Protecting Our Oceans Starts With Testing – Part Two
The evolving landscape of marine sampling, monitoring and analysis.
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Standard methods of sample collection and analysis have long been the cornerstone of understanding the health of marine ecosystems. Yet, as we navigate through the complexities of contemporary pollution challenges, the need for innovative approaches to ocean environmental monitoring becomes increasingly apparent. From the manual efforts involved in grab sampling, to the emergence of dynamic passive techniques, the landscape of marine water testing is evolving rapidly.
Beyond the surface
Traditionally, a representative sample is taken by going out into the field in a boat. You take a sample that you may need to pre-concentrate because contaminant levels are typically at nanograms per trillion in the marine environment, which adds to the time involved and the manual aspect of the work. It can also introduce contamination, and therefore you have to consider lots of blanks and controls within the analysis. Once you are sure that the sample hasn't been contaminated, you then need to apply the analytical methods required, depending on what you are looking for. For example, pharmaceutical analysis is going to be different to testing for pesticides and antibiotics.
Before collecting a sample, it’s essential to consider what you want to measure carefully. Different concentration methods may be necessary for different purposes. For instance, with passive sampling (PS), you can deploy polymer materials in the field for approximately four to six weeks. These materials accumulate substantial sample volumes as water flows through them over time. However, it’s essential to consider the polymer properties in view of the analyte you’re measuring beforehand.
Another emerging method is dynamic passive sampling (DPS) for the marine environment. As demonstrated in the Danube survey, this method actively takes a water sample through a material over a period of four days. If you can imagine a vessel passing through the marine environment at a certain speed, the volume of sample that you can collect is massive.
When conducting sampling in the open ocean, you need to ensure minimal interference from the vessel. Similarly, coastal sampling demands meticulous precautions to prevent contamination, alongside the selection of representative sites. While increasing the number of samples is recommended for better spatial resolution, the time-consuming nature of this approach often renders it impractical.
In targeting certain chemical groups, we also need to match their characteristics with the material used in passive or dynamic samplers. Typically, the dynamic samplers would have used silicon rubbers, which are more inclined to absorb the more organic compounds, but we also now have polymeric materials that offer versatility for any group of chemicals.
After returning to the lab, the expertise of analytical chemists proficient in volumetric analysis, separation science and mass spectrometry becomes indispensable. When conducting non-targeted screening, collaboration with specialists in data analysis is particularly necessary.
The Role of Decision Support Tools
When it comes to marine water testing, decision support tools can play a crucial role in guiding our actions. By providing rapid or near real-time information, these tools enhance our understanding of water quality, and enable us to make informed decisions that can help mitigate environmental impacts, for example when thresholds are exceeded. By integrating data from various sources, decision support tools help industries and researchers respond effectively to environmental challenges.
In terms of the marine environment, however, we haven’t yet reached a stage where we possess comprehensive tools for precise measurement or monitoring that can significantly enhance our decision-making regarding water quality. But we do have certain indicators that we can use. For instance, we collect information on phenomena like algal blooms; in situ sensors provide valuable data—for example, they can alert us to rising temperatures, optimal light conditions for algal blooms or fluctuations in dissolved oxygen levels. After collecting all this information, marine machine learning algorithms allow us to identify conditions conducive to algal blooms occurring. Industries are now using this type of data and also integrating satellite data on water color and coastlines for better decision support. These tools are readily available, but mostly around coastal monitoring.
While some tools and data are available, particularly for coastal monitoring, there is still a need for improved technologies to improve prioritization of substances and contaminants in marine environments. The TechOceanS project is worth noting. It is led out of the University of Southampton and the National Oceanographic Centre (NOC), where they are looking at developing technologies that can go on to an autonomous underwater vehicle to measure marine toxins due to algal blooms, as well as pesticides and estrogenic compounds.
At Dublin City University (DCU), we have a postdoctoral fellowship funded by the Irish Marine Institute to measure the occurrence of contaminants of emerging concern in marine waters around Ireland. In addition to exploring novel marine sampling approaches like PS or DPS, our analytical tool of choice is a liquid chromatograph-6470 triple quadrupole mass spectrometer for quantitation and target analysis of samples for the contaminants of emerging concern. We are also involved in two EU projects aimed at advancing marine environmental monitoring. The first project, AquaBiosens, is newly funded and focuses on antibody- and environmental RNA-based sensing. These innovative approaches hold promise for detecting emerging contaminants in the marine environment. We are also involved in COMPAS, a European project led by physicists dedicated to developing sensor technology for marine monitoring purposes.
The unique challenge posed by the concentrations of contaminants in the marine environment pushes the limits of both technology and analytical capability. In some instances, we are contending with concentrations that are up to 1,000 times lower than those found in other environments. While such low levels may not directly impact human health, their potential effects on biodiversity remain uncertain.
Our understanding of the biological effects on the marine environment is severely limited for two primary reasons. Firstly, comprehensive studies have never been conducted and secondly, there is a lack of reliable biological indicators for the marine environment. In contrast, this is where the freshwater environment is well ahead of us.
Revolutionizing data interpretation
I am part of a network of scientists focusing on emerging contaminants and our emphasis is on non-targeted screening to gather extensive data across global sites, helping to address the current limitations outlined above. Our vision is to monitor the planet for emerging contaminants, with non-targeted screening playing a pivotal role in assessing marine environmental quality.
The state-of-the-art monitoring equipment is remarkable in terms of the developments that have been made, including technologies that have inbuilt machine learning capabilities in their data management systems. There is a lot of work happening within the industry when it comes to interpreting samples, revisiting legacy data and reinterpreting existing data.
Continuous monitoring
Over the years, we've recognized the existence of environmental challenges. Fortunately, recent advancements in analytical systems and data management software offer promising solutions, especially concerning antibiotics—a significant challenge in the marine environment due to their association with antibiotic resistance. These technologies not only allow us to identify transformation products but also detect previously overlooked compounds. As a result, our understanding of contaminants in marine ecosystems has improved.
Collaborating with instrument manufacturers to identify and define future challenges will shape the growth of their technologies. This exciting prospect motivates us to deepen our involvement. Additionally, I'm enthusiastic about the development, testing and potential commercialization of biosensing technologies designed for continuous monitoring of certain chemicals.
Looking ahead, we need to see the emergence of automatic sampling technologies that can collect an adequate volume of sample to allow detection at very low (nano gram per Liter) levels. Our vision is to develop sensor platforms that can collect a sample, interrogate the sample for the target analytes and deliver a result in near real-time. However, for now, the focus remains on enhancing existing technologies for both target and suspect screening. In the context of a changing climate the need to understand the impact of increased ocean temperature and acidification on chemical contamination is an area lacking data but requiring new and complementary tools to help understand the effects.
