“Physical and Anthropogenic Controls

of the Biogeochemistry of the Ji-Paraná

River Basin (Western Amazônia)”

1Ballester, M.V.R.; 1Krusche, A.V.; 1Kavaguishi, N.L.; 2Gomes, B.M.;

1Victoria, D. de C.; Montebelo, A.A.; 3Neill, C.; 3Deegan, L.; 4Richey, J.E.

and 1Victoria, R.L.1Centro de Energia Nuclear na Aagricultura – Universidade de São Paulo; 2Universidade

Federal de Rondônia; 3Marine Biological Laboratory; 4University of Washington

CD-06, ND-03 and ND-09

What are the water stores and fluxes, and the controls on water movement and What are the water stores and fluxes, and the controls on water movement and

transport of constituents on and below the surface of small uniform basins? transport of constituents on and below the surface of small uniform basins?

How does change of land use affect the sustainability of the ecosystem for different How does change of land use affect the sustainability of the ecosystem for different

soil types and topographies, and how can the larger scale models be improved to soil types and topographies, and how can the larger scale models be improved to

represent these small scale processes? represent these small scale processes?

What are the spatial and temporal patterns of surface and sub-surface water What are the spatial and temporal patterns of surface and sub-surface water

storage and flux in the soils and river corridors of the Amazon Basin, and how are storage and flux in the soils and river corridors of the Amazon Basin, and how are

they influenced by variations in climate and land use? they influenced by variations in climate and land use?

What are the characteristics of soil moisture and river flow for mesoscale basins What are the characteristics of soil moisture and river flow for mesoscale basins

and how can they be predicted?and how can they be predicted?

Land surface Hydrology and Water Biogeochemistry specific questions

How do the pathways and fluxes of organic matter, nutrients and How do the pathways and fluxes of organic matter, nutrients and

associated elements through river corridors associated elements through river corridors (riparian, floodplain, channels (riparian, floodplain, channels

and wetlands)and wetlands) change as a function of land cover? change as a function of land cover?

RATIONALE

Several LBA studies have shown that forest clearing

in the Amazon can alter the transport of sediments,

organic matter and associated nutrients to the rivers

Our previous results demonstrated that both soil properties

and land use are the main drivers of river biogeochemistry

and metabolism

Na+

Ca2+

Mg2+

K+

ECCl-

PO43-

TZ+

0 - 200

201 - 450

451 - 700

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

The pasture explained 99% (p < 0,01) of

the variability observed in most of the ions

concentrations

Cattle pasture are statistically correlated

with nutrient content

Ballester et al., 2003

River biogeochemistry drivers

0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350

Julian Day

0

50

100

150

200

250

[Na] (µM)

Q (m3.s-1)

- Differential effect of geology and soil properties - Human effects

Rio Urupá

JIP em Cacoal

River ions concentrations are control by different mechanism

Spatially integrated analysis of Ji-Paraná basin

(RO).

OBJECTIVE

Evaluate physical and anthropogenic controls

on river biogeochemistry at the mesoscale

level

Ji-Paraná

Study area

Is the 3rd most deforest State in the

Braziliam Amazon (INPE, 2003)

Is responsible for ~10% of the Braziliam

Amazon deforestation, around 20.000

km2 year-1 are cleaned in RO

Classe

Pasto

Flor esta

Água

Ur baniz ação

Cer r ado

Cult ur as Anuais

Rebr ot a

Solos expostos

Nuvens

Out r os

Legenda

Land use/cover (1999)

habitantes

2527 - 8233

8234 - 21862

21863 - 47382

47383 - 106800

106801 - 334661

estradas

habitantes

0

1 - 15434

15435 - 36542

36543 - 95356

95357 - 334741

estradas

habitantes

0

1 - 23156

23157 - 48759

48760 - 97799

97800 - 287534

estradas

habitantes

0

1 - 34751

34752 - 67030

67031 - 133882

estradas

habitantes

0

27016

84048

estradas

2000

19961991

19801970

In 30 years: the population grew 12x,

there is an increase in cattle pastures

and a loss of about 24% natural

forest

Legend

Soil unit (area)

Alfisol (12.6%)

Entisol (16.2%)

Eptisol (1.8%)

Oxisol (46.1%)

Ultisol (23.1%)

Water (0.3%)

estradas

20001999

199819971996

199519941993

199219911990

Legenda: = 5.000 cabeças

estradas

20001999

199819971996

199519941993

199219911990

Legenda: = 5.000 cabeças

Ordem

1

2

3

4

5

6

7

Field work at 38 sites during both Wet

(January) and Dry (June) seasons

Spatially oriented (GIS physical template)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

D F A J A O D F A J A

Dis

charge (

m3.s

-1)

