PS 60-25
Investigating effects of bridge construction on water quality using physical, chemical, and biological analyses
Human activities such as bridge constructions can be a major contributor to water pollution. The immediate areas of construction sites and downstream of streams and rivers may be negatively affected due to increased input of sediments and nutrients through runoff. The University of Hartford reconstructed a new bridge over the Park River from July 2012 to February 2013 to alleviate flooding problems. This project was conducted to assess effects of the bridge construction on water quality using a series of physical, chemical, and biological indices including turbidity, dissolved oxygen, nitrate, total phosphate, and benthic macroinvertebrate biodiversity. Three periods of datasets were compared to determine effects of the bridge construction on water quality: before the construction – from September 2011 to February 2012, during the construction – from September 2012 to February 2013, and after the construction – from September 2013 to February 2014.
Results/Conclusions
Results revealed annual variations between the three periods and localized negative impacts of the bridge construction. Although the construction had no effects on the chemical parameters including dissolved oxygen, total phosphorus and nitrate, the turbidity increased significantly during the construction period at the site immediate after the construction site and was back to its original state within the first year after the completion of the bridge (from 2.5±0.4 NTU to 4.0±0.9 NTU and to 2.4±0.2 NTU). Species richness of benthic macroinvertebrates decreased significantly due to the construction (from 7.3±0.4 to 2.8±0.7, and to 2.8±0.8) as well as their biodiversity (from 1.3±0.2, to 0.9±0.1, and to 0.7±0.1) at that site. There were no impacts at the site further away from the construction site. In conclusion, benthic macroinvertebrates showed no improvement after completion of the bridge construction, suggesting that the construction had negative effects on aquatic organisms and the effects may be long lasting. A longer term study should be conducted to investigate whether the macroinvertebrate community will recover from the bridge construction.