Ambiental dust speciation and metal content variation in TSP, PM10 and PM2.5 in urban atmospheric air of Harare (Zimbabwe) |
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Authors: | A T Kuvarega P Taru |
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Institution: | (1) Environmental Conservation Branch, Environment Canada Atlantic Region, 45 Alderney Drive, Dartmouth, NS, B2Y 2N6, Canada;(2) Environmental Conservation Branch, Environment Canada, P.O. Box 23005, Moncton, NB, E1A 6S8, Canada;(3) NS Department of Natural Resources, P.O. Box 698, Halifax, NS, B3J 2T9, Canada |
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Abstract: | The effects of timber harvesting on stream water quality and efficiency of alternate streamside management zones were evaluated
in Pockwock Lake and Five Mile Lake watersheds in central Nova Scotia, Canada. The streamside management zone (SMZ) included
a 20 m no cut, 20 m select cut and a 30 m select cut buffer strips along the stream. Water quality of eight streams, six in
harvested and two in not-harvested watersheds were monitored for two years before and two years after the harvesting of timber.
Nonparametric statistical tests on stream water quality showed that there was significant change in the concentration of potassium
in six streams, manganese in five streams, zinc in two streams and total nitrogen in one stream after timber harvesting. There
was no significant change in the quality of water in two streams used as control sites in the neighboring watersheds of similar
size and hydrological characteristics. The results show that forest management practices were most favorable in streams maintained
with 30 m select cut followed by 20 m no cut and 20 m select cut SMZ. The streamside zone width and treatment of select cut
or no cut in the zone played an important role in filtering or retaining the minerals in surface water runoff. In buffer zones
of similar width, the buffer zone with no cut or forested buffer was relatively more effective at protecting stream water
quality than select cut SMZ. The vegetation in the zone may have decreased the flow velocity and increased residence time
and thus increased filtration and retention of minerals in the riparian soil. |
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Keywords: | Forestry management practices Nova Scotia Stream water quality Streamside management zone Timber harvesting Watersheds |
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