Phoslock is the commercial name for a
bentonite
Bentonite () is an 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 swelling capacity than Ca-mon ...
clay in which the sodium and/or calcium ions are exchanged for
lanthanum
Lanthanum is a chemical element with the 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 between lantha ...
. 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 with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
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
The Australian Government, also known as the Commonwealth Government, is the national government of Australia, a federal parliamentar ...
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 (Djarlgarra in Nyungar) 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 a ...
, 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 in animal tissues and there are still concerns and precautions to be taken as currently there is not enough complete and independent information
Aquatic ecotoxicity of lanthanum – A review and an attempt to derive water and sediment quality criteria
/ref> without conflict of interest (the majority of studies are authored by workers or funded commissioned works by the manufacturers or sellers) and there are effects in human and ecosystem health due to higher lanthanum concentrations resulting from Phoslock disposal in the environment.
See also
* Eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...
* Harmful algal bloom
A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural phycotoxin, algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are ...
References
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Ecology
Environmental engineering
Water technology