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In 1581 a Cossack raider crossed the Ural Mountains to plunder and claim for Tsar Ivan IV the land called "Sibir" by its Tatar inhabitants. Within half a century, Moscow's reach would extend nearly six thousand miles to the east. Thus Russia has a long history as part of Asia. Does it have a future there as well? Rediscovering Russia in Asia takes the reader on a trans-Siberian expedition to encounter the peoples, cultures, and riches of Russia's eastern expanses. The expert guides are scholars with the language skills and the sense of adventure to explore a "crossroads of civilizations" at long last reopened to the world

Biofiltration processes help to remove trace organic chemicals (TOrCs) both in wastewater and drinking water treatment systems. However, the detailed TOrCs biotransformation mechanisms as well as the underlying drivers behind the variability of site specific transformation processes remain elusive. In this study, we used laboratory batch incubations to investigate the biotransformation of 51 TOrCs in eight bioactive filter materials of different origins treating a range of waters, from wastewater effluents to drinking water. Microscopy, 16S rRNA amplicon and whole metagenome sequencing for assessing associations between the biotransformation rate constants, microbial composition and genetic potential complemented chemical analysis. We observed strong differences in the mean global removal of TOrCs between the individual sand filters (−1.4–58%), which were mirrored in overall biomass, microbial community composition, and enzyme encoding genes. From the six investigated biomass markers, ATP turned out to be a major predictor of the mean global biotransformation rate, while compound specific biotransformations were correlated with the microbial community composition. High biomass ecosystems were indicated in our systems by a dominance of Nitrospirae, but individual TOrC biotransformation showed a correlation with rare taxa (<2%) such as Hydrogenophaga, or individual functions such as the enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase encoding genes. In general, this study provides new insights into so far rarely addressed variability of TOrCs biotransformation. We propose potential novel biological indicators for the removal performance of TOrCs in biofiltration systems, highlighting the role of living biomass in predicting and normalizing the global transformation, and the role of the microbial community for the individual transformation of TOrCs in engineered and natural systems.