TABLE 1.

Hydrodynamic and microbiological characteristics of original soil, soil from control columns, and soil from columns amended with one, two, or three pulses of 2,4-D

Treatment	Soila	Apparent dispersion coefficient (cm2 h−1)	Solute exchange coefficient (h−1)	Fraction of mobile water	No. of heterotrophs per g [dry wt] of soil	No. of 2,4-D degraders per g [dry wt] of soil	% of 2,4-D degraded	Determination of spatial distributionb
Original soil	S	NRc	NR	NR	3.6 × 107	1.9 × 102	NR	+
Control column	Ca	NDd	ND	ND	2.7 × 107	3.1 × 102		+
	Cb	ND	ND	ND	4.0 × 107	3.7 × 103		+
	Cc	ND	ND	ND	ND	ND	NR	+
	Cd	ND	ND	ND	ND	ND		+
	Ce	ND	ND	ND	ND	ND		+
Column amended	IP1a	0.05	0.03	0.83	3.8 × 107	2.0 × 105	25	+
with one pulse	IP1b	ND	ND	ND	ND	5.6 × 105	ND	+
	IP1c	ND	ND	ND	ND	ND	ND	+
Column amended	IIP1a	0.05	0.03	0.83	ND	ND	46	−
with two pulses	IIP2a	0.22	0.03	0.82	5.7 × 107	5.5 × 106	97	+
	IIP2b	ND	ND	ND	1.4 × 107	9.4 × 105	75	+
	IIP2c	ND	ND	ND	3.8 × 107	1.1 × 106	98	+
Column amended	IIIP1	0.05	0.03	0.83	ND	ND	50	−
with three pulses	IIIP2	0.22	0.03	0.83	ND	ND	59	−
	IIIP3	0.22	0.03	0.83	3.8 × 107	6.2 × 106	73	+

^aS, original soil; C, soil from control column; IP, IIP, and IIIP, soil from columns amended with one, two, and three pulses of 2,4-D, respectively. The first, second, and third pulses are indicated by 1, 2, and 3, respectively. The suffixes a, b, c, d, and e indicate replicates.

^b+, spatial microsampling performed; −, spatial microsampling not performed.

^cNR, not relevant.

^dND, not determined.