc and Gv significantly increased (p<0.05) soil acid phosphatase activities and available P concentrations and hence resulted in significantly higher (p<0.05) plant P acquisitions. However, only Gv significantly increased (p<0.05) kangkong yield, while Gc only significantly elevated (p<0.05) the shoot P concentration. It suggested that AM fungi have played key roles in Cd stabilization and P mobilization in the intercropping system, and such positive responses seemed to be sustainable and valuable in post-harvest soils.

We studied the effects of N deposition (0, 10, 20 and 50 kg N ha⁻¹ year⁻¹) on cover and physiology of Pleurochaete squarrosa, a terricolous moss from semiarid Mediterranean ecosystems. We also investigated the effects of N fertilization under competition with vascular plants or under water stress. Under greenhouse conditions, vascular plant competition reduced moss cover, and there was a significant interaction between N and competition. Water stress reduced moss cover under high and low competition conditions. Nitrogen fertilization increased moss cover irrespectively of the N dose supplied at low competition conditions. Under field conditions, N deposition affected moss physiology but not cover. Most of the physiological variables analyzed responded to N deposition, although the response of some of them was saturated with only 10 kg N ha⁻¹ year⁻¹ over the background (nitrate reductase; phosphomonoesterase; tissue N and K⁺). The response of indicators such as chlorophyll a and lutein contents did not show any evidence of saturation, which probably makes them the best candidates in monitoring programs. Based on the data provided, the applicability of the phosphomonoesterase can also be considered. In addition, the importance of taking into account the existence of superimposed environmental gradients (such as those in soil mineral N content) interacting with the response of P. squarrosa to predict impacts of N deposition has been demonstrated. Therefore, detailed soil surveys and integrative physiological evaluations will be required to produce a significantly better picture of the effects of N deposition on Mediterranean ecosystems along extant N deposition gradients.

The use of Cu-based fungicide can pose a risk to nearby surface water bodies due to the run-off of accumulated Cu from agricultural soils. In 2008, we conducted a reconnaissance survey of the presence and concentration of copper in sediments at 18 sites within the Yarra River Catchment, an important horticultural production system in south-eastern Australia. Observed Cu concentrations in sediment samples from the study sites (mean (95 % confidence interval) 12.0 (10.6-13.6) mg/kg dry weight) were similar to the concentrations present in the samples from the reference sites (mean (95 % confidence interval) 12.0 (6.7-16.8) mg/kg dry weight). The data on Cu and other metals in the sediments suggest that that there is unlikely to have been wide spread, diffuse, off-site transport of Cu from the soils of horticultural properties to nearby surface waterways in the Yarra River Catchment and that that observed sediment metal concentrations are unlikely to pose an ecological risk to sediment-dwelling organisms at the study sites. © 2013 Springer Science+Business Media Dordrecht.

Two cadmium-resistant bacteria, Ralstonia sp. TAK1 and Arthrobacter sp. TM6, produced exopolymers that promoted cadmium solubilization in contaminated soil. The enhancement of cadmium uptake and accumulation in a monocot (Vetiveria nemoralis, vetiver grass) and a dicot (Ocimum gratissimum, African basil) was investigated in a greenhouse study. Compared with the uninoculated control, Ralstonia sp. TAK1 and Arthrobacter sp. TM6 increased cadmium accumulation in the roots and shoots of V. nemoralis. These cadmium-resistant bacteria increased the cadmium content of whole V. nemoralis plants similarly to ethylenediaminetetraacetic acid (EDTA) treatment alone. In contrast, only Arthrobacter sp. TM6 enhanced cadmium accumulation in the roots and shoots of O. gratissimum. The highest cadmium content of whole O. gratissimum plants was observed when the plant was treated with EDTA following treatment with Arthrobacter sp. TM6. The phytoextraction coefficient and translocation factor (TF) of bacteria-inoculated V. nemoralis were higher than those of O. gratissimum. Arthrobacter sp. TM6 increased the phytoextraction coefficients and TFs in V. nemoralis and O. gratissimum. These results indicate that Arthrobacter sp. TM6 and both tested plant species promote cadmium phytoextraction in contaminated soil.

A simple flow-based method was developed for the selective separation of arsenic species (+3 and +5) using a macrocycle-immobilized solid phase extraction (SPE) system, commonly known as molecular recognition technology (MRT) gel. Arsenic species in solution or in the eluent were subsequently quantified with graphite furnace atomic absorption spectrometry. The separation behaviors of As(III) and As(V) on MRT–SPE were investigated. It was found that As(V) can be selectively collected on the SPE system within the range of pH 4 to 9, while As(III) was passed through the MRT–SPE. The retention capacity of the MRT–SPE material for As(V) was found to be 0.25 ± 0.04 mmol g⁻¹. The detection limit of the method for As(V) was 0.06 μg L⁻¹, and the relative standard deviation was 2.9 % (n = 10, C = 1 μmol L⁻¹). Interference from the matrix ions was studied. In order to validate the developed method, certified reference materials of effluent wastewater and groundwater samples were analyzed, and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of tri- and pentavalent arsenic in natural water samples showing satisfactory recoveries (≥ 98.7 %).

