Singapore scientists demonstrate that some tropical plants have potential to remove toxic heavy metals from the soil

Peer-Reviewed Publication

NANYANG TECHNOLOGICAL UNIVERSITY

 

IMAGE: (L-R) PHD STUDENT MS WANG YAMIN FROM NTU’S SCHOOL OF MATERIALS SCIENCE AND ENGINEERING (MSE), PROF LAM YENG MING, CHAIR OF NTU’S MSE, AND ASSOC PROF TAN SWEE NGIN FROM THE ACADEMIC GROUP OF NATURAL SCIENCES AND SCIENCE EDUCATION AT NTU’S NATIONAL INSTITUTE OF EDUCATION PRESENTING PLANTS FOUND TO HAVE THE ABILITY TO REMOVE TOXIC HEAVY METALS AND METALLOIDS FROM CONTAMINATED SOIL. view more 

CREDIT: NTU SINGAPORE

A team of researchers from Nanyang Technological University, Singapore (NTU Singapore) and Singapore’s National Parks Board (NParks), has demonstrated that some plant species could help to remove toxic heavy metals and metalloids from contaminated soil.  

 

Phytoremediation is the use of plants to extract and store contaminants from soil. As a first step to determine if candidate plants had phytoremediation abilities, the team examined samples of them for levels of heavy metals and metalloids. A high concentration detected suggested an ability to absorb the pollutants.

 

The study by the Singapore research team discovered that there are existing tropical plants which could potentially play a role in the remediation of contaminated lands. The plants examined in the study are widely available and include species that are native or naturalised to Singapore. They could thus, be introduced and removed from plots of land with minimal impact to ecosystems and could lead to the development of a sustainable and environmentally friendly way of managing contaminants in soil (see video).

 

The findings were published in the scientific peer-reviewed journal Environmental Pollution in February.

 

Professor Lam Yeng Ming, Chair of NTU’s School of Materials Science and Engineering, who co-led the study, said: “In a small nation like Singapore, land may be repurposed to support new development plans, so it is important that we have a green and sustainable way to remediate land that is contaminated. We set out to uncover how to better make use of tropical plants to do phytoremediation and through advanced characterisation techniques, we showed how some of these tropical plant species can be an environmentally friendly and literally a “green” way to remove contaminants in soil. Phytoremediation also has benefits of cost effectiveness, simplicity of management, aesthetic advantages, and long-term applicability and sustainability. The strategy prevents erosion and metal leaching by stabilising or accumulating heavy metals, so that helps reduce the risk of contaminant spread.”

 

The team conducted a field survey and collected soil and plant samples between March 2019 and January 2020. A total of 46 plant species were studied as potential candidates for phytoremediation.

 

Among them, 12 plant species, which include the commonly seen Cow Grass (Axonopus compressus), hyperaccumulators like the Brake Fern (Pteris vittata) and the Indian Pennywort (Centella asiatica), were effective for the accumulation of several types of heavy metals and metalloids.

 

The elements investigated in the study were heavy metals and metalloids that are potentially toxic to humans and animals, such as cadmium, arsenic, lead, and chromium. They occur naturally in soils, but rarely at toxic levels. However, they can accumulate and reach higher levels over a long period of time, as heavy metal particles from air pollution (e.g. vehicle emissions, construction activities) tend to accumulate and remain in the top layers of soil.

 

Other factors that could result in high levels of heavy metals in soil include the use of synthetic products such as pesticides, paints, batteries, industrial waste, and land application of industrial or domestic sludge.

 

To assess whether the levels of heavy metal were dangerous, the team used the Dutch Standard, which provides values for the acceptable threshold of environmental pollutants in soils. This mode of assessment has also been adopted by Singapore’s government agencies.

CAPTION

The scientists found that Centella asiatica, commonly known as Indian pennywort, could effectively absorb cadmium, a toxic metal, from affected soils.

CREDIT

NTU Singapore

Associate Professor Tan Swee Ngin, from the Academic Group of Natural Sciences and Science Education at NTU’s National Institute of Education, who was the study’s co-author, said: “Our results revealed there were regions where levels of heavy metals and metalloids were relatively high and could affect the environment and the health of flora and fauna in Singapore. This would call for preventive actions, such as our method of using plants to remove these toxic materials, to be employed to minimise heavy metal contamination.”

