This NSF funded research is now in its 9^th year as an Ocean Acidification study and collaborative project with J. Adkins and his group (Caltech)—our objective is to use novel geochemical approaches and new devices to examine carbonate dissolution kinetics--in the lab, in the field and in silico. This is actually a well-studied topic, yet there is disagreement in the field regarding the formulation of the dissolution rate equation. One of the issues we have overcome is determining slow dissolution rates that occur near saturation. We have grown biogenic and abiogenic particles under heavy ¹³C conditions, and can use this mineral to detect very small dissolution rates in <3 days. We are able to control saturation state in sea water by changing TA, we are also able to conduct experiments at different pressures, thus control saturation state by modifying K_sp. We have built a novel Niskin incubator device and used it successfully on a research cruise in the North Pacific Ocean (See papers by Subhas, Dong, Naviaux and Adkins et al. 2021). We have also studied dissolution kinetics using atomic force microscopy (papers by Dong) and are developing methods to apply SIMS analyses of carbonate as a metric of dissolution mechanism and rate.

As part of our NSF funded research on carbonate dissolution kinetics, we are developing a new system of pore water extraction from deep sea sediments and we are also developing an in situ dissolution-within-pore water experimental setup. The ‘needles’ and ‘blades’ are shown in the figures. These devices have been deployed successfully to 4000 m and extracted pore waters, in situ! Jaclyn Pittman (USC) and Holly Barnhart (Caltech) will be working with Blade and Needle data from cruises in 2020 and 2021. Summaries of their work on pore water carbonate chemistry can be seen in abstracts presented at the AGU Ocean Sciences 2022 meeting.

W. Berelson and many other colleagues at USC are involved in studies of Urban air, soil and water quality. Berelson has particularly focused on urban CO2 and methane sources and sinks and has a rooftop sampling protocol that can monitor Los Angeles air at a very high temporal resolution. We measure CO2 concentrations and its isotopic composition and can extract information about the relative importance of petroleum vs. natural gas burning as CO2 sources. We are eager to expand this project to include other air constituents, develop a network of sensors (Carbon Census), target specific urban landscapes and understand more deeply the urban built environment and ecosystem in terms of air quality. Students encouraged with interest in this topic.

The Berelson Lab group is also deeply involved with studies of urban air quality using hand-held, homemade AQ sensors as well as a network of BEACO2N sensors located around mid-city as shown on the figure. Subtle variations in CO2 and other constituent concentration both in amount and time of increase and decrease helps us deconvolve sources and sinks of these parameters. We’ve recently looked at CO2 during the year of Covid, 2020 and our new network has just added its final node in Oct. 2021. Further, with colleagues in SSI and Architecture, supported by USC Dornsife, we have an Urban Trees initiative that utilizes hand-held sensors to detect small variations in NOx and Ozone in and around trees.

We are working to define how sea water that is pumped through carbonate-poor sands change with respect to carbonate chemistry. We find that as ocean water acidifies via CO2 addition to our atmosphere, the carbonate minerals in sands will neutralize that acid, although this occurs as a function of residence time of water within the sand column.

With F. Corsetti (USC) and other colleagues, we are presently (NASA grant, 2019-2023) studying the role of Fe precipitation/reduction in promoting stromatolite growth. We are using a system in Yellowstone National Park to study stromatolites that we know grow on timescales of months-years and our research also delves into the ancient stromatolites preserved in sedimentary rocks.

The Eastern Tropical South Pacific includes a zone of strong coastal upwelling, an intense OMZ and portions of the oligotrophic S. Pacific gyre. A group of us (D. Capone, USC; A. Knapp, FSU; K. Casciotti, Stanford) set out to determine N cycling in these waters, to examine if N fixation were an important contributor to production and export in this region. My contribution included measurements of Radon in surface waters as a tracer for gas exchange, measurements of underway O₂/Ar, deployment and measurement of particle fluxes to floating sediment traps, deployment and recovery of two deep sea sediment traps, and the determination and modeling of pore water nitrate and Si(OH)₄ profiles.

Papers/Manuscripts related to ETSP work:

Berelson et al. 2014; Haskell et al. 2013, 2014; Prokopenko et al. 2014; Knapp et al. 2014; Yeung et al. 2014; Johnston et al. 2014; Santoro et al. 2020

ANACONDAS was a large group project led by T. Yager (U. Georgia) aimed at understanding the role that the Amazon Plume plays and played in modifying ocean ecology and C fluxes in the NW Atlantic Ocean. Several cruises between Barbados and the Amazon River mouth provided the opportunity to deploy floating sediment traps, determine oxygen triple isotopes, and collect over 40 sediment cores. The coring effort (lead by graduate student L. Chong) aimed to define the extent of biogenic sedimentation under the plume region and examine Glacial and Holocene sedimentation patterns in this broad region.

Papers/Manuscripts related to ANACONDAS work:

Yeung et al. 2012; Chong et al. 2013; Chong et al. 2016; Goes et al. 2014; Lund et al. 2018

What is the influence of the hypoxic water column on iron, manganese and nutrient fluxes in the GoM? Here, collaborators J. McManus (Bigelow Labs) and S. Severmann (Rutgers) and I continue our work on benthic fluxes of iron and manganese from shelf sediments and explore the use of iron isotopes as a tracer of benthic iron recycling. This is still a work in progress but is an extension of work we’ve conducted off the Oregon/California margin.

Papers/Manuscripts related to Gulf of Mexico work:

Berelson et al. 2013; McManus et al. 2012; Homoky et al. 2012; Severmann et al. 2010; Baronas et al. 2016

The relationship between N cycling in oxygen minimum zones and in anoxic sediments has been a subject our group has been studying for a long time. We take a keen interest in the microbial transformations involving N uptake, production and transport in sediments underlying OMZs and in the potential to translate N isotope patterns into an understanding of OMZ behavior in the past. C. Tems (graduate student) is presently (2014) working on N paleoproxies in laminated sediments off Mexico and California.

Papers/Manuscripts related to N work:

Tems et al. 2014; Deutsch et al. 2014; Townsend-Small et al. 2014; Prokopenko et al. 2013; Chong et al. 2012; Prokopenko et al. 2011; Prokopenko et al. 2006

This is a topic that was recently supported by an NSF award (primarily to L. Yeung, former post-doc in Berelson lab now Asst. Prof. Rice U.). J. Fleming (graduate student) is also in the process (2014) of writing a dissertation on the topic of oxygen uptake rates and their controls. We are examining the variability of these rates, how nutrient addition, changes in pH and temperature impact them and what maximum uptake rates are under glucose additions. Previous work in my lab (Reidel, PhD student) examined oxygen consumption in bacterial cultures under conditions of nutrient stress, in LTSP.

Papers/Manuscripts related to O2 Respiration work:

Riedel et al. 2013; Fleming et al. 2014; Collins et al. 2010

Over the course of many years, H. Johnson (CSUF) and I have worked with students in the International Geobiology Summer Course investigating the growth rate of microbial mat layers under conditions of +/- light and various trace element additions. These efforts have led to various published abstracts but no publications.

Papers/Manuscripts related to this work:

Riedel et al. 2013; Wilmeth et al. 2018