poster - International Conference of Agricultural Engineering

3.2. Variability of parameters
The spatial distribution of the overall means of measured parameters is shown in Fig.
4. The greatest values for temperature, electrical conductivity, pH and dissolved
organics was measured in the south of the lake in agreement with the direction of the
water flow, from northeast to southwest. Totals of N and P were higher near the
entrance of the channels which discharge into the WL (Fig 4.). COD and Chl.a are very
consistent in this spatial distribution, thus revealing the discharge of wastewater into the
WL. Nitrogen and P consumption by reed which covers about 15% of the lake might
explain the decrease in the concentrations along the flow.
4. Conclusions
The main factors influencing temporal variations in water quality seem to be
agricultural losses of nutrients as well as wastewater discharge into the channels which
lead into the WL. Winter seems to be the season where the water has a greater load of
nutrients and evaporation during summer may influence parameters concentration. The
direction of water flow and the position of channels in and out of the WL also influenced
the concentration of parameters concentration in the water.
Acknowledgments
We would like to thank the lake research team in Inner Mongolia Agricultural
University for their persistent efforts in collecting/measuring the data in this study. The
study is supported by the Sino-Portuguese cooperative research project, MOST, China,
and FCT, Portugal .
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