Multivariate relationships between groundwater chemistry and toxicity in an urban aquifer.
Multivariate statistical methods were used to investigate the causes of toxicity and controls on groundwater chemistry from 274 boreholes in an urban area (London) of the United Kingdom. The groundwater was alkaline to neutral, and chemistry was dominated by calcium, sodium, and sulfate. Contaminants included fuels, solvents, and organic compounds derived from landfill material. The presence of organic material in the aquifer caused decreases in dissolved oxygen, sulfate and nitrate concentrations, and increases in ferrous iron and ammoniacal nitrogen concentrations. Pearson correlations between toxicity results and the concentration of individual analytes indicated that concentrations of ammoniacal nitrogen, dissolved oxygen, ferrous iron, and hydrocarbons were important where present. However, principal component and regression analysis suggested no significant correlation between toxicity and chemistry over the whole area. Multidimensional scaling was used to investigate differences in sites caused by historical use, landfill gas status, or position within the sample area. Significant differences were observed between sites with different historical land use and those with different gas status. Examination of the principal component matrix revealed that these differences are related to changes in the importance of reduced chemical species.
Department of Geology, Royal Holloway, University of London, Egham Hill, Egham, Surrey, TW20 0EX, United Kingdom.
Rachel E
RE
Dewhurst
N Claire
NC
Wells
Mark
M
Crane
Amanda
A
Callaghan
Richard
R
Connon
John D
JD
Mather
D000818:Animals; D001681:Biological Assay; D002947:Cities; D003621:Daphnia; D015999:Multivariate Analysis; D009930:Organic Chemicals; D012037:Refuse Disposal; D012044:Regression Analysis; D018570:Risk Assessment; D012989:Soil Pollutants / Q000633:toxicity*; D014733:Vibrio; D014867:Water / Q000737:chemistry*; D014873:Water Pollutants / Q000633:toxicity*; D014881:Water Supply
D009930:Organic Chemicals; D012989:Soil Pollutants; D014873:Water Pollutants; D014867:Water