2000 2001

Drainage area: 75. 400 km2

Q = 700m3.s-1,

To answer our research on land use change and soil properties as

drivers of water chemistry in the Ji-Paraná River Basin, we:

Impact SBases

Low 0.26 - 0.79

Medium 0.39 – 0.52

High 0.57 – 0.91

Very high 0.76 – 0.96

Each site represents a different mixture of cover type and soil properties

Legend

Soil unit (area)

Alfisol (12.6%)

Entisol (16.2%)

Eptisol (1.8%)

Oxisol (46.1%)

Ultisol (23.1%)

Water (0.3%)

Impact (% of pasture area) Area %

Low - 0 –15% 37

Medium 15 - 30% 16

High 30 - 50% 16

Very high 50 - 75% 32

To quantify the effects of these two drivers, we performed a

multiple linear regression analysis, relating basin characteristics

and RBGC

Data Analysis

Independent variables

Saturation of bases and percentage of

pastures

River water:

Electrical conductivity (EC) Na+,

Ca2+, Mg2+, K+, Cl- , DOC, TSS, DIC

and PO43- concentrations

Dependent variables

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

RESULTS

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

y = 6.1355e2.3397x

R2 = 0.5611

0

10

20

30

40

50

60

70

80

0 0.2 0.4 0.6 0.8 1 1.2

Base saturationPa

stur

e ar

ea (

%)

~90% of the pasture areas were in

eutrophic soils in 1999

Pasture areas are related to more fertile soils (higher

ECEC and BS) and this relation is statically significant

(p<0.01)

Higher values of all ions were associated with areas dominated by

pasture

Spatial patterns

Lower reaches, forests dominate the landscape, and the concentrations

drop.

Highest concentrations found in the central part of the basin, where

pasture areas and soil fertility are at a maximum

TZ+

0 - 200

201 - 450

451 - 700

Pasture

ECEC

1

2

3

4

5

6

7

8

9

10

11

12

TZ+ values for the

waters of the Ji-

Paraná river

Higher DOC concentrations were related to higher values of

TSS

During the dry season this pattern was not observed.

TSS, in turn, were originated in pasture areas.

17 Fevereiro - Floresta

0

10

20

30

40

50

60

70

9:3

7

9:4

7

9:5

7

10:0

7

10:1

7

10:3

8

10:4

8

10:5

8

11:0

8

11:3

3

12:1

3

12:5

3

13:3

3

Horas

Flu

xo

(m

g.s-1)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Descarg

a (L

.s -1)

Fluxo COD Descarga

17 Fevereiro - Pastagem

0

500

1000

1500

2000

2500

9:4

1

9:5

1

10:0

1

10:1

1

10:2

1

10:3

1

10:4

1

10:5

1

11:1

6

11:5

6

12:3

6

13:1

6

Horas

Flu

xo

(m

g.s

-1)

0

20

40

60

80

100

120

140

Descarg

a (L

.s-1)

Fluxo COD Descarga

Gouveia Neto et al., CD 36.13

Forest: higher infiltration

deeper into the soils and

canopy interaction

Pasture: soil is compacted,

there is less infiltration and

higher surface run off

promoting the leaching of

soil superficial layers caring

more DOC to the stream

The pasture stream showed higher “peaks ” of DOC fluxes when compared to the forest stream

DOC during the wet season as a function of land use

impactImpact Area % Min DOC MAX DOC

Low 37 4 313

Medium 16 170 399

High 16 183 367

Very high 32 296 423

Electric Conductivity

0

20

40

60

80

100

120

140

Wet Dry

Na +

WET DRY50

60

70

80

90

100

110

120

130

140

150K +

WET DRY36

38

40

42

44

46

48

50

52

54

56

58

60

62

64

66

Mg 2+

WET DRY30

35

40

45

50

55

60

65

70

75

80

Wet x Dry season

DOC

WET DRY120

140

160

180

200

220

240

260

280

300

320

340

360

Ca 2+

WET DRY30

40

50

60

70

80

90

100

110

120

TSS

WET DRY8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

Wet x Dry season

Wet x Dry season and Pasture x Soils

R2 Pasture Soil Base Saturation

Na+ 0,74 58 38

Cl- 0,54 67 13

K+ 0,72 68 25

Mg2+ 0,87 19 81

Ca2+ 0,8 14 80

DOC 0,82 44 56

Statistically significant for p < 0.01

The percentage of the basin

area covered by pasture was

consistently the best

predictor for all parameters

during the wet season.

Concluding remarks

Conversion of forest into pastures is

changing river biogeochemical composition

However, the degree of effect of each of these end members varies along a

wide range and regional (and local) patterns remains still to be investigated