Qz. Yang et al., MAJOR FEATURES OF GLACIOCHEMISTRY OVER THE LAST 110,000 YEARS IN THE GREENLAND ICE-SHEET PROJECT-2 ICE CORE, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(D19), 1997, pp. 23289-23299
Major chemical species (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, Ca2+) a
nd delta(18)O covering the last 110,000 years from the Greenland Ice S
heet Project 2 (GISP2) ice core were utilized in this study in order t
o reconstruct the soluble chemistry of the atmosphere over Greenland a
nd interpret major climate events that have affected the region. Durin
g the Holocene the major chemical species and delta(18)O do not displa
y any significant relationship. However, a strong inverse correlation
was found between concentrations of the major chemical species and del
ta(18)O (a proxy for temperature) during the last glacial period, sugg
esting that in general during periods of decreased temperature, there
is an increase in atmospheric chemical loading. Examination of changes
in major chemical composition over the last 110,000 years of the GISP
2 ice core reveals that during the Holocene, the atmosphere was acidic
; during interstadials the atmosphere was neutral or alkalescent; and
during stadials the atmosphere was alkaline. In addition, the relative
abundance of major chemical species varied during the Holocene, stadi
als, and interstadials. During the Holocene, NH4+ and NO3- are the dom
inant cations and anions; while Ca2+ and SO42- are the dominant cation
s and anions during the stadials and interstadials, This suggests that
source regions or types differed between the Holocene and the last gl
acial period. In addition, changes in chemical composition and changes
in chemical ratios also indicate that source regions differed during
the Holocene, stadials, and interstadials. Twenty-four previously iden
tified Dansgaard-Oeschger (stadial/interstadial) events [Dansgaard: et
al., 1993] were in the GISP2 chemical series. The duration of the sta
dials is inversely correlated with variations in sea level over the la
st glacial period (i.e., the more extensive the northern hemisphere ic
e sheet, the longer the duration of the stadial). There is also a clos
e correspondence between the duration of interstadials and the timing
of Heinrich events (massive icebergs discharged into the ocean) in the
GISP2 ice core. Long. (up to 2000 years) warm periods follow each Hei
nrich event, suggesting perhaps that enhanced deep-water circulation i
s re-initiated following Heinrich events.