Updated: Feb 7, 2023
Mankind’s pursuit of hunting whales, or whaling, for fat in their blubber during the Industrial Revolution is why several whale species are currently endangered. This might be a familiar subplot for all the movie buffs out there who have been relentlessly waiting for the release of Spielberg’s Avatar: The Way of Water this year! However, what might not be so familiar is the other pathway of how these giant aquatic mammals are threatened by toxic chemicals that are released into the environment by humans. A group of scientists at the University of Oslo, Norway found that Norwegian Killer Whales might be subject to such toxicological threat, publishing their findings in 2020 and 2021 articles.
Anthropogenic pollution and their potential threat to human and ecological health, resulted in global responses in the form of the Stockholm Convention on persistent organic pollutants and the Minamata Convention on Mercury. Organic contaminants that are chemically stable, and hence persistent in the environment long after their use has been discontinued or banned, are often known as legacy persistent organic pollutants (POPs) because their present-day contamination is a ‘legacy’ of previous releases. The process by which POPs like polychlorinated biphenyls (PCBs) and pesticides like dichlorodiphenyltrichloroethane (DDT) get concentrated in the bodies of organisms is called bioaccumulation. The consumption of contaminated prey is greater than the organism’s ability to eliminate the pollutants – and this means that pollutants are “biomagnified” up the food chain and organisms at the top have the highest levels. In response to the regional and global ban of legacy POPs, replacement chemicals are often used. These chemicals are not yet regulated, and thus have become “contaminants of emerging concern”. New brominated flame retardants (BFRs) and perfluoroalkyl substances (PFAS) are some examples of emerging contaminants.
Top predators like killer whales are considered regulators of the marine ecosystem health. The fact that these legacy and emerging contaminants are found in the bodies of such top predators in environments without clear local sources, like the Artic, hints at the persistent nature and biomagnification potential of these chemicals. But not much is known about how these emerging contaminants are transferred from mother to calf. One of the reasons is the difficulty of obtaining samples - sampling is usually from opportunistically stranded individuals and may be impacted by the cause of the death, which is hard to interpret.
Clare Andvik, the first author of both the 2020 and 2021 articles, is a Doctorate Research Fellow at the Department of Biosciences, University of Oslo, Norway who is interested in studying the movement and effects of contaminants in wildlife, especially marine mammals like Norwegian Killer Whales. Her studies were a collaborative effort between the University of Oslo, Norwegian Orca Survey and the Norwegian University of Life Sciences to provide evidence of the persistent and bioaccumulative nature of legacy and emerging contaminants in the Arctic marine ecosystem.
Figure 1: (a-b) Biopsy sampling of Norwegian Killer Whales (c) Sampling dart, (d) Sample, (e) Photo-identification, (f) Calves are never sampled, (g) MULTIWHALE team. (Source: Twitter thread of Clare Andvik Dec 6, 2021, pictures a-b by Krisztina Balotay and pictures c-g by Norwegian Orca Survey)
As a part of her previous work, Andvik found that killer whales feeding on marine mammals like seals had almost four times higher pollutant burdens compared to those feeding on lower trophic level organisms like fish. As a follow up of this previous work, one of the primary aims of the current study was to conduct a detailed screening of legacy and emerging contaminants in killer whales. Norwegian Orca Survey collected tissue samples [Figure 1] from a total of eight individual killer whales,of which one adult male had seal hair in his throat indicating that he had recently been feeding on a seal. This whale in particular was found to have the highest levels of total PCB and hexabromobenzene (HBB, an emerging BFR) in his blubber and mercury (Hg) in his skin as compared to the other sampled whales. Seven out of the eight whales were washed ashore in Northern Norway. The cause of death could be inferred for an adult male which was drowned after getting entangled in a herring purse seine and a calf which was stranded alive on the rocks in a shallow area where its group was feeding. The age of the calf was determined to be no more than 10 days, as milk was found in its stomach and all teeth were still inside the gum.
