https://www.selleckchem.com/products/usp22i-s02.html 1 ± 0.06 ‰) and heavy Cu isotopes (Δ65Cusorbed-solution = +0.17 ± 0.06 ‰) during the day at high pH and the excretion of Zn light isotopes (‒0.4 less then Δ66Znexcreted-biofilm less then +0.14 ‰) and Cu heavy isotopes (Δ65Cuexcreted-biofilm = +0.7 ± 0.3 ‰) during the night at lower pH. We interpreted Zn and Cu diel cycles as a combination of a desorption of EPS-metal complexes and a small active efflux during the night with an adsorption and an incorporation via an active uptake during the day. The hysteresis of metal concentration in solution over diel cycle suggested the more important role of uptake compared to desorption and efflux from the biofilm. The phototrophic biofilm presents a non-negligible highly labile metal pool with an important potential for contrasting isotopic fractionation at the diel scale.Effective modeling of semivolatile organic chemical (SVOC) partitioning between air and indoor dust is investigated by calculating partition ratios for selected SVOCs between air and n-octanol as well as 8 other oligomers similar in chemical structure to common components of household dust. COSMO-RS solvation theory was used to calculate air-oligomer partition ratios, which were converted to estimates for KOA (octanol-air) and Kdust-air. The results are compared with reported monitored partition ratios with good agreement for the more volatile SVOCs of vapor pressure (VP) exceeding 10-5 Pa and corresponding calculated log Kdust-air (m3 g-1) of less then 5.5 or unitless log KOA of less then 11.5. For less volatile SVOCs, reported values of KDA are significantly lower than predicted, with the deviation increasing with decrease in VP. This effect is attributed to a kinetic delay in which characteristic times for equilibration exceed the dust-air contact time, and equilibrium is not achieved. It is hoped that the approach of computing partition ratios of SVOCs using oligomers selected on the basis of likely dus