Stable isotopic and geochemical variability within shallow groundwater beneath a hardwood hammock and surface water in an adjoining slough (Everglades National Park, Florida, USA)

作者：Florea Lee J^*; McGee Dorien K

来源：Isotopes in Environmental and Health Studies, 2010, 46(2): 190-209.

DOI：10.1080/10256016.2010.494770

• isotope ecology
• hydrogen-2
• oxygen-18
• Everglades National Park
• USA
• delta D to delta(18)O excess
• Everglades agricultural area
• mid-summer drought

Data from a 10-month monitoring study during 2007 in the Everglades ecosystem provide insight into the variation of delta(18)O, delta D, and ion chemistry in surface water and shallow groundwater. Surface waters are sensitive to dilution from rainfall and input from external sources. Shallow groundwater, on the other hand, remains geochemically stable during the year. Surface water input from canals derived from draining agricultural areas to the north and east of the Everglades is evident in the ion data. delta(18)O and delta D values in shallow groundwater remain near the mean of -2.4 and -12%, respectively. (18)O and D values are enriched in surface water compared with shallow groundwater and fluctuate in sync with those measured in rainfall. The local meteoric water line (LMWL) for precipitation is in close agreement with the global meteoric water line; however, the local evaporation line (LEL) for surface water and shallow groundwater is delta D = 5.6 delta(18)O + 1.5, a sign that these waters have experienced evaporation. The intercept of the LMWL and LEL indicates that the primary recharge to the Everglades is tropical cyclones or fronts. delta deuterium to delta(18)O excess (D(ex) values) generally reveal two moisture sources for precipitation, a maritime source during the fall and winter (D(ex) > 10%) and a continental-influenced source (D(ex) < 10%) in the spring and summer.

• 出版日期2010