. Soil formation is the result of a complex network of biological as well as chemical and physical processes. The role of soil microbes is of high interest, since they are responsible for most biological transformations and drive the development of stable and labile pools of carbon (C), nitrogen (N) and other nutrients, which facilitate the subsequent establishment of plant communities. Forefields of receding glaciers provide unique chronosequences of different soil development stages and are ideal ecosystems to study the interaction of bacteria, fungi and archaea with their abiotic environment. In this review we give insights into the role of microbes for soil development. The results presented are based on studies performed within the Collaborative Research Program DFG SFB/TRR 38 ( http://www.tu-cottbus.de/ecosystem ) and are supplemented by data from other studies. The review focusses on the microbiology of major steps of soil formation. Special attention is given to the development of nutrient cycles on the formation of biological soil crusts (BSCs) and on the establishment of plant–microbe interactions.

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The role of microorganisms at different stages of ecosystem development for soil formation

Contents 531 I. 531 II. 532 III. 534 IV. 535 V. 535 VI. 535 Acknowledgements 536 References 536 SUMMARY: There is growing evidence that life has been on land for billions of years. Microbial mats fuelled by oxygenic photosynthesis were probably present in terrestrial habitats from c. 3.0 billion yr ago (Ga) onwards, creating localized 'oxygen oases' under a reducing atmosphere, which left a characteristic oxidative weathering signal. After the Great Oxidation c. 2.4 Ga, the now oxidizing atmosphere masked that redox signal, but ancient soils record the mobilization of phosphorus and other elements by organic acids in weathering profiles. Evidence for Neoproterozoic 'greening of the land' and intensification of weathering c. 0.85-0.54 Ga is currently equivocal. However, the mid-Palaeozoic c. 0.45-0.4 Ga shows global atmospheric changes consistent with increased terrestrial productivity and intensified weathering by the first land plants.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.14338

Matworld – the biogeochemical effects of early life on land

Quantitative determination of the effect of temperature on mudstone decay during wet–dry cycles: A case study of ‘purple mudstone’ from south-western China

Biogenic deterioration of Egyptian limestone monuments: treatment and conservation

Lake Baikal is the largest freshwater body on Earth, once famous for its pristine conditions. However, the lake and its drainage basin with their unique ecosystems have in recent decades been subject to both climate warming above the world average and severe anthropogenic pressures from mining and agriculture. Although previous studies have targeted various hydroclimatic, geochemical, and biological conditions of the Lake Baikal basin, the heterogeneous nature and large size of the basin leave considerable knowledge gaps regarding ongoing metal contamination of the basin’s suspended sediments and waters. To address these knowledge gaps, the main objectives of this study are to (i) determine regional background values for water and suspended sediment quality with respect to multiple metals (representing undisturbed conditions) and (ii) further evaluate spatio-temporal concentration patterns of these metals, including regions with heavy anthropogenic impacts. We synthesize data from extensive field measurements within the Selenga River basin performed between 2011 and 2016, covering over 100 sampling locations. Results show that although the background metal concentrations (of both dissolved and suspended metal forms) in the alkaline Selenga River waters were close to the world averages, metal concentrations of up to two orders of magnitude above the background values were seen for Zn, As, Cd, Cu, Mo, and Pb in regions subject to anthropogenic impacts (cities and the mining industry). Specifically, dissolved As levels within the Selenga River basin were 2–5 times higher than the world average and well above the global guideline value in several regions. Notable hotspots for anthropogenic impacts of Cd were particularly found in Zakamensk and Ulaanbaatar. Our results highlight clear anthropogenic impacts and large-scale spreading of several pollutants of concern, with risks even to downstream parts including the Selenga delta and Lake Baikal. We expect that these results will aid in increasing the understanding of large-scale metal transport processes, as well as for designing relevant measures to mitigate further spreading of metals to Lake Baikal.

https://www.mdpi.com/2073-4441/12/8/2137/pdf

River Water Quality of the Selenga-Baikal Basin: Part I—Spatio-Temporal Patterns of Dissolved and Suspended Metals

The bio-weathering of basalt, granite and gneiss was experimentally investigated in this study These rock-forming minerals weathered more rapidly via the ubiquitous psychrotrophic heterotrophic bacteria With indigenous bacteria of Bacillus spp from sediments of Lake Baikal, we traced the degradation process of silicate minerals to understand the weathering processes occurring at the change temperature in the subsurface environment with organic input The bacteria mediated dissolution of minerals was monitored with solution and solid chemistry, X-ray analyses as well as microscopic techniques We determined the impact of the bacteria on the mineral surface and leaching of K, Ca, Mg, Si, Fe, and Al from silicate minerals In the samples the release of major structural elements of silicates was used as an overall indicator of silicate mineral degradation at 4°C and 18°C from five medium exchanges over 255 days of rock bioleaching The increase of temperature importantly affected the efficiency of Fe extraction from granite and basalt as well as Si extraction from granite and gneiss In comparison with elemental extraction order at 4°C, Ca was substituted first by Fe or Si It is evident that temperature influences rock microbial weathering and results in a change of elements extraction

I. Štyriak

Papers

Rock weathering by indigenous heterotrophic bacteria of Bacillus spp. at different temperature: a laboratory experiment