A second focus of the study was to investigate the maternal transfer of these contaminants. To this effect, emerging BFRs and PCBs were found in several organs of the calf indicating substantial maternal transfer of these chemicals. This study was the first to show the maternal transfer of these unregulated emerging BFRs by documenting their presence in the nursing neonate. The PFAS (in liver) and total mercury levels in the neonate were relatively lower than in the adults. This indicated that the maternal transfer of these chemicals is less efficient as compared to PCBs and BFRs. The importance of the cause of death was analyzed by comparing PCB levels in the neonate in this study with those in a German killer whale of similar age and sex from a previous study. It was found that the German whale, that was starved and had poor body condition, had higher PCB levels in its body as compared to the neonate in this study that was accidentally stranded. It was deduced that the poor body conditions at the time of death contributed to higher levels of PCBs for killer whales that might not be representative of the population.
The third focus of the study was to investigate the tendency of legacy and emerging contaminants to get attached to different kinds of tissues. For this, the screening of these contaminants was conducted on multiple tissues including blubber from 8 individuals, muscle from 5 individuals and kidney, liver, heart and spleen from the neonate. It was found that the emerging BFR levels (pentabromotoluene (PBT) and HBB) were twice as high in the blubber than in the muscle. This confirmed that these emerging contaminants preferentially accumulated in the lipid-rich tissues and have lipophilic properties much like legacy compounds (PCBs).
How do these contaminants interact with the various environmental components that drive them so far from their actual source of release? What is the current state of regulation of the emerging contaminants and how far into the future is their legacy going to last? Why are killer whales choosing seals over lower trophic level fish as a dietary preference? Given the results of this work and the questions that follow how do we protect the killer whales of Norway and save them from becoming extinct? “A big part of my work is to get certain chemicals regulated or banned. The bottom line is that we need to do this research to show that these chemicals are present in wildlife, because then we can take it to the authorities and hopefully, they can work with other European authorities to gather a lot of evidence to get these chemicals banned”, says Andvik, in a recent Women in Ocean Science podcast.
Updated: Dec 17, 2022
It is often fascinating to sit back and wonder how we got into what we are doing currently. It might seem a very futile exercise in the beginning. But, when you start connecting the dots, it can be quite an interesting story; in fact, an important one that shapes the future direction of one’s life’s trajectory. Cleaning up the environment works on a similar philosophy. It is important to be aware of the legacy of the environmental contaminants one is dealing with, know where their source lies and understand their movement patterns to be able to formulate methods of eradicating them.
I left home for the first time in 2012 to attend the Miranda House college at the University of Delhi, India where I did my Bachelor’s in Chemistry. It was the first time I was making my own decisions independently. Chemistry was not my first choice at the time and for a very long time towards the end of high school I felt a certain pull towards pursuing Physics. The decision was influenced by the fact that I could secure in my XII standard board exams, the university-set cut-off grades, only in Chemistry, to get admission in the college of my choice. My grades in Physics did not make the high cut-offs. With passing years, as I got into research, I have realized that in research you need a diverse range of knowledge that can cross the boundaries of a single discipline. It is often helpful to have diverse interests and there is no reason to believe that you cannot change your path to pursue something different from where you started your journey. In the third year of my Bachelor’s, we were taught Inorganic Chemistry by Dr. Bani Roy.
Inorganic Chemistry has a certain whim. There are rules and there are exceptions. Most often it was the exceptions to the rules that stumped me in the exams. One of the examples that I distinctly remember was calculating the ionization enthalpy of atoms. Ionization enthalpy (IE) which is defined as the amount of energy required to remove an electron from an atom has the general trend of decreasing as we move down within a group (a column in the periodic table). This is a result of the increasing distance between outermost electrons and nucleus with the addition of extra shells. But the exception to this rule is when there is poor shielding offered by d-orbitals which is why, IE of Gallium (Ga) is more than that of Aluminum (Al). I never scored high in the Inorganic Chemistry exams. But I found it interesting.
I liked how Dr. Roy made the quirks of Inorganic Chemistry look less overwhelming for her students by explaining the justifications for the exceptions to the rules, instead of blankly stating them. Nevertheless, it did get overwhelming towards the end of the semester when we had to remember all the rules and exceptions for the exams. But in my opinion, that was a problem of procrastination more at our end as students.
