Examination of the Community Multiscale Air Quality (CMAQ) model performance over the North American and European domains

Copyright 2011 Elsevier B.V., All rights reserved.The CMAQ modeling system has been used to simulate the air quality for North America and Europe for the entire year of 2006 as part of the Air Quality Model Evaluation International Initiative (AQMEII). The operational model performance of tropospheric ozone (O), fine particulate matter (PM) and total particulate matter (PM) for the two continents has been assessed. The model underestimates daytime (8am-8pm LST) O mixing ratios by 13% in the winter for North America, primarily due to an underestimation of daytime O mixing ratios in the middle and lower troposphere from the lateral boundary conditions. The model overestimates winter daytime O mixing ratios in Europe by an average of 8.4%. The model underestimates daytime O by 4-5% in the spring for both continents, while in the summer daytime O is overestimated by 9.8% for North America and slightly underestimated by 1.6% for Europe. The model overestimates daytime O in the fall for both continents, grossly overestimating daytime O by over 30% for Europe. The performance for PM varies both seasonally and geographically for the two continents. For North American, PM is overestimated in the winter and fall, with an average Normalized Mean Bias (NMB) greater than -30%, while performance in the summer is relatively good, with an average NMB of -4.6%. For Europe, PM is underestimated throughout the entire year, with the NMB ranging from -24% in the fall to -55% in the winter. PM is underestimated throughout the year for both North America and Europe, with remarkably similar performance for both continents. The domain average NMB for PM ranges between -45% and -65% for the two continents, with the largest underestimation occurring in the summer for North American and the winter for Europe.Peer reviewedSubmitted Versio

Bioaccumulation of Zinc in some organs of rabbits

Zinc bioaccumulation in various organs of rabbits, Oryctolagus cuniculus, was determined using Atomic Absorption Spectrophotometer. The study was conducted under laboratory conditions. Three replicates were done, each replicate is composed of six two to three months old male rabbits that were evenly divided into control and treated groups. Intravenous injection of 0.9 percent saline solution for control group was made, while, the treated group was exposed to 16.54 mg/kg sub lethal dose of zinc. Organs of rabbits were analyzed, these are the small intestine, large intestine, stomach, muscles, kidneys, lungs, liver and heart. Results showed that the organ that accumulated the highest zinc concentration in the treated group is the small intestine with a mean value of 0.1905 + 0.0083 mg/g, followed by (in decreasing order) large intestine 0.1701 + 0.0083 mg/g, stomach 0.1709 + 0.0155 mg/g, lungs 0.1733 + 0.0021 mg/g, kidney 0.1710 + 0.0020 mg/g, lungs 0.1733 + 0.0021 mg/g, liver 0.1880 + 0.0123 mg/g and heart 0.1370 + 0.0030 mg/g. Statistical analysis showed that there was a slight significant difference in the accumulation of zinc between the control and treated groups in most part of the organs except liver and heart were the zinc concentration is insignificant