REVISITING THE NEODYMIUM PARADOX IN THE OCEAN
Lead Research Organisation:
Imperial College London
Department Name: Earth Science and Engineering
Abstract
Global climate change is one of the big challenges society faces today. Warming of the climate system is unequivocal, and evident from observations of increasing global average temperatures. Warming is also observed in the oceans, and is accompanied by a change in salinity, with the high latitudes becoming 'fresher' (i.e., less saline) and the subtropics and tropics becoming more saline - a redistribution of properties that has the potential to affect ocean circulation. There are also clear effects of climate change on the chemistry of the oceans. Whilst increased uptake of more abundant atmospheric carbon dioxide leads to an acidification of the oceans that threatens marine ecosystems, only little is known about the effects of higher concentrations of certain trace metals, as a result of anthropogenic pollution and changing erosion patterns on land. Such changes are very important, however, as the ability of the ocean to take up carbon dioxide from the atmosphere is strongly coupled to the supply of so-called nutrients, elements that are essential for life in the ocean.
As part of this project, we will develop a better understanding of such 'biogeochemical cycles'. We picked out three trace metals, neodymium (Nd), cadmium (Cd), and lead (Pb), which together represent the behaviour of many different elements in the ocean. For example, both Cd and Pb are today supplied to the environment by human activity and this may alter their natural cycles. As Cd is an important micronutrient in the ocean, such changes could also affect the global carbon cycle. As part of our project, a PhD student will focus on understanding whether the natural flux of dust from desert areas to the ocean and the anthropogenic particles the dust scavenges in the atmosphere have an important impact on the marine Cd and Pb cycles. The student will furthermore study, how the cycling of these elements in the ocean is altered by changing oxygen concentrations. Oxygen is (next to the nutrients) another important player in biogeochemical cycles, and its solubility in seawater is temperature dependent. Climate models predict that extended zones with low oxygen concentrations will develop in the future oceans.
Another important aspect of the ocean system is that ocean currents are the key mechanism for distributing heat, and thus they have a significant impact on regional and local climate. Furthermore, water mass movements (both vertical and lateral) are very important for the carbon cycle, as the deep ocean contains 50-60 times more carbon than the atmosphere. Today we can monitor ocean circulation by measuring the physical properties of seawater. Observations over the past 50 years, however, do not give us any clear indication whether the pattern of ocean circulation is changing. From studies of the past we know, however, that ocean water masses had a different configuration during the ice ages and past periods of extreme warmth. Neodymium isotopes in seawater are often used for such reconstructions, and the results show stunning relationships between past temperatures, carbon dioxide levels, and ocean circulation.
A patchy understanding the modern Nd cycle however limits our confidence in such reconstructions, and thus our ability to transfer the inferred mechanisms to future models. In particular, it is generally assumed that away from ocean margins, Nd isotopes are an ideal ocean circulation tracer as they are only modified by mixing between water masses. However, there are many potential marine processes, which may not be in accord with this simplistic view. Such uncertainties will be addressed by the current project, based on a comprehensive suite of new observational data that will be collected for samples from strategic locations in the Atlantic Ocean. In conjunction with modelling efforts, our new data will shed light on the processes governing the marine Nd cycle and the suitability of Nd isotopes as circulation tracer.
As part of this project, we will develop a better understanding of such 'biogeochemical cycles'. We picked out three trace metals, neodymium (Nd), cadmium (Cd), and lead (Pb), which together represent the behaviour of many different elements in the ocean. For example, both Cd and Pb are today supplied to the environment by human activity and this may alter their natural cycles. As Cd is an important micronutrient in the ocean, such changes could also affect the global carbon cycle. As part of our project, a PhD student will focus on understanding whether the natural flux of dust from desert areas to the ocean and the anthropogenic particles the dust scavenges in the atmosphere have an important impact on the marine Cd and Pb cycles. The student will furthermore study, how the cycling of these elements in the ocean is altered by changing oxygen concentrations. Oxygen is (next to the nutrients) another important player in biogeochemical cycles, and its solubility in seawater is temperature dependent. Climate models predict that extended zones with low oxygen concentrations will develop in the future oceans.
