A bird is caught in a mist nest set up in a forest to trap small animals while researching signs of mercury contamination, at the Los Amigos Biological Station, in Los Amigos, in the Madre de Dios region, Peru. File
| Photo Credit: Reuters

Tropical birds, from kingfishers to wrens to warblers, are showing signs of mercury contamination as artisanal and small-scale gold mining operations reach deeper into jungles, finds a new research.

Birds living within 7 km (4 miles) of such gold mining activity were found to have mercury concentrations over four times higher than those living at other sites across the tropics of Central and South America, according to the study published on Tuesday in the journal Ecotoxicology.

“It’s a wake-up call for bird conservation internationally across the tropics,” said lead author Chris Sayers, a conservation biologist at the University of California Los Angeles.

Tropical bird biodiversity has been declining in recent decades, but scientists are not fully sure why. “Based on the levels here, it’s reasonable to suggest that mercury may be playing a role,” Mr. Sayers said.

Over a 17-year period ending in 2023, dozens of scientists collected thousands of feather, blood and tissue samples from 322 bird species across nine countries in Central and South America and the West Indies, creating the world’s largest database to date on mercury concentrations in birds.

The research adds to a growing understanding of how mercury, which is used by gold miners to separate the precious metal from sediment, is impacting wildlife in the tropics.

Artisanal gold mining is often either carried out illegally in protected areas, or done informally outside reserves but without explicit government permission.

Earlier this year, Reuters reported for the first time that scientists were finding mammals, from titi monkeys to ocelots, showing signs of mercury contamination near a Peruvian gold mining hotspot.

Absorbing or ingesting mercury-contaminated water or food has been found to cause neurological illness, immune diseases and reproductive failure in humans and some birds.

Birds are the “canary in the gold mine,” Mr. Sayers said, as they are sensitive to mercury pollution and easily accessible, allowing scientists to take the temperature of overall ecosystem health.

The collected samples revealed some of the highest-ever recorded mercury concentrations in songbirds. Birds that ate meat or lived in aquatic habitats were also found to have the highest overall mercury levels.

Hotspots for mercury contamination included Madre de Dios, Peru, and Ayapel, Colombia — centres of artisanal gold mining.

Birds in central Belize also had high mercury concentrations, with scientists speculating it could be due to gaseous mercury emissions from local landfill incineration, or coal combustion in the surrounding region.

Ruixiang Zhang, Assistant Professor, University of California, Berkeley, U.S.
| Photo Credit: www.berkeley.edu.in

Ruixiang Zhang, Assistant Professor, University of California, Berkeley, USA will be awarded with the 2023 SASTRA Ramanujan Prize for his outstanding contributions in mathematics.

The annual cash prize of USD 10,000 will be given at an international conference in Number Theory during December 20 and December 22 at SASTRA University in Kumbakonam, mathematician Srinivasa Ramanujan’s hometown.

The age limit for the prize has been set at 32 influenced by Ramanujan’s achievements in his brief life of 32 years, a press release said.

Dr. Zhang is a young mathematician whose fundamental work spans from analytic number theory, combinatorics, Euclidean harmonic analysis to geometry. Building on his Princeton PhD thesis, Zhang in collaboration with Shaoming Guo proved a multivariable generalisation of the main conjecture in Vinogradov’s Mean Value Theorem. This work, which has appeared in Inventiones Mathematicae in 2019, is considered a major achievement.

While working on his thesis, Zhang branched out to work in restriction theory in Fourier and classical harmonic analysis. He contributed to solving two long-standing problems in restriction theory: (i) Carleson’s problem on pointwise convergence of solutions to the Schr¨odinger equation, and (ii) the two-dimensional case of Sogge’s local smoothing conjecture for wave equations.

In a 2019 Annals of Mathematics paper, Dr. Zhang along with Xiumin Du introduced novel techniques tailored to the problem raised by Carleson and settled the question in all dimensions. The highly skilled mathematician has had a major impact in a wide range of areas like harmonic analysis and its striking applications.

Dr. Zhang received his PhD in mathematics at Princeton University in 2017. After holding various positions at different institutions, he is now at the University of California since 2021. Besides many awards, Dr. Zhang currently holds a Sloan Fellowship (2022-24) and an NSF CAREER award (2022-27).

The 2023 SASTRA Ramanujan Prize Committee comprised Krishnaswami Alladi -Chair (University of Florida), Don Blasius (University of California, Los Angeles), Sergei Konyagin (Lomonosov Moscow State University), Jonathan Pila (Oxford University), Bjorn Poonen (MIT), Zeev Rudnick (Tel Aviv University), and Wadim Zudilin (Radboud University, The Netherlands).