Featured articles
Space for school and home science!, Jorge Santos & Suneetha Gunawickrama, September 08, 2021
From Nurdles to Microplastics: how they form and how to measure them?, Yogya Bandara, September 08, 2021
Remediation technologies in an oil spill scenario, Dhanushka Dilini, June 19, 2021
Space for school and home science!, Jorge Santos & Suneetha Gunawickrama, September 08, 2021
From Nurdles to Microplastics: how they form and how to measure them?, Yogya Bandara, September 08, 2021
Remediation technologies in an oil spill scenario, Dhanushka Dilini, June 19, 2021
Space for school and home science!
Jorge Santos & Suneetha Gunawickrama September 08, 2021 When scientists need a quick answer to a problem, they turn into their colleagues, or they read the scientific literature. When they don’t find what they look for, they open up their investigative minds’ and try to find answers themselves through observations, new hypotheses and experimentation. That research must follow a structured, scientific method to be conclusive, otherwise, nobody trusts it. An inquisitive mind regardless of prior level of experience is perhaps all what it takes to do science or even home science! The X-Press Pearl was a vessel that carried many products and chemicals, a cargo unknown to many, with strange names. The list includes plastic nurdles, fuel oil, nitric acid, and heavy metals. While scientists are working on different aspects of the disaster [1], we can try to understand the fate and impact of these compounds, as well as possibilities for remediation, by doing observation-led experiments. Some statements and research ideas follow. You can develop your own hypotheses to lead, but ask also the teachers or our editors for assistance. If doing lab research is not a possibility, you can try to relate to existing information online. 1-How persistent are plastics, and may they be passed along the food chain by some types of fish? Two experiments: A) Keep plastic or plastic nurdles in water for some months, with some containers exposed to light and others in the darkness, but otherwise in the same conditions. Do you detect any differences in the plastic? B) If you can get hold of different marine fish in the market, look at their gills and open their stomachs. Try to find what they eat, and if they contain plastic. What is the relationship between species, type of natural food, and occurrence of plastics? 2-Does nitric acid cause eutrophication (water too green and toxic) in the ocean? Fill three similar transparent glasses with a water culture (WC), which is a mix of drinking water and one spoon of pond water. Now, make three treatments in these glasses: WC (control), WC with vinegar (an acid without nitrogen), and WC with a little nitrogen fertilizer or banana peel tea. Shake, wait and observe for weeks. How do you explain the results? (You can test the impact of chemical bases too.) 3-Do different oils give different types of pollution? Three treatments: WC (as above), WC with little diesel, and WC with little cooking oil (instead of heavy oil). Shake, wait and observe for weeks. 4-Are heavy metals poisonous? Three treatments: WC (control), WC with a little copper sulfate and WC with a little sulphate fertilizer. Shake, wait and observe for weeks. OBS! Do not drink any of these mixes. Store them carefully. The wreckage of the X-Press Pearl was probably a preventable accident. However, we should learn from it. Doing school science with simple means introduces an inquisitive, practical, and creative spirit to schoolers and students, makes learning fun and raises environmental awareness. Develop your own research! Find solutions! Report your findings in our website. Reference [1] X-Press Pearl maritime disaster- Sri Lanka report of the UN Environmental Advisory Mission july 2021. https://www.unep.org/resources/report/x-press-pearl-maritime-disaster-sri-lanka-report-un-environmental-advisory-mission |
From Nurdles to Microplastics: how they form and how to measure them?