 

The NParks researchers involved in the study are from its Centre for Urban Greenery and Ecology. They include Dr Subhadip Ghosh, Senior Researcher and Mr Mohamed Lokman Mohd Yusof, Senior Research Executive.

 

The development of this plant-based solution to improve soil quality is part of the University’s efforts to mitigate our impact on the environment, that is aligned with the NTU 2025 strategic plan, which aims to develop sustainable solutions to address some of humanity’s pressing grand challenges.

 

Team’s findings expand potential of environmentally friendly methods

 

Phytoremediation could serve as a more environmentally friendly alternative to existing industrial options to remove the heavy metals from polluted soil, which include methods such as soil washing and acid leaching. These methods can be costly and may utilise harsh chemicals to remove pollutants from soil.

 

Heavy machinery to conduct excavation and transportation of soil is also usually required in such processes and these procedures may negatively affect the environment by affecting soil health and fertility. These methods also run a high risk of exposing humans or animals to the heavy metals.

 

However, phytoremediation is a slow and long-term commitment and requires prudent management in the removal and disposal of the contaminated plant samples. Using different types of efficient plants to carry out phytoremediation in polluted soils, and with enough growth cycles through repeated planting, can ultimately lead to reductions in the level of heavy metals and metalloids in the soil.

 

The joint research team is currently testing the plants on plots of land in Singapore that have high concentrations of heavy metals to better determine the effectiveness of the plants in an urban setting.

 

They are also testing the usage of other inorganic particles that are incorporated into plants and that can both help in the plant growth and improve the uptake of these contaminants by the plants. This will reduce the time taken for the absorption of the heavy metals and hence speed up the remediation time.

 

###

---

JOURNAL

Environmental Pollution

DOI

10.1016/j.envpol.2021.118681 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Assessment of heavy metal and metalloid levels and screening potential of tropical plant species for phytoremediation in Singapore

A 4 V-class metal-free organic lithium-ion battery gets closer to reality

Peer-Reviewed Publication

TOHOKU UNIVERSITY

 

IMAGE: AN ILLUSTRATION OF CROCONIC ACID AND AN IMAGE OF A HIGH-VOLTAGE ENVIRONMENTALLY FRIENDLY ORGANIC LITHIUM-ION BATTERIES. view more 

CREDIT: YUTO KATSUYAMA ET AL.

A joint research team from Tohoku University and the University of California, Los Angeles (UCLA) has made a significant advancement towards high-voltage metal-free lithium-ion batteries that use a small organic molecule, croconic acid. The breakthrough moves us closer to realizing metal-free, high-energy, and inexpensive lithium-ion batteries.

Unlike conventional lithium-ion batteries, which depend on rare-earth materials such as cobalt and lithium, organic batteries exploit naturally abundant elements such as carbon, hydrogen, nitrogen, and oxygen. In addition, organic batteries have greater theoretical capacities than conventional lithium-ion batteries because their use of organic materials renders them lightweight. Most reported organic batteries to date, however, possess a relatively low (1-3V) working voltage. Increasing organic batteries' voltage will lead to higher energy density batteries.

Itaru Honma, a professor of chemistry at Tohoku University's Institute of Multidisciplinary Research for Advanced Materials, Hiroaki Kobayashi, an assistant professor of chemistry at Tohoku University, and Yuto Katsuyama, a graduate student at UCLA, found that croconic acid, when used as a lithium-ion battery cathode material, maintains a strong working voltage of around 4 V.

Croconic acid has five carbon atoms bonded to each other in a pentagonal form, and each of the carbons is bonded to oxygen. It also has a high theoretical capacity of 638.6 mAh/g, which is much higher than the conventional lithium-ion battery cathode materials (LiCoO2 ~ 140 mAh/g). "We investigated the electrochemical behavior of croconic acid in the high-voltage range above 3 V using theoretical calculations and electrochemical experiments," said Kobayashi. "We discovered that croconic acid stores lithium ions at roughly 4 V, giving a very high theoretical energy density of 1949 Wh/kg, which is larger than most inorganic and organic lithium-ion batteries."

