Ecological diversity of streams and rivers is related to their chemistry
What is it about?
In the past limits for the maximum permitted concentration of pollutant metals (e.g., copper, zinc, lead etc.) in surface water (stream, river, lake) were based on fixed concentrations that took no account of how that metal interacted with other chemical constituents in the water, nor considered the effect of multiple metals in the same water body. This has evolved somewhat so they currently consider availability of the metal for organism uptake by considering binding to a theoretical receptor based on a fish gill. However, this also fails to account for mixtures of different metals and how these interact with the water pH, which is acidic for many historical mine sites. This study defines a relationship between stream-water chemistry (considering major ions*, pollutant metals, pH and dissolved organic carbon) and the diversity of stream biology (in this case mayflies, caddisflies and stoneflies). *These are the things you see listed on a bottle of mineral water such as calcium, magnesium, sulfate, nitrate etc.
Why is it important?
This study demonstrates that we can evaluate the potential ecological harm that exists from the entirety of the water chemistry. This allows a much more pragmatic approach to evaluation of water quality than looking only at single metals, where we may end up setting over-protective limits. This will enable regulators to better prioritise impacted systems for management and remediation.
The following have contributed to this page: Anthony Stockdale