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Chemistry

Are coastal waters receiving drugs? Are the rivers distributing them?

Jiang, Jheng-Jie; Lee, Chon-Lin; and Fang, Meng-Der (2014) Emerging organic contaminants in coastal waters: Anthropogenic impact, environmental release and ecological risk.  Marine pollution bulletin, v. 85,  pp.  391-399, http://ds.doi.org/0.1016/j.marpolbul.2013.12.045

Background:

Emerging organics contaminants (EOCs) are organic compounds, often synthesized, that show up in an environment where they don’t belong. EOCs can be toxic to the aquatic environment with potential to alter the ecosystems and impact human health. Widespread and long term use and disposal of EOCs for medical, veterinary, agriculture, aquaculture, and recreational uses has led to drug residues being transported in sewage water, rivers, and ground water to the ocean.  Scientists in Taiwan measured concentrations and distributions of EOCs in coastal Taiwan, an area impacted by densely populated cites, intensive husbandry and aquaculture, river discharge, and discussed potential sources and the associated risks. The EOCs measured include illicit drugs, nonsteroidal anti-inflammatory drugs (NSAIDS), antibiotics, blood lipid regulators, anti-epileptic drugs, UV filters, caffeine, atenolol, and omeprazole.

Methods:

Sea water samples collected in October 2010 from 53 sites in the southwest Taiwan coastal waters (figure 1) were stored in clean bottles at 4°C (when samples are kept frozen they are less likely to alter). Samples were analyzed by solid phase extraction and high performance liquid chromatography coupled to tandem mass spectrometry (SPE-LC-MS/MS), which in essence separates and measures different components of a pressurized fluid. Standard solutions for all 31 EOC’s were prepared and also analyzed along with the samples.

Figure 1: Samples sites along southwest coast of Taiwan. T stations are in the Tainan coast, K stations are in the Kaohsiung coast, and P stations are in the Pingdong coast.

Figure 1: Samples sites along southwest coast of Taiwan. T stations are in the Tainan coast, K stations are in the Kaohsiung coast, and P stations are in the Pingdong coast.

The analytical technique used was not straight forward partly because this type of work is not overwhelming common, and also because residual concentrations of components investigated are present in minute levels, like nanograms per liter (to compare the weight of a human cell is about 1 nanogram). Researchers had to be meticulous about recovery and detection limits; they determined that their analytical technique was plausible and the results reliable.

In addition to chemical analysis scientists also assessed the risk factor (or risk quotient, RQ) associated with the presence of EOCs. To summarize, a risk quotient for an aquatic organism is determined from the measured concentration and the ‘predicted no-effect concentration’ (the concentration that has no impact on the surroundings). The scores will either be minimal risk if RQ is less than .1, medium risk is RQ is less than 1, or high risk if the RQ is greater than or equal to 1.

Results

Of the 31 drugs studied only 13 were detectable in the samples measured (figure 2).   The three EOCs detected in all samples were acetaminophen (taken for aches and pains), caffeine (taken as a stimulant), and pseudoephedrine (taken for colds and allergies). Codeine was detected in 98% of the samples. Seven of the EOCs investigated were detected in less than 46% of the samples. The highest concentration of EOCs detected was 157.1 ng/L at site K12 near the Jhongjhou sewage treatment plant outfall, which treats sewage from the densely populated city Kaohsiung (9,948 persons/km2) but does not treat to remove EOC’s.

EOC concentration profiles in seawater samples off southwestern Taiwan.

EOC concentration profiles in seawater samples off southwestern Taiwan.

Higher concentrations of EOCs (10’s ng/L) were observed along the coast closest to urbanized areas, like Kaohsiung. They also tend to be concentrated in areas of river discharge (estuaries), which may be impacted by running through areas of agriculture and may receive treated and untreated sewage.  At sites far from urbanized area and rivers the EOCs levels were at trace amounts (1- 10 ng/L). There was some discrepancy of the EOC concentrations near outfalls. For examples while samples near the outfall of Kaohsiung had high concentrations this was not the case at the two other outfalls in the sample area, which had lower concentrations by a factor of up to 8. It was noted that perhaps the sewage treatment plants role in EOC concentration is dependent on outfall characteristics like type of wastewater and the discharge capacity.

Principle component analysis was preformed to determine the likely sources of contamination. It was no surprise that the source is anthropogenic, related to human and animal medicine, as well as land and marine farming.

Risk assessment determined that aquatic organisms are at low risk to the EOCs from codeine and acetaminophen. Codeine poses a higher risk near densely populated areas. The site near the Jhongjhou outfall had an RQ greater than 1. Future work on the effects of EOCs has a whole must be investigated to improve risk assessments.

This study is only one a few that investigated the role of EOCs in the marine environment. Much more work can be done in the area; the scientists of this study suggest starting with a study on the temporal variation of EOCs at these sites.

Conclusion

Pollution at minute levels can leave an imprint with a potential to harm the environment.  Information from studies like the one summarized here can be used to inform environmental policy at a regional level and provide a platform for assessment of future impacts from EOC’s.

Research like this is attempting to stay ahead of the game on organic micropollutants in the coastal waters, and its significance may become greater in the future as populations grow, technology advances, and human knowledge and ability to synthesize organic compounds evolves.

Anne M. Hartwell
Hello, welcome to Oceanbites! My name is Annie, I’m an earth scientist (geology and oceanography). My favorite job as a scientist is working in the laboratory and the field because I love interacting with my research!

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