Another important aspect of the ocean system is that ocean currents are the key mechanism for distributing heat, and thus they have a significant impact on regional and local climate. Furthermore, water mass movements (both vertical and lateral) are very important for the carbon cycle, as the deep ocean contains 50-60 times more carbon than the atmosphere. Today we can monitor ocean circulation by measuring the physical properties of seawater. Observations over the past 50 years, however, do not give us any clear indication whether the pattern of ocean circulation is changing. From studies of the past we know, however, that ocean water masses had a different configuration during the ice ages and past periods of extreme warmth. Neodymium isotopes in seawater are often used for such reconstructions, and the results show stunning relationships between past temperatures, carbon dioxide levels, and ocean circulation.
A patchy understanding the modern Nd cycle however limits our confidence in such reconstructions, and thus our ability to transfer the inferred mechanisms to future models. In particular, it is generally assumed that away from ocean margins, Nd isotopes are an ideal ocean circulation tracer as they are only modified by mixing between water masses. However, there are many potential marine processes, which may not be in accord with this simplistic view. Such uncertainties will be addressed by the current project, based on a comprehensive suite of new observational data that will be collected for samples from strategic locations in the Atlantic Ocean. In conjunction with modelling efforts, our new data will shed light on the processes governing the marine Nd cycle and the suitability of Nd isotopes as circulation tracer.
Planned Impact
This proposals aims to deliver substantial and lasting impact by providing an increased understanding of the role of diverse processes that control the chemical environment in the ocean. Ocean chemistry in turn is fundamentally coupled to global climate change and the stability of marine ecosystems. Global biogeochemical cycles are currently strongly altered by human activity, and future changes may have significant impacts on natural resources, economy and the environment of countries globally.
The outputs of this study will therefore be of direct and lasting benefit to a wide user community of policy forming bodies such as international and national Governmental Environment and Climate Change Departments (e.g. the European Union, the UK Met Office, UK Government departments, including DECC and DEFRA, and international equivalents), as well as international bodies and NGOs (IPCC, environmental and fisheries charities and pressure groups) interested in oceanography, climate modelling, and the way in which these systems can be managed, protected, and any undesirable changes predicted and mitigated against.
Societal impact is furthermore achieved by the fact that the isotope geochemical methods developed and deployed by the MAGIC group are used far beyond the fields of marine geochemistry and palaeoceanography, and even beyond fields such as the evolution of our solar system and planet Earth. We also apply stable isotope techniques to research in medical and life sciences and, most recently, the rapidly growing field of nanoparticle toxicology. In addition, we also have an excellent track record of publishing our method development work in the peer-reviewed literature, to ensure that novel procedures can be readily implemented by others.
For this project, we chose a range of methods for the dissemination of research results. We will engage the general public with 'Nature Live' outreach talks at the Natural History Museum (www.nhm.ac.uk/nature-live; see letter of support). Nature Live is a program delivered through the Attenborough studio and facilitated by Nature Live staff. It brings together scientists and visitors to explore, discover and discuss the natural world. The Natural History Museum in London is a world class visitor attraction welcoming 4 million public visitors each year. We furthermore plan to participate in science fairs hosted by Imperial College London and the Royal Society. We will also publicize our results through the Imperial College press centre, the MAGIC website (www.imperial.ac.uk/ese/research/magic), and the project web pages of UK GEOTRACES (www.ukgeotraces.com) and International GEOTRACES (www.geotraces.org) The project will also contribute to the education of the next generation of young scientists, by employing a PDRA who will be taught new methods and become an integral part of the wider chemical oceanography and ocean modelling community. The same is true for the PhD student, who will work on a stand-alone project that is well integrated with and complements the overall research goals. We also plan to involve undergraduate students in the research by offering small, well-defined MSci projects.
All junior researchers involved in the project will also participate in the workshop we will organize in year 3, entitled 'Seawater neodymium isotopes - modern constraints for a palaeo tracer'. For the workshop, we will invite the international community involved in marine Nd isotope research, additional researchers working on other marine geochemical cycles and ocean modellers, as well as stakeholders in public service. Finally, throughout the project, we will present research results at conferences (AGU, Goldschmidt, EGU), GEOTRACES workshops, and deliver seminars at academic institutions. In year 3 of the project we will also organize a special session that focuses on global marine biogeochemical cycles at one of these conferences.