It was towards the end of this class that we learnt about the arsenic (As) heavy metal pollution in the groundwater wells of the Indo-Gangetic plains of West Bengal and Bangladesh. Part of the reason why it made a special impact on me could be because I learnt it from Dr. Roy, a Bengali herself just like me. Arsenic is a heavy metal pollutant that is responsible for the highest risks of mortality worldwide because of its toxicity and the number of people exposed. [1] Arsenic pollution contaminates the soil impacting a staple source of the diet of the Indo-Gangetic region, rice and groundwater that is a major source of water for drinking and irrigation purposes in the region.
The long-term toxic effect of inorganic arsenic (iAs) has been known since the nineteenth century and was classified as a carcinogen by the International Agency for Research on Cancer (IARC) in 1980[2]. The Indo-Gangetic alluvium is the largest alluvial plain in the world and studies concluded that the source mineral responsible for the releasing of arsenic in the groundwater of the area is arsenolite (As2O3)[3]. An agrarian economy like India with agriculture-related sectors representing half the labor market[4], has 14% of its rice production coming from the state of West Bengal[5]. The wet-dry cycle of this area quickens the movement of As throughout the environment. Rice is grown in water-logged paddy fields. Arsenic exists in the pentavalent (As V) oxidation state under aerobic (i.e., with oxygen) conditions and in the trivalent state (As III) under anaerobic (i.e., oxygen-less) conditions. In the monsoon season when paddy fields are flooded, the waterlogged conditions near the roots of the paddy lead to an anaerobic condition, converting pentavalent As, otherwise present near the soil surface exposed to the air, to its more toxic trivalent state. Trivalent As is easily soluble in water and is readily taken up by the plant roots and accumulated in the paddy. Further contamination of the shallow groundwater is brought about by the infiltration of arsenic into deeper soil layers during monsoon flooding.[6] It was estimated that in 2012 about 39 million people in Bangladesh alone were still exposed to arsenic concentrations above WHO provisional guideline value of 10 μg/L.[7] While the plight of the people from my home state suffering from the adverse effects of the contamination deeply impacted me, I was fascinated by the complexity of the chemistry of heavy metals and their pathways to get into the human diet. I felt the need to explore this more.
I started my master’s in environmental sciences at the Nalanda University, India. I was exposed to the opportunity of choosing from a diverse range of electives from Geohydrology and Nanoparticles to Environmental Sociology. The freedom to choose a future direction of work helped me explore and find my specific interest in quantitative research. In the summer of 2016, second year of my masters, I was offered an internship at the Department of Earth Sciences in the Indian Institute of Science, Education and Research (IISER) Kolkata.
I worked with Dr. Niharika Anand, a PhD student at the time working with Dr. Sujata Ray, to review articles to examine the trends in reported organochlorine pesticide (OCP) levels in human milk. Regulated by the Stockholm Convention on Persistent Organic Pollutants, India has banned the use of organochlorines such as DDT in agriculture but continues restricted use for controlling the spread of malaria. Human milk is a sensitive measure of the general exposure of a population. Dr. Anand was comparing the contamination status of OCPs, pyrethroids and the neonicotinoids, between a semi-urban location with both agricultural and built-up areas (Nadia) and an urban location (Kolkata) in West Bengal, India.[8] Unlike heavy metals like As, OCPs are often hydrophobic (dislikes water) and lipophilic (loves fats and other hydrocarbons). The lipophilic nature of these molecules is what makes them dangerous for aquatic organisms and humans. The affinity to the lipids in animals makes OCPs hard to eliminate, leading to its accumulation after prolonged exposure, termed bioaccumulation. The bioaccumulation potential of a hydrophobic chemical like organochlorine pesticides poses a risk to the ecological and human health. A large portion of the human diet consists of freshwater and estuarine fish in the state of West Bengal in India and Bangladesh and has been attributed as one of the bioaccumulation pathways for these organochlorine pesticides by several studies.[9] [10] [11] [12] The fundamental processes that guide the transport of heavy metals and pesticides into different environmental substrates and finally into organisms, are interestingly different from one another. While pesticides are hydrophobic and tend to bind with anything but water, heavy metals can readily form an aqueous solution to be available for bio-uptake. The differences in the exposure pathways for different chemicals can be key to determining targeted cleanup (technically called remediation) methodologies.
