A multi-model study of the hemispheric transport and deposition of oxidised nitrogen.

Fifteen chemistry-transport models are used to quantify, for the first time, the export of oxidised nitrogen (NOy) to and from four regions (Europe, North America, South Asia, and East Asia), and to estimate the uncertainty in the results. Between 12 and 24% of the NOx emitted is exported from each region annually. The strongest impact of each source region on a foreign region is: Europe on East Asia, North America on Europe, South Asia on East Asia, and East Asia on North America. Europe exports the most NOy, and East Asia the least. East Asia receives the most NOy from the other regions. Between 8 and 15% of NOx emitted in each region is transported over distances larger than 1000 km, with 3–10% ultimately deposited over the foreign regions

Hydroxylation of benzo[a]pyrene and binding of (-)trans 5-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene metabolites to deoxyribonucleic acid catalyzed by purified forms of rabbit liver microsomal cytochrome P-450 : Effect of 7,8-benzoflavone, butylated hydroxytoluene and ascorbic acid

The catalytic activities of hepatic microsornes from untreated, phenobarbital-treated and 3-methylcholanthrene-treated adult rabbits with respect to benzo[a]pyrene hydroxylation and the activation of (-)(rflw-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene[(-)trans-7,8-diol] to DNA-binding metabolites were determined in the absence and presence of mixed-function oxidase inhibitors and compared to the corresponding activities of the individual enzyme systems. Treatment of rabbits with phnobarbital led to induction of P-450LM2 and a concomitant 3-fold enhancement in microsomal benzo[a]pyrene hydroxylase activity, whereas the conversion of (-)trans-7,8-diol to DNA-binding products was unaffected. Homogeneous phenobarbital-inducible P-450LM2 exhibited the highest activity and specificity toward benzo[a]pyrene and the lowest activity toward (-)trans-7,8-diol. Conversely, P-450LM4 was the major form of cytochrome P-450 induced in rabbit liver by 3-methylcholanthrene or [beta]-naphthoflavone, and this was associated in microsomes with an increase in the metabolism of (-)trans-7, 8-diol but not of benzo[a]pyrene. Homogeneous P-450LM4 preferentially Catalyzed the oxygenation of (-)trans-7,8-diol, but was largely ineffective with benzo[a]pyrene. Partially purified P-450LM7 lacked substrate specificity, for it metabolized both benzo[a]pyrene and (-)trans-7, S-diol at comparable rates. Additionally, 7,8-benzoflavone strongly inhibited benzo[a]pyrene hydroxylation by P-450LM4 and phenobarbital-induced microsomes, as well as (-)trans-7,8-diol metabolism by P-450LM4 and 3-methyl-cholanthrene-induced microsomes; in contrast, the activity of control microsomes with either substrate, and the activities of P-450LM4 and LM2 with benzo[a]pyrene and (-)trans-7 ,8-diol, respectively, were only partially or slightly decreased by 7,8-benzoflavone. Unlike 7,8-benzoflavone, butylated hydroxytoluene inhibited benzo[a]pyrene hydroxylation only. Thus, different forms of rabbit liver microsomal cytochrome P-450 were involved in the metabolism of benzo[a]pyrene and its 7,8-dihydrodiol. The results also demonstrate that the changes in substrate specificity and inhibitor sensitivity seen in phenobarbital- and 3-methylcholanthrene-induced microsomes relative to control rabbit liver microsomes can be accounted for by the catalytic properties of a specific form of cytochrome P-450 that prevails in these preparations, P-450LM2 and LM4, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23220/1/0000149.pd

Acknowledgment to Reviewers of Pollutants in 2021

Rigorous peer-reviews are the basis of high-quality academic publishing [...

Acknowledgment to the Reviewers of Pollutants in 2022

High-quality academic publishing is built on rigorous peer review [...

Control Strategies for Sub-Micrometer Particles Indoors: Model Study of Air Filtration and Ventilation

The effects of air filtration and ventilation on indoor particles were investigated using a single-zone mathematical model. Particle concentration indoors was predicted for several I/O conditions representing scenarios likely to occur in naturally and mechanically ventilated buildings. The effects were studied for static and dynamic conditions in a hypothetical office building. The input parameters were based on real-world data. For conditions with high particle concentrations outdoors, it is recommended to reduce the amount of outdoor air delivered indoors and the necessary reduction level can be quantified by the model simulation. Consideration should also be given to the thermal comfort and minimum outdoor air required for occupants. For conditions dominated by an indoor source, it is recommended to increase the amount of outdoor air delivered indoors and to reduce the amount of return air. Air filtration and ventilation reduce particle concentrations indoors, with the overall effect depending on efficiency, location and the number of filters applied. The assessment of indoor air quality for specific conditions could be easily calculated by the model using user-defined input parameters

Acknowledgment to Reviewers of <i>Pollutants</i> in 2021

Rigorous peer-reviews are the basis of high-quality academic publishing [...