A study on temporal and spatial distribution characteristics of dissolved oxygen in surface water of megacities
2020, 2020 (6):
The dissolved oxygen (DO) zoning method was used to analyze the temporal and spatial characteristics of 259 river monitoring sites in Shanghai in 2016. The results showed that: ① Time periods with the highest mean DO can be ranked according to the following sequence: winter > spring > autumn > summer, non-flood period > flood period. ② DO had significant spatial stratification. Low-oxygen areas (DO < 2 mg/L) were mainly distributed in highly urbanized geographies, such as the city center and nearby suburban areas, changing with both season and flood period and seemingly affected by surface runoff and the discharge of pumping stations. High-oxygen areas (DO > 6 mg/L) were distributed in areas with high water ecological environmental requirements and occasionally appeared in the suburbs. Most of the annual changes in DO belonged to the median areas (DO: 4 ~ 6 mg/L), and were affected by both industry and agriculture. ③ Correlation anlysis of water quality factors indicated that DO was significantly correlated with water temperature (–0.434), pH(0.332), CODMn(–0.219), CODCr(–0.234), BOD5(–0.197), NH3-N(–0.299), TP(–0.370), TN(–0.191), Vol-P(–0.159), petroleum(–0.207). Stepwise regression analysis showed that DO was significantly affected by T, pH, NH3-N, TP and petroleum; the analysis showed, furthermore, that DO restricted factors varied in different seasons.
Related Articles |