Environmental Engineering Reference
In-Depth Information
N
Q inghai Lake
Xining
8
Gonghe County
145 km
0
72.5
Lonyan gxia Dam
Tongren County
Duoqinankelang R.
Eling Lake
6 7
Gannan Tibetan
autonomous
prefecture
Zha ling La ke
Maduo County
Maqin County
1
2 3
M aqu C ounty
4 5
Dari Cou nty
Fig. 10.42
Location of the 8 sampling sites in the source region of the Yellow River
with gravel beds, the gravels were washed and sieved with a kick-net with holes of 0.5 mm, and organic
and inorganic detritus with macro-invertebrates collected. The detritus was subsequently placed on a
white tray, and the invertebrates were collected. Invertebrate species were thereafter examined and
identified to family or genus level under a microscope. The sampled area was 1.5 m 2 consists of three
sub-sampling areas in order to reflect diversified ecological conditions. After sampling, macro-invertebrates
and associated material were immediately preserved in ethanol and were subsequently processed and
identified in the laboratory (Duan et al, 2010). There is little pollution and the water quality is very good.
In general, the community of benthic invertebrates is different if the environmental conditions are
different. The main environmental factors for benthic invertebrates are stream substrate, water depth,
flow velocity, and water quality (Wang et al., 2009). At the site ķ the Zequ River is a tributary of the
Yellow River with meandering channel. In its drainage area there are numerous swamps and rivulets with
small but stable flow. The rivulets wriggle on vast meadows with grass coverage almost 100%. The site
of streamlet represents the habitat type. Near the Yellow River by Kesheng town (site ĸ ) there is an
oxbow lake (site Ĺ ), which is abandoned channel of the Yellow River and has been cutoff from the river
for a very long period of time. The site ĺ is a riparian lake, which may connect with the Yellow River
during high floods. The Dari bay Ļ is a riparian wetland where the Yellow River flows from a normal
channel to a very wide valley with shallow water. The main water flow has a deep channel, but plume of
low sediment concentration drifts into the bay. The site ļ is a wetland by the Yellow River. The Eling
Lake Ľ is the source of the Yellow River with a capacity of 10 billion m³. The pool level in the lake is
not stable depending on the incoming water and operation of a hydropower station just below it. The
water level had been rising since a month before the field investigation. The Qinghai Lake ľ has
brackish water with low concentration of salt. It is near by the source of the Yellow River and represents
a type of habitat in the region.
Table 10.2 lists the species of macro-invertebrates identified from the samples of each site with the
number density (ind/m 2 ) of each species in the parentheses (Wang et al., 2010). The taxa richness, or the
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