Elements of Change 1995: Session IIITaoShu

Beginning in 1972, The Department of Urban and Environmental Science (formally the Department of Geography) at Peking University launched its environmental research and education program. The initial projects included a baseline investigation of trace metals in Chinese soils. The Division of Environmental Science of the department has carried out over 50 studies including analyses of the amount, distribution, characterization, and origin of naturally-occurring organic compounds in major rivers of eastern China, a preliminary study of organic pollutants in soil in the Beijing-Tianjing area, and the development of a database management system for routine environmental monitoring of Tianjing. Currently the division is carrying out an environmental impact assessment of the Shenzhen River Regulation Project. The department's recent focus is environmental geochemistry, geostatistical analysis, environmental planning, environmental assessment, and environmental database management system development. The following three case studies are examples of how the department has worked to gain insight into the environmental problems facing China.

To establish a baseline for trace element concentrations in the soils of the Shenzhen area, a project was initiated as part of the nation-wide effort. In this study, data on the amounts and distributions of 12 metals, soil pH, clay, and soil organic matter (SOM) was collected from 83 locations. The study provided many conclusions including documentations of unusual distributions and concentrations of mercury in local agricultural soils.

To study the spatial distribution pattern and to map the metal contents in the soil of the area, the contents of all metals were analyzed using semi-variance analysis and Kriging analysis. While the experimental semi-variograms of all metals can be fitted well using spherical models with zero nugget, the range value of the variogram of mercury was considerably smaller than those of all other elements suggesting localized high concentrations of the element. In addition, the analysis of mercury distributions yielded a geometrically isotropic (circular) variogram. In contrast, the other elements studied exhibited anisotropic distributions (directional). The short variogram range and non-directional distribution pattern of mercury indicate that the high-value patches on a mercury map tend to be circular and are generally smaller in size than those of the other elements.

High concentrations of mercury were generally found in patty fields. Evidence of mercury contamination through agricultural activity includes the recorded extensive use of mercury as fungicide in the paddy fields before the middle 1970s.

The results of a principle component analysis followed by the semi-variance analysis, Kriging analysis, and factor score mapping demonstrated that 12 elements can be divided into three categories for their spatial distribution patterns. The similarity in spatial distribution patterns between the first two components (F1: Cu, Co, Ni, Cr, and V; F2: Pb, Zn, and Mn) and parent material indicates that the levels of these elements are governed by the parent material from which the soil was derived. The one exception to this pattern was mercury which is the only major element to fall into the third component, though it is geochemically similar to the elements in the first component. Unlike the others elements, mercury distributions seem to fit well with the land use map. High concentrations of mercury were generally found in patty fields. This result suggests that there is some degree of mercury pollution associated with agricultural practices in this region.

In addition, the results of an analysis of variance and SNK multiple comparisons show that mercury content in all other soils are significantly lower than in paddy soil in which mercury had accumulated in the surface horizon. Other evidence of mercury contamination through agricultural activity includes the recorded extensive use of mercury as fungicide in the paddy fields before the middle 1970s.

This conclusion can also explain the wide spread mercury contamination associated with paddy-based agriculture throughout much of Southern China.

Case 2: Contamination of wastewater-irrigated soil in Beijing-Tianjing area [Tao, 5]

The Beijing-Tianjing region is one of the fastest growing areas in China. Unfortunately the region is also characterized by limited wastewater treatment facilities, drastic water short ages, and more than a 20-year history of wastewater irrigation which has probably resulted in significant soil contamination.

Although a series of wastewater treatment plants have been built recently or are planned for the near future (using external funding), the facilities are not fully operational because of the financial limitations of the local governments and improper management systems (e.g. low water prices and free discharge of domestic wastewater). Wastewater (with and without treatment) is used by local farmers, together with sludge from wastewater treatment plants, to irrigate and fertilize their land. Without effective regulations on waste water irrigation, the agricultural soils, as well as crops which go directly to the local markets, become contaminated.