I continued working with hydrophobic organic contaminants (HOCs) in my doctoral research at the University of Maryland Baltimore County, focused on Polychlorinated Biphenyls (PCBs). PCBs were domestically manufactured between 1929 and 1979 and used extensively in the industry for their non-flammability, chemical stability, and high boiling point which made them perfect for electrical insulation. Their use was banned in the year 1979 by the Toxic Substances Control Act (TSCA) and the USEPA established by the late 1990s that PCBs are probable human carcinogens.[13] Because of their stable chemical structures, PCBs persist in the environment several decades after their ban, interacting with the different environmental substrates to cause adverse ecological and human health impacts. At UMBC, I am working to understand the existing methods of sampling environmental levels of PCBs to improve ways of monitoring them more efficiently.
Efficiently monitoring contaminant levels in the environment is critical to decision making for setting reasonable remediation goals and performing targeted remediation to reach those set goals. Remedial efforts are incredibly extensive and ridiculously expensive, and sometimes they don’t work. An interesting case study in this aspect is the story of the cleanup of PCB contamination in the Hudson River, USA. In 1984, 200 miles of the 315-mile-long river ended up being the country’s one of the largest superfund sites and placed on EPA’s National Priorities List. The river that served as a major transportation route during the Industrial Revolution, was contaminated with approximately a million pounds of PCBs that were discharged from General Electric (GE) capacitor manufacturing plants located in New York. In February 2002, the EPA issued a Record of Decision (ROD) for the Hudson River PCBs Superfund Site that called for targeted environmental dredging of approximately 2.65 million cubic yards of contaminated sediments[14]. Removing contaminated sediments by dredging can often lead to re-suspension and partial re-dissolution of the PCBs in the water column. The first five-year review that came out in 2017 reported elevated levels of PCBs in surface sediments with re-contamination in certain dredged areas and higher than target concentrations of the 2002 ROD in fish tissue. [15]
The one take-away that I have gathered over the years of being associated with the world of environmental contaminants is that the story of toxins is a complex one. The lack of understanding of the fundamental scientific processes that drive these environmental contaminants through the environment is costly. Improving the ways to predict and measure the outcome of contaminant pollution and remediation is crucial to moving towards a cleaner, more functional world.
References:
[1] C. Hopenhayn, Arsenic in drinking water: impact on human health, Elements 2 (2006) 103–107. [2] International Agency for Research on Cancer (IARC), Monographs on the evaluation of carcinogenic risks to humans. Lyon, France 84, 526 (2004) [3] Goel, P. (2018). Identification of the Source Mineral Releasing Arsenic in the Groundwater of the Indo-Gangetic Plain, India. In: Hussain, C. (eds) Handbook of Environmental Materials Management. Springer, Cham. https://doi.org/10.1007/978-3-319-58538-3_129-1 [4] https://www.trade.gov/country-commercial-guides/india-food-and-agriculture-value-chain [5] https://ipad.fas.usda.gov/countrysummary/Default.aspx?id=IN&crop=Rice [6]Shrivastava, A. et al. (2017) ‘Arsenic contamination in agricultural soils of Bengal deltaic region of West Bengal and its higher assimilation in monsoon rice’, Journal of Hazardous Materials, 324, pp. 526–534. Available at: https://doi.org/10.1016/j.jhazmat.2016.11.022. [7] https://www.who.int/news-room/fact-sheets/detail/arsenic [8] Anand, N. (2019). Pesticide Residues in Urban and Semi-Urban Regions of West Bengal, India: Risk Assessment in Human Milk and Water (Doctoral dissertation, Indian Institute of Science Education and Research Kolkata). http://eprints.iiserkol.ac.in/821/ [9] Aktar, M.W., Paramasivam, M., Sengupta, D. et al. Impact assessment of pesticide residues in fish of Ganga river around Kolkata in West Bengal. Environ Monit Assess 157, 97–104 (2009). https://doi.org/10.1007/s10661-008-0518-9 [10] Agnihotri, N.P., Gajbhiye, V.T., Kumar, M. et al. Organochlorine insecticide residues in Ganga river water near Farrukhabad, India. Environ Monit Assess 30, 105–112 (1994). https://doi.org/10.1007/BF00545617 [11] K. K. Vass, S. K. Mondal, S. Samanta, V. R. Suresh, P. K. Katiha; The environment and fishery status of the River Ganges. Aquatic Ecosystem Health & Management 15 November 2010; 13 (4): 385–394. doi: https://doi.org/10.1080/14634988.2010.530139 [12] Mohapatra, S.P., Gajbhiye, V.T., Agnihotri, N.P. et al. Insecticide pollution of Indian rivers. Environmentalist 15, 41–44 (1995). https://doi.org/10.1007/BF01888888 [13] https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs [14] https://www.epa.gov/hudsonriverpcbs/hudson-river-cleanup [15] https://scenichudson.org/wp-content/uploads/legacy/Technical-Supplement-Second-Five-Year-Review.pdf
Updated: Apr 25, 2023
This is an article to introduce you and take you through my art journey.
