Environmental impacts of sand and gravel mining on water quality and biodiversity in Kalak sub-district

الملخص EN

Nine sites were chosen, five of them were old excavation pits and the other three new excavation pits with one (un excavation pit) in the Greater Zab river.

Samples were collected at nine sites for six months, from July to December 2013.

Some physical and chemical parameters were analyzed at studied sites including, water and air temperature, pH, EC, turbidity, DO, BOD5, COD, NH4 +, NO2 -, NO3 -, TDN and TDP.

Sites 6, 7 and 8 tended to have higher turbidity.

The lower value of dissolved oxygen recorded at site 2.

The highest COD, BOD5, NH4 + and TDP levels were recorded at Site 2.

Site 8 had the highest value of NO3 -, NO2 -and TDN.

The average value of the Water Quality Index based on European standard -WQI was ranged from 47% to 67%.

WQI for sites 1, 3, 4, 5 and 9 fall under medium category, meanwhile, for the rest sites (sites 2, 6, 7, 8) fall under bad category.

Sixty nine species of zooplankton were identified, which belonged to rotifer with fourteen families and forty four species with percentage composition of 88.17%.

Rotifera forms a prominent group among the zooplankton, followed by Copepoda with one family and eleven species with percentage composition of 6.02%, then by Cladocera with four families and fourteen species with percentage composition of 5.79%.

The highest density of zooplankton was obtained at site 2.

According to Shanon-Weiner index, site 4 had the highest diversity.

Concerning to Sorensen similarity index, the highest percentage of similarity to zooplankton community occurred between site 2 and site 4 reached to 84%.Concerning to the benthic macro –invertebrates, only three species-Limnodrilus hoffmeistern; Limnodrilus spirals; Limnodrilus claparedeianus were found.

The high density of benthic invertebrate was observed at sites 1 and 2, on the other hand, zooplanktons and benthic macro –invertebrates were clearly absent at sites 6, 7, 8 and 9.