Phoslock is the commercial name for a
bentonite
Bentonite ( ) is an Absorption (chemistry), absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelli ...
clay in which the sodium and/or calcium ions are exchanged for
lanthanum
Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements bet ...
. The lanthanum contained within Phoslock reacts with phosphate to form an inert mineral known as rhabdophane (
LaPO4.\mathitH2O). Phoslock is used in lake restoration projects to remove excess
phosphorus
Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
from aquatic systems, thereby improving water quality and inducing biological recovery in impaired freshwater systems.
It was developed in Australia by the
CSIRO
The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications.
CSIRO works with leading organisations arou ...
in the late 1990s by Dr Grant Douglas (US Patent 6350383) as a way of utilising the ability of lanthanum to bind phosphate in freshwater natural aquatic systems. The first large-scale trial took place in January 2000 in the
Canning River
The Canning River ( or ) is a major tributary of the Swan River in the South West Land Division of Western Australia. It is home to much wildlife including dolphins, pelicans, swans and many other bird species.
Source and route
With headwate ...
, Western Australia.
During its development, patenting and commercialisation by CSIRO and subsequent commercial production, Phoslock has been a subject in academic research and has been used globally in lake restoration projects. The largest number of whole lake applications and the most comprehensive pre- and post-application monitoring has taken place in Europe, primarily Germany (where it is sold under the tradename Bentophos), the Netherlands and the UK.
There are studies indicating that lanthanum release due to application of this clay could lead to increased concentrations of this rare element in water and soils, resulting in
bioaccumulation
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. T ...
in animal tissues and there are still concerns and precautions to be taken as currently there is not enough complete and independent information.
See also
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Eutrophication
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...
*
Harmful algal bloom
A harmful algal bloom (HAB), or excessive algae growth, sometimes called a red tide in marine environments, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, ...
References
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Ecology
Environmental engineering
Water technology