Analysis of Bio-Obtainable Endocrine Disrupting Metals in River Water and Sediment, Sewage Influent/Effluent, Sludge, Leachate, and Concentrated Leachate, in the Irish Midlands Shannon Catchment

Table 10

Concentrations of metals found in sludge (mg/kg) for each treatment type.

Metal	Site type	Sediment concentration (mg/kg)
Δ (MPC mg/kg)		Nov	Dec	Jan	Feb	Mar	Apr	Kruskal-Wallis 𝑃 value for 𝑋 versus 𝑌 versus 𝑍^†	Mean % RSD
Ni 300–400	𝑋	2905	2310	2210	2278	2180	375	.220	1.5
	𝑌	3625	4700	4055	3408	910	325		4.1
	𝑍	2633	2925	3208	3010	2480	175		2.1
Mn	𝑋	243	358	185	658	698	410	.109	3.5
	𝑌	320	220	150	740	240	1642		1.9
	𝑍	178	180	123	90	241	615		2.4
Cd 20–40	𝑋	15	16	12	15	20	100	.059	11.3
	𝑌	7	8	13	9	6	20		14.6
	𝑍	15	14	15	13	17	30		15.2
Zn 2500–4000	𝑋	1187	1048	952	925	981	2001	.484	0.4
	𝑌	3400	1625	1002	1845	643	1745		0.3
	𝑍	846	844	888	1162	1081	2826		0.4
Co	𝑋	8	10	8	9	10	7	.044	2.3
	𝑌	23	13	20	15	10	10		7.5
	𝑍	16	19	24	37	9	5		5.6
Pb 750–1200	𝑋	150	300	325	250	375	750	.109	1.3
	𝑌	150	100	250	275	150	700		0.5
	𝑍	300	350	325	375	375	675		2.0
Cr n/a	𝑋	253	296	410	372	473	372	.003	8.2
	𝑌	213	35	134	212	68	137		7.8
	𝑍	253	334	403	486	455	289		9.1
Cu 1000–1750	𝑋	212	200	155	145	155	703	.164	3.4
	𝑌	625	373	373	478	33	1003		1.7
	𝑍	275	240	265	435	398	531		2.0
*Hg 16–25	𝑋	—	0.16	—	0.34	—	0.42	.054*	—
	𝑌	—	0.42	—	0.36	—	0.40		—
	𝑍	—	0.88	—	1.14	—	0.88		—

Δ Maximum permitted concentration as per EU directive 278/86.
^†Using Minitab15. This test, applied following evidence of nonnormality of the observed levels, tests for equality of medians of the treatment types (𝑋, 𝑌, and 𝑍), that is, if 𝑃<.05 we conclude that the medians are not the same. Adjustments made for ties as required.
*Only 3 samples from each site were chosen for mercury analysis