Adsorption of dissolved phosphate onto loess particles in surface and deep Eastern Mediterranean water

Barak Herut; Tamar Zohary; Richard D. Robarts; Nurit Kress

doi:10.1016/S0304-4203(98)00073-5

Adsorption of dissolved phosphate onto loess particles in surface and deep Eastern Mediterranean water

Barak Herut, Tamar Zohary, Richard D. Robarts, Nurit Kress

Research output: Contribution to journal › Article › peer-review

Abstract

The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with ³²PO₄/^-3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (~11% of the total P concentration). Biological activity and inorganic particles removed similar: amounts of the tracer (30-40%) from SSW. It was estimated that about 0.2 μmol P/g of 'aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate 'deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (~27) reported by others.

Original language	English
Pages (from-to)	253-265
Number of pages	13
Journal	Marine Chemistry
Volume	64
Issue number	4
DOIs	https://doi.org/10.1016/S0304-4203(98)00073-5
State	Published - Apr 1999
Externally published	Yes

Bibliographical note

Funding Information:
We thank the captain and the crew of the RV Meteor and Prof. W. Roether for organizing this cruise. The cruise was funded by the Deutsche Forschungsgemeinschaft. The chemical determinations of dissolved nutrients were carried out by L. Israilov at IOLR. We thank Dr. M.D. Krom for useful discussions and comments on early drafts, M.D. Krom, A. Gray and L.M. Eijsink (Leeds Univ., NERC Grant GR3/10016) for carrying out X-ray and P fractionation analyses on the loess. BH, NK and TZ received partial financial support from the Israeli Ministry of Infrastructure (Grant 95-17-026) and the Ministry of Environment. RDR was partially funded by Environment Canada's International Partners Program (Germany) and the National Hydrology Research Institute. The authors wish to thank Dr. R.W. Murray, Dr. R.A. Feely and two anonymous reviewers for providing helpful comments.

Keywords

DIN
DIP
Loess

ASJC Scopus subject areas

Oceanography
General Chemistry
Environmental Chemistry
Water Science and Technology

Access to Document

10.1016/S0304-4203(98)00073-5

Cite this

@article{396d300ece7745d5aefc3fecae0c3af8,

title = "Adsorption of dissolved phosphate onto loess particles in surface and deep Eastern Mediterranean water",

abstract = "The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with 32PO4/-3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (~11% of the total P concentration). Biological activity and inorganic particles removed similar: amounts of the tracer (30-40%) from SSW. It was estimated that about 0.2 μmol P/g of 'aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate 'deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (~27) reported by others.",

keywords = "DIN, DIP, Loess",

author = "Barak Herut and Tamar Zohary and Robarts, {Richard D.} and Nurit Kress",

note = "Funding Information: We thank the captain and the crew of the RV Meteor and Prof. W. Roether for organizing this cruise. The cruise was funded by the Deutsche Forschungsgemeinschaft. The chemical determinations of dissolved nutrients were carried out by L. Israilov at IOLR. We thank Dr. M.D. Krom for useful discussions and comments on early drafts, M.D. Krom, A. Gray and L.M. Eijsink (Leeds Univ., NERC Grant GR3/10016) for carrying out X-ray and P fractionation analyses on the loess. BH, NK and TZ received partial financial support from the Israeli Ministry of Infrastructure (Grant 95-17-026) and the Ministry of Environment. RDR was partially funded by Environment Canada's International Partners Program (Germany) and the National Hydrology Research Institute. The authors wish to thank Dr. R.W. Murray, Dr. R.A. Feely and two anonymous reviewers for providing helpful comments. ",

year = "1999",

month = apr,

doi = "10.1016/S0304-4203(98)00073-5",

language = "English",

volume = "64",

pages = "253--265",

journal = "Marine Chemistry",

issn = "0304-4203",

publisher = "Elsevier",

number = "4",

}

TY - JOUR

T1 - Adsorption of dissolved phosphate onto loess particles in surface and deep Eastern Mediterranean water

AU - Herut, Barak

AU - Zohary, Tamar

AU - Robarts, Richard D.

AU - Kress, Nurit

N1 - Funding Information: We thank the captain and the crew of the RV Meteor and Prof. W. Roether for organizing this cruise. The cruise was funded by the Deutsche Forschungsgemeinschaft. The chemical determinations of dissolved nutrients were carried out by L. Israilov at IOLR. We thank Dr. M.D. Krom for useful discussions and comments on early drafts, M.D. Krom, A. Gray and L.M. Eijsink (Leeds Univ., NERC Grant GR3/10016) for carrying out X-ray and P fractionation analyses on the loess. BH, NK and TZ received partial financial support from the Israeli Ministry of Infrastructure (Grant 95-17-026) and the Ministry of Environment. RDR was partially funded by Environment Canada's International Partners Program (Germany) and the National Hydrology Research Institute. The authors wish to thank Dr. R.W. Murray, Dr. R.A. Feely and two anonymous reviewers for providing helpful comments.

PY - 1999/4

Y1 - 1999/4

N2 - The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with 32PO4/-3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (~11% of the total P concentration). Biological activity and inorganic particles removed similar: amounts of the tracer (30-40%) from SSW. It was estimated that about 0.2 μmol P/g of 'aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate 'deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (~27) reported by others.

AB - The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with 32PO4/-3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (~11% of the total P concentration). Biological activity and inorganic particles removed similar: amounts of the tracer (30-40%) from SSW. It was estimated that about 0.2 μmol P/g of 'aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate 'deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (~27) reported by others.

KW - DIN

KW - DIP

KW - Loess

UR - http://www.scopus.com/inward/record.url?scp=0032998359&partnerID=8YFLogxK

U2 - 10.1016/S0304-4203(98)00073-5

DO - 10.1016/S0304-4203(98)00073-5

M3 - Article

AN - SCOPUS:0032998359

SN - 0304-4203

VL - 64

SP - 253

EP - 265

JO - Marine Chemistry

JF - Marine Chemistry

IS - 4

ER -

Adsorption of dissolved phosphate onto loess particles in surface and deep Eastern Mediterranean water

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this