“化学地球”大科学计划:全球关键元素分布与循环

doi:10.13745/j.esf.sf.2024.10.33

摘要/Abstract

摘要：

“化学地球”的概念于2008年提出,2016年由联合国教科文组织全球尺度地球化学国际研究中心发起“化学地球”大科学计划倡议,2023年被联合国教科文组织正式批准。目标:将元素周期表绘制在地球上,建立化学属性数字地球,服务于全球资源环境可持续发展。科学技术问题:关键元素在地球上的时空分布和循环,全球不同地质地貌景观特点的地球化学探测技术、元素高精度分析和大数据开发技术。主要成果如下:(1)建立全球陆地1/3地球化学基准网,提供76个元素地球化学基准值,初步揭示关键元素全球分布规律,发现一批稀土元素(REE)、锂、铜和金等超常富集区,据此发现云南红河州超大规模中重稀土矿;(2)全球8个有毒重金属元素分布显示,欧洲超过风险限值的面积最大,占欧洲面积的48%,欧洲早期工业历史,没有清洁生产技术,导致大量有害物质排放;(3)中国地球化学观测网揭示镉、汞、砷和钙4个元素近30年发生显著变化,并发现汞的循环是以纳米辰砂微粒为主,而不是传统认为的气体形式迁移和循环;(4)地球化学大数据揭示我国7大粮食主产区,耕地质量总体安全,并利用大数据技术赋予绿色土地二维码标识,通过手机客户端实现绿色食品溯源。“化学地球”大科学计划入选习总书记主持的全球发展高层对话会主席声明成果清单,服务了高层决策和全球发展。

关键词: 化学地球, 大科学计划, 关键元素, 全球分布和循环

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

中图分类号:

P632
P595

王学求. “化学地球”大科学计划:全球关键元素分布与循环[J]. 地学前缘, 2025, 32(1): 1-10.

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

图/表 10

图1 全球铅元素地球化学基准图(已完成全球陆地约1/3)

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

图2 全球地球化学基准数据揭示中国、欧洲、澳大利亚和美国重金属元素超过风险限制比例

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

图3 全国地球化学观测网观测点位图

Fig.3 China geochmeical observation network with observation sites

表1 全国土壤重金属镉超过风险限值的点位占比变化

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

图4 我国7大粮食主产区重金属镉平均值和中位数(红色虚线为风险限值)

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

图5 扫描电镜下观测到的微纳米辰砂矿物(据文献[15]) 左图表示河流沉积物中天然纳米辰砂矿物,右图表示煤燃烧形成的微纳米辰砂矿物。

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

图6 特提斯成矿带稀土元素地球化学图

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

图7 老挝国家尺度金地球化学图

Fig.7 National-scale gold geochemical map of Laos

图8 中国稀土元素超常富集规律和在云南红河州新发现超大规模离子吸附型稀土矿

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

图9 绿色农产品产地二维码溯源(一村一码、一园一码)

Fig.9 QR codes for green-food producing areas

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