The results of many studies show that there is significant heavy metal accumulation in these soils. A preliminary study has also revealed that a wide variety of organic compounds, including PAHs, chlorinated pesticides, phthalates, alkanes, isoprenoids, fatty acids, triterpanes, steranes, etc., are present in these soils at elevated levels as the likely result of wastewater irrigation and industrial fallout. In the future, both science and policy research efforts will be necessary in order to develop technical and managerial mitigation measures to solve these pollution problems.

The Beijing-Tianjing region is one of the fastest growing areas in China, and has a 20-year history of wastewater irrigation which has probably resulted in significant soil contamination.

Case 3: A specific database management system for an EIA study [Peking Univ., 6,7]

One of the major recent projects carried out by the Division is an Environmental Impact Assessment for the Shenzhen River Regulation Project.

The Shenzhen River will be realigned, widened and deepened in a three-stage project for flood control. The Shenzhen River flows along the border between Shenzhen and Hong Kong and empties into Deep Bay. At the river mouth, there is a wetland system of international importance with mudflats, mangroves, fishponds, and a number of birds including some rare and endangered species. The potential impacts of the project on various habitats in the wetland system through changes in hydrology, water quality, erosion and sedimentation pattern is one of the key issues to be assessed by the EIA study.

In addition to primary consulting by Peking University (led by the Department of Urban and Environmental Sciences), there are also a number of sub-consultants, including two environmental consulting companies based in Hong Kong, involved in the Environmental Impact Assessment (EIA). Data management and distribution became a critical issue during this study. A database management system with demonstration modules showing the major findings was developed during the early stages of the study. This helped facilitate internal data exchange and management as well as provide clients with a computer-based information system for evaluation of the environmental performance of regulation projects. The database was then distributed among the various teams and delivered together with the final report of the EIA (the system is also available by request from the Tao).

Since the database was a project-oriented system for internal use and not all the participants had the adequate hardware needed for commercially-available database and GIS packages, the database management system was coded using Turbo-Pascal with limited hardware requirements (any PC compatible with DOS and VGA card). The system is bilingual (it uses one optional parameter to select English or Chinese interfaces) and fully menu-driven. The Chinese version can be run under regular DOS without a Chinese platform. Forty-six subsystems of the database are available for water, air and noise, sediment and soil, ecology, and engineering. All data collected in the study has been entered into the database system through spreadsheet-like interfaces defined by the user. The data can be either analyzed statistically or mapped two-dimensionally to show the results of the investigation on the screen graphically. The results of two-dimensional dynamic modeling of water quality in the Deep Bay can be simulated for a 24-hour cycle to show the predicted temporal change in water quality.

Other examples graphically presented using the database include the results of the mud contamination assessment based on either a Hong Kong regulation or the Harkenson Index, the TSP modeling with or without mitigation measures, a conceptual model of nutrient flow within the ecosystem, the variation in the number of birds in the wetland system, and the results of the survival experiments of planned mangrove along the river with or without protection.

Techniques such as these show considerable promise in facilitating both effective internal data management and decision making during large-scale environmental impact assessment projects.

The results of many studies show that there is significant heavy metal accumulation in soils in the Beijing-Tianjing region.

[1] Tao, S., Spatial structures of copper, lead and mercury contents in surface soil in Shenzhen area, Water, Soil and Air Pollution, 82:583-591, 1995.

[2] Tao, S., Kriging and mapping of copper, lead and mercury contents in surface soil in Shenzhen Area, Water,Soil and Air Pollution, 86:161-172, 1995.

[3] Tao, S., Multi-element mapping of regional soil geochemical data for Shenzhen area, Proceedings of International Symposium on Computer Applications in Geosci , pp. 416-419, Beijing, China, 1991.

[4] Tao, S., W. Y. Cheng, Mercury pollution in soils from Shenzhen, China, Environmental Science, 39:172-177, 1992.

[5] Tao, S., B. S. Deng, B. Hermosin, C. Saiz-Jimenez, Identification of organic pollutants in agricultural soils from Tianjin, China, Fresenius Environ. Bull., 2:677-682, 1993.

[6] Peking University, Stage 1 Report of Shenzhen River Regulation EIA Study, 1994.

[7] Peking University, Final Report of Shenzhen River Regulation EIA Study, 1995.