|Figures 7a,b. Ternary diagrams of the major cations and anions in
groundwater according to land use. Based on previous studies
conducted on Long Island (deLaguna, 1964; SCDHS, 1987; Leamond et al.,
1992; Pearsall, 1996). Residential and agricultural waters plot in
distinct fields with little overlap.
|Figures 7c,d. Ternary diagrams of the major cations and anions in
monitoring-well samples. Symbol size reflects nitrate
concentration. Samples were collected from monitoring wells in
residential neighborhoods except for one obtained from an agricultural
area (Ag) and one collected downgradient from a landfill (LF). Most
samples plot within the residential field except that liming of turf grass
tends to blur the distinction between the agricultural and the residential
field on the cation plot.
|Figures 7e,f. Ternary diagrams of the major cations and anions in public
supply wells. Symbol size reflects nitrate concentration. The only
wells that show the enrichment in both calcium and sulfate characteristic
of agricultural land use are those at Gun Club Road. PResent land use in
the vicinity of these wells is agricultural.