Air pollutant contamination and acidification of surface waters in the North York Moors, UK: Multi-proxy evidence from the sediments of a moorland pool

Richard W Battarbee,Paula J Reimer,Simon Turner,Kevin Roe,Handong Yang,Ewan Shilland,Frank Oldfield,Vivienne J Jones,Peter M Smyntek,Neil L Rose,Roger J Flower,Maarten Blaauw

doi:10.1177/0959683614556380

Abstract

Despite the extensive geographical range of palaeolimnological studies designed to assess the extent of surface water acidification in the United Kingdom during the 1980s, little attention was paid to the status of surface waters in the North York Moors (NYM). In this paper, we present sediment core data from a moorland pool in the NYM that provide a record of air pollution contamination and surface water acidification. The 41-cm-long core was divided into three lithostratigraphic units. The lower two comprise peaty soils and peats, respectively, that date to between approximately 8080 and 6740 cal. BP. The uppermost unit comprises peaty lake muds dating from between approximately ad 1790 and the present day (ad 2006). The lower two units contain pollen dominated by forest taxa, whereas the uppermost unit contains pollen indicative of open landscape conditions similar to those of the present. Heavy metal, spheroidal carbonaceous particle, mineral magnetics and stable isotope analysis of the upper sediments show clear evidence of contamination by air pollutants derived from fossil-fuel combustion over the last c. 150 years, and diatom analysis indicates that the naturally acidic pool became more acidic during the 20th century. We conclude that the exceptionally acidic surface waters of the pool at present (pH = c. 4.1) are the result of a long history of air pollution and not because of naturally acidic local conditions. We argue that the highly acidic surface waters elsewhere in the NYM are similarly acidified and that the lack of evidence of significant recovery from acidification, despite major reductions in the emissions of acidic gases that have taken place over the last c. 30 years, indicates the continuing influence of pollutant sulphur stored in catchment peats, a legacy of over 150 years of acid deposition.

Highlights

The problem of ‘surface water acidification’ was first identified in the United Kingdom following a chemical and biological survey of streams and lakes in Galloway, southwest Scotland
Spheroidal carbonaceous particle, mineral magnetics and stable isotope analysis of the upper sediments show clear evidence of contamination by air pollutants derived from fossil-fuel combustion over the last c. 150 years, and diatom analysis indicates that the naturally acidic pool became more acidic during the 20th century
The threefold distinction shown by the loss on ignition (LOI) data is reflected by the x-ray fluorescence (XRF) data on major elements (Figure 2), with relatively high Al, Si, K, Ti and Zr values characterising the basal and uppermost zones, reflecting the inclusion of mineral material from lithospheric sources, separated by the middle section of almost pure peat where these mineral elements occur in very low abundance

Summary

Introduction

The problem of ‘surface water acidification’ was first identified in the United Kingdom (by Wright et al, 1980) following a chemical and biological survey of streams and lakes in Galloway, southwest Scotland They maintained that the highly acidic waters in the region were similar in character to those in parts of southern Norway and southwest Sweden where the loss of salmonid fish populations had been previously documented (Almer et al, 1974; Jensen and Snekvik, 1972). Only one site, a stream site, was included in the Pennines, and there was no site in the North York Moors (NYM) These upland regions of Northern England, dominated by moorland with acidic, peaty soils and acid waters and lying in areas of high acid deposition, contain few natural lakes with none sensitive to acid deposition.

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