Although the theoretical capacity was not achieved in this study, the researchers are optimistic this can be enhanced by the development of stable electrolytes at high-voltage and chemical modifications to croconic acid. Since most electrolytes cannot stand for such a strong working voltage of croconic acid, developing new electrolytes is vital. Additionally, the structures of small organic molecules, including croconic acid, can be easily modified. Appropriate structural modification can stabilize the molecule, leading to greater capacity and reversibility.

---

JOURNAL

Advanced Science

DOI

10.1002/advs.202200187 

ARTICLE PUBLICATION DATE

10-Mar-2022

The triumph of secular individualism – A new mathematical model offers clear-cut answers to how morals will change over time

Peer-Reviewed Publication

INSTITUTE FOR FUTURES STUDIES

Corporal punishment of children, such as spanking or paddling, is still widely accepted in the world’s most influential country, the US. But public opinion is changing rapidly, and in the United States and elsewhere around the world this norm will soon become a marginal position. The right to abortion is currently being threatened through a series of court cases – but though change is slow, the view of abortion as a right will eventually come to dominate. A majority of Americans today reject the claim that parental leave should be equally shared between parents, but within 15 years public opinion will flip, and a majority will support an equal division.  

"Almost all moral issues are moving in the liberal direction. Our model is based on large opinion surveys continuously conducted in the US, but our method for analyzing the dynamics of moral arguments to predict changing public opinion on moral issues can be applied anywhere," says social norm researcher Pontus Strimling, a research leader at the Institute for Futures Studies, who together with mathematician Kimmo Eriksson and statistician Irina Vartanova conducted the study that will be published in the high-ranking journal Royal Society Open Science on Wednesday, April 13th.  

Applying the model to data on public opinion surveyed in 2018, the article presents year by year predictions for how public opinion will develop on a number of issues up until 2030. This allows for empirical tests of the model through comparisons with actual developments in the coming decade. The results of the first test, against data from 2020, are promising.   

"Our model did considerably better than all known methods for predicting opinion change. The key is to understand the mechanisms that underlie the change. How opinions change depends on the arguments used to argue for and against a certain stance. The model gives a clear picture of what societies will look like in the near future."  

Contact:   
Pontus Strimling (Principal Investigator), pontus.strimling@iffs.se, + 46 70 375 18 62 
Erika Karlsson (Communications Officer), erika.karlsson@iffs.se, + 46 70 604 58 55 

Read the article: 
The article "Predicting how US public opinion on moral issues will change from 2018 to 2020 and beyond" will be published here: https://royalsocietypublishing.org/journal/rsos on Wednesday, April 13:th.     

---

JOURNAL

Royal Society Open Science

DOI

10.1098/rsos.211068 

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

Predicting how US public opinion on moral issues will change from 2018 to 2020 and beyond

ARTICLE PUBLICATION DATE

13-Apr-2022

Austerity is worsening NHS waiting time inequality in Scotland

Peer-Reviewed Publication

SAGE

Research analysing the impact of the Scottish government’s initiative to reduce NHS waiting times concludes the programme of investment and reform is associated with a reduction in waiting time inequality, benefiting the most socioeconomically deprived patients. However, austerity measures introduced in 2010 are reversing these gains.

The researchers analysed three common elective surgery procedures, primary hip and knee replacements and knee arthroscopies, between 1 April 1997 to 31 March 2019. Hip replacements are commonly used to assess healthcare equity.

The Scottish NHS waiting time initiative was launched in 2002. The analysis shows that between 1 July 2002 and 31 March 2010 waiting time inequality between the most and least deprived patients fell. These gains were reversed between 1 April 2010 and 31 March 2019 during the period of austerity and budget cuts.

Inequality in mean waiting time for hip replacements increased by 1.07 days per quarter between 1 April 1997 and 30 June 2002; decreased by 1.26 days per quarter between 1 July 2002 and 31 March 2010; and increased by 0.58 days per quarter between 1 April 2010 and 30 June 2019.

The analysis was carried out by researchers at the Population Health Sciences Institute at Newcastle University. Senior research associate Graham Kirkwood said: “The drive to reduce waiting times in Scotland from July 2002 had the effect of reducing inequalities between the most and least socioeconomically deprived patients. This finding held true for each of the three elective procedures analysed: primary hip replacements, primary knee replacements and arthroscopies.

