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Chemical Leaching Near the Waiawa Shaft, Oahu, Hawaii: 2. Modeling Results
Author(s) -
Loague Keith,
Miyahira Robert N.,
Green Richard E.,
Oki Delwyn S.,
Giambelluca Thomas W.,
Schneider Randi C.
Publication year - 1995
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1995.tb00268.x
Subject(s) - environmental science , diazinon , metribuzin , leaching (pedology) , groundwater , leachate , water table , chlorpyrifos , hydrology (agriculture) , groundwater recharge , pesticide , soil water , soil science , environmental chemistry , aquifer , geology , chemistry , geotechnical engineering , weed control , biology , agronomy
This paper is the second part of a two‐part series concerned with assessing the potential for organic chemical leaching to a ground‐water skimming tunnel in the Pearl Harbor Basin, Oahu, Hawaii, as a direct result of proposed urban development. The Pesticide Root Zone Model (PRZM) was used, after testing with field and laboratory data described in the companion paper, to make long‐term predictions of the movement of chlorpyrifos, diazinon, metribuzin, and nitrate under various recharge scenarios. The PRZM simulations revealed that, with the exception of chlorpyrifos, detectable levels of all the chemicals considered in this study may leach through the unsaturated zone to the water table from where they may eventually migrate to the skimming tunnel. The simulated concentrations in leachate reaching the water table were sufficiently low, considering subsequent mixing in the ground water, to suggest no adverse health effects. The reliability of the simulated results are laced with enough uncertainty, however, to suggest the need for monitoring for diazinon, metribuzin, and nitrate, if development does proceed. The methodology presented in this series is a first attempt at establishing a protocol for using numerical modeling, supported by field and laboratory measurements to aid in land‐use change consideration in Hawaii when nonpoint ground‐water contamination from organic chemicals is of concern.