TABLE 1.

Geochemistry of the north and deep central sediment cores obtained from lignite mine Lake 77

Sediment zone	Depth (cm)	pH	Amt (mM) of:
			Fe(II)		Fe(III)
			Dissolveda	HCl extractedb	Dissolved	HCl extracted
North I	0-1	2.8	4.5	17.4	NDc	211.7
North II	1-4	2.9	7.3	13.1	ND	87.5
North III	4-10.5	3.7	15.1	11.9	ND	ND
North IV	10.5-20.5	5.3	12.5	30.6	ND	ND
Deep I	0∼1	2.7	1.5	7.0	ND	81.0
Deep II	1∼4	2.9	4.6	11.9	ND	129.7
Deep III	4∼10.5	3.2	5.9	13.8	ND	10.9
Deep IV	10.5∼20.5	4.1	4.2	16.3	ND	ND

^aFe measured in the supernatant after centrifugation.

^bFe measured after preextraction of sediment in 0.5 M HCl.

^cND, not detected.