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.

This study investigates the impacts on the Australian native eastern long-necked turtle Chelodina longicollis of wetland waters derived from (1) precipitation and groundwater flow and wetlands also supplemented with (2) irrigation runoff from agricultural lands, (3) tertiary-treated sewage effluent and (4) harvested stormwater. Influences of water quality parameters on population attributes of the turtle population are considered. A total of 951 C. longicollis were captured in a mark-recapture study over 8 months. Overall, a female sex ratio bias was observed, and a larger number of smaller turtles were found in wetlands not contaminated by recycled tertiary-treated effluent. Dissolved oxygen, temperature, surface area and emergent vegetation had the greatest impact on turtle population structure. The lower the dissolved oxygen, the smaller the surface area of the wetland, and the higher the percentage of emergent vegetation, the greater the number of juveniles present. Water quality parameters which would be detrimental to fish predators appear to provide a ‘safe haven’ for juvenile turtles at the most vulnerable life stage of turtles.

Clay minerals have been utilized for the remediation of heavy metal-polluted soil. However, information on the remediation stability of various clay minerals with different performances is limited. In this study, a kind of palygorskite (PAL) with a sorption amount for Cd²⁺about 40 mg/g, which is much larger than common minerals, was selected as amendment for in situ immobilization field demonstration. Besides, sorption stability which is essential for remediation was investigated in an ideal solid solution system by sorption and desorption behaviors of Cd²⁺on PAL, including isotherms, kinetics, and various stimulated environmental factors such as pH, temperature, and background electrolytes. The calculated thermodynamic parameters confirmed the sorption process was endothermic and driven by entropy changes. Only minimal desorption was caused by stimulated irrigation or runoff and acid rain. The temperature, pH, and background electrolyte dependence confirmed that the sorption of Cd²⁺on PAL was stable. Various characterization results including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) mapping, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) confirmed the sorption mechanisms were surface precipitation of CdCO₃and surface complexation with hydroxyl groups.