Yogya Bandara September 08, 2021 Reviewers: Jorge Santos, Kumudu De Silva Following the massive fire onboard the X-press pearl ship on 20th May, 9 nautical miles off the West coast of Sri Lanka, around 78 metric tons of plastic nurdles were released to the ocean. Large quantities were stranded along the coastal belt from Mannar to Dickwella, and many arrived on the East coast, as far as Yala, Arugam Bay and Trincomalee, hundreds of kilometers away . Will these low-density plastic nurdles become an inevitable source of microplastics, and how can we trace them? Microplastics (MPs) are defined as plastic particles smaller than 5mm. These micro fragments are often invisible to the human eye, and can be categorized as primary or secondary, depending on their origin. Primary MPs are added to the ocean mainly via industrial runoff, in the form of exfoliants in cosmetics and textile products. Secondary MP are produced by fragmentation and degradation of large plastic particles and outnumber primary MPs in world oceans [1]. Nurdles released from the X-Press Pearl will be subjected to diverse and complex biological, physical and chemical reactions over a long period of time, degrade (photodegradation, biodegradation and degradation by the wave actions in ocean and, chemicals) and eventually produce secondary MPs [2]. Monitoring of microplastics in sea water, seabed sediments and beach samples in Sri Lanka is an important and timely requirement. All the methodologies to measure microplastics include three main steps: 1) sampling, 2) extraction and 3) quantification and identification [3]. The following method is applicable to plastics that float in the seawater, which has a density of 1.03 g/m, like polyethylene and polypropylene, but also to those that sink, like polyvinyl chloride and polystyrene. The collection in the water is made with a surface sampling net (0.335 mm) to filter solid material, including hard plastics, soft plastics (like foams), films, lines, fibers and sheets. Beach sand is inspected with shovel or spade. Plastic debris in seabed sediments are collected with a corer or grab sampler. The solid materials are then wet sieved through coarse 5.6-mm and/or fine 0.3-mm sieves. The samples are then dried and cleaned using a wet peroxide oxidation (WPO). The combination of hydrogen peroxide (H2O2) and a Fe (II) catalyst digests the organic matter while keeping the plastic debris unaltered. The density of this solution is then increased by adding salt (NaCl) or lithium metatungstate, both of which have densities above 1.15 g/mL. This enhances the floating of microplastic and separate it from other debris. Using a density separator, the solvent fraction containing the floating micro particles is filtered. The microplastics are then weighed or counted manually using an optical microscope. To identify the type of microplastic, more advanced technology is required. Scanning Electron Microscope, Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIS) are currently used for the polymer identification (morphology and structure, shape, color and, chemical composition) [4,5]. This long sequence of procedures is the everyday work of an analyst, and they are required to understand how the small plastics are penetrating the ecosystem. References [1] Avio, C., Gorbi, S. and Regoli, F., (2017). Plastics and microplastics in the oceans: From emerging pollutants to emerged threat. Marine Environmental Research, 128, pp.2-11.DOI- https://doi.org/10.1016/j.marenvres.2016.05.012 [2] GESAMP (2015). “Sources, fate and effects of microplastics in the marine environment: a global assessment” (Kershaw, P. J., ed.). (IMO/FAO/UNESCO-IOC/ UNIDO/WMO/IAEA/UN/ UNEP/UNDP Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection). Rep. Stud. GESAMP No. 90, 96 p. [3] Hanvey, J., Lewis, P., Lavers, J., Crosbie, N., Pozo, K. and Clarke, B., (2017). A review of analytical techniques for quantifying microplastics in sediments. Analytical Methods, 9(9), pp.1369-1383.DOI- http://dx.doi.org/10.1039/C6AY02707E [4] Masura, J., et al. (2015). Laboratory methods for the analysis of microplastics in the marine environment: recommendations for quantifying synthetic particles in waters and sediments. NOAA Technical Memorandum NOS-OR&R-48. [5] Nguyen, Brian & Claveau-Mallet, Dominique & Hernandez, Laura & Xu, Elvis Genbo & Farner, Jeffrey & Tufenkji, Nathalie. (2019). Separation and Analysis of Microplastics and Nanoplastics in Complex Environmental Samples. Accounts of Chemical Research. 52. 10.1021/acs.accounts.8b00602. |
