Azo dyes, common in textile wastewater, have high photolytic and chemical stabilities, which make them difficult to be removed using conventional treatments. This study aims to evaluate a combined process using heterogeneous photocatalysis, with ZnO/UV or TiO 2 /UV (0.6 g catalyst L −1 solution/2-hr UV radiation), and a biological process for textile wastewater treatment. After the proposed treatments, the color and organic matter removals from synthetic wastewater (SW) and industrial wastewater (IW) were evaluated. For SW, the coupled photocatalytic (ZnO/UV or TiO 2 /UV)-biological system promoted a high extent of color removal (98%) and total organic carbon (TOC) reduction (>80%). Promising results were obtained with IW using combined photocatalytic (TiO 2 /UV)-biological treatments, reaching 97% and 63% of color and TOC removal, respectively. This process, coupling heterogeneous photocatalysis and a bioprocess, has proved to be a good alternative for the treatment of textile wastewater, not only for color removal but also for dye mineralization purposes. • Practitioner points• A combined process using heterogeneous photocatalysis (ZnO/UV or TiO 2 /UV) and biological process was evaluated for synthetic (SW) and industrial (IW) textile wastewaters treatment. • For SW, coupled process promoted high extent of colour and organic matter removals. • For IW, promising results were obtained with TiO 2 /UV-biological treatment (97% of colour and 63% of organic matter removals).

Grapevines grown on acid soils with low fertility in southern Brazil are treated with intense foliar applications of copper (Cu) fungicides, resulting in an increased level of Cu in the soil and increased toxicity. The present study evaluated the accumulation and bioavailability of Cu, and soils with varying levels of Cu from the main producing regions of southern Brazil were collected. The forms of Cu present in the soil were assessed using chemical extractants; additionally, oat cultivation was performed, reflecting the use of the plant as an indicator of Cu bioavailability. Cu accumulated in the topsoil, mainly in bioavailable forms, and there was also an increase of Cu up to a depth of 0.4 m. Cu was primarily found in the mineral fraction, with apparent saturation of the soil organic matter functional groups. Inceptisol and Alfisol soils with a long history of cupric fungicide application were found to have levels of Cu toxic to oat plants. Furthermore, accumulated copper in Alfisol soil from the Campanha Gaúcha region of the state of Rio Grande do Sul had higher bioavailability compared to Cu accumulated in Inceptisol soil from the Serra Gaúcha region. In addition, the copper concentration in roots was found to serve as an indicator of Cu bioavailability in soil, but not of copper phytotoxicity in plants.

A B S T R A C TThis study aimed to evaluate the performance of grapevine rootstocks under increasing levels of Zn in the soil and to identify physiological variables that can be used as indicators of excess of Zn in the soil. The rootstocks SO4, Paulsen1103, IAC572, IAC313 and 420A were grown in pots containing soil, which received Zn doses of 0, 20, 40, 80 or 160 mg kg

Core Ideas Alkaline hydrolyzable nitrogen recovery is influenced by soil drying. N‐STaR soil test quantifies a portion of clay‐fixed ammonium. NaOH recovered more clay‐fixed ammonium than KOH. The Nitrogen Soil Test for Rice (N‐STaR, Oryza sativa L.) has been calibrated and is being used to predict rice nitrogen (N) fertilizer rates. Research has identified the organic forms of N quantified via N‐STaR (NH4 released by distillation with 10 mol L–1 NaOH), but no research has looked at the ability of N‐STaR to quantify clay‐fixed NH4 (CF‐NH4). This laboratory trial was initiated to determine the amount of CF‐NH4 quantified via N‐STaR as well as the influence of soil drying conditions (oven dry vs. field moist) and alkali distillation method (NaOH vs. KOH) on the CF‐NH4 recovered. Seven soils representing five clayey and two loamy soil textures were collected from various rice‐producing regions across Arkansas from the 0‐ to 15‐cm and 15‐ to 30‐cm soil depths. Total CF‐NH4 and CF‐NH4 recovered by N‐STaR varied greatly across soils and soil depths with a range of 35 to 299 mg N kg soil–1 and 6 to 21 mg N kg soil–1, respectively. The N‐STaR recovered as much as 15% of total CF‐NH4 and recovery was greatest for silt loam soils. Alkaline hydrolyzable‐N (AH‐N) concentrations were strongly influenced by soil drying conditions and the alkali used with a higher level (22%) of AH‐N recovered from oven‐dry than field‐moist soils and a higher (7%) recovery of AH‐N with NaOH than KOH. These results indicate that the N‐STaR method recovers a small, but significant percentage of total CF‐NH4 and may capture the portion of CF‐NH4 that may be plant available during the growing season.