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Message from Ass. Prof. Cheng:

 “The unity of human and nature (天人合一)” is a philosophical idea that has crossed the three studies of Confucianism, Buddhism, and Taoism in China since ancient times. Until the Industrial Revolution, humans, whether in the East or the West, consciously or unconsciously followed this philosophy to coexist with nature in harmony. After the Industrial Revolution, productivity exploded and the quality of human life improved while the balance with nature that had lasted for thousands of years was broken. The ensuing energy crisis, environmental pollution, and climate extremes have taken a heavy toll on human society and forced us to reflect on our relationship with nature, thus the era of "carbon neutrality" has come.


In this new era, we want to reduce and eventually eliminate the negative impact of human activity on nature without unduly affecting the existing quality of life. Further, we want to develop next-generation energy and production technologies in order to maintain the current rate of economic and technological development. This requires a deep understanding of both nature and ourselves, and in fact, we are not doing well enough on either side. One of the knowledge gaps is the tendency of traditional science to use reductionism to deconstruct nature and human society. This is basically possible for simple, unliving, non-dissipative, approximately linear systems. However, the real world is complex, living, dissipative, and highly nonlinear, so traditional reductionism is no longer sufficient for the future development of science. As a result, various schools of complexity science based on holism have emerged.


The Environmental Toxicology group in the Cross lab is working to combine reductionism and holism to quantitatively assess the effects of human activities on ecosystems and to further explore methods to eliminate them. We are now working on the toxicological evaluation of microplastics or microfibers on the marine organism and micro-ecosystem.  In addition, we will further attempt to develop new energy technologies for the carbon-neutral era, including energy storage and microbial fuel cell technologies. We welcome people who love nature and are interested in environmental, biological, and energy sciences and engineering to join us.


概要 Introduction

  Over the past ten years, microplastics (MPs) have become a prominent environmental concern of the public and scientific community, mainly because of their frequent and ubiquitous detection in salt- and freshwater ecosystems. The term “microplastic” was first proposed by Ryan and Moloney in the 1980s and was defined as a small plastic particle < 5 mm in diameter by NOAA in 2008. Aquatic organisms can interact with MPs through various pathways, including direct or indirect ingestion, respiration, or attachment to their surface. Microfibers (MFs), as one of the most common MPs, distribute highly overlaps with the dense population areas and pose a threat to biota, especially to humans. 
  The members of the Environmental Toxicology Group focus on the toxicological evaluation of MPs/MFs in the microcosmic system. The results can provide the necessary data for ecological risk assessment and help raise public risk perception of MFs. Eventually, contribute to the formulation of risk management policies for MPs.


研究テーマ 1:Uptake and Effects of Microfibers on Freshwater Indoor Microcosm System

  This research proposes to conduct synthetic, plant, and mineral MFs exposure experiments in a freshwater indoor microcosmic system with three trophic levels of the food chain (producer, first-level consumer, and second-level consumer). The stress response and adaptation of three model species on introduced MFs will be evaluated from molecule to community level under controlled biotic and abiotic conditions. Combining multivariate and statistical analysis methods, qualitative and quantitative analysis of the comprehensive effect of different materials and different concentrations of MFs on the microcosm will be carried out. We want to figure out:

    a. Does MFs provide special effects on the biota due to their fibrous shape?

    b. Compared with the natural MFs, what is the difference in the effects of synthetic MFs on the biota?

    c. To obtain data with higher ecological relevance than previous studies on each species separately

  It is possible to build a bridge between the laboratory and the ecosystem, which helps confirm extrapolations from laboratory data to the environment.


研究テーマ 2:Uptake and Effects of Microplastic Fibers and Fragments on Seawater Commercial Bivalves

Jessica (Master Graduates, GEDES best master research presentation award)


  In 2018, global plastic production has almost reached 360 million tons and approximately 8 million metric tons of plastic enter the ocean annually. Petroleum-based plastics do not biodegrade; they will break down into smaller pieces over time into microplastics. In the ocean water column, microplastics are mostly found in fiber shapes and fragments with a concentration of 52% and 29% respectively. In terms of polymer type, the greatest proportion found was polypropylene (PP) with 17% followed by polyethylene (PE) and polyethylene terephthalate(PET) with 15% each. The presence of these microplastics in the ocean poses risks to marine biota as they are ingested by various marine organisms. Due to their high surface area to volume ratio, microplastics are able to adsorb hydrophobic contaminants such as Persistent Organic Pollutants (POPs) which may increase their toxicity when ingested. Nevertheless, clams, especially Manila clams (Ruditapes philippinarum), hold an important economic and ecological role as the second most captured shellfish group and filter feeders. This research aims to study the effects of microplastic ingestion by bivalves. PP and PET with benzo(a)pyrene (BaP) are used to represent plastics and POPs in the ocean. Exposure of plastics is carried out in the form of microplastic fragments and fiber to find the type and shape preferred by the bivalves during ingestion. Qualitative and quantitative analysis is carried out by using a laser scanning confocal microscope. Subsequently, the most ingested plastic will be spiked with BaP to observe the transfer of contaminant into the oysters and scallops. The toxicological analysis will be performed to determine the systematic effects on the bivalves.



Cheng Shuo

Tokyo Tech 2-12-1 (post S6-15) Ookayama, Meguro-ku, Tokyo 152-8552 Japan


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