Abstract
Natural attenuation of organic contaminants in groundwater can give rise to a series of complex biogeochemical reactions that release secondary contaminants to groundwater. In a crude oil contaminated aquifer, biodegradation of petroleum hydrocarbons is coupled with the reduction of ferric iron (Fe(III)) hydroxides in aquifer sediments. As a result, naturally occurring arsenic (As) adsorbed to Fe(III) hydroxides in the aquifer sediment is mobilized from sediment into groundwater. However, Fe(III) in sediment of other zones of the aquifer has the capacity to attenuate dissolved As via resorption. In order to better evaluate how long-term biodegradation coupled with Fe-reduction and As mobilization can redistribute As mass in contaminated aquifer, we quantified mass partitioning of Fe and As in the aquifer based on field observation data. Results show that Fe and As are spatially correlated in both groundwater and aquifer sediments. Mass partitioning calculations demonstrate that 99.9% of Fe and 99.5% of As are associated with aquifer sediment. The sediments act as both sources and sinks for As, depending on the redox conditions in the aquifer. Calculations reveal that at least 78% of the original As in sediment near the oil has been mobilized into groundwater over the 35-year lifespan of the plume. However, the calculations also show that only a small percentage of As (∼0.5%) remains in groundwater, due to resorption onto sediment. At the leading edge of the plume, where groundwater is suboxic, sediments sequester Fe and As, causing As to accumulate to concentrations 5.6 times greater than background concentrations. Current As sinks can serve as future sources of As as the plume evolves over time. The mass balance approach used in this study can be applied to As cycling in other aquifers where groundwater As results from biodegradation of an organic carbon point source coupled with Fe reduction. Capsule Biodegradation of oil coupled with iron reduction results in the mobilization of sediment-bound arsenic to groundwater, though natural attenuation processes result in >99% of As remaining in sediment.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1351-1361 |
| Number of pages | 11 |
| Journal | Environmental Pollution |
| Volume | 231 |
| DOIs | |
| State | Published - Dec 1 2017 |
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Keywords
- Arsenic
- Biodegradation
- Iron
- Mass distribution
- Petroleum
Cite this
A mass balance approach to investigate arsenic cycling in a petroleum plume. / Ziegler, Brady A.; Schreiber, Madeline E.; Cozzarelli, Isabelle M.; Ng, Gene-Hua C.
In: Environmental Pollution, Vol. 231, 01.12.2017, p. 1351-1361.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A mass balance approach to investigate arsenic cycling in a petroleum plume
AU - Ziegler, Brady A.
AU - Schreiber, Madeline E.
AU - Cozzarelli, Isabelle M.
AU - Ng, Gene-Hua C
PY - 2017/12/1
Y1 - 2017/12/1
N2 - Natural attenuation of organic contaminants in groundwater can give rise to a series of complex biogeochemical reactions that release secondary contaminants to groundwater. In a crude oil contaminated aquifer, biodegradation of petroleum hydrocarbons is coupled with the reduction of ferric iron (Fe(III)) hydroxides in aquifer sediments. As a result, naturally occurring arsenic (As) adsorbed to Fe(III) hydroxides in the aquifer sediment is mobilized from sediment into groundwater. However, Fe(III) in sediment of other zones of the aquifer has the capacity to attenuate dissolved As via resorption. In order to better evaluate how long-term biodegradation coupled with Fe-reduction and As mobilization can redistribute As mass in contaminated aquifer, we quantified mass partitioning of Fe and As in the aquifer based on field observation data. Results show that Fe and As are spatially correlated in both groundwater and aquifer sediments. Mass partitioning calculations demonstrate that 99.9% of Fe and 99.5% of As are associated with aquifer sediment. The sediments act as both sources and sinks for As, depending on the redox conditions in the aquifer. Calculations reveal that at least 78% of the original As in sediment near the oil has been mobilized into groundwater over the 35-year lifespan of the plume. However, the calculations also show that only a small percentage of As (∼0.5%) remains in groundwater, due to resorption onto sediment. At the leading edge of the plume, where groundwater is suboxic, sediments sequester Fe and As, causing As to accumulate to concentrations 5.6 times greater than background concentrations. Current As sinks can serve as future sources of As as the plume evolves over time. The mass balance approach used in this study can be applied to As cycling in other aquifers where groundwater As results from biodegradation of an organic carbon point source coupled with Fe reduction. Capsule Biodegradation of oil coupled with iron reduction results in the mobilization of sediment-bound arsenic to groundwater, though natural attenuation processes result in >99% of As remaining in sediment.
AB - Natural attenuation of organic contaminants in groundwater can give rise to a series of complex biogeochemical reactions that release secondary contaminants to groundwater. In a crude oil contaminated aquifer, biodegradation of petroleum hydrocarbons is coupled with the reduction of ferric iron (Fe(III)) hydroxides in aquifer sediments. As a result, naturally occurring arsenic (As) adsorbed to Fe(III) hydroxides in the aquifer sediment is mobilized from sediment into groundwater. However, Fe(III) in sediment of other zones of the aquifer has the capacity to attenuate dissolved As via resorption. In order to better evaluate how long-term biodegradation coupled with Fe-reduction and As mobilization can redistribute As mass in contaminated aquifer, we quantified mass partitioning of Fe and As in the aquifer based on field observation data. Results show that Fe and As are spatially correlated in both groundwater and aquifer sediments. Mass partitioning calculations demonstrate that 99.9% of Fe and 99.5% of As are associated with aquifer sediment. The sediments act as both sources and sinks for As, depending on the redox conditions in the aquifer. Calculations reveal that at least 78% of the original As in sediment near the oil has been mobilized into groundwater over the 35-year lifespan of the plume. However, the calculations also show that only a small percentage of As (∼0.5%) remains in groundwater, due to resorption onto sediment. At the leading edge of the plume, where groundwater is suboxic, sediments sequester Fe and As, causing As to accumulate to concentrations 5.6 times greater than background concentrations. Current As sinks can serve as future sources of As as the plume evolves over time. The mass balance approach used in this study can be applied to As cycling in other aquifers where groundwater As results from biodegradation of an organic carbon point source coupled with Fe reduction. Capsule Biodegradation of oil coupled with iron reduction results in the mobilization of sediment-bound arsenic to groundwater, though natural attenuation processes result in >99% of As remaining in sediment.
KW - Arsenic
KW - Biodegradation
KW - Iron
KW - Mass distribution
KW - Petroleum
UR - http://www.scopus.com/inward/record.url?scp=85029719707&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029719707&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2017.08.110
DO - 10.1016/j.envpol.2017.08.110
M3 - Article
C2 - 28943347
AN - SCOPUS:85029719707
VL - 231
SP - 1351
EP - 1361
JO - Environmental Pollution
JF - Environmental Pollution
SN - 0269-7491
ER -