Oelkers, E.H., and E. Valsami-Jones. 2008. Phosphate mineral reactivity and global sustainability. Elements 4:83-87.
Phosphorus is a unique element. It is the limiting nutrient controlling
biological productivity in many terrestrial and marine environments. When in
excess, however, dissolved phosphate leads to uncontrollable biological growth
and water-quality problems through a process called eutrophication. The use of
phosphate minerals and their products as fertilizers has increased tremendously
global food production; it would not be possible to feed the current world
population without phosphate fertilizers. Yet phosphate is a limited global
resource; current estimates suggest economic phosphorus supply may be severely
depleted over the next 100 years. Nevertheless, mineralogists and geochemists
have invested little time investigating phosphate mineral stability,
reactivity, and transformations. This issue attempts to bring phosphates to the
forefront of our scientific endeavours.
Filippelli, G.M. 2008. The global phosphorus cycle: past, present, and future. Elements 4:89-96.
The cycling of phosphorus, a biocritical element in short supply in nature,
is an important Earth system process. Variations in the phosphorus cycle have
occurred in the past. For example, the rapid uplift of the Himalayan-Tibet
Plateau increased chemical weathering, which led to enhanced input of
phosphorus to the oceans. This drove the late Miocene "biogenic bloom."
Additionally, phosphorus is redistributed on glacial timescales, resulting from
the loss of the substantial continental margin sink for reactive P during
glacial sea-level lowstands. The modern terrestrial phosphorus cycle is
dominated by agriculture and human activity. The natural riverine load of
phosphorus has doubled due to increased use of fertilizers, deforestation and
soil loss, and sewage sources. This has led to eutrophication of lakes and
coastal areas, and will continue to have an impact for several thousand years
based on forward modeling of human activities.
Pasteris, J.D., B. Wopenka, and E. Valsami-Jones. 2008. Bone and tooth mineralization: Why apatite? Elements 4:97-104.
Through evolution, vertebrates have "chosen" the calcium phosphate mineral
apatite to mineralize their teeth and bones. This article describes the key
characteristics of apatite in biological mineralization and explores how the
apatite structure allows biology to control mineral composition and
functionality. Through the synthesis and testing of calcium phosphates for
biomaterials applications, we have gained further understanding of how
sensitive the chemical and physical properties of apatite are to its growth
conditions.
Manning, D.A.C. 2008. Phosphate minerals, environmental pollution and sustainable agriculture. Elements 4:105-108.
The availability of phosphorus in soils is controlled by the ability of
plants to dissolve phosphate-bearing minerals, including apatite and feldspars.
To satisfy the requirement of plants for phosphate, mineral dissolution
competes with precipitation such as, for example, reactions involving lead or
other heavy metals. Plants exude organic acid anions that very effectively
enhance mineral dissolution but that may also liberate harmful solutes, such as
aluminium. To make readily soluble chemical fertilisers, apatite in igneous and
sedimentary rocks is mined and processed; in organic farming, phosphate-rich
rocks are crushed and applied directly to the soil, relying on compounds
produced by plant roots (exudates) to extract the phosphorus that plants need.
Parsons, S.A., and J.A. Smith. 2008. Phosphorus removal and recovery from municipal wastewaters. Elements 4:109-112.
Phosphorus is a key pollutant in municipal wastewater. To minimise
eutrophication, treatment facilities must often reduce phosphorus levels to
less than 1 mg/L. Two main approaches to achieving this are chemical
precipitation and enhanced biological uptake. Chemical precipitation is widely
used and relatively simple; biological phosphorus removal is more complex but
relies less on the addition of chemicals and also offers the opportunity to
reuse the phosphorus. Phosphorus can be released from cells and converted to
calcium phosphate or the mineral struvite. While the products have been shown
to be excellent fertilisers, the economic drivers for recovery are still not
clear.
Oelkers, E.H. 2008. Phosphates and nuclear waste storage. Elements 4:113-116.
A significant effort has been made by the scientific community to evaluate
the potential of phosphate minerals and glasses as nuclear waste storage hosts.
Radioactive waste-bearing phosphates, including monazites, apatites, and
glasses, can be readily synthesized in the laboratory. Because of their low
solubilities and slow dissolution rates, these phosphates are more resistant to
corrosion by geological fluids than many other potential nuclear waste storage
hosts, including borosilicate glass. Phosphates are, however, not currently
being used for nuclear waste storage, in part because their synthesis at the
industrial scale is relatively labor intensive, often requiring the separation
of the waste into distinct fractions of elements. Such limitations may be
overcome by adding phosphate amendments to backfill material, which could
provoke the precipitation of stable radiactive waste-bearing phosphate minerals
in situ.