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Spatiality, seasonality and ecological risks of heavy metals in the vicinity of a degenerate municipal central dumpsite in Enugu, Nigeria.

Ajah KC, Ademiluyi J, Nnaji CC - J Environ Health Sci Eng (2015)

Bottom Line: On the other hand, the concentrations of arsenic, cobalt and iron continued to decrease even at a depth of 2 m.The high pollution loading index represents a significant level of deterioration.It can be concluded that the dumpsite constitute a serious environmental and health hazard.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil Engineering, University of Nigeria, Nsukka, Enugu State Nigeria.

ABSTRACT

Background: Improper waste disposal is responsible for the contamination of both surface and ground water resources. Heavy metals leached from improperly disposed solid waste constitute grave environmental and health hazards because of their toxic and persistent nature. There are thousands of open dumps in Nigeria one of which is the Enugu State Waste Management Authority dumpsite.

Method: Forty sampling nodes were systematically established around the Enugu State waste Management Authority central dumpsite located at Ugwuaji, Enugu State, Nigeria. Ten heavy metals (arsenic, cadmium, cobalt, copper, chromium, iron, lead, manganese, nickel and zinc) were sampled at different depths of each node in both rainy and dry seasons.

Result: Iron and lead were the predominant metals in the vicinity of the waste dump with average values of 132.10 mg/kg and 117.52 mg/kg respectively. The order of abundance of the ten heavy metals monitored is Pb > Fe > As > Zn > Cu > Co > Ni > Cd > Cr > Mn. Generally, there was significant correlation (0.25 to 0.74) among all the metals except between cobalt and manganese in the rainy season. In the dry season, all the metals were significantly correlated (0.29 to 0.813) except for copper and lead, copper and arsenic, zinc and arsenic, and cobalt and manganese. The concentrations of most of the heavy metals approached a constant level at a depth of 1 m. On the other hand, the concentrations of arsenic, cobalt and iron continued to decrease even at a depth of 2 m. The pollution loading index values for the soil are 1.706 for rainy season and 2.54 for dry season.

Conclusion: The high pollution loading index represents a significant level of deterioration. It can be concluded that the dumpsite constitute a serious environmental and health hazard.

No MeSH data available.


Related in: MedlinePlus

Seasonal variation of pollution index.
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Fig3: Seasonal variation of pollution index.

Mentions: In almost all cases, concentration of heavy metals peaked at the dump site but gradually tailed to the environs. Figures 2 and 3 show that there was a gradual attenuation of lead in both lateral and vertical directions. This is evidenced by the undulating nature of the curves and by the closeness of the concentration lines for different depths. This can be attributed to the effect of leaching by infiltrating water. Besides, during heavy rainfall, runoff from the dumpsite spreads to the surrounding soil, thereby redistributing the heavy metals. The same phenomenon applies to copper and zinc as depicted by the curves. For most of the metals especially lead, cobalt, cadmium and iron, the vertical variation of metal concentration becomes almost insignificant at a distance of about 80 m from the dumpsite. This suggests persistence, and that the preferred direction of transport is downward. Moreover, the spatial variation of heavy metals in a given catchment area decreases with depth. This is easily visualized from Figures 2 and 4. Curves of heavy metals variation at 0.5 m depth are much more pronounced than those of 2 m depth. It has been observed that it is this persistence and low mobility of heavy metals in the environment, even under high precipitation, that aggravates the risk posed by heavy metals [43].Figure 2


Spatiality, seasonality and ecological risks of heavy metals in the vicinity of a degenerate municipal central dumpsite in Enugu, Nigeria.

Ajah KC, Ademiluyi J, Nnaji CC - J Environ Health Sci Eng (2015)

Seasonal variation of pollution index.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4363377&req=5

Fig3: Seasonal variation of pollution index.
Mentions: In almost all cases, concentration of heavy metals peaked at the dump site but gradually tailed to the environs. Figures 2 and 3 show that there was a gradual attenuation of lead in both lateral and vertical directions. This is evidenced by the undulating nature of the curves and by the closeness of the concentration lines for different depths. This can be attributed to the effect of leaching by infiltrating water. Besides, during heavy rainfall, runoff from the dumpsite spreads to the surrounding soil, thereby redistributing the heavy metals. The same phenomenon applies to copper and zinc as depicted by the curves. For most of the metals especially lead, cobalt, cadmium and iron, the vertical variation of metal concentration becomes almost insignificant at a distance of about 80 m from the dumpsite. This suggests persistence, and that the preferred direction of transport is downward. Moreover, the spatial variation of heavy metals in a given catchment area decreases with depth. This is easily visualized from Figures 2 and 4. Curves of heavy metals variation at 0.5 m depth are much more pronounced than those of 2 m depth. It has been observed that it is this persistence and low mobility of heavy metals in the environment, even under high precipitation, that aggravates the risk posed by heavy metals [43].Figure 2

Bottom Line: On the other hand, the concentrations of arsenic, cobalt and iron continued to decrease even at a depth of 2 m.The high pollution loading index represents a significant level of deterioration.It can be concluded that the dumpsite constitute a serious environmental and health hazard.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil Engineering, University of Nigeria, Nsukka, Enugu State Nigeria.

ABSTRACT

Background: Improper waste disposal is responsible for the contamination of both surface and ground water resources. Heavy metals leached from improperly disposed solid waste constitute grave environmental and health hazards because of their toxic and persistent nature. There are thousands of open dumps in Nigeria one of which is the Enugu State Waste Management Authority dumpsite.

Method: Forty sampling nodes were systematically established around the Enugu State waste Management Authority central dumpsite located at Ugwuaji, Enugu State, Nigeria. Ten heavy metals (arsenic, cadmium, cobalt, copper, chromium, iron, lead, manganese, nickel and zinc) were sampled at different depths of each node in both rainy and dry seasons.

Result: Iron and lead were the predominant metals in the vicinity of the waste dump with average values of 132.10 mg/kg and 117.52 mg/kg respectively. The order of abundance of the ten heavy metals monitored is Pb > Fe > As > Zn > Cu > Co > Ni > Cd > Cr > Mn. Generally, there was significant correlation (0.25 to 0.74) among all the metals except between cobalt and manganese in the rainy season. In the dry season, all the metals were significantly correlated (0.29 to 0.813) except for copper and lead, copper and arsenic, zinc and arsenic, and cobalt and manganese. The concentrations of most of the heavy metals approached a constant level at a depth of 1 m. On the other hand, the concentrations of arsenic, cobalt and iron continued to decrease even at a depth of 2 m. The pollution loading index values for the soil are 1.706 for rainy season and 2.54 for dry season.

Conclusion: The high pollution loading index represents a significant level of deterioration. It can be concluded that the dumpsite constitute a serious environmental and health hazard.

No MeSH data available.


Related in: MedlinePlus