Rapid Analysis of Eukaryotic Bioluminescence to Assess Potential Groundwater Contamination Events

Table 2

Concentrations of endogenous groundwater constituents and exogenous chemical compounds required to produce a 50% reduction in Pyrocystis lunula bioluminescence during eight different exposure periods.

(a)

Endogenous compounds
Arsenic		Barium		Selenium		Strontium
Exposure (hours)	IC50 concentration (mg/L)	Exposure (hours)	IC50 concentration (mg/L)	Exposure (hours)	IC50 concentration (mg/L)	Exposure (hours)	IC50 concentration (mg/L)
4	2.55	4	40	4	200	4	5400
6	2.53	6	65	6	451	6	7650
8	2.52	8	68	8	493	8	10010
12	2.65	12	88	12	314	12	3600
24	2.55	24	68	24	307	24	3200
48	2.50	48	68	48	400	48	4000
72	2.55	72	62	72	378	72	4490
96	2.55	96	70	96	359	96	5100

(b)

Exogenous compounds
Glutaraldehyde		HCl
Exposure (hours)	IC50 concentration (mg/L)	Exposure (hours)	IC50 concentration (mg/L)
4	4.60	4	136
6	5.96	6	178
8	4.36	8	182
12	4.24	12	199
24	5.14	24	194
48	4.10	48	235
72	4.28	72	276
96	4.46	96	274

IC₅₀ values were interpolated graphically from measurements collected with varying concentrations during each exposure period. Nominal exposure concentrations used at each time point are illustrated in Table 1.