A Heavy Metal Module Coupled in SWAT Model and Its Application

Transcription

1 216 International SWAT Conference A Heavy Metal Module Coupled in SWAT Model and Its Application Lingfeng Zhou* Yaobin Meng* Chao Lu* Wan Ye* Ganlin Wu* *Academy of Disaster Reduction and Emergency Management, Beijing Normal University, China

2 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative implementation 4. Results 5. Conclusion and discussion

3 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

4 1. Introduction Heavy metal pollution in mining area

5 1. Introduction land process [1] channel/reservoir process [1] [1]. Statements E I. Comparison of Predicted and Actual Water Quality at Hardrock Mines[J].

6 1. Introduction SWAT model The soil and water Assessment Tool (SWAT) has been proven to be an effective tool for nonpoint-source pollution problem. such as nitrogen and phosphorus and pesticide. However, as far as heavy metals is concerned, the SWAT model, by its own version, only allows point source loading inputs and includes no algorithms to model in-stream processes but simple mass balance equations [2]. which addresses a small part of heavy metal pollution issues. SWAT Model Simulate the behavior of heavy metal Heavy metal module [2] Neitsch, S.L., Arnold, J.G., Kiniry, J.R. and Williams, J.R., 211. Soil and water assessment tool theoretical documentation version 29, Texas Water Resources Institute

7 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

8 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

9 2. Heavy Metal module -- Challenges Primary Source identification Drains Waste rocks Tailings Contaminated soil... Chemical speciation Solid phase: labile(adsorbed); non-labile(strong bonded, minerals) Aqueous phase: free ions, complexes, colloids Physical movement Wind erosion, transport Soil erosion, transport Surface runoff Lateral flow Groundwater flow

10 2. Heavy Metal module -- Challenges Primary Source identification Drains Waste rocks Tailings Contaminated soil Chemical speciation Solid phase: labile(adsorbed); non-labile(strong bonded, minerals) Aqueous phase: free ions, complexes, colloids Physical movement Wind erosion, transport Soil erosion, transport Surface runoff Lateral flow Groundwater flow

11 2. Heavy Metal module -- Challenges Primary Source identification Drains Waste rocks Tailings Contaminated soil Chemical speciation Solid phase: labile(adsorbed); non-labile(strong bonded, minerals) Aqueous phase: free ions, complexes, colloids Physical movement Wind erosion, transport Soil erosion, transport Surface runoff Lateral flow Groundwater flow

12 2. Heavy Metal module Fig. Molecular-scale environmental processes of metals in soils and aquatic systems [3] [3]. Brown Jr G E, Chianelli R, Stock L, et al. Molecular environmental science: speciation, reactivity, and mobility of environmental contaminants[c]//report of the DOE Molecular Environmental Science Workshop

13 2. Heavy Metal module Transformation model Tab. Three major reactions in soil-water environment Reaction Formulation Equation Adsorption & desorption Complexation Slow reaction M l n M + + M k des M n k ads k a kd L k 1 k1 M n+ ML l n+ d M θ = k θ M + k ρm dt n+ ads des l dm l k n ads M + = k des M l ρ θ ρ dt [ ] d ML dt d M dt n+ = [ ] [ ] n+ ka M L kd ML = + dm dt l [ ] [ ] n+ ka M L kd ML = km + k M 1 l 1 dm n = km 1 l k 1 M n dt n

14 2. Heavy Metal module Land phase process Chemical transformation: Sorption Complexation Slow(aging) reaction Physical transport: Leaching Upward migration Erosion

15 2. Heavy Metal module Channel phase process Chemical transformation: Sorption Complexation Slow(aging) reaction Physical transport: Settling Resuspension Diffusion Burial

16 2. Heavy Metal module -- Module framework

17 2. Heavy Metal module Flow chart

18 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

19 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

20 3. Demonstrative Implementation The upstream Basin of Liuyang River Location: south-central china Study area: 199 km 2 Precipitation: Hydrology: mm(yearly). Daxi river (blue) Xiaoxi river (green) Baoshan steram (yellow) Mining area: Qibaoshan mine, 6.5km 2 Metal: Zn, Pb, Cu, Cd