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Remediation technologies in an oil spill scenario
Dhanushka Dilini June 19, 2021 Reviewers: Jorge Santos, Suneetha Gunawickrama It is reported that the X-Press Pearl cargo vessel contained more than 300 metric tons of bunker oil, engine lubricants and other toxic chemicals when a fire erupted onboard. Those products may create potential hazardous spills in Sri Lankan Western coast. Petroleum remediation can be performed by physical, chemical, and biological methods. Floating containment barriers (booms) restrain oil expansion to sensitive coastal areas, and skimmers enhance the collection of oil slicks from the sea surface. The configuration of floating booms around the mouth of the Negombo lagoon has reduced the risk of penetration of oil slicks. Use of sorbents has received renewed attention for recovery of spilled oil, including inorganic sorbents such as zeolite, clay, activated carbon, silica aerogel, diatomite; natural organic sorbents namely kapok fibers, peat moss, sugarcane bagasse, and synthetic materials such as polyurethane foam, polymer nanofiber, graphene [1]. Some of these products are inexpensive, less invasive (degradable or innocuous) and more manageable than chemical or bio- remediation methods. Recently, carbon nano tube sponges (CNTs), cellulosic sorbent, super oil sorbents widely were used in oil spills in the Gulf Mexico and Solomon Islands with promising results [2]. Super oil absorbents such as CNT foam, micro- fibrillated cellulose fibers, cotton, and cellulose/TiO2 have recently been used in Canada, USA to clean the oil spills in surface water. These products have high adsorption capacity and affordable cost. Cotton, natural fibers and wood chips, which are natural products readily available in Sri Lanka are eco-friendly and cost-effective alternatives for oil recovery. Combination of aerogel with biocompatible cellulose fibers (cellulose aerogels) has received great attention in China due to the high efficiency of oil absorption, cost effectiveness and biodegradability [3]. Application of chemical agents such as flocculant, dispersant, coagulants, or solidifying agents can facilitate subsequent removal of petroleum via absorption and/or adsorption [1]. The method of in-situ combustion with fire resistance booming is a widely used technique for immediate control of oil spill in ocean resulting from pipeline, fuel storage tank, and ship accidents in USA (Gulf of Mexico oil spill), Canada and Scandinavian countries, but it must be performed under very controlled conditions [1]. Another method, bioremediation, relies on microbial action (oleophilic bacteria; Acinetobacter acetate, Pseudomonas putida, Salfobacillus) to biodegrade the spilled oil using bio-stimulation and bioaugmentation processes [1]. However, both processes require nutrient medium of good quality, quiet water, and long action time. Alternatively, the application of clay mineral powder (montmorillonites) contributes to both a physical and a bioremediation function in oil cleanup. They enhance bacterial digestion of oil rather than hydrocarbon adsorption. This is an effective and economically interesting way of reducing the impact of the oil slicks in the western coast. The oil spill from the X-Press Pearl vessel can lead to durable, harmful effects in marine biota and sensitive ecosystems. There is no single method that fulfills all criteria of mitigation of oil spills. Multiple treatment scenarios can be suggested to tackle efficiently oil spills, depending on the ecosystem, costs, resources and urgency of the situation. References (1) Oliveira, L. M., Saleem, J., Bazargan, A., Duarte, J. L. D. S., McKay, G., & Meili, L. (2020). Sorption as a rapidly response for Oil Spill accidents: a material and mechanistic approach. Journal of Hazardous Materials, 124842. https://doi.org/10.1016/j.jhazmat.2020.124842 (2) Piperopoulos, E., Calabrese, L., Khaskhoussi, A., Proverbio, E., & Milone, C. (2020). Thermo-physical characterization of carbon nanotube composite foam for oil recovery applications. Nanomaterials, 10(1), 86. doi.org/10.3390/nano10010086 (3)ben Hammouda, S., Chen, Z., An, C., & Lee, K. (2021). Recent advances in developing cellulosic sorbent materials for oil spill cleanup: A state-of-the-art review. Journal of Cleaner Production, 127630. https://doi.org/10.1016/j.jclepro.2021.127630 |