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Impacts of the volcanic plumes in North Kivu (D.R. Congo)Preliminary results

Impacts of the volcanic plumes in North Kivu (D.R. Congo)Preliminary results

1 1 2 3 1Caroline Michellier , Benoît Smets , Michèle Dramaix-Wilmet , Jean-Bosco Kahindo , François Kervyn

1- Department of Earth Sciences, Royal Museum for Central Africa, Belgium2- Ecole de Santé Publique, Université Libre de Bruxelles, Belgium

3- CEMUBAC, Université Libre de Bruxelles, Belgium

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2011 Belgian Biodiversity & Public Health Conference - 30th November, 20112011 Belgian Biodiversity & Public Health Conference - 30th November, 2011

General Context

CONTACTcaroline.michellier@africamuseum.be

Impacts of the volcanic plume on vegetation biodiversity

Impact of the volcanic plume on public health: preliminary results

Nyamulagira

NyiragongoVegetation zoning

Vegetation zoning

N

REFERENCESBluth & Carn (2008) - Intern. Journal of Remote Sensing, 29 (22). / Carn (2003) - Acta Vulcanologica, 15 (1-2). / Delmelle et al. (2002) - Bull Volcanol., 64. /GORISK (2010) - Final Report. / Hansell & Oppenheimer (2004) - Archives of Environmental Health, 59 (12).

Our study aims at assessing the risk on population health and vegetation resulting from the volcanic plumes emitted by Nyiragongo and Nyamulagira, two of the mostactive volcanoes in Africa, located in the East Democratic Republic of Congo (DRC). Here are presented the studied region and the preliminary results.

Nyiragongo (3470 m a.s.l.) - Semi-permanent -rich gas plume

- Last eruption: 17th Jan. 2002 (0.093 Mt SO )2

- SO emissions = 2 to 50 kt per day (Carn, 2003; GORISK, 2010)2

Nyamulagira (3058 m a.s.l.) - Eruption every 2-4 years with huge release of SO .2

- Currently in eruption. - SO emissions = 0.31 to 4.2 Mt per eruption (Bluth & Carn, 2008).2

Virunga National Park (790 000 ha; 680 m to 5109 m a.s.l.) - Endangered UNESCO World Heritage (illegal woodcuts, poach, etc.) - One of the African national parks with the highest biodiversity, especially in terms of vegetation (equatorial forest, swamps, steppes, savannahs). - Vegetation affected by volcanic activity.

The studied region - Densely populated - Very low standard of living. - Goma region (>700 000 inhabitants) directly threatened by Nyiragongo lava flows (2002 eruption = ~150 victims, ~10% of the city destructed). - Sparse appropriate medical infrastructure to face effects of the extended volcanic plumes.

SO2

Figure 1 - Map of the studied area. Nyiragongo and Nyamulagira volcano are located in the Virunga, a volcanic chain ofthe East African Rift.

Sulfur dioxide from eruptions and degassing events are commonly associated with acute respiratory infections (ARI) as well as irritations (e.g. Hansell & Oppenheimer, 2004), butthe risk has not yet been assessed in the Nyiragongo-Nyamyulagira region. CEMUBAC (ULB’s NGO; RMCA's partner in the GORISK project) is supporting the health information system in theDRC (15-year data collection). After data selection (80 health centres under the average SO plume; 4 studied pathologies, ARI kept), data cleaning (double data checking) and statistical2

imputation (data gap removal)), and based on the hypothesis that the ARI risk decreases accordingly to the increasing distance to volcano, ARI data were plotted (Figures 3 to 7).

eye and skin

Figure 3 - The ARI cases number is relativelystable. A huge peak following the Nyiragongo 2002eruption is observed, despite low SO discharges.2

It could be due to both gas bursts and emanationsaround lava flows as well as ash falls.

Figure 4 - Data correspond to the highest region(1500 to 2500 m). The high altitude could explainpart of the respiratory morbidity. Seasonal effectshould be statistically study (time series analysis).

Figure 5 - No apparent relationship is observed>49 km from the volcanoes. The ARI casesnumber increasing registered from 2006 is mainlydue to data collection extended to additionalhealth centres in this area.