The outputs of this study will therefore be of direct and lasting benefit to a wide user community of policy forming bodies such as international and national Governmental Environment and Climate Change Departments (e.g. the European Union, the UK Met Office, UK Government departments, including DECC and DEFRA, and international equivalents), as well as international bodies and NGOs (IPCC, environmental and fisheries charities and pressure groups) interested in oceanography, climate modelling, and the way in which these systems can be managed, protected, and any undesirable changes predicted and mitigated against.
Societal impact is furthermore achieved by the fact that the isotope geochemical methods developed and deployed by the MAGIC group are used far beyond the fields of marine geochemistry and palaeoceanography, and even beyond fields such as the evolution of our solar system and planet Earth. We also apply stable isotope techniques to research in medical and life sciences and, most recently, the rapidly growing field of nanoparticle toxicology. In addition, we also have an excellent track record of publishing our method development work in the peer-reviewed literature, to ensure that novel procedures can be readily implemented by others.
For this project, we chose a range of methods for the dissemination of research results. We will engage the general public with 'Nature Live' outreach talks at the Natural History Museum (www.nhm.ac.uk/nature-live; see letter of support). Nature Live is a program delivered through the Attenborough studio and facilitated by Nature Live staff. It brings together scientists and visitors to explore, discover and discuss the natural world. The Natural History Museum in London is a world class visitor attraction welcoming 4 million public visitors each year. We furthermore plan to participate in science fairs hosted by Imperial College London and the Royal Society. We will also publicize our results through the Imperial College press centre, the MAGIC website (www.imperial.ac.uk/ese/research/magic), and the project web pages of UK GEOTRACES (www.ukgeotraces.com) and International GEOTRACES (www.geotraces.org) The project will also contribute to the education of the next generation of young scientists, by employing a PDRA who will be taught new methods and become an integral part of the wider chemical oceanography and ocean modelling community. The same is true for the PhD student, who will work on a stand-alone project that is well integrated with and complements the overall research goals. We also plan to involve undergraduate students in the research by offering small, well-defined MSci projects.
All junior researchers involved in the project will also participate in the workshop we will organize in year 3, entitled 'Seawater neodymium isotopes - modern constraints for a palaeo tracer'. For the workshop, we will invite the international community involved in marine Nd isotope research, additional researchers working on other marine geochemical cycles and ocean modellers, as well as stakeholders in public service. Finally, throughout the project, we will present research results at conferences (AGU, Goldschmidt, EGU), GEOTRACES workshops, and deliver seminars at academic institutions. In year 3 of the project we will also organize a special session that focuses on global marine biogeochemical cycles at one of these conferences.
Organisations
- Imperial College London (Lead Research Organisation)
- University of Plymouth (Collaboration)
- University of East Anglia (Collaboration)
- Alfred-Wegener Institute for Polar and Marine Research (Collaboration)
- Columbia University (Project Partner)
- Royal Netherlands Institute for Sea Research (Project Partner)
- Alfred Wegener Institute for Polar and Marine Research (Project Partner)
- University of East Anglia (Project Partner)
- University of Southampton (Project Partner)
Publications
Lambelet M
(2016)
Neodymium isotopic composition and concentration in the western North Atlantic Ocean: Results from the GEOTRACES GA02 section
in Geochimica et Cosmochimica Acta
Lambelet M
(2018)
The Neodymium Isotope Fingerprint of Adélie Coast Bottom Water
in Geophysical Research Letters
Mawji E
(2015)
The GEOTRACES Intermediate Data Product 2014
in Marine Chemistry
Murphy K
(2014)
Comment on "The isotopic composition of cadmium in the water column of the South China Sea"
in Geochimica et Cosmochimica Acta
Murphy K
(2016)
Improvements in Cd stable isotope analysis achieved through use of liquid-liquid extraction to remove organic residues from Cd separates obtained by extraction chromatography.
in Journal of analytical atomic spectrometry
Olivelli A
(2023)
Decline of anthropogenic lead in South Atlantic Ocean surface waters from 1990 to 2011: New constraints from concentration and isotope data.
in Marine pollution bulletin
Packman H
(2022)
Tracing natural and anthropogenic sources of aerosols to the Atlantic Ocean using Zn and Cu isotopes
in Chemical Geology
Pahnke K
(2012)
GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 2: Systematic tests and baseline profiles
in Limnology and Oceanography: Methods
Paul M
(2015)
Tracing the Agulhas leakage with lead isotopes LEAD ISOTOPES TRACE AGULHAS LEAKAGE
in Geophysical Research Letters
Paul M
(2015)
High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.
