Long-term trends in soil solution and stream water chemistry at the Hubbard Brook Experimental Forest: relationship with landscape position

Abstract. Stream water chemistry in the Cyff and Gwy subcatchments within the headwaters of the River Wye has been monitored regularly since 1980. In the Gwy, which is a predominantly semi-natural grassland catchment, land use has remained relatively static over the monitoring period, whilst the Cyff catchment is more buffered because of base cation inputs from agricultural improvement and ground water sources. Using a variety of statistical techniques, the long-term data are examined for evidence of trends after eliminating seasonal effects. The results highlight some of the difficulties associated with the analysis of longterm water quality data which show considerable variability over a variety of timescales. Some of this variability can be explained in terms of hydrochemical responses to climatic extremes and episodic events such as large atmospheric inputs of seasalts. The long-term fluctuations in solute concentration underline the continuing need for maintaining consistent long-term monitoring at sensitive upland sites if underlying trends related to gradual changes in pollutant deposition or climate are to be detected with any certainty.

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Response of Water Chemistry to Long-Term Human Activities in the Nested Catchments System of Subtropical Northeast India

Water ◽

10.3390/w11050988 ◽

2019 ◽

Vol 11 (5) ◽

pp. 988 ◽

Cited By ~ 1

Author(s):

Paweł Prokop ◽

Łukasz Wiejaczka ◽

Hiambok Jones Syiemlieh ◽

Rafał Kozłowski

Keyword(s):

Trace Metals ◽

Population Density ◽

Water Chemistry ◽

Chemical Element ◽

Anthropogenic Impact ◽

Chemical Elements ◽

Stream Water ◽

Stream Water Chemistry ◽

The Tropics

The subtropics within the monsoonal range are distinguished by intensive human activity, which affects stream water chemistry. This paper aims to determine spatio-temporal variations and flowpaths of stream water chemical elements in a long-term anthropogenically-modified landscape, as well as to verify whether the water chemistry of a subtropical elevated shield has distinct features compared to other headwater areas in the tropics. It was hypothesized that small catchments with homogenous environmental conditions could assist in investigating the changes in ions and trace metals in various populations and land uses. Numerous physico-chemical parameters were measured, including temperature, pH, electrical conductivity (EC), dissolved organic carbon (DOC), major ions, and trace metals. Chemical element concentrations were found to be low, with a total dissolved load (TDS) below 52 mg L−1. Statistical tests indicated an increase with significant differences in the chemical element concentration between sites and seasons along with increases of anthropogenic impact. Human influence was clearly visible in the case of cations (Ca2+, K+, Mg2+, Na+) and anions (Cl−, HCO3−, NO3−, SO42−), compared to trace metals. The order of most abundant metals Fe > Zn > Al > Sr was the same in springs and streams, regardless of population density, land use, and season. Principal component analysis (PCA) demonstrated that major ion concentrations in stream water followed the pattern forest < cultivated land < grassland < built-up area. Surface water chemistry of the subtropical elevated shield has mixed features of tropical and temperate zones. Low concentrations of chemical elements; small seasonal differences in headwater streams; and increased concentrations of NO3−, SO42−, DