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Assessment of river health in Australia by diatom assemblages ? a review

100%

John J.

Oceanological and Hydrobiological Studies

2004

issue 2

95-104

This paper summarises the findings of two national projects carried out by the author, covering the largest area ever investigated on the use of diatoms for monitoring river health in Australia, as well as to recommend future directions in diatom river monitoring in Australia. The first project (1995 to 1998) involved South-west Western Australia ? well known for its forests and abundance of streams and rivers. Data on environmental variables and diatom taxa were obtained from 136 sites, out of which 117 were used as reference sites and 29 as monitoring (impacted) sites. Some 20 sites were randomly selected from the reference sites and used as ?test sites? to verify internal consistency of the reference sites which were considered to be relatively pristine. The streams and rivers were finally classified into four distinct groups based upon environmental factors and diatom distribution pattern. The second project involved monitoring the health of urban streams around the city of Perth, western Australia. The investigation (1996 to 1999) focussed on classification of the urban streams based on water quality parameters and ?stream conditions? and development of a predictive model using diatoms as biomonitors. Close to 180 sites were sampled with 30 environmental variables measured. All the sites were classified on the basis of seven environmental variables with the highest correlation coefficient with the sites, using the multivariate pattern analysis program PATN. The reference and monitoring sites were mostly separated on the basis of environmental factors and distinct diatom assemblages. Currently, a national protocol for assessing the health of all rivers using diatoms in Australia is being compiled.

Plant cell responses to heavy metals ? biotechnological aspects

88%

Gwozdz E.

Biotechnologia

2003

issue 3

107-123

Heavy metals have been increasing in the environment as a result of either natural processes or human industrial activities. Many of the heavy metals affect and damage various developmental and biochemical processes causing reduction in growth, inhibition of photosynthesis and respiration and degeneration of main cell organelles. It is mostly due to the promoting effect of heavy metals on the formation of harmful reactive oxygen species (ROS) which disturb the whole cellular machinery. There is a requirement for a balance between the uptake of essential metal ions and the ability of plants to protect sensitive cellular structures and activities from excessive level of metals. The resistance of plants to heavy metals depends on the reduction of uptake and translocation from the root to the shoot, binding by appropriate ligands and, finally, transferring to the vacuole. The phytotoxic effect of heavy metals is effectively counteracted by the metal-binding proteins and peptides like metalothioneins, chaperones and phytochelatins as well as some organic acids. Another very important aspect of the heavy metal detoxication is the presence of an efficient ROS scavenging system consisting of low molecular antioxidants and antioxidant enzymes. Some plants can hyperaccumulate metal ions that are toxic for other species. Such plants can serve as donors of traits that could be used to clean up the environment. Several methods can be applied to create plants able to remove the xenobiotics from the environment: sexual or somatic hybridization, mutagenesis, in vitro selection of metal-resistant cell lines and engineering of metal-accumulating transgenic plants. The use of specially selected and engineered metal-accumulating plants for environmental clean-up is a novel technology called phytoremediation. This rapidly emerging biotechnology consists of some branches suitable to toxic metals remediation: 1) phytoextraction ? the use of plants to remove heavy metals from the soil, 2) phytostabilization ? the use of plants to complex and eliminate the availability of toxic metals in soils, 3) rhizofiltration ? the use of plant roots to remove heavy metals from polluted waters. Some new approaches concerning the use of transgenic plants as sensitive bioindicators of toxic heavy metals and soils contaminated with radionuclides are presented.

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Assessment of river health in Australia by diatom assemblages ? a review

Plant cell responses to heavy metals ? biotechnological aspects