Article: Karsten Nödler , Dimitra Voutsa, Tobias Licha. Polar organic micropollutants in the coastal environment of different marine systems. Marine Pollution Bulletin. 85 (2014) 50–59. DOI: 10.1016/j.marpolbul.2014.06.024
Micropollutants are those compounds usually at low concentration levels in the environment (ng/L or µg/L). They are toxic, bioaccumulative and hard to degrade. They can pose risks to the local ecosystem or even human health.
We are not unfamiliar with these substances; they exist everywhere in our daily life. For example, we often use β-blockers as antihypertensives, antibiotics for fighting with bacteria and herbicides for gardening, just to name a few.
These compounds are named as pharmaceuticals, corrosion inhibitors, biocides or stimulants. They are some of the most frequently detected micropollutants in the aquatic environment. They enter the marine environment via many sources such as rivers, atmosphere, direct discharge of raw and treated wastewater, shipping, harbor and port activities, offshore oil exploration, and aquaculture.
Methods and Results
In order to better understand the distribution of these micropollutants, 153 water samples were taken from shorelines of the Baltic Sea (Germany), Northen Adriatic Sea (Italy). Aegean Sea and Dardanelles (Greece & Turkey), San Francisco Bay (USA), Pacific Ocean (from Muir Beach to Monterey Bay; USA), Mediterranean Sea (Israel), and Balearic Sea (Spain) during 2009 to 2011. 0.5 L of water for each site were collected in glass bottles and treated by solid phase extraction using cartridges. Then, high performance liquid chromatography-tandem mass spectrometry was used for analysis. The results of the analysis were as follows.
Among all the compounds detected, caffeine (It is the magic in the coffee that keeps you awake and it belongs to stimulants.) and selected metabolites (paraxanthine, theobromine) were the most abundant (as shown in Fig 1). It is interesting to see that caffeine is present at high concentrations in raw sewage while it is efficiently removed by wastewater treatment plants. Therefore, a high concentration of caffeine detected in the marine environment can be a good indicator of raw sewage presence. In addition, a clear link between raw sewage and algal blooms (due to elevated nutrient input) was reported, and a modest correlation with fecal coliforms was found in Canada. Thus, caffeine concentrations have the potential to be used in monitoring the health risk of coastal water.
Caffeine and cocaine (another type of stimulants) metabolite benzoylecgonine can also be good indicators of tourism. During the tourist season, concentrations of caffeine detected 16km off the coast of Venice—where they should be rather low—were comparable to levels within Venice. There were higher detection frequencies of benzoylecgonine within Venice as well.
1H-benzotriazole and tolyltriazole are widely used in detergents for dishwashers, deicing/anti-icing fluids and corrosion inhibitors and also had high detection frequencies. They were detected in ng/L level near shore and much diluted at 300km off shore. Toxicology studies show that exposure to just 10 µg/L of 1H-benzotriazole has noticeable effects on the expression levels of different genes in a marine fish species.
Atrazine is a herbicide banned by the EU in 2004, however ongoing contamination was indicated by water samples. In the U.S., atrazine is still applied (Sass and Colangero, 2006). Interestingly neither atrazine nor its metabolites desethylatrazine and desisopropylatrazine were detected in San Francisco Bay or the Pacific Ocean. This surprising result could be due to either the wrong sampling time with low herbicide application rate (or it has not been in catchment at all) or the dilution factor from tidal exchanges with the Pacific Ocean. Diuron is a biocide widely used in façade coatings and antifouling paints. It was detected exclusively in harbor areas or marinas. One important pathway is through direct release from ship hulls.
Of all the antibiotics, sulfamethoxazole is the mostly frequently detected; and erythromycin showed the highest concentration. Their concentrations were 13-61 ng/L and 217 ng/L, respectively. Of all the antihypensives, the β-blockers atenolol and metoprolol were most frequently detected. Other pharmaceutical residues, such as antiallergics (cetirizine and loratadine), NSAIDs (acetaminophen), psychoactive drugs (carbamazepine), lipid regulators clofibric acid and bezafibrate were also detected in this study.
Significance of the Study
It is important to monitor micropollutants in the marine environment because they may have adverse effects on aquatic life and eventually on human beings. Some of them, for example, pharmaceutical residues are designed to take effect at low level. Synergistic effects need to be studied to see how these substances act together to influence marine life, and humans under current concentrations.
Caoxin is a graduate student in the Graduate School of Oceanography at the University of Rhode Island. Her research interest lies in persistent organic pollutants in the environment. When she is not doing research she likes to create new cuisines.