Toxic effects of Pb2+ on the growth and mineral nutrition of signal grass (Brachiaria decumbens) and Rhodes grass (Chloris gayana)

Although grasses are commonly used to revegetate sites contaminated with lead (Pb), little is known regarding the Pb-tolerance of many of these species. Using dilute solution culture to mimic the soil solution, the growth of signal grass (Brachiaria decumbens Stapf cv. Basilisk) and Rhodes grass (Chloris gayana Kunth cv. Pioneer) was related to the mean activity of Pb2+ {Pb2+} in solution. There was a 50% reduction in fresh mass of signal grass shoots at 5 mu M {Pb2+} and at 3 mu M {Pb2+} for the roots. Rhodes grass was considerably more sensitive to Pb in solution, with shoot and root fresh mass being reduced by 50% at 0.5 mu M {Pb2+}. The higher tolerance of signal grass to Pb appeared to result from the internal detoxification of Pb, rather than from the exclusion of Pb from the root. At toxic {Pb2+}, an interveinal chlorosis developed in the shoots of signal grass (possibly a Pb-induced Mn deficiency), whilst in Rhodes grass, Pb2+ caused a bending of the root tips and the formation of a swelling immediately behind some of the root apices. Root hair growth did not appear to be reduced by Pb2+ in solution, being prolific at all {Pb2+} in both species

A community-based intervention increases physical activity and reduces obesity in school-age children in North Carolina.

BACKGROUND: Community-based interventions are promising approaches to obesity prevention, but few studies have prospectively evaluated them. The aim of this study was to evaluate a natural experiment—a community intervention designed to promote active living and decrease obesity within a small southern town. METHODS: In 2011, community leaders implemented the Mebane on the Move intervention—a community-wide effort to promote physical activity (PA) and decrease obesity among residents of Mebane, North Carolina. We measured child PA and BMI before and after the intervention, using a nearby town not implementing an intervention as the comparison. In total, we assessed 64 children from Mebane and 40 from the comparison community 6 months before, as well as 34 and 18 children 6 months after the intervention. We assessed PA with accelerometers worn for 7 days and calculated BMI z-scores using children's height and weight. We conducted multivariable linear regressions examining pre- to postintervention change in minutes of PA and BMI z-score, adjusting for confounders. RESULTS: At follow-up, children in Mebane modestly increased their moderate-to-vigorous PA (1.3 minutes per hour; 95% confidence interval (CI): 0.2, 2.3; p=0.03) and vigorous activity (0.8 minutes per hour; 95% CI: 0.1, 1.5; p=0.04) more than comparison children. In intervention children, BMI z-scores decreased 0.5 units (kg/m(2); 95% CI: -0.9, -0.02; p=0.045), compared to children in the comparison community. CONCLUSIONS: We observed positive effects on PA level and weight status of children in Mebane, despite high rates of attrition, suggesting that the community-based intervention may have been successful

A comparison of the properties of manufactured soils produced from composting municipal green waste alone or with poultry manure or grease trap/septage waste

Manufactured soil for landscaping purposes was produced by composting for 6 weeks (1) municipal green waste alone, (2) green waste amended with 25% v/v poultry manure, or (3) green waste immersed in, and then removed from, a mixture of liquid grease trap waste/septage. Composting temperatures increased most rapidly and reached highest values (78°C) in the grease trap/septage-amended green waste. In comparison with green waste alone, addition of poultry manure prolonged the period of elevated temperatures and increased the maximum temperature attained from 52°C to 61°C. Following composting, each of the materials was split into (1) 100% compost, (2) 80% compost plus 20% v/v soil, and (3) 70% compost plus 20% soil plus 10% coal fly ash. Addition of poultry manure or grease trap/septage to green waste prior to composting increased bulk density and reduced total porosity of the composted product. Addition of soil, or soil and ash, to composts increased bulk density, reduced total porosity, decreased percentage macropores, and increased percentage mesopores and available water-holding capacity. Bicarbonate-extractable P, exchangeable NH and NO, electrical conductivity (EC), soluble C, soluble C as a percentage of organic C, basal respiration, and metabolic quotient were all markedly greater in the grease trap/septage-amended than poultry manure-amended or green waste alone treatments. Values for extractable P and EC were considered large enough to be damaging to plant growth and germination index (GI) of watercress was less than 60% for all grease trap/septage composts. Extractable P and EC were also high, and GI was 100%

Mg induced Ca deficiency under alkaline conditions

Little is known about Mg induced Ca deficiency in alkaline conditions, and the relationship between Mg induced Ca deficiency and Na induced Ca deficiency. Dilute nutrient solutions (dominated by Mg) were used to investigate the effect of Ca activity ratio (CAR) on the growth of mungbeans (Vigna radiata (L.) Wilczek cv. Emerald). At pH 9.0, root growth was reduced below a critical CAR of 0.050 (corresponding to 90 % relative root length). Root growth was found to be limited more in Mg solutions than had been previously observed for Na solutions. Using a CAR equation modified with plasma membrane binding constants (to incorporate the differing antagonistic effects of Mg and Na), new critical CAR values were calculated for both Na (0.56) and Mg (0.44) dominated solutions. This modified CAR equation permits the calculation of CAR irrespective of the dominant salt present