Benthic Dissolved Silicon and Iron Cycling at Glaciated Patagonian Fjord Heads.

Glacier meltwater supplies silicon (Si) and iron (Fe) sourced from weathered bedrock to downstream ecosystems. However, the extent to which these nutrients reach the ocean is regulated by the nature of the benthic cycling of dissolved Si and Fe within fjord systems, given the rapid deposition of reactive particulate fractions at fjord heads. Here, we examine the benthic cycling of the two nutrients at four Patagonian fjord heads through geochemical analyses of sediment pore waters, including Si and Fe isotopes (δSi and δFe), and reaction-transport modeling for Si.

Micromagnetic Tomography for Paleomagnetism and Rock-Magnetism.

Our understanding of the past behavior of the geomagnetic field arises from magnetic signals stored in geological materials, e.g., (volcanic) rocks.

Formation of the Lunar Primary Crust From a Long-Lived Slushy Magma Ocean.

Classical fractional crystallization scenarios of early lunar evolution suggest crustal formation by the flotation of light anorthite minerals from a liquid magma ocean. However, this model is challenged by the Myr age range of primitive ferroan anorthosites, their concordance with Mg-suite magmatism and by the compositional diversity observed in lunar anorthosites. Here, we propose a new model of slushy magma ocean crystallization in which crystals remain suspended in the lunar interior and crust formation only begins once a critical crystal content is reached.

introgression and consequences for shell traits in longline cultivated mussels.

Mussels belonging to the species complex (. , ; . , ; and .

An Abrupt Aging of Dissolved Organic Carbon in Large Arctic Rivers.

Permafrost thaw in Arctic watersheds threatens to mobilize hitherto sequestered carbon. We examine the radiocarbon activity (FC) of dissolved organic carbon (DOC) in the northern Mackenzie River basin. From 2003-2017, DOC-FC signatures (1.

Genome-wide insights into introgression and its consequences for genome-wide heterozygosity in the species complex across Europe.

The three mussel species comprising the complex are widespread across Europe and readily hybridize when they occur in sympatry, resulting in a mosaic of populations with varying genomic backgrounds. Two of these species, and , are extensively cultivated across Europe, with annual production exceeding 230,000 tonnes. The third species,  , is considered commercially damaging as hybridization with this species results in weaker shells and poor meat quality.

Organic Compounds in a Sub-Antarctic Ice Core: A Potential Suite of Sea Ice Markers.

Investigation of organic compounds in ice cores can potentially unlock a wealth of new information in these climate archives. We present results from the first ever ice core drilled on sub-Antarctic island Bouvet, representing a climatologically important but understudied region. We analyze a suite of novel and more familiar organic compounds in the ice core, alongside commonly measured ions.

The Melting Column as a Filter of Mantle Trace-Element Heterogeneity.

The observed variability of trace-element concentration in basaltic lavas and melt inclusions carries information about heterogeneity in the mantle. The difficulty is to disentangle the contributions of source heterogeneity (i.e.

Radiocarbon Age Offsets Between Two Surface Dwelling Planktonic Foraminifera Species During Abrupt Climate Events in the SW Iberian Margin.

This study identifies temporal biases in the radiocarbon ages of the planktonic foraminifera species Globigerina bulloides and Globigerinoides ruber (white) in a sediment core from the SW Iberian margin (so-called ). Leaching of the outer shell and measurement of the radiocarbon content of both the leachate and leached sample enabled us to identify surface contamination of the tests and its impact on their C ages. Incorporation of younger radiocarbon on the outer shell affected both species and had a larger impact downcore.

Detailed insights into pan-European population structure and inbreeding in wild and hatchery Pacific oysters () revealed by genome-wide SNP data.

Cultivated bivalves are important not only because of their economic value, but also due to their impacts on natural ecosystems. The Pacific oyster () is the world's most heavily cultivated shellfish species and has been introduced to all continents except Antarctica for aquaculture. We therefore used a medium-density single nucleotide polymorphism (SNP) array to investigate the genetic structure of this species in Europe, where it was introduced during the 1960s and has since become a prolific invader of coastal ecosystems across the continent.

Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate-Based Standardization.

About a decade after its introduction, the field of carbonate clumped isotope thermometry is rapidly expanding because of the large number of possible applications and its potential to solve long-standing questions in Earth Sciences. Major factors limiting the application of this method are the very high analytical precision required for meaningful interpretations, the relatively complex sample preparation procedures, and the mass spectrometric corrections needed. In this paper we first briefly review the evolution of the analytical and standardization procedures and discuss the major remaining sources of uncertainty.

A Comparison of Late Quaternary Organic Proxy-Based Paleotemperature Records of the Central Sea of Okhotsk.

The long-chain diol index (LDI) is a new organic sea surface temperature (SST) proxy based on the distribution of long-chain diols. It has been applied in several environments but not yet in subpolar regions. Here we tested the LDI on surface sediments and a sediment core from the Sea of Okhotsk, which is the southernmost seasonal sea ice-covered region in the Northern Hemisphere, and compared it with other organic temperature proxies, that is, and TEX .

Pliocene-Pleistocene evolution of sea surface and intermediate water temperatures from the southwest Pacific.

Over the last 5 million years, the global climate system has evolved toward a colder mean state, marked by large-amplitude oscillations in continental ice volume. Equatorward expansion of polar waters and strengthening temperature gradients have been detected. However, the response of the mid latitudes and high latitudes of the Southern Hemisphere is not well documented, despite the potential importance for climate feedbacks including sea ice distribution and low-high latitude heat transport.