Particulate aluminium in boreal streams : Towards a better understanding of its sources and influence on dissolved aluminium speciation

• The adverse impacts of the inorganic labile monomeric Al (Al-i) fraction on aquatic organisms have meant that Al (Al-tot) determination and even speciation has become a routine part of environmental monitoring and assessment. However, if samples are not filtered prior to analysis then particulate Al (Al-tot(p)) could influence the determination of Al-tot, and therefore the determination of the more toxicologically important (Al-i), both when it is measured analytically or modelled from Al-tot. This paper shows that the Al/DOC ratio in unfiltered samples can identify the Al-tot(p) fraction, and thus improve the speciation of Al-i. These findings are based on data from a study in a 67 km(2) catchment in northern Sweden during the snowmelt-driven spring flood of two consecutive years. Filtered and unfiltered samples were studied to determine the spatial and temporal patterns in Al-tot(p). The concentrations of Al-tot(p) were greatest in larger downstream sites where significant silt deposits are located. The sites with no silt in their drainage area showed a mean difference between filtered (Al-tot(f)) and unfiltered (Al-tot(uf)) samples of 6%, while sites with silt deposits had a mean difference of 65%. The difference between filtered and unfiltered samples was greatest at peak flow. Spikes in Al-tot(p) did not behave consistently during fractionation with a cation exchange column, resulting in increases in either measured Al-i(f) or non-labile monomeric Al (Al-o(f)). Al-tot(p) spikes were associated with sharp increases in the Al:DOC ratio. The baseflow Al:DOC ratio could be used to model filtered Al-tot from DOC with a Spearman rho of 0.75. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

LANTBRUKSVETENSKAPER  -- Annan lantbruksvetenskap -- Miljö- och naturvårdsvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Other Agricultural Sciences -- Environmental Sciences related to Agriculture and Land-use (hsv//eng)

Nyckelord

organic-carbon

northern sweden

spring flood

water samples

trace-metals

river

catchment

runoff

fractionation

variability

Earth sciences

Geovetenskap

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