[1] SW Texas State Univ, Dept Geog, Texas Ctr Geog Informat Sci, San Marcos, TX 78666 USA
[2] BioMedware Inc, Ann Arbor, MI USA
[3] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China
[4] Univ Texas Brownsville, Dept Chem & Environm Sci, Brownsville, TX 78520 USA