Apparent resistance to fall in forced vital capacity in children with increasing mass level of fine particulate: A physiological phenomenon

Abstract

Forced vital capacity (FVC) of children in the age group 10–12 years are reported as a function of quantum increase in PM_2.5 level in ambient air. The data are reported for the children in the categories based on their respective body mass index (BMI). FVC (% predicted) values decreased with increasing level of PM_2.5. The subjects are found to respond in a selective manner as plateau was observed for FVC values against some selected ranges of PM_2.5 concentration levels (74 µgm^?3 to >117 µgm^?3). To explain this unusual behavior, sac theory is proposed which explains the observations of FVC for subjects of all categories with different BMI values.     

Field evaluation of heat units for predicting crop residue carbon and nitrogen mineralization

More efficient fertilization practices could conceivably be developed if nutrient availability from manures and crop residues could be accurately predicted under field conditions. Heat units were recently found useful for describing the combined thermal and temporal relationships with papermill sludge C and N mineralization. This study was conducted to describe C and N mineralization of corn (Zea mays L. cv. ‘King 1113’), lupin (Lupinus albus L. cv. ‘ultra’), and potato (Solanum tuberosum L. cv. ‘russet burbank’) residues and to field test the utility of heat units in predicting these processes. Residues of each crop were applied to soil microplots in May, June, and July of 1987. Carbon mineralization was monitored by periodic capture of evolved CO₂ in alkali traps. Nitrogen mineralization-immobilization processes were followed by frequent sampling for KCl extractable inorganic N. Net N mineralization from the potato residue occurred almost immediately after residue application, apparently owing to its relatively low C/N of 15/1. Net N mineralization from the corn and lupin residues began 119, 99, and 317 d after application in the May, June, and July application months, respectively. These respective times represented 2346, 1990, and 2360 degree days after application. Heat units appear to provide a mathematically simple, pragmatic approach for predicting crop residue N mineralization under field climatic conditions.