in Analytica chimica acta
Description | Ocean currents are a key mechanism for distributing heat around our globe, and thus they have a significant impact on regional and local climate. Furthermore, water mass movements (both vertical and lateral) are very important for the carbon cycle, as the deep ocean contains 50-60 times more carbon than the atmosphere. Today we can monitor ocean circulation by measuring the physical properties of seawater. Observations over the past 50 years, however, do not give us any clear indication whether the pattern of ocean circulation is changing. From studies of the past we know, however, that ocean water masses had a different configuration during the ice ages and past periods of extreme warmth. Neodymium (Nd) isotopes in seawater are often used for such reconstructions, and the results show stunning relationships between past temperatures, carbon dioxide levels, and ocean circulation. With this grant we could improve our understanding of the modern cycle of Nd in the ocean by measuring its isotopic composition and concentrations in more than 200 seawater samples and >50 marine particulate samples. Our results reveal that in areas of strong ocean currents, and away from continental margins, Nd isotopes indeed can trace individual water masses in a stunning way. Detailed comparison of the dissolved and particulate phase of the rare earth element Nd and its isotopes shows that along the major flow path of North Atlantic deep water particles act as a sink rather than as a source for seawater Nd. Beyond these insights on the marine cycle of the element Nd and its applicability to studies of past circulation, we made a range of important observations on the environmental sector. Lead (Pb) is an element that has been added in large amounts to our atmosphere by the use of leaded gasoline. This Pb can be traced in the ocean, as the atmosphere is the main source of Pb. Results from the tropical Atlantic show that after the phasing out of leaded gasoline we now see a return of natural Pb in the area. While encouraging, there is a still a large amount of anthropogenic Pb in the environment from other industrial sources. In contrast, analyses of aerosol samples collected in the Tropical Atlantic for the cadmium content do not show any major signs of anthropogenic pollution. |
Exploitation Route | All data produced in this project have been deposited in GDAC, a database accessible for the broad research community as well as general public. Our results provide unique insights into the marine cycle of Nd, and the environmental cycles of Pb and Cd polluion. |
Sectors | Environment |
Description | NERC large grant - SWEET |
Amount | £2,800,000 (GBP) |
Funding ID | NE/P019080/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 09/2017 |
End | 09/2022 |
Description | NERC standard grant - Bridging the Timing Gap |
Amount | £201,826 (GBP) |
Funding ID | NE/N001141/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 09/2015 |
End | 09/2018 |
Description | Ocean-ice Interaction in the Ross Sea during Past Warm Periods |
Amount | £25,152 (GBP) |
Funding ID | NE/R018219/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 03/2018 |
End | 12/2019 |
Title | IDP2017 |
Description | GEOTRACES Intermediate Data Product 2017. |
Type Of Material | Database/Collection of data |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | Contains six years worth of data hydrographical and biogeochemical data from the international GEOTRACES programme to be used by the broader ocean research community. |
URL | https://www.bodc.ac.uk/geotraces/data/idp2017/ |
Title | Particulate Neodymium Isotopes and Concentrations in the Western North Atlantic |
Description | Particulate neodymium (Nd) isotopes and concentration were measured on samples collected along a transect during cruises PE-319 and PE-321 (R/V Pelagia, NED) in 2010. Samples were collected using in-situ pumps (ISP) at 5 stations at 6 depths each. Samples were analysed for Nd isotopes and concentrations at Imperial College London (UK). Detailed methodology and data interpretation can be accessed via the peer-reviewed publication: doi:acsearthspacechem.0c00034 |
Type Of Material | Database/Collection of data |
Year Produced | 2020 |
Provided To Others? | Yes |
URL | https://doi.pangaea.de/10.1594/PANGAEA.922598 |
Description | Particulate sample analysis from the Tropical Atlantic Ocean |
Organisation | University of Plymouth |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Utilised data from collaborator for publication. |
Collaborator Contribution | Trace metal analysis on particulate samples. |
Impact | Publication. |
Start Year | 2013 |
Description | Particule Nd isotope composition in the North Atlantic |
Organisation | Alfred-Wegener Institute for Polar and Marine Research |
Country | Germany |
Sector | Private |
PI Contribution | We analysed sample splits from marine particulates from the North Atlantic for their Nd isotope composition. |
