PubMed · 14798981
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H H HUDSON. 1951. Maximum allowable concentrations.. https://pubmed.ncbi.nlm.nih.gov/14798981/
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Previous research has indicated that foliar mercury (Hg) flux is bi-directional, with influence from both atmospheric and soil Hg. This work investigated the role of soil and air Hg concentrations on foliar Hg exchange using a single-plant gas-exchange system. The exchange of Hg vapor with aspen seedlings grown in soil Hg concentrations of 0.03+/-0.01, 5.8+/-0.5, and 12.3+/-1.3 microg g(-1) and exposed to atmospheric Hg concentrations of 2.4+/-0.5, 11.0+/-0.9, and 30.4+/-2.2 ng m(-3) was measured. At background atmospheric Hg concentrations of 2.4 ng m(-3), foliage released Hg at all three soil Hg concentrations and fluxes ranged from 1.6 to 5.5 ng/m(2)/h. At higher atmospheric Hg concentrations (>11 ng m(-3)), net deposition to foliage ranged from -9 to -47 ng/m(2)/h, exhibiting increase uptake with higher air Hg concentrations. Fluxes associated with aspen showed an immediate response to changes in atmospheric Hg concentrations. Compensation points, the air concentration where no net flux of Hg vapor occurred, were 3-4 ng m(-3) in the light and 2-3 ng m(-3) in the dark for trees grown in soils of 0.03 and 6 microg g(-1) Hg content, and 5-6 ng m(-3) in the light and 2.5-3.5 ng m(-3) in the dark for trees grown in 12 microg g(-1) Hg soils.
A photochemical process is proposed as a new efficient N(2)O removal technique in N(2) or air at atmospheric pressure and room temperature without using any catalysts. N(2)O diluted in N(2) or air was decomposed into N(2), O(2), and NO by using a 193 nm ArF excimer laser. The maximum conversion of N(2)O in N(2)O/N(2) or N(2)O/N(2)/O(2) mixtures was 93% at a laser power of 136 mJ, a repetition frequency of 5 Hz, and an irradiation time of 30 min. The formation ratios of N(2):O(2):NO in N(2)O/N(2) and N(2)O/N(2)/O(2) mixtures were 64:31:5.1% and 60:27:13%, respectively. The decomposition mechanism of N(2)O under 193 nm photolysis was discussed by comparing experimental data with calculated model using known photochemical and gas kinetic data.
Elution of metals from Ni- and Fe-based alloy (i.e. Inconel 625 and SUS 316) under hydrothermal conditions was investigated. Results showed that metals could be eluted even in a short contact time. At subcritical conditions, a significant amount of Cr was extracted from SUS 316, while only traces of Ni, Fe, Mo, and Mn were eluted. In contrast, Ni was removed in significant amounts compared to Cr when Inconel 625 was tested. Several factors including temperature and contact time were found to affect elution behavior. The presence of air in the fluid even promoted elution under subcritical conditions.