Deep-C storage: Biological, chemical and physical strategies to enhance carbon stocks in agricultural subsoils

Due to their substantial volume, subsoils contain more of the total soil carbon (C) pool than topsoils. Much of this C is thousands of years old, suggesting that subsoils offer considerable potential for long-term C sequestration. However, knowledge of subsoil C behaviour and manageability remains incomplete, and subsoil C storage potential has yet to be realised at a large scale, particularly in agricultural systems. A range of biological (e.g. deep-rooting), chemical (e.g. biochar burial) and physical (e.g. deep ploughing) C sequestration strategies have been proposed, but are yet to be assessed. In this review, we identify the main factors that regulate subsoil C cycling and critically evaluate the evidence and mechanistic basis of subsoil strategies designed to promote greater C storage, with particular emphasis on agroecosystems. We assess the barriers and opportunities for the implementation of strategies to enhance subsoil C sequestration and identify 5 key current gaps in scientific understanding. We conclude that subsoils, while highly heterogeneous, are in many cases more suited to long-term C sequestration than topsoils. The proposed strategies may also bring other tangible benefits to cropping systems (e.g. enhanced water holding capacity and nutrient use efficiency). Furthermore, while the subsoil C sequestration strategies we reviewed have large potential, more long-term studies are needed across a diverse range of soils and climates, in conjunction with chronosequence and space-for-time substitutions. Also, it is vital that subsoils are more consistently included in modelled estimations of soil C stocks and C sequestration potential, and that subsoil-explicit C models are developed to specifically reflect subsoil processes. Finally, further mapping of subsoil C is needed in specific regions (e.g. in the Middle East, Eastern Europe, South and Central America, South Asia and Africa). Conducting both immediate and long-term subsoil C studies will fill the knowledge gaps to devise appropriate soil C sequestration strategies and policies to help in the global fight against climate change and decline in soil quality. In conclusion, our evidence-based analysis reveals that subsoils offer an untapped potential to enhance global C storage in terrestrial ecosystems

Precambrian non-marine stromatolites in alluvial fan deposits, the Copper Harbor Conglomerate, upper Michigan

Laminated cryptalgal carbonates occur in the Precambrian Copper Harbor Conglomerate of northern Michigan, which was deposited in the Keweenawan Trough, an aborted proto-oceanic rift. This unit is composed of three major facies deposited by braided streams on a large alluvial-fan complex. Coarse clastics were deposited in braided channels, predominantly as longitudinal bars, whereas cross-bedded sandstones were deposited by migrating dunes or linguoid bars. Fine-grained overbank deposits accumulated in abandoned channels. Gypsum moulds and carbonate-filled cracks suggest an arid climate during deposition. Stromatolites interstratified with these clastic facies occur as laterally linked drapes over cobbles, as laterally linked contorted beds in mudstone, as oncolites, and as poorly developed mats in coarse sandstones. Stromatolites also are interbedded with oolitic beds and intraclastic conglomerates. Stromatolitic microstructure consists of alternating detrital and carbonate laminae, and open-space structures. Radial-fibrous calcite fans are superimposed on the laminae. The laminae are interpreted as algal in origin, whereas the origin of the radial fibrous calcite is problematic. The stromatolites are inferred to have grown in lakes which occupied abandoned channels on the fan surface. Standing water on a permeable alluvial fan in an arid climate requires a high water table maintained by high precipitation, or local elevation of the water table, possibly due to the close proximity of a lake. Occurrence of stromatolites in the upper part of the Copper Harbor Conglomerate near the base of the lacustrine Nonesuch Shale suggests that these depositional sites may have been near the Nonesuch Lake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72022/1/j.1365-3091.1983.tb00713.x.pd

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Addition of iron to agricultural topsoil and subsoil is not an effective C sequestration strategy

The interaction of soil organic matter (SOM) with Fe-containing minerals represents a key mechanism that promotes carbon (C) stabilisation in soil. The addition of Fe-rich industrial by-products to soil may therefore help accelerate C storage. Our understanding of the effects of exogenous Fe addition (Fe (oxy)hydroxide vs. Fe chloride) on SOM dynamics and C dynamics in agricultural soils, especially in subsoils, however, remains poor. Here, we simulate the addition of Fe in an arable soil context and assess its effectiveness based on CO2 emissions and soil chemistry. We hypothesised that insoluble and soluble Fe would reduce the mineralization of newly added unprotected organic materials more than native SOM and that soluble Fe would cause mineralisation of native SOM. To investigate this, insoluble Fe(OH)3 or soluble FeCl2 (0–5 g kg−1) were added to arable top- (0–10 cm) or subsoils (50–60 cm) and CO2 emissions, pH and nutrient dynamics (e.g. P, N) measured in a laboratory incubation over a 45 d period. We also compared the effect of Fe on the turnover of native SOM and newly added C (i.e. 14C-labelled glucose, citrate and crop residues) which was pre-mixed with exogenous Fe. We found that: (1) despite a reduction in P and DOC, Fe(OH)3 did not suppress total CO2 efflux; (2) high FeCl2 rates induced a rapid and significant release of CO2, which we attribute almost entirely to FeCl2-induced soil acidification increasing DOC availability and carbonate dissolution; (3) 14C-substrate mineralisation was weakly suppressed by Fe(OH)3 but strongly by FeCl2 following the series: citrate < glucose < crop residues; and (4) Fe addition to subsoils induced a stronger C mineralisation response but weaker effect on soil solution chemistry compared to topsoil, possibly due to subsoils having a lower buffering ability and less microbial biomass. We conclude that addition of extra Fe was not effective in promoting greater C sequestration in the arable soil we tested

Movement variability in the golf swing

Traditionally, golf biomechanics has focused upon achieving consistency in swing kinematics and kinetics, whilst variability was considered to be noise and dysfunctional. There has been a growing argument that variability is an intrinsic aspect of skilled motor performance and plays a functional role. Two types of variability are described: 'strategic shot selection' and 'movement variability'. In 'strategic shot selection', the outcome remains consistent, but the swing kinematics/kinetics (resulting in the desired ball flight) are free to vary; 'movement variability' is the changes in swing kinematics and kinetics from trial to trial when the golfer attempts to hit the same shot. These changes will emerge due to constraints of the golfer's body, the environment, and the task. Biomechanical research has focused upon aspects of technique such as elite versus non-elite kinematics, kinetics, kinematic sequencing, peak angular velocities of body segments, wrist function, ground reaction forces, and electromyography, mainly in the search for greater distance and clubhead velocity. To date very little is known about the impact of variability on this complex motor skill, and it has yet to be fully researched to determine where the trade-off between functional and detrimental variability lies when in pursuit of enhanced performance outcomes

Modeling and Simulation of Mucus Flow in Human Bronchial Epithelial Cell Cultures – Part I: Idealized Axisymmetric Swirling Flow

A multi-mode nonlinear constitutive model for mucus is constructed directly from micro- and macro-rheology experimental data on cell culture mucus, and a numerical algorithm is developed for the culture geometry and idealized cilia driving conditions. This study investigates the roles that mucus rheology, wall effects, and HBE culture geometry play in the development of flow profiles and the shape of the air-mucus interface. Simulations show that viscoelasticity captures normal stress generation in shear leading to a peak in the air-mucus interface at the middle of the culture and a depression at the walls. Linear and nonlinear viscoelastic regimes can be observed in cultures by varying the hurricane radius and mean rotational velocity. The advection-diffusion of a drug concentration dropped at the surface of the mucus flow is simulated as a function of Peclet number