BUILDING NATIONAL MULTI-TARGET LOCALIZATION DATABASE FOR SIX NORTHERN BORDER PROVINCES

The meaning of multi-objective localization
The geochemical background reflects the natural variation in the content of chemical elements, its compounds in the surface environment. Multi-objective geochemistry is important because it can: help determine the natural state of the environment; supporting optimal mitigation strategies to help address environmental issues; improve understanding of immediate risks; can help find mineral deposits; it is a scientific basis for orienting the development of a number of economic sectors, especially agriculture and providing important information in medical geological research. The geochemical background is used as a reference point to assess environmental fluctuations over time.

In the world, the construction of geochemistry began around the middle of the 20th century and was promoted on a national and regional scale. Since 1988, the "Global Mapping" Program has been formed in the form of the IGCP-259 project "International Geochemical Mapping" under the "International Geochemistry Program" of UNESCO. In 1993, it became the "Global Geochemical Baseline" IGCP-360 project. Currently, the Committee on "Global Geochemistry" has 231 representatives from 73 countries.

In our country, although there have been studies on the application of elemental geochemistry in mineral prospecting, soil quality assessment in agriculture, environmental pollution manifestations have been carried out in some areas of mineral exploration and exploitation, and some agricultural land (rice, corn), but the study of localization and the establishment of a set of multi-objective geochemistry maps for the territory of Vietnam and each territory have not been implemented.

Aware of the urgent need for a multi-objective geochemistry database for the territory of Vietnam in the face of increasing fluctuations in the surface environment and various needs of economic development and environmental protection, the Vietnam Academy of Science and Technology has approved the implementation of the project "Building a multi-item localization national budget for six northern border provinces". This is the first phase of the project "Building a multi-objective national localization of Vietnam", belonging to the key science and technology program at the level of Vietnam Academy of Science and Technology. The project is led by Assoc. Prof. Dr. Tran Tuan Anh, chaired by the Institute of Geology and the Institute of Geography. 

Successfully build a multi-objective localization database and other outstanding research results

Phase I of the project will be implemented in the period of 2021 - 2024 in the provinces of Lai Chau, Lao Cai, Ha Giang, Cao Bang, Lang Son and Quang Ninh with an area of about 44,000 km2. The project focuses on researching and establishing the geochemistry for topsoil environments (layer A), subsoil (layer C), surface water, groundwater and flow sediments on a map scale of 1:250,000. The samples are taken according to a network of sizes of 4 × 4 km for the whole territory and 1 × 1 km for key areas, so that each square has at least 01 sample for each object. Depending on each subject, the analysis indicators are different. Specifically, as follow:

• For soil samples (layers A and C), the analysis indicators include: Main element groups: SiO₂, TiO₂, Al₂O₃, Fe₂O₃, MnO, MgO, CaO, Na₂O, K₂O, P₂O₅, SO₃; trace element group: Ag, As, Au, B, Ba, Be, Bi, Cd, Cl, Co, Cr, Cu, F, Hg, I, Mo, N, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Th, U, V, W, Zn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and other parameters: pH, Ec, OM,  OC, TC.
• For water samples (surface water and groundwater), the analysis indicators include: Basic ions: HCO₃-, Cl-, SO₄^2-, NO_3-, PO₄^2-, Na⁺, K⁺, Ca²⁺, Mg²⁺, NH⁴⁺, elements Na, K, Ca, Mg, Al, Fe, Mn, Ti, Si, P, S, Cl, F, I, N, As, B, B, Ba, Be, Bi, Cd, Co,  Cr, Cu, Hg, Mo, N, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Th, U, V, W, Zn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and other parameters: T, pH, Eh, Ec, TDS, Turbidity.
• For flow sediment samples, the analysis indicators include: Main element groups: SiO₂, TiO₂, Al₂O₃, Fe₂O₃, MnO, MgO, CaO, Na₂O, K₂O, P₂O₅, SO₃; trace element group: Ag, As, Au, B, Ba, Be, Bi, Cd, Cl, Co, Cr, Cu, F, Hg, I, Mo, N, Ni, Pb, Rb, Sb, Sc, Sn, Sr, Th, U, V, W, Zn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y.

The project has collected and analyzed a total of 7629 acres of all kinds, of which 3,799 acres of floor A soil, 1,081 acres of floor C soil, 1,083 acres of surface water, 617 acres of groundwater and 1,049 acres of sediments. The results of the analysis are processed by statistical methods and specialized software to determine the basic statistical parameters and necessary information. The project has developed a set of geochemical background maps with over 200 maps for each of the above analysis indicators and a combination of 1:250,000 and 1:50,000 scale elements (for key areas) with detailed explanations. The geochemical background maps clearly reflect the spatial distribution of the content of the elements as well as a number of other environmental parameters. In addition, the geochemical background map also shows the distribution of geochemical anomalies. The spatial distribution of the elements is carefully analyzed and evaluated, determining the causes, especially the causes of geochemical anomalies, the relationship between the content of the elements and geological factors. The results of the analysis are also compared with the National Environmental Regulations to assess the level of pollution for different environments. The results obtained have been built into a localized database and uploaded to the Web-GIS environment with a mobile application, easy to access and consult.

Map of lead (Pb) geochemical substrate in topsoil in six northern border provinces

Map of heavy metal geochemical background in surface water in six northern border provinces

Map of copper geochemical substrate (Cu) in flow sediments in six northern border provinces

Although it is only the first step, the multi-objective geochemistry database is built for a limited scope (six northern border provinces), the results obtained have opened up many very useful application directions such as: assessment of the current state of the environment, orientation of mineral search and a number of applications in agricultural development (serving the development of specialty crops of some localities) are also being researched.

One of the outstanding results of the project is the development and completion of the methodology for determining the localization in our country. Accordingly, the guiding documents including implementation processes and recommendations from sampling strategies, sampling and processing methods, methods of data analysis, processing and interpretation, and data management have been completed. The project has trained and built a team of staff with full capacity to implement the project. The success of phase I is the basis for ensuring the implementation of the project for the whole country in the next phase. Some of the initial results of the project have been published in prestigious domestic and international specialized journals, including five articles in the ISI list, two articles in the Scopus list, six articles in domestic specialized journals.

Translated by Phuong Ha
Link to Vietnamese version