I grew up in the city of Durgapur, in the eastern state of West Bengal in the Indian subcontinent. Durgapur is an industrial city about 170 km (105miles) to the south-east of the capital city of Kolkata. I moved to the USA in 2017 for pursuing my PhD in Environmental Engineering and currently, I stay in Maryland on the eastern coast.
My passion for art developed mostly by looking at my father who would often sit down with a paper and a pencil and sketch something or someone from life. My grandfather, I have heard, was a professional artist based in Calcutta. I never saw him myself. We lost him before I was born. But I saw my father. He once sketched my new-born baby cousin brother from life. I remember to have sat beside him the whole time while he worked. I saw his patience with every line and how much he enjoyed the process. I would never miss the chance of watching my father put covers on my new textbooks every time I was promoted to a new class. His work was a piece of art! He would measure the length of the paper needed for a book and cut off the piece from the roll with one neat stroke of the pen-knife. And then he would not touch the scissors or the knife. He minimized the number of scraps of paper by neatly folding the extra parts inside, in a way that there was no extra folds to be seen from the outside. My textbooks would be the most neatly covered ones in the entire class with marked labels on top. And yes, I took care of them too. Not one would have a mark on them until the end of the year! Soon, I learned, just by watching. My father would always help me with the covers whenever he could. With time, I had to assign him with more difficult things to do: the diagrams for my Biology class for example. He would stay up past midnight to finish them and keep them ready with neatly drawn arrows for me to finish the labeling in my handwriting.
I was always an indoors kid, who would never go out to play, introverted and shy. I always enjoyed staying home enclosed in a room full of blank papers around me. My father would very rarely buy ready-made cards on someone's birthday or Christmas! He would buy me a bunch of blank cards and ask me to fill them up! I did. And I enjoyed it so much! When I came of age, I was put under a tutor who taught me some techniques of painting with water-colors and ways to enhance the art of making cards. Soon, my parents found me humming some tunes at the back of my father's motorcycle. I would usually sit sandwiched between my father in the driver's seat and my mother at the back. And wherever we used to go, I would sing under my breath, these songs that I would hear on the television and picked up quite quickly. My parents thought I had a nice voice and I was put under another tutor for music and soon another for tabla, to keep me on my tempo. Gradually, I had no more time for painting. And soon, I had no more time to invest in my hobbies. In a middle-class Indian family, this is a very common scenario where, close to the tenth standard, kids are advised to focus more on academics than any other passion they might have.
I think I started painting again when I came here to the USA in 2017. I started saving some money from my monthly student stipend to invest in supplies. With time, I have been able to set up a mini-studio worth of supplies and make some progress on the quality and quantity of my work. I find myself motivated to create every time I feel saturated with my research or life in general and find solace when I channelize all the negativity into creating something.
I am mostly self-taught, nowhere close to a professional. I have however, made some gifts for my friends. Some of them, very kind ones, got back to me asking if I was willing to draw something for them if they paid for it. I have accepted art commissions for very special cases because I felt they would not be too disheartened if I made mistakes. I think I want to do it for myself and for the love of the process at this point and not get swayed by the business side of things.
I hope you enjoy the pieces you see here and let me know what you think of them. :)