Le journal de l'IRD
n° 41 September-October 2007
Translator: Nicholas Flay
Abstracts for the international issue
p. 1, 6-10 Special feature
New Caledonia
Climate change
and cholera in Africa
Economic and ecological
Issues reconciled?
Adaptation and the
ultramafic rock environment
(microbial carbon, total organic carbon,
symbiotic fixation of nitrogen, and so on)
must therefore be sought and developed
in order to monitor and predict the evolution and biogeochemical functioning of
soils in tropical mining environments.
IRD and CNRS researchers recently found
Hunger and malnutrition
in the Sahel: renewed
mobilization needed
Delpeuch, expert advisors to the WHO and FAO,
call for lessons to be learnt, in both technical
and political terms, from the famine which hit
Niger in 2005. Their analysis, drawn from
decades of experience with the Institute, constitutes a veritable road map for checking the
recurrence of such tragedies in Africa. (extract)
Exceptional fungi
T
he diverse range of ectomycorrhizal
fungi associated with plants endemic
to the mining maquis surely contains the
largest number of new species of fungi
that remain to be described. Understanding of ectomycorrhizal fungi’s functional roles (notably metal speciation) and
dynamics necessitates supplementary
research. Results from this will be
A Among the conclusions that
(…) can be drawn from these analyses, several observations stand out clearly
for the future, if we are really looking for
permanent solutions. The sterile opposition between emergency relief staff and
development personnel must stop,
because the nutritional situation in the
Sahel has become a “chronic emergency”. There must be a prevailing continuum between the treatment of severe
acute cases in therapeutic nutrition centres, outpatient treatment of less severe
and moderate malnutrition and preven-
o meet one of the scientific recommendations of the Noumea conference, the systematic mapping of morphological palaeosurfaces bearing laterite
weathering from the summit of the mining
massifs down to the lagoon. The survey
brought fundamental information on the
geological and geomorphological phenomena responsible for the structure of
mining massifs.
A research model
I
n order to understand
mechanisms involved in
the tolerance of
plants and their
associated microorganisms to heavy
metals, the ectomycorrhizal symbiosis
which links Tristaniopsis guillainii to
Pisolithus albus in the ultramafic soils of
New Caledonia was chosen as the
research model.
The researchers hope eventually to be able
to test the implantation of a functional
ectomycorrhizal symbiosis for heavy metal
tolerance.
From the land to the lagoon
T
he need to monitor the risks of pollution is being tackled by a sustained
long-term effort to develop methods for
determining the concentrations of all possible forms of nickel in the waters. The
resulting techniques led to the use of nickel as an accurate tracer of terrigenous
material input into the lagoon.
Bio-indicators used to detect contamination are closely monitored by a surveillance
network. Particular species have been chosen as biological contamination indicators,
following investigation of their behaviour
in the presence of nickel.
Mining maquis:
from soil biogeochemistry
to restoration
n particularly metal-rich laterite environments, prediction of the possible fates
of the metals requires knowledge of
where they are located within the mineral
phases of the soil.
The dynamics of metals in the environment is controlled by a system of sources,
sinks and fluxes and by biological activity,
especially that of microbes. The interactions between microorganisms, minerals,
organic matter and solutions play a major
role in the functioning of soils by modifying and regulating the fate and availability
of metals (solubilization, immobilization,
change of status, and so on). A number of
principal types of interaction come into
play:
● microbial or abiotic oxidation of sulfides
can lead to the acidification of waters and
to their pollution by metals;
● microbial reduction of oxides of manganese and iron, which induces the solubilization of these elements and associated metals (cobalt, nickel, and so on), and
also their reorganization in the solid phase
towards generally more labile compartments;
● sorption, bioaccumulation and precipitation of metals which thus limit their
availability;
● rhizospheric weathering.
The whole set of soils’ physical, chemical
and biological characteristics must be
taken into account in mining site rehabilitation projects and management. Relevant
indicators of the fertility of these soils
tion by actions targeting the various
major causes of malnutrition, favouring a
community-based approach. For maximum effectiveness, the most timely window of intervention goes from 6 months
before the start of pregnancy up to the
child’s second birthday. It is desirable also
to think about large-scale preventive
usage of new therapies which have revolutionized the treatment of severe cases
of malnutrition. It goes without saying
that large amounts of sustained funding
are necessary. It is necessary to persuade
the funding agencies that not only is it a
© IRD/A.-S. Lepetit
I
Human communities and
their mining environment
T
he studies available have already
brought into relief the special relationship Kanaks have with Nature. However,
there are few updated reports that describe
changes and developments in the perception New Caledonian communities have
regarding ecological and economic
upheavals produced by the development of
mining. Research projects on this subject
area are under way.
