Improvement of Vicia-micronucleus test for assessment of soil quality: a proposal for international standardization

The Viciafaba root tip micronucleus test is one of the most employed plant genotoxicity assays, and has been used on various types of contaminated materials. This test has been standardized by AFNOR, the French member organization of ISO. However, this test is usually performed with a water extraction step but soil genotoxicity assessment would be more relevant when performed directly in the soil itself. In order to harmonize these protocols, an ISO standard for the V.faba micronucleus test in both liquid phase (exposure of plants to different liquid matrix, including soil water extracts) and solid phase (direct exposure of plants to the soil) would be very useful. In this context, we compared two exposure durations in the solid phase (48 h and 5 d) for the V.faba micronucleus test with two different well-known genotoxicants, maleic hydrazide and copper sulfate. We concluded that these two durations induced equivalent sensitivity: the micronucleus frequency was significantly increased with 5 μmol maleic hydrazide per kg dry soil and with 2 mmol copper sulfate per kg dry soil with both exposure durations. However, exposing roots to soil during 48 h is more practical. Moreover, organically and conventionally cultured seeds were employed to determine whether the seed provenance influenced the test sensitivity. Organic seeds were less sensitive to copper, possibly because copper-based treatments are permitted, and often applied, in organic farms. Therefore, in the absence of completely non-treated seeds, organically-cultured seeds did not appear to offer any advantages over conventional seeds.     

Influence of papermill sludge on growth of Medicago sativa, Festuca rubra and Agropyron trachycaulum in gold mine tailings: a greenhouse study

A greenhouse study was undertaken to determine the suitability of adding papermill sludge to neutral/alkaline gold mine tailings to improve the establishment of Festuca rubra, Agropyron trachycaulum and Medicago sativa. Festuca rubra root and shoot biomass and A. Trachycaulum shoot biomass were increased with papermill sludge amendment. The addition of papermill sludge and fertilizer drastically increased the shoot and root biomass of M. sativa (20-30 times) while A. trachycaulum and F. rubra showed a more moderate increase in growth. Photosynthetic pigment content of the leaves was higher in papermill sludge treatments than in the treatments without papermill sludge. The organic carbon content, macro-aggregate content and field capacity of the gold mine tailings were increased while the bulk density was decreased by the addition of papermill sludge. This study suggests that addition of papermill sludge and adequate fertilization can alleviate some of the adverse conditions of neutral/alkaline gold mine tailings.     

Children's appreciation of outdoor places in a poor neighborhood

Children 7–12 years of age, living in a poor neighborhood, photographed outdoor places where they liked to go in their neighborhood. In individual interviews, they discussed their photos, selected their favorite place, and discussed the places they disliked. Children identified parks and playgrounds most often both as liked and disliked places, and spaces near an acquaintance's home as their favorite place. Liked places varied according to children's age and degree of vegetation. Children's negative perceptions of places were centered on safety threats. Children distinguish favorite places from liked places only by the greater number of positive characteristics and activities they offer children. The study highlights how positive and negative features coexist in places of importance to these children.     

Biodegradation of naphthenic acids by rhizosphere microorganisms

Naphthenic acids are components of most petroleums, including those found in the Athabasca Oil Sands of northeastern Alberta. Some naphthenic acids that are solubilized during bitumen extraction from oil sands are acutely toxic to a variety of organisms. Four-month enrichment cultures obtained from the rhizospheres of five plant species native to Alberta, and established with the addition of bitumen (0.5%) as the sole carbon source, revealed a high potential for aerobic degradation of a Merichem commercial preparation of naphthenic acids. Changes in the concentration and composition of the naphthenic acids mixtures during incubation were followed using high-performance liquid chromatography and gas chromatography-electron impact mass spectrometry. Concentrations did not significantly change in the sterile control, but they decreased by up to 90% after 10 days of incubation in the viable cultures. Lower molecular mass naphthenic acids were preferentially degraded, while the proportion of high molecular mass acids increased during incubation. By day 17, the most abundant ions were derived from cellular membranes, corresponding to an increase in microbial numbers in the cultures as naphthenic acids were metabolized. This study is the first to demonstrate the biodegradation potential of microorganisms from rhizosphere soils to biodegrade naphthenic acids.     

Assessment of a sewage sludge treatment on cadmium, copper and zinc bioavailability in barley, ryegrass and earthworms

The toxicity and bioavailability of metals were assessed to verify the efficiency of a new chemical leaching process (METIX-AC) to minimize the risk of metals found in municipal sewage sludge. For this purpose, sludge samples were spiked with cadmium, copper and/or zinc before being treated using METIX-AC. The sludge decontamination resulted in a removal of spiked metals (79-89%), in a decrease of the more labile fractions, and in a corresponding increase of the residual fraction. The toxicity observed after exposure of two plant species, barley (Hordeum vulgare) and ryegrass (Lolium perenne), and a terrestrial invertebrate, Eisenia andrei, to sludge-soil mixtures, disappeared after treatment, although the adverse effects were minor before treatment. The sludge treatment also significantly decreased the bioaccumulation of cadmium, copper, and zinc in the exposed species. For cadmium, maximum tissue concentrations of 0.45+/-0.08 mg/kg in barley, 0.79+/-0.27 mg/kg in ryegrass, and 21.82+/-1.85 mg/kg in earthworm exposed to sludge before treatment decreased after treatment to values similar to those observed with negative controls.     

Synthesis of Biobased Soft-Packaging Polyesters from 2,5 Thiophenedicarboxylic Acid

Journal of Polymers and the Environment - Demand for light-packaging materials for food and beverages is on the rise globally, especially in developing countries where several depend on packaged...