21 3. Demonstrative Implementation Metal concentration of zinc and cadmium in soil Matrial ph OC (%) Total(ug L -1 ) Acid-Soluble(ug L -1 ) Reducible (ug L -1 ) Oxidizable (ug L -1 ) Residual (ug L -1 ) Zn Cd Zn Cd Zn Cd Zn Cd Zn Cd waste rock a) (4797 ) b) (97) (2822) (76.6) (15) (1.94) (95) (.8) (1825) (17.4) Soils (near the waste rock) (756) (2.7) 51-8 (69) (.4) 5-5 (2) (.13) (65) (.2) (637) (1.97) Soils(near the drain outlet) (538) (1.4) (7) (.35) 5-28 (12) (.8) 1-45 (33) (.8) (44) (.92) undisturbed soils (157).2-.9 (.45) 1-15 (9) (.15) 1-1 (5) (.7) 2-4 (14).1-.8 (.5) (137) (.19)

22 3. Demonstrative Implementation Basic data for SWAT model Type Description Data source Digital elevation model (DEM) Land use data 9 m 9 m Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences (RESDC) Soil data 1:1 Meteorological data Daily The Institute of Soil Science, Chinese Academy of Sciences Hydrology bureau of hunan province; Hydrological data Daily Hydrology bureau of hunan province

23 3. Demonstrative Implementation K d (in riverbed sediment ) Additional data of heavy metal module Parameter Unit Metl typical(initial) value/ fitted value Source K d L kg (in soil) -1 Zn 1.-1./1.5 a) Cd 1.-1./3.4 K d L kg (in channel) -1 Zn 1.-5./12.3 Cd 5-1/2153. L kg -1 Zn 1.-5./38. Cd 1.-8./27.7 (Sauve et al., 2; Allison and Allison, 25) k 1 d -1 Zn Cd 1.3* *1-4 (Crout et al., 26; Buekers et al., k -1 d -1 Zn Cd 8.4* *1-4 28) Point source a) Non-point sourcre Parameter Description Typical range/value Source Flow Flow of point source for a day(m 3 d -1 ) 96/96/24 Average Point-Zn Point loading of Zn to reach for the day(kg) 6.5/6.5/17.5 Average Point-Cd Point loading of Cd to reach for the day(kg) // Average M l Labile metal concentration in the 1st layer soil(mg kg - Zn:3/1/.5 1 Cd:15/1/.2 ) Average M n Hmfr hmrock Weathering rate b) Non-labile metal concentration in the 1st layer soil(mg kg -1 ) Fractions of waste dumps and tailings area in HRUs (%) Heavy metal in waste rock (kg ha -1 ) Weathering rate of waste rocks and tailings (d -1 ) Zn:3/4/1 Cd:3/3/1 Average 1.%- 43.6%(1.%) c) remote sensing Zn:1 Average Cd: (Bennett et al., 2)

24 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

25 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

26 4.Results Calibration and validation of flow and sediment Calibration Monthly Validation Calibration daily Validation Calibration Monthly Validation Calibration daily Validation Stream flow Sediment Period Time resolution E ns r 2 Calibration monthly (29-211) daily Validation monthly ( ) daily Calibration monthly.7.72 (29-211) daily Validation monthly ( ) daily.5.56

27 4.Results Calibration and validation of HM module Calibration Validation Dissolved Zn output (watershed outlet)

28 4.Results Zn (two rainfall events) ug/l ug/l ug/l ug/l ug/l Subbasin 12 Number ug/l ug/l Subbasin 12 Number ug/l ug/l ug/l ug/l

29 4.Results Cd (two rainfall events) Cd (ug/l) 3 Cd (ug/l) Cd (ug/l) Cd (ug/l) 5 Cd (ug/l) 5 Cd (ug/l) 1 Cd (ug/l) Cd (ug/l) Cd (ug/l) 15 1 Cd (ug/l) Cd (ug/l)

30 4.Results Different transport paths

31 4.Results Model outputs at watershed outlet Preciptation Discharge m 3 /s Suspended sediment mm Dissolved Zn kg tons/d 1 Solid phase Zn kg Precipitation Flow Suspended sediment Dissolved Zn Solid Zn day form January 1st, 29

32 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

33 Contents 1. Introduction 2. Heavy Metal module 3. Demonstrative Implementation 4. Results 5. Conclusion and discussion

34 5. Conclusion and discussion The simulation of stream flow and suspended sediment is good both on monthly basis and daily basis. A heavy metal module coupled with SWAT model is established to simulate the Zn, Cd dynamics in Liuyang river upstream basin. This modified model contains the processes of weathering, leaching, sorption, complexation and so on, which embodies the process of source release, migration and transformation of heavy metal at the watershed scale. More measured data are needed to test and improve the heavy metal module.

35 Thank you very much!

36 Key parameter: partition coefficient K d K d M = s [ M ] Different K d in different processes 1. Partition between soil and water 2. Partition between suspended sediment and water 3. Partition between bottom sediment and water Determine the appropriate K d for various medium

37 recognize the mine/tailing/piling area in the remote sensing image