Figure 6 - The trend is stable, apart from the2005-2007 period. Although the paroxysm in ARIcases number is recorded just after the 2006Nyamulagira eruption, it requires more statisticalresearches.

Figure 7 - 2002: the high RR is a possibleconsequence of the Nyiragongo eruption.2008-2010: High RRs could be due to themassive presence of refugees around Goma,fleeing conflict situation.

Refe

rence y

ear

= 1

999 (

RR =

1)

Concluding remarks

- Not possible to conclude at any relationship between ARI and

concentrations, despite study results from other volcanic areas (e.g. Hansell & Oppenheimer, 2004).

- The ARI cases number 2002 peak contrasts with low SO2

discharges linked to the Nyiragongo 2002 eruption.

- The preliminary results require statistical approach as times-series analysis to reduce the seasonal data effect.

- New spatial and statistical approaches can be developed: e.g. using population age groups, origin of the population (close to the health center or further), etc.

SO2

X

X

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Direct impactThe response of vegetation to high atmospheric dose of volcanic SO sustained exposure results in a strong2

reduction in the number of plant communities (Delmelle et al, 2002).

Indirect impactRainwater + acidic gases = acidic rainfall and mistConsequences: foliar injuries for a large number of plants, which participate to deforestation (WHO Air QualityGuideline, 2005)

Figure 2 - The presence of volcanic plumes at Nyiragongo and Nyamulagira creates a clear vegetation zoning on the volcano flanks (up to 300 ha).

Figure 8 - Map of the studied area with total number of ARI cases, from 2000 to 2010.

ARI Relative Risk (RR) decreases with distance (Poisson regression): with reference health centres (RR = 1) located >102 km from the volcano, RR = 2.61 [1.57; 4.35] for health centres ≤26 km;

RR = 2.63 [1.61; 4.30] for those >26 to ≤48 km; RR = 1.93 [0.99; 3.75] for those >48 to ≤102 km.

0

0,5

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01/2000 01/2002 01/2004 01/2006 01/2008 01/2010

Tota

l nu

mb

er o

f A

RI (

81

hea

lth

cen

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)

ARI vs. SO2 flux (≤ 26 km)

SO2

ARIJan

20

02

-N

yira

gon

go

Feb

20

00

-N

yam

ula

gira

Feb

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-N

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SO2

flu

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t)

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No

SO

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esti

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e

0

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01/2000 01/2002 01/2004 01/2006 01/2008 01/2010

Tota

l nu

mb

er o

f A

RI (

81

hea

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ARI vs. SO2 flux (> 26 to ≤ 48km)

SO2

ARIJan

20

02

-N

yira

gon

go

Feb

20

00

-N

yam

ula

gira

Feb

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yam

ula

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July

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yam

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Jun

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Nya

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SO2

flu

x(k

t)

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20

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-N

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No

SO

2fl

ux

esti

mat

e

0

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1

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01/2000 01/2002 01/2004 01/2006 01/2008 01/2010

Tota

l nu

mb

er o

f A

RI (

81

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ARI vs. SO2 flux (> 48 to ≤ 102 km)

SO2

ARIJan

20

02

-N

yira

gon

go

Feb

20

00

-N

yam

ula

gira

Feb

20

01

-N

yam

ula

gira

July

20

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-N

yam

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gira

Jun

e 2

00

4-

Nya

mu

lagi

ra

Dec

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06

-N

yam

ula

gira

SO2

flu

x(k

t)

Jan

20

10

-N

yam

ula

gira

No

SO

2fl

ux

esti

mat

e

0

0,5

1

1,5

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2,5

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3,5

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0

500

1.000

1.500

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3.500

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6.000

01/2000 01/2002 01/2004 01/2006 01/2008 01/2010

Tota

l nu

mb

er o

f A

RI (

81

hea

lth

cen

tres

)

ARI vs. SO2 flux (> 102 km)

SO2

ARIJan

20

02

-N

yira

gon

go

Feb

20

00

-N

yam

ula

gira

Feb

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-N

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July

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Jun

e 2

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Nya

mu

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-N

yam

ula

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SO2

flu

x(k

t)

Jan

20

10

-N

yam

ula

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No

SO

2fl

ux

esti

mat

e