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Pollution levels of stormwater discharges and resulting environmental…
Pollution levels of stormwater discharges and resulting environmental impacts
Citation
Brudler S, Rygaard M, Arnbjerg-Nielsen K, Hauschild MZ, Ammitsøe C, Vezzaro L. Pollution levels of stormwater discharges and resulting environmental impacts. The Science of the total environment. 2019;663:754–763.
http://dx.doi.org/10.1016/j.scitotenv.2019.01.388
. doi:10.1016/j.scitotenv.2019.01.388
Possible working link to original paper:
https://www.sciencedirect.com/science/article/pii/S004896971930436X
Stormwater runoff pollutants occur from various sources: roadways (brake and tire dust and wear off, particulates from car accidents, oil and gas chemicals, and so on), certain roof components on houses, agricultural chemicals, etc.
Life cycle assessment (LCA) and life cycle impact assessment (LCIA) are both measurements used in testing stormwater runoff to determine the highest concentrations of the worst pollutants and provide a risk factor for water environments. This is a standard used around the globe.
Determining accurate and wholly investigated water pollutants is a difficult task as there are many factors and contributors in play. Tracking down sources is also hard. Finding average overall most harmful pollutants and determining their potential long-term impacts was the goal of this study.
Data in this article was found in databases linking pollutants and destructive events around the US and Europe with only the most relevant data being used for reference, to lend credibility.
Various mathematical formulas were used to calculate highest and lowest concentrations of several toxic substances that are known. Data from several sources were used and compiled into a basic table to show said concentrations from areas around the world.
Uncertainty was calculated to the best of the ability of the researchers in this article with this math. It was mentioned several times that some inaccuracy may be part of this study do to its dynamic nature in data gathering, furthering credibility to the research and the limit of their bias.
To further credible data collection, only initial "dumping sites" of stormwater runoff were used in determining toxic concentrations.
A potential harmful event looked at included eutrophication. Specifically, phosphorus and nitrogen in high concentrations causing algal blooms in marine environments, were assessed.
Agricultural areas are of main concern. Eutrophication was found to be only a little over 1% of a problem for toxic events. Also, it was found most pollution comes from agriculture since urban areas are small in comparison. This pollution was less so because it stayed in soil on farms before reaching water.
For legality, highest concentrations of hazardous runoff were looked at to determine if it was in a "safe" range. Unfortunately, insufficient data made this difficult to determine for the researchers
Legally speaking, researchers are quoted in this study as saying that "7 pollutants were over half" what their limit in concentration should be.
Many organic pollutants weren't "defined in legislation," and could potentially cause issues, regardless.
Figure 2 in the article is a collection of the average concentrations throughout the world on available data, of the most potentially toxic particulates found in stormwater runoff. Not enough data could be used for more accuracy, so it is considered "long term" averages.
Disturbingly, 17 metals were found to be in higher concentration than they should, most notably zinc and lead. This data was slightly skewed as it looked at dissolved concentrations, making it difficult to determine insoluble product.
Too little data was found for the organic compounds present and thus best guesses and worst case situations were considered and represented, but mentioned anyway for transparency.
Almost all harmful products in the data were represented majorly by metals showing "97%" of the problems. Most harmful metals were determined to be copper and zinc.
The study found the most harmful organics were "pesticides, dioxins, and hydrocarbons." For metals, freshwater was more affected than marine water, species wise. Figure 3 shows a great pie chart for concentrations found for metals and organics.
The study theorized that most pollutants, notably metals, were from degradation of roofs, pipes, and cars. Overall, it was found that freshwater was more affected by pollutants than marine water, which is concerning.
Half the metals looked at exceeded their concentration limits of where they're considered safe in water environments.
Conclusions from the article relate that mathematical corrections and assumptions were highly needed due to the dynamic nature of data collection on water pollutants. Metals were found to be the biggest problem, specifically zinc and copper, being "90%" of the issues. Urban stormwater was also considered the biggest pollution problem compared to the others mentioned and alternatives to these problems and further studies were suggested on the topic.