Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary
Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a larg...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2020
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| Online Access: | https://hdl.handle.net/10356/145016 |
| _version_ | 1826123880463335424 |
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| author | Chen, Mengli Boyle, Edward A. Lee, Jong-Mi Intan Nurhati Zurbrick, Cheryl Switzer, Adam D. Carrasco, Gonzalo |
| author2 | Asian School of the Environment |
| author_facet | Asian School of the Environment Chen, Mengli Boyle, Edward A. Lee, Jong-Mi Intan Nurhati Zurbrick, Cheryl Switzer, Adam D. Carrasco, Gonzalo |
| author_sort | Chen, Mengli |
| collection | NTU |
| description | Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb isotopes and that of the regional aerosols. We propose that this difference results from isotope exchange between dissolved Pb supplied by anthropogenic aerosol deposition and adsorbed natural crustal Pb on weathered particles delivered to the ocean by coastal rivers. To investigate this issue, Pb isotope exchange was assessed through a closed-system exchange experiment using estuarine waters collected at the Johor River mouth (which discharges to the Singapore Strait). During the experiment, a known amount of dissolved Pb with the isotopic composition of NBS-981 (206Pb/207Pb = 1.093) was spiked into the unfiltered Johor water (dissolved and particulate 206Pb/207Pb = 1.199) and the changing isotopic composition of the dissolved Pb was monitored. The mixing ratio of the estuarine and spike Pb should have produced a dissolved 206Pb/207Pb isotopic composition of 1.161, but within a week, the 206Pb/207Pb in the water increased to 1.190 and continued to increase to 1.197 during the next two months without significant changes of the dissolved Pb concentration. The kinetics of isotope exchange was assessed using a simple Kd model, which assumes multiple sub-reservoirs within the particulate matter with different exchange rate constants. The Kd model reproduced 56% of the observed Pb isotope variance. Both the closed-system experiment and field measurements imply that isotope exchange can be an important mechanism for controlling Pb and Pb isotopes in coastal waters. A similar process may occur for other trace elements.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. |
| first_indexed | 2024-10-01T06:11:53Z |
| format | Journal Article |
| id | ntu-10356/145016 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:11:53Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | ntu-10356/1450162020-12-08T08:19:50Z Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary Chen, Mengli Boyle, Edward A. Lee, Jong-Mi Intan Nurhati Zurbrick, Cheryl Switzer, Adam D. Carrasco, Gonzalo Asian School of the Environment Earth Observatory of Singapore Engineering::Environmental engineering Isotope Exchange Experiment Aerosol Sampling Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb isotopes and that of the regional aerosols. We propose that this difference results from isotope exchange between dissolved Pb supplied by anthropogenic aerosol deposition and adsorbed natural crustal Pb on weathered particles delivered to the ocean by coastal rivers. To investigate this issue, Pb isotope exchange was assessed through a closed-system exchange experiment using estuarine waters collected at the Johor River mouth (which discharges to the Singapore Strait). During the experiment, a known amount of dissolved Pb with the isotopic composition of NBS-981 (206Pb/207Pb = 1.093) was spiked into the unfiltered Johor water (dissolved and particulate 206Pb/207Pb = 1.199) and the changing isotopic composition of the dissolved Pb was monitored. The mixing ratio of the estuarine and spike Pb should have produced a dissolved 206Pb/207Pb isotopic composition of 1.161, but within a week, the 206Pb/207Pb in the water increased to 1.190 and continued to increase to 1.197 during the next two months without significant changes of the dissolved Pb concentration. The kinetics of isotope exchange was assessed using a simple Kd model, which assumes multiple sub-reservoirs within the particulate matter with different exchange rate constants. The Kd model reproduced 56% of the observed Pb isotope variance. Both the closed-system experiment and field measurements imply that isotope exchange can be an important mechanism for controlling Pb and Pb isotopes in coastal waters. A similar process may occur for other trace elements.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. 2020-12-08T08:19:49Z 2020-12-08T08:19:49Z 2016 Journal Article Chen, M., Boyle, E. A., Lee, J.-M., Intan Nurhati, Zurbrick, C., Switzer, A. D., & Carrasco, G. (2016). Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 374(2081), 20160054-. https://doi.org/10.1098/rsta.2016.0054 1471-2962 https://hdl.handle.net/10356/145016 10.1098/rsta.2016.0054 29035266 2-s2.0-84992372673 2081 374 20160054 en Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences © 2016 The Author(s). Published by The Royal Society. All rights reserved. |
| spellingShingle | Engineering::Environmental engineering Isotope Exchange Experiment Aerosol Sampling Chen, Mengli Boyle, Edward A. Lee, Jong-Mi Intan Nurhati Zurbrick, Cheryl Switzer, Adam D. Carrasco, Gonzalo Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title | Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title_full | Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title_fullStr | Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title_full_unstemmed | Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title_short | Lead isotope exchange between dissolved and fluvial particulate matter : a laboratory study from the Johor River estuary |
| title_sort | lead isotope exchange between dissolved and fluvial particulate matter a laboratory study from the johor river estuary |
| topic | Engineering::Environmental engineering Isotope Exchange Experiment Aerosol Sampling |
| url | https://hdl.handle.net/10356/145016 |
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