© IRD/ D. Poignonec
© IRD/M. Vilayleck
p. 16 Forum
© Alexandre Lagrange
T
he founding of a national research centre (Centre national de recherche et de
technologie sur le nickel, CNRT) “Nickel et
son Environnement” stimulated wide interest. A public joint research venture (groupement d’intérêt public) was set up. It is built
on dual foundations: the human means and
analytical facilities available for the scientific
establishments present in New Caledonia
(IAC/Cirad, UNC, the IRD, IPNC, Ifremer, and
BRGM) and joint projects with the mining
industries federation, Syndicat des Industries
de la Mine, secure in the strength of its mining companies and survey firms. It also benefits from the skills of laboratories of excellence in metropolitan France, Australia and
New Zealand, in the context of joint regional programmes. In addition, the public institutions of New Caledonia (Government,
Congress, Provinces) have provided strong
support for the project, which they will help
to run and finance. The CNRT will officially
come into being at the end of 2008 and will
be doted with an operational budget of
5 million euros for 5 years; it will work in
response to calls for project proposals and
facilitate international treatment of research
topics by public authorities and the world of
mining.
IRD nutritionists Yves Martin-Prével and Francis
© IRD/D. Couret
E
cological research has identified the
characteristics of pioneer species of
degraded mining sites. Among these, certain Cyperaceae (the family to which Carex
(sedges etc.) belongs) were identified for
their ability to recolonize bare ground. The
IRD, working jointly with the UNC and the IAC
has made the first demonstration in the
species of this family, of the role of arbuscular mycorrhizal fungi in the growth and
survival of young plants. In parallel, a collection of bacterial isolates coming from the
rhizosphere of plants growing in their natural habitat has been compiled. The characterization of these bacteria has made
selection of isolates possible for their ability
to render phosphorus soluble and tolerate
nickel.
Nickel and its environment
Brasília, from utopia
to sustainable development
rasília was an avant-garde utopian
capital created in the 1950s, founded
on a functionalist vision of bringing about
social integration. How has the city become
a sprawling, fragmented and segregated
agglomeration? IRD geographers working
alongside University of Brasília research
partners used the Brasilia’s case history to
identify the social and environmental risks
that result from combined effects of the
frequent discrepancies that arise between
planned urban projects and the development dynamics of cities of the South, subjected as they are to phases of strong and
rapid growth.
Endemic plants
for revegetation
T
extremely usefulfor preparing the soil surface layer prior to the sustainable restoration of ecosystems after mining exploitation.
© IRD/P. Jourand
© IRD/ F. Colin
H
p. 4 Partners
Urban environment
B
he flora of New Caledonia is considered to be one of the richest on Earth
and its particularity is partly linked to the
special character of its soils. These are
derived from weathering of ultramafic rocks
composed essentially of iron (>50%) and
which manifest high concentrations of nickel, manganese, cobalt, chromium, deficiencies in the major nutrient elements (nitrogen, phosphorus and potassium) and a
strong imbalance in the calcium/magnesium
ratio. Plants cannot resist, grow, interact
and develop in this restricting hostile environment unless they establish highly special
adaptations. The ultramafic ecosystem
therefore serves as a substantial source of
information on the mechanisms underlying
the adaptive processes plant communities
and their associated microorganisms adopt,
under certain harsh edaphic stresses.
ow can what is an essential mining
industry be maintained without
destroying the ecosystem? This is one of
the challenges New Caledonia is facing up
to. Research in this field bears a great
responsibility: that of identifying environmental strategies compatible with a sustainable form of development. In 2003, an
international conference brought scientists
and mining professionals together to examine this problem. What has become of their
recommendations? What new information
has the research brought in answer to their
questions? Four years on from the conference, Sciences au S reviews the situation in
a special six-page feature.
Uplift, weathering and
erosion of New Caledonia
© IRD/P. Jourand
T
© IRD/C. Dejoux
In-depth seismic survey
A network of over 80 seismometers
has been used for the first time to
produce a record of seismicity of the
Lesser Antilles island arc, taken over a
period of 6 consecutive months.
These instruments were deployed
both in marine areas and on terrestrial sites on the islands. The data
recorded during these survey campaigns will give clues to the nature of
microearthquakes produced in the
contact zone at sea between the
Atlantic Plate and the Caribbean
Plate, determine the mechanisms
involved and detect possible transient
seismic signals. In addition, natural
seismicity recording and seismic shots
conducted during the “Sismantilles”
campaign will help realize the threedimensional mapping of the geological structure of the Lesser Antilles arc,
with the aim of defining the physical
properties of its environment, particularly where the plates come into
contact.
Such data will aid researchers in their
search to improve assessment of the
risk of violent subduction earthquakes in the Lesser Antilles.
© IRD/ N. Perrier
evidence for a strong correlation
between cholera and climate variations
in West Africa. They are hopeful that
the results of their investigations will
provide the opportunity to construct a
predictive model which would help
anticipate the emergence of centres of
infection and therefore improve forecasting of risks from the disease.
matter of real investments, but also of a
fundamental issue of human rights.
Consult the articles in full on the IRD Internet site: http://www.ird.fr
© Juliette Martin-Prével
p. 2 News