Big Science program on CHEMICAL EARTH: Global distribution and cycle of key elements

doi:10.13745/j.esf.sf.2024.10.33

Abstract

Abstract:

The Big Science Program on CHEMICAL EARTH was first proposed by Wang et al. in 2008. An initiative was lunched in 2016 by the UNESCO International Centre on Global-scale Geochemistry and accepted by the UNESCO in 2023. The goal was to establish a digital CHEMICAL EARTH presenting all naturally occuring chemical elements on Earth to provide data services for sustainable global development; the scientific and technical aims were to understand the spatiotemporal distribution and cyclying of key elements on Earth, and to develop high-quality laboratory chemical analysis and big data mining technology. This article summaries the major achievements to date. (1) A Global Geochemical Baselines Network is established covering 33% of the world’s land area. It provides spatial distribution patterns and geochemical baselines of 76 chemical elements, allowing delineation of REE, Li, Cu and Au super-enrichment targets and, whereby, the discovery of giant HREE deposits in Yunnan. (2) A global distribution map of eight toxic heavy metals in soil is completed. It finds that Europe has the highest pollution risks compared to China and the United States, with 48% of its land area exceeding the pollution risk limits for the studied heavy metals. This results from Europe’s long history of industrial development without early pollution control technology, allowing large-scale toxins release into the environment. (3) China Geochemical Observation Network is established based on three rounds of resampling campaigns throughout China. It finds significant increase of Cd, Hg, As, and Ca in the past 30 years, and that cycling of Hg occurs in the form of nano cinnabar (HgS) grains, not mercury vapor as traditionally recognized. (4) The program promotes public access to geochemical big data by providing QR codes, which allow anyone to query big data through websites and mobile phones. Geochemical big data show that farmlands in China’s major grain-produing regions overall are of good quality in terms of food safety.

Key words: CHEMICAL EARTH, big science program, key elements, global distribution and cycling

CLC Number:

P632
P595

WANG Xueqiu. Big Science program on CHEMICAL EARTH: Global distribution and cycle of key elements[J]. Earth Science Frontiers, 2025, 32(1): 1-10.

Figures/Tables 10

Fig.1 Global geochemical baseline map of Pb covering ~1/3 world’s landsuface

Fig.2 Proportion of land area exceeding soil risk limits of toxic metals in China, Europe, Australia, and USA based on Global Geochemical Baseline Data

Fig.3 China geochmeical observation network with observation sites

Table 1 Proportion of observation sites exceeding China risk threshold for Cd in soil

采样时间	样品	全部监测点总数/个	清洁土壤(<0.3 μg/g)		超过风险限值(>0.3 μg/g)
采样时间	样品	全部监测点总数/个	点位数/个	占比/%	点位数/	占比/%
1995年	表层土壤	845	809	95.7	36	4.3
2010年	表层土壤	3 284	2 879	87.2	405	12.3
2020年	表层土壤	1 589	1 403	88.3	186	11.7

Fig.4 Average and median Cd contents in seven major grain-producing regions of China (risk limit indicated by yellow dashed line)

Fig.5 Naturally-occuring nano cinabar in alluvial sediments(left)/coal-burning micro cinabar (right) under SEM. Adapted from [15].

Fig.6 Spatial distribution of REEs in the Tethys metallogenic belt

Fig.7 National-scale gold geochemical map of Laos

Fig.8 Nationwide REE super-enrichment patterns and location of newly discovered large-scale ionic absoption type REE deposits

Fig.9 QR codes for green-food producing areas

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