Collaborator Contribution | Colleagues from the Alfred Wegener Institute in Germany, participated in a research expedition and collected particulate samples using in-situ pumps. Subsequently the samples were prepared at AWI and tests were conducted to make multi-element analysis and collect sample splits for Nd isotopes. |
Impact | Multiple conference abstracts. Paper in preparation. |
Start Year | 2012 |
Description | Trace metal isotopes in aerosols from the Tropical and North Atlantic Ocean |
Organisation | University of East Anglia |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Analysed trace metal isotopes in aerosols from the Tropical Atlantic Ocean. |
Collaborator Contribution | Collected aerosol samples at sea and conducted major and trace element analyses. |
Impact | Multiple publications. |
Start Year | 2013 |
Description | Evening lecture in Cardiff |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Sparked questions and discussion. |
Year(s) Of Engagement Activity | 2016 |
Description | Fall AGU 2014 talk |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Present preliminary results on Nd isotopes in seawater at the annual Fall AGU meeting in San Francisco. Yet to take place. |
Year(s) Of Engagement Activity | 2014 |
Description | Geological Society - Shackleton conference |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | Keynote talk at a Shackleton conference, organised by the Marine Studies Group of the Geological Society in the year of carbon. |
Year(s) Of Engagement Activity | 2019 |
URL | https://www.shackletonmeeting.com/conference-schedule |
Description | Gordon Conference |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | Invited talk at a Gordon Conference on Chemical Oceanography. >50 scientists and graduate students attended. The presentation sparked questions and discussion. |
Year(s) Of Engagement Activity | 2017 |
Description | ICP poster |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Poster presentation at the International Conference on Paleoceanography for an audience of >500 scientists. The poster sparked questions and discussion. |
Year(s) Of Engagement Activity | 2016 |
Description | MAGIC Elements |
Form Of Engagement Activity | Participation in an open day or visit at my research institution |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Hundreds of under-12s visited the Imperial Festival stand on MAGIC Elements with their parents. They dressed up as scientists, learned about elements and isotopes, and even about how Antarctica once was a continent with palm trees at its shorelines. |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.imperial.ac.uk/news/185986/imperial-festival-transforms-under-12s-into-mini/ |
Description | Media contact Grantham |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Part of a small group of Grantham affiliates that helps with media requests. My expertise is in the are of palaeoclimate and Antarctic ice sheets |
Year(s) Of Engagement Activity | 2016,2017,2018,2019 |
Description | Ocean Science talk 2014 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Talk on Pb isotope results in seawater at the bi-annual Ocean Science meeting in Hawaii. Great comments and overall interest in the new Pb isotope methodology to use for seawater samples set up at Imperial College London. |
Year(s) Of Engagement Activity | 2014 |
Description | Open Day 2014 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Talk about Earth Science at College wide Open Day. Hopefully it inspires pupils to come and study Earth Sciences! |
Year(s) Of Engagement Activity | 2014 |
Description | Royal Society meeting |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Presentation sparked questions and discussion among the audience and increased interest in related subject areas. |
Year(s) Of Engagement Activity | 2015 |
URL | https://royalsociety.org/events/2015/12/ocean-chemistry/ |
Description | Short virtual course - isotopes in ocean earth and environment research |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | Virtual summer school - >100 people from all around the world attended and asked questions about isotopes in the ocean |
Year(s) Of Engagement Activity | 2021 |
Description | Southern Ocean biogeochemistry workshop, Hobart 2019 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | This small workshop was aimed at bringing together people from across the world who work on Southern Ocean biogeochemistry. The key outcome of the workshop was fostering new collaborations and cross-disciplinary work. |
Year(s) Of Engagement Activity | 2019 |
URL | http://www.geotraces.org/meetings/meetings-by-year/eventdetail/357/-/southern-ocean-biogeochemistry-... |
Description | |
Form Of Engagement Activity | Engagement focused website, blog or social media channel |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Tweets about climate change, Antarctica, women in science, STEM related topics and (Earth) Science in general. |
Year(s) Of Engagement Activity | 2014,2015,2016,2017,2018,2019,2020 |