Geochemistry and microbiology of tropical serpentine soils in the Santa Elena Ophiolite, a landscape-biogeographical approach.

The Santa Elena Ophiolite is a well-studied ultramafic system in Costa Rica mainly comprised of peridotites. Here, tropical climatic conditions promote active laterite formation processes, but the biogeochemistry of the resulting serpentine soils is still poorly understood. The aim of this study was to characterize the soil geochemical composition and microbial community of contrasting landscapes in the area, as the foundation to start exploring the biogeochemistry of metals occurring there.

Reduced plate motion controlled timing of Early Jurassic Karoo-Ferrar large igneous province volcanism.

Past large igneous province (LIP) emplacement is commonly associated with mantle plume upwelling and led to major carbon emissions. One of Earth's largest past environmental perturbations, the Toarcian oceanic anoxic event (T-OAE; ~183 Ma), has been linked to Karoo-Ferrar LIP emplacement. However, the role of mantle plumes in controlling the onset and timing of LIP magmatism is poorly understood.

New age constraints on the Lower Jurassic Pliensbachian-Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina).

The Pliensbachian-Toarcian boundary interval is characterized by a ~ 3‰ negative carbon-isotope excursion (CIE) in organic and inorganic marine and terrestrial archives from sections in Europe, such as Peniche (Portugal) and Hawsker Bottoms, Yorkshire (UK). A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from the Southern Hemisphere Arroyo Chacay Melehue section, Chos Malal, Argentina, corroborating the global significance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment are accompanied by high-resolution ammonite and nannofossil biostratigraphy together with U-Pb CA-ID-TIMS geochronology derived from intercalated volcanic ash beds.

The Microbiology of Metal Mine Waste: Bioremediation Applications and Implications for Planetary Health.

Mine wastes pollute the environment with metals and metalloids in toxic concentrations, causing problems for humans and wildlife. Microorganisms colonize and inhabit mine wastes, and can influence the environmental mobility of metals through metabolic activity, biogeochemical cycling and detoxification mechanisms. In this article we review the microbiology of the metals and metalloids most commonly associated with mine wastes: arsenic, cadmium, chromium, copper, lead, mercury, nickel and zinc.

An astronomically dated record of Earth's climate and its predictability over the last 66 million years.

Much of our understanding of Earth's past climate comes from the measurement of oxygen and carbon isotope variations in deep-sea benthic foraminifera. Yet, long intervals in existing records lack the temporal resolution and age control needed to thoroughly categorize climate states of the Cenozoic era and to study their dynamics. Here, we present a new, highly resolved, astronomically dated, continuous composite of benthic foraminifer isotope records developed in our laboratories.

In situ arsenic oxidation and sorption by a Fe-Mn binary oxide waste in soil.

The ability of a Fe-Mn binary oxide waste to adsorb arsenic (As) in a historically contaminated soil was investigated. Initial laboratory sorption experiments indicated that arsenite [As(III)] was oxidized to arsenate [As(V)] by the Mn oxide component, with concurrent As(V) sorption to the Fe oxide. The binary oxide waste had As(III) and As(V) adsorption capacities of 70mgg and 32mgg respectively.

Mercury evidence for pulsed volcanism during the end-Triassic mass extinction.

The Central Atlantic Magmatic Province (CAMP) has long been proposed as having a causal relationship with the end-Triassic extinction event (∼201.5 Ma). In North America and northern Africa, CAMP is preserved as multiple basaltic units interbedded with uppermost Triassic to lowermost Jurassic sediments.

Charcoal evidence that rising atmospheric oxygen terminated Early Jurassic ocean anoxia.

The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth's oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO) leading to termination of an OAE after ∼1 Myr. Wildfire is highly responsive to changes in pO implying that fire-activity should vary across OAEs.

Fungal decomposition of terrestrial organic matter accelerated Early Jurassic climate warming.

Soils - constituting the largest terrestrial carbon pool - are vulnerable to climatic warming. Currently existing uncertainties regarding carbon fluxes within terrestrial systems can be addressed by studies of past carbon cycle dynamics and related climate change recorded in sedimentary successions. Here we show an example from the Early Jurassic (early Toarcian, c.

Jurassic climate mode governed by ocean gateway.

The Jurassic (∼201-145 Myr ago) was long considered a warm 'greenhouse' period; more recently cool, even 'icehouse' episodes have been postulated. However, the mechanisms governing transition between so-called Warm Modes and Cool Modes are poorly known. Here we present a new large high-quality oxygen-isotope dataset from an interval that includes previously suggested mode transitions.