The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners.
As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i
Saltwater Intrusion Affects Nitrogen, Phosphorus And Iron Transformations Under Oxic And Anoxic Conditions: An Incubation Experiment
-
2021
-
Source: Biogeochemistry 154: 451–469
[PDF-3.87 MB]
Details:
-
Journal Title:Biogeochemistry
-
Personal Author:
-
NOAA Program & Office:
-
Sea Grant Program:
-
Description:Low-lying coastal ecosystems are rapidlysalinizing due to sea level rise and associated saltwaterintrusion (SWI). In agricultural soils, SWI can alterbiogeochemical cycling of key nutrients such asnitrogen (N), phosphorus (P), and iron (Fe). The mainobjective of this study was to quantify the amount ofnitrate–N (NO3–N), ammonium–N (NH4–N), solublereactive P (SRP), and total dissolved iron (TDFe)released from agricultural soils undergoing SWI todetermine their potential loss to downstream water-ways. Agricultural soils were incubated for 0, 15, and30 days (under oxic and anoxic conditions) withvarious salt solution combinations of sodium chlo-ride (NaCl), sodium sulfate (Na2SO4), calcium sulfate(CaSO4), and Instant OceanÒto mimic (1) differentionic constituents of saltwater at different ionicstrengths and (2) the presence or absence of gypsum,a soil amendment, through the addition of CaSO4.Wealso included a set of incubations treated withdeionized water as a no ionic strength control(0.00M). To increase statistical power, we groupedindividual salt treatments based on our initial hypothe-ses at the end of the incubation period (day 30) todetermine the effects of high (0.26–0.28M) and low(0.03–0.04M) ionic strength on inorganic N releaseand combinations of Ca and SO42-additions on SRPrelease to microcosm soil solution. Calcium additionsdecreased SRP release relative to saltwater thatcontained only NaCl additions under oxic and anoxicconditions. Additionally, high ionic strength treat-ments, which were about 7 times the ionic strength oflow ionic strength treatments, released two times asmuch NH4–N to the soil solution, which suggests anon-linear relationship between ionic strength andNH4–N release. At day 30, anoxic microcosm soilstreated with Instant OceanÒto simulate 15 parts perthousand seawater (ionic strength 0.26M) releasedsignificantly more NH4–N (by 782 times), SRP (by 6times), and TDFe (by 197 times) to the soil solutionthan oxic microcosm soils (P\0.05). This treatmentwas designed to reflect a field inundated by brackish seawater for almost a month, which is representativeof conditions on farm fields undergoing SWI. Underthese anoxic conditions, as much as 22% of bioavail-able soil P (as SRP) and 45% of total inorganic N (asNH4–N) could be released to overlying water wheninundated with saltwater. Our work indicates that theinflux of salts and inundation of SWI-affected farmfields could lead to a large export of N and P fromagricultural soils and potentially affect downstreamwater quality.
-
Keywords:
-
Source:Biogeochemistry 154: 451–469
-
DOI:
-
Document Type:
-
Funding:
-
Rights Information:Accepted Manuscript
-
Compliance:Submitted
-
Main Document Checksum:
-
Download URL:
-
File Type:
