Cadmium spiked soil modulates root organic acids exudation and ionic contents of two differentially Cd tolerant maize (Zea mays L.) cultivars.

Our earlier work described that the roots of two maize cultivars, grown hydroponically, differentially responded to cadmium (Cd) stress by initiating changes in medium pH depending on their Cd tolerance. The current study investigated the root exudation, elemental contents and antioxidant behavior of the same maize cultivars [cv. 3062 (Cd-tolerant) and cv.

Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements.

The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid contents. Plants were treated with a combination of As, Pb, Cu, Cd, and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48-120 h.

Preschool boys' development of emotional self-regulation strategies in a sample at risk for behavior problems.

Little longitudinal research has been conducted on changes in children's emotional self-regulation strategy (SRS) use after infancy, particularly for children at risk. In this study, the authors examined changes in boys' emotional SRS from toddlerhood through preschool. Repeated observational assessments using delay of gratification tasks at ages 2, 3, and 4 years were examined with both variable- and person-oriented analyses in a low-income sample of boys (N = 117) at risk for early problem behavior.

Root penetration through sealing layers at mine deposit sites.

To prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. Plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. The objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits.

Root penetration of sealing layers made of fly ash and sewage sludge.

Fly ash and sewage sludge are suggested materials for constructing sealing layers covering mine tailings impoundments. Little is known, however, of their effect on vegetation or resistance to root penetration. We investigate: (i) the ability of different plant species to grow in sealing layers comprising fly ash and sewage sludge, (ii) the impact on plant growth of freshly hardened fly ash compared to aged and leached ash, and (iii) the plant stress response to fly ashes of different properties.