Uptake, bioaccumulation, and assimilation of ferricyanide by three different species of willows was investigated. Intact prerooted weeping willows (Salix babylonica L.), Hankow willows (Salix matsudana Koidz), and hybrid willows (S. matsudana Koidz × alba L.) were grown hydroponically and treated with ferricyanide at 25.0 ± 0.5 °C for 144 h. Willows without leaves were also investigated as a treatment to quantify effect of transpiration on transport and assimilation of ferricyanide. Dissociation of ferricyanide to free cyanide in solution in absence of light was negligible. Phytotransport of ferricyanide was apparent. The phytoremoval rate of ferricyanide obtained varied with willow species (p < 0.05). Remarkable decreases in the removal rate were detected with the trees without leaves compared with the intact trees (p < 0.01). Due to small amounts of the applied ferricyanide recovered in plant materials, ferricyanide removed from the hydroponic solution was largely assimilated by plants. Transpiration stream concentration factor (TSCF) was also estimated using the content of iron (Fe). These information suggests that phytodegradation is a major process involved in botanical assimilation of ferricyanide through an undefined degradation pathway.

Application of an agricultural residue (rice husk, RH) as a raw material for catalyst support for advanced oxidative processes (AOPs) was evaluated. The supported catalyst was produced by the calcination of TiCl₄ impregnated in RH, thereby providing a composite TiO₂/Si-C, which was characterized by elemental analysis (CHN), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX), X-ray photoelectron spectroscopy (XPS), UV/VIS diffuse reflectance spectroscopic (DRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), atomic force microscopy (AFM), SEM, and nitrogen adsorption–desorption isotherms (BET and BJH). Catalytic photodecomposition of methylene blue (MB), naphthalene, phenol, and abamectin and acid drainage of a mine by a titania-based catalyst composite were investigated. For comparative purposes, a commercial photocatalyst (TiO₂) was also employed. Photocatalytic degradation of MB, phenol, naphthalene, abamectin, and from coal mining effluent ranged from 8 to 93 % of the initial concentration. Performances of both catalysts were comparable. Additionally, in these evaluated systems, the toxicity of the effluent decreased after photocatalysis, either for Daphnia magna or for Scenedesmus subspicatus (employed as bioindicators).

As a polycyclic aromatic hydrocarbon (PAH), pyrene is one of hazardous persistent organic pollutants in the aquatic environment. The aim of this study was to investigate the influence of denitrifying conditions on pyrene degradation in a pure culture. With a strain isolated from petrol-contaminated river sediment, treatments of pyrene biodegradations were set up using various ratios of nitrate to nitrite (NO₃ ⁻/NO₂ ⁻). Results showed that various NO₃ ⁻/NO₂ ⁻ conditions significantly influenced the anaerobic pyrene degradation efficiency. Nitrite could induce the complete denitrification process so that NO₂ ⁻ acted as a key factor to promote high degradation efficiency. The low N treatment of NO₃ ⁻ and NO₂ ⁻ concentrations made the denitrifying-pyrene-degradation process more effective. Additionally, high C/N value stimulated high degradation rates. High concentrations of NO₃ ⁻ and NO₂ ⁻ as well as toxic intermediate product accumulation might inhibit the bacterial growth and biodegradation process. The information from this study should be useful to design bioremediation strategies of PAH.

Mining creates large amounts of processed waste in the form of mine tailings. Sulfide mine tailings are of particular concern due to the biotic and abiotic oxidation of sulfide minerals that release acidity and metals into the environment. Revegetation can be employed to mitigate the spread of tailings in the environment. Revegetation often involves ameliorating tailings with organic materials to promote plant growth and improve tailings physicochemical structure. We amended plots in the Central Manitoba Mine tailings pond with humic substances applied at rates up to 4 g C kg-1 through roto-tilling and seeded with Medicago sativa and Elymus trachycaulus in 2003 and 2004. The humic substances improved tailings fertility by increasing macro aggregation, organic carbon, and macronutrients but also resulted in a short-term increase in electrical conductivity levels. In the first growing season the humic amendment had little effect on plant yield, except in the 2003 experiment where the yield of E. trachycaulus decreased by 84 % with 4 g C kg-1 amendment. After 7 years, the addition of humic amendment resulted in a cover of over 38 % for M. sativa, compared to less than 2 % in control plots. In addition, non-seeded species cover increased with amendment rate in the 2003 experiment but not the 2004 experiment, most likely due to lower pH in the latter. Our results suggest that short-term patterns of plant performance do not reflect longer-term performance or invasion by volunteer plant species. Our long-term data suggest that humic amendments can be effective in establishing plant invasion of mine tailings, although the effects vary depending on the pH of the tailings. © 2013 Springer Science+Business Media Dordrecht.

A comparative long-term study of three subsurface horizontal-flow (HF) constructed wetlands (CW) treating winery wastewater was carried out. The water depth for HF1 was 0.3 m, while the depth for HF2 and HF3 was 0.6 m, respectively. Hydraulic loading rate ranged from 7 to 93 mm/d, while surface loading rates fell into the following ranges: 4–85 g COD/m²·d, 2–49 g BOD₅/m²·d and 0.5–6 g TSS/m²·d. The percentage of biological oxygen demand (BOD₅) removal clearly decreased when influent concentration increased, while surface removal rate increased and reached a maximum of approximately 8 g BOD₅/m²·d removed in the range of 10–20 g BOD₅/m²·d fed, depending on the CW depth. HF1 showed a worse performance than the other units, appearing to be more affected by high influent concentrations. Solids accumulation on gravel media, hydraulic conductivity and gas emissions were monitored over the 2.8 years of operation.