“Prior to this, for all three treatments, patients in the most deprived areas had longer waits than those in the least deprived areas. The introduction of austerity measures in 2010, with a real-term freeze on health spending, appears to have reversed the gains with waiting times increasing for all patients and the pre-2002 pattern of inequality returning.”

The authors say further research is needed to analyse, compare and contrast the trends and effects of the use of the private sector on waiting time inequalities in Scotland with England. Unlike Scotland, England has increased the proportion of elective surgery that is being outsourced from the NHS to the private sector under the patient choice programme and the numbers of patients paying to go private has also increased.

---

JOURNAL

Journal of the Royal Society of Medicine

DOI

10.1177/01410768221090672 

METHOD OF RESEARCH

Content analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Socioeconomic inequality, waiting time initiatives and austerity in Scotland: an interrupted time series analysis of elective hip and knee replacements and arthroscopies

ARTICLE PUBLICATION DATE

12-Apr-2022

Climate change will reshuffle marine ecosystems in unexpected ways, Rutgers study finds

Sophisticated model reveals how predator-prey relationships affect species’ ranges

Peer-Reviewed Publication

RUTGERS UNIVERSITY

 

IMAGE: LARGE PREDATORY FISH ARE EXPECTED TO LAG BEHIND TEMPERATURE SHIFTS DUE TO FOOD-WEB DYNAMICS. view more 

CREDIT: GERALD SCHÖMBS

Warming of the oceans due to climate change will mean fewer productive fish species to catch in the future, according to a new Rutgers study that found as temperatures warm, predator-prey interactions will prevent species from keeping up with the conditions where they could thrive.

The new study, published in the journal Proceedings of the Royal Society B, presents a mixed picture of ocean health. Not only will large species and commercially important fisheries shift out of their historical ranges as climate warms, but they will likely not be as abundant even in their new geographic ranges. For instance, a cod fisherman in the Atlantic might still find fish 200 years from now but in significantly fewer numbers.

“What that suggests from a fisheries perspective is that while the species we fish today will be there tomorrow, they will not be there in the same abundance. In such a context, overfishing becomes easier because the population growth rates are low,” said study coauthor Malin Pinsky, an associate professor in Rutgers’ Department of Ecology, Evolution, and Natural Resources. “Warming coupled with food-web dynamics will be like putting marine biodiversity in a blender.”

Previous studies of shifting habitat ranges focused on the direct impacts of climate change on individual species. While these “one-at-a-time” species projections offer insights into the composition of ocean communities in a warming world, they have largely failed to consider how food-web interactions will affect the pace of change.

The new study looked at trophic interactions – the process of one species being nourished at the expense of another – and other food-web dynamics to determine how climate change affects species’ ranges.

Using sophisticated computer models, the researchers determined that predator-prey interactions cause many species, especially large predators, to shift their ranges more slowly than climate.

“The model suggests that over the next 200 years of warming, species are going to continually reshuffle and be in the process of shifting their ranges,” said lead author E. W. Tekwa, a former Rutgers postdoc in ecology, evolution and natural resources now at the University of British Columbia. “Even after 200 years, marines species will still be lagging behind temperature shifts, and this is particularly true for those at the top of the food web.”

As climate warms, millions of species are shifting poleward in a dramatic reorganization of life on earth. However, our understanding of these dynamics has largely ignored a key feature of life -- animals and other organisms must eat. The researchers have filled this knowledge gap by examining how the basic need for nourishment affect species’ movements.

The researchers developed a “spatially explicit food-web model” that included parameters such as metabolism, body size and optimal temprature ranges. By accounting for climate change, their model revealed that dynamic trophic interactions hamper species’ ability to react quickly to warming temperatures. They also found that larger-bodied top predators stay longer than smaller prey in historical habitats, in part because of the arrival of new food sources to their pre-warming ranges.

“These dynamics will not only be in one place but globally,” Pinsky said. “That does not bode well for marine life, and this is not an effect that has been widely recognized.”

---

JOURNAL

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2021.2755 

ARTICLE TITLE

Body-size and food-web interactions mediate species range shifts under warming

Beyond the honeybee: how many bee species does a meadow need?

Research led in part by UMD reveals the importance of pollinator diversity, highlighting the role of rare bees in wild ecosystems

Peer-Reviewed Publication

UNIVERSITY OF MARYLAND

 

IMAGE: UMD ENTOMOLOGIST MICHAEL ROSWELL COLLECTS BEES FOR A SURVEY OF POLLINATION NEEDS IN A NEW JERSEY MEADOW. HE AND COLLEAGUES FOUND 2.5 TO 7.5 TIMES MORE BEE SPECIES WERE IMPORTANT FOR POLLINATION THAN PREVIOUSLY DOCUMENTED. AND RARE SPECIES WERE MORE SIGNIFICANT THAN KNOWN. view more 

CREDIT: JAMES REILLY

A meadow’s lush array of flowers needs a full phalanx of bees to pollinate them—far more than just the honeybees and bumblebees that most people are familiar with, according to a new study by a team of researchers including University of Maryland entomologist Michael Roswell. A postdoctoral associate in the Department of Entomology, Roswell helped demonstrate that less common bees are much more important for ecosystem health than previously documented.

Previous research on bees as pollinators tended to focus on specific plants—frequently crops—or on entire communities of plants as if they were a single entity. This tended to over-emphasize the contribution of the most common bees, especially since 2% of the bee species provided 80% of the pollination in crops. But no previous work had asked the basic question: How many pollinator species are needed to pollinate all the species in a given community of plants? 

Roswell and his colleagues have now shown that the more plant species there are, the more bee species are needed for pollination. They found that the less common bees often visited specific plants others didn’t. Their findings shed new light on the role of rare species in ecosystems—critical to conservation efforts because rare species are most at risk of extinction from habitat loss, pollution, climate change and other factors. The study appeared April 13, 2022, in the Proceedings of the Royal Society B.

“Our work shows that things that are rare in general, like infrequent visitors to a meadow, can still serve really important functions, like pollinating plants no one else pollinates,” said Roswell, who studies diversity and pollination in the UMD Department of Entomology and is a co-author of the study.  “And that’s a really good argument for why biodiversity matters.”

CAPTION

A female Agapostemon virescens on an Echinacea purpurea flower.

CREDIT

Barry Rosenthall

The researchers surveyed 10 plots in New Jersey that included wild meadows and seeded fields over one year. They observed bees from over 180 species making nearly 22,000 visits to over 130 different plant species. The team used these encounters to estimate the pollination services each type of bee provided to each plant, because a plant’s most frequent floral visitors are typically its most important pollinators.

Their analyses showed that an entire meadow community relied on 2 ½ to 7 ½ times more bee species for pollination than a single typical plant species does. They also found that the locally rare species accounted for up to 25% of the important pollinator species, and that number was greatest in meadows with the most plant diversity. This suggests that at larger scales like entire ecosystems, the number of locally rare species that are important for pollination is even greater.

“We were looking at meadows that might be a few acres in size,” Roswell said, “but a typical bee flies over a couple of square miles, which is a really large and complicated landscape filled with lots of different kinds of plants that flower at different times and are visited by different insects. At that scale, even more diversity of pollinators is likely to be important.”

  

CAPTION

A female Ceratina bee visits a black-eyed Susan (Rudbeckia laciniata) blossom.

CREDIT

Barry Rosenthall

---

JOURNAL

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2021.2689 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Many bee species, including rare species, are important for function of entire plant-pollinator networks

ARTICLE PUBLICATION DATE

12-Apr-2022

Your morning coffee could hasten species’ extinction

Richer nations increase species extinction risk in poorer ones, new University of Sydney and IUCN research finds

Peer-Reviewed Publication

UNIVERSITY OF SYDNEY

 

IMAGE: THE US DRIVES 24 PERCENT OF THE EXTINCTION-RISK FOOTPRINT OF THE NOMBRE DE DIOS STREAMSIDE FROG (CRAUGASTOR FECUNDUS), A CRITICALLY ENDANGERED FROG FOUND IN HONDURAS. view more 

CREDIT: JOE TOWNSEND

As negotiations before the 15th Conference of the Parties to the Convention on Biological Diversity (COP-15) take place, international research has quantified the impact of human consumption on species extinction risk.

Around 1 million species already face extinction, many within decades, according to the recent Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) assessment report.

Spanning more than 5,000 species in 188 countries, the research finds consumption in Europe, North America, and East Asia (such as Japan and South Korea) primarily drives species extinction risk in other countries. Affected species include the Nombre de Dios Streamside Frog in Honduras and the Malagasy Giant Jumping Rat in Madagascar.

Published in Nature: Scientific Reports, the research is led by Ms Amanda Irwin at the University of Sydney’s Integrated Sustainability Analysis research group and is co-authored by the International Union for Conservation of Nature (IUCN) chief scientist Dr Thomas Brooks and chief economist Dr Juha Siikamäki.

The authors liken the biodiversity crisis to the climate one, albeit with less publicity. “These crises are occurring in parallel,” Ms Irwin said. “The upcoming COP-15 will hopefully raise the profile of the other human-driven natural crisis of our generation – irreparable biodiversity loss – and our findings can provide valuable insights into the role that global consumption plays as one of the drivers of this loss.”

Key findings

• Consumption in 76 countries, concentrated in Europe, North America, and East Asia, primarily drives extinction risk in other countries.
• In 16 countries, concentrated in Africa, this extinction-risk footprint is driven by offshore consumption.
• In 96 countries – around half of those studied – domestic consumption is the greatest driver of the extinction-risk footprint.
• International trade drives 29.5 percent of the global extinction-risk footprint.
• Consumption of products and services from the food, beverage and agriculture sectors is the greatest driver of consumption-driven extinction risk, together constituting 39 percent of the global extinction-risk footprint, followed by consumption of goods and services from the construction sector (16 percent).

PhD candidate Ms Irwin said: “The complexity of economic interactions in our globalised world means that the purchase of a coffee in Sydney may contribute to biodiversity loss in Honduras. The choices we make every day have an impact on the natural world, even if we don’t see this impact.”

“Everything that we consume has been derived from the natural world, with raw materials transformed into finished products through a myriad of supply chain transactions. These transactions often have a direct impact on species.”

Co-author, IUCN chief economist Dr Juha Siikamäki notes: “This insight into how prevalently consumption patterns influence biodiversity loss across the globe is critical to inform ongoing international negotiations for nature, including the 15th Conference of the Parties to the Convention on Biological Diversity, which aims to finalise the post-2020 global biodiversity framework later this year.

“The finding from this study that about 30 percent of the global extinction-risk footprint is embedded in international trade underlines the need to consider the responsibilities of different countries and all actors, including financing of conservation, not only in the context of their national boundaries but extending to their impacts internationally.”

Co-author, Associate Professor Arne Geschke from the Integrated Sustainability Analysis research group at the University of Sydney said: “The activities which threaten species in a given location are often induced by consumption patterns in far-away locations, meaning that local interventions may be insufficient. 

“Appropriate interventions to address extinction risk in Madagascar, for example, where 66 percent of the extinction-risk footprint is exported, should be different from those implemented in Colombia, where 93 percent of the extinction-risk footprint is generated by domestic consumption.”

CAPTION

The extinction risk of the the Malagasy Giant Jumping Rat in Madagascar 

is increased by consumption in other countries.

CREDIT

Josh More.

About the study

Using data available in IUCN’s Red List of Threatened Species, the authors introduced the non-normalised Species Threat Abatement and Restoration (nSTAR) metric as a measure of extinction risk.

They then applied the methodology widely-used to quantify carbon footprints – of which the Integrated Sustainability Analysis research group is a world leader – to link this extinction risk to global consumption patterns using the global supply chain database Eora.

An extinction-risk footprint was calculated by species, by economic sector, for 188 countries.

Co-author Associate Professor Arne Geschke previously co-wrote a Nature paper that demonstrated international trade is a key driver of biodiversity threats.

This new paper is a collaboration between the University of Sydney, IUCN, Newcastle University (UK) and the International Institute for Sustainability in Brazil. 

---

JOURNAL

Scientific Reports

DOI

10.1038/s41598-022-09827-0