3. Results
3.1. Physico-chemical environment
Table 1 presents the values recorded for physicochemical variables in the samplings carried out in the
study period. Temperature is an important factor which controls all chemical reactions and biological
processes in a water body. During the current study period, water temperature varied between 3.7 and
21.2 °C, with high values in Aug. and low Jan. The pH values indicated an alkaline condition, with pH
ranging between 8.89 and 9.29. The higher pH value was observed after ice-bound period could be
attributed to enhanced rate of evaporation and photosynthetic activity. The maximum value of alkalinity
was observed in January while minimum in October. Alkalinity ranged between the lowest value of 867
and the highest value of 1790 mg/l. Total hardness values were between 62.0 and 190.7 mg/l. The Hulun
Lake water is moderate hard water conditions, which in turn useful for the higher productivity.
During the study period, the salinity of the Hulun Lake ranged from 2076.6 to 3149.7 mg/l. The
highest value caused by ice-sheet was recorded in January. The values of COD varied between 14.80 and
22.74 mg/l, the high value of COD was probably due to the addition of waste [10]. The concentration of
ammonia nitrogen content was ranged between 0.64 mg/l and 0.81 mg/l. Average nitrate nitrogen content
was ranged between 0.03 mg/l to 0.04 mg/l. Average phosphate values were ranged between 0.06 mg/l to
0.23 mg/l. The annual mean value of the N: P (nitrate nitrogen: phosphate ratio) was 0.33.