Hydrochemical and Stable Isotope Analyses Show Limited Interactions Between Groundwater and Lake Water in the Lake Bosomtwi Impact Crater, Ghana.

doi:10.21203/rs.3.rs-1093447/v1

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Hydrochemical and Stable Isotope Analyses Show Limited Interactions Between Groundwater and Lake Water in the Lake Bosomtwi Impact Crater, Ghana.

https://doi.org/10.21203/rs.3.rs-1093447/v1

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The relationship between groundwater and surface water in the Lake Bosumtwi impact crater has been assessed using hydrochemical data and stable water isotopes of δ18O and δD. This study aimed to define likely groundwater flow and recharge zones, estimate the rate of evaporation, and examine the relationship between the lake and groundwater in the study area. The results of Q-Mode hierarchical cluster analysis (HCA) clearly differentiate the lake water from the groundwater based on their spatial relationship. These preliminary results indicated that groundwater recharge occurs on the hilltops of the crater, where it is slightly acidic with low levels of dissolved minerals, characterized by short residence time and rapid unrestricted vertical infiltration and recharge. The groundwater becomes more mineralized with longer contact times and deeper circulation with the host rock, while it flows from the recharge areas towards the lake at lower elevations. Analyses of stable water isotopes of δ18O and δD showed a high evaporation rate on the lake surface, of ~90% with a relatively significant evaporative enrichment, whereas groundwater showed a relatively lower evaporation rate ranging between 54-60%. Both reservoirs do not appear to be hydraulically connected, and where such a connection exists, it is expected to favour the lake.

Environmental Engineering

Lake Bosumtwi

Stable Isotopes

Kinetic Fractionation

Surface Water

Groundwater

Ghana

Table 1: Statistical summary of the physico-chemical parameters of the clusters

CLUSTER 1
	Elevation (m)	pH	T(ºC)	EC (µS/cm)	TDS (mg/l)	K (mg/l)	Na (mg/l)	Mg (mg/l)	Ca (mg/l)	Sr2+ (mg/l)	Si (mg/l)	F (mg/l)	Cl (mg/l)	NO₃^- (mg/l)	SO₄^2- (mg/l)	HCO₃^- (mg/l)
Min	259	5.08	25.04	138	69	0.23	9.64	3.49	13	0.07	23.8	0.01	3.53	0.15	0.13	31
Max	358	5.73	26.03	270	135	4.80	18.8	11.7	11.6	0.17	52	0.26	6.16	3.13	1.98	70
Mean	307.75	5.51	25.48	189	95	1.05	15.07	5.74	4.95	0.12	36.14	0.1	4.47	0.87	0.9	51.75
Std.Dev	27.88	0.26	0.36	46.14	23.10	1.53	3.35	2.68	3.44	0.03	9.5	0.1	0.82	1.02	0.74	15.62
Median	306	5.61	25.39	188	94	0.57	15.75	4.81	4.6	0.12	35.2	0.08	4.15	0.54	0.61	51
CLUSTER 2
	Elevation (m)	pH	T(ºC)	EC (µS/cm)	TDS (mg/l)	K (mg/l)	Na (mg/l)	Mg (mg/l)	Ca (mg/l)	Sr2+ (mg/l)	Si (mg/l)	F (mg/l)	Cl (mg/l)	NO₃^- (mg/l)	SO₄^2- (mg/l)	HCO₃^- (mg/l)
Min	111	5.54	24.55	295	147	0.28	17.2	7.97	1.6	0.178	13.9	0.02	4.3	0.02	0.06	57
Max	448	7.29	28.23	662	331	4.4	67.2	23.8	69.9	0.52	38.4	1.11	60.1	13.5	22.5	290
Mean	251.3	6.43	26.48	510.2	255.4	1.28	37.75	16.23	34.45	0.32	25.74	0.23	20.17	3.04	9.71	183.2
Std.Dev	120.96	0.55	1.31	105.08	52.7	1.26	17.87	4.86	20.88	0.13	6.47	0.32	21.89	5.42	8.57	87.46
Median	253	6.56	26.19	507	254	0.87	33.7	16.05	38.75	0.33	26.55	0.14	7.73	0.62	10.02	198.5
CLUSTER 3
	Elevation (m)	pH	T(ºC)	EC (µS/cm)	TDS (mg/l)	K (mg/l)	Na (mg/l)	Mg (mg/l)	Ca (mg/l)	Sr2+ (mg/l)	Si (mg/l)	F (mg/l)	Cl (mg/l)	NO₃^- (mg/l)	SO₄^2- (mg/l)	HCO₃^- (mg/l)
Min	108	6.2	25.46	599	300	0.44	26.7	9.9	18.8	0.2	8.1	0.02	8.63	0.02	17.9	182
Max	244	7.04	29.18	1746	873	4.89	105	84	120	0.86	22.4	0.38	69.6	21.3	79.3	494
Mean	163.25	6.7	27.43	959	480	1.46	59.03	31.52	65.91	0.42	16.68	0.15	31.44	4.17	36.27	353.75
Std.Dev	57.51	0.23	1.18	293.26	146.68	1.24	21.92	18.7	28.21	0.21	3.95	0.11	19.54	6.14	17.54	93.21
Median	128.5	6.73	27.57	888.5	444	0.97	60.6	24.1	65.2	0.36	17	0.14	26.55	1.8	28.6	361
CLUSTER 4
	Elevation (m)	pH	T(ºC)	EC (µS/cm)	TDS (mg/l)	K (mg/l)	Na (mg/l)	Mg (mg/l)	Ca (mg/l)	Sr2+ (mg/l)	Si (mg/l)	F (mg/l)	Cl (mg/l)	NO₃^- (mg/l)	SO₄^2- (mg/l)	HCO₃^- (mg/l)
Min	103	8.39	26.59	1262	634	119	80.8	6.79	4.5	0.105	4.6	0.18	107	0.04	0.6	500
Max	112	9.06	27.50	1344	672	28.8	260	14.3	9.2	0.2	11.6	0.41	138	0.32	0.9	526
Mean	107.43	8.87	27.24	1313.29	657.57	25.04	224.97	12.63	7.73	0.19	9.94	0.26	112	0.13	0.79	514.43
Std.Dev	3.36	0.23	0.34	36.2	17.21	6.29	66.31	2.72	1.52	0.04	2.6	0.07	11.47	0.11	0.12	9.69
Median	109	8.95	27.41	1337	669	28.1	257	14	8	0.2	11.2	0.24	108	0.08	0.78	516

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Reviews received at journal
11 Jan, 2022
Reviewers invited by journal
10 Jan, 2022
Editor assigned by journal
19 Nov, 2021
First submitted to journal
18 Nov, 2021

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Hydrochemical and Stable Isotope Analyses Show Limited Interactions Between Groundwater and Lake Water in the Lake Bosomtwi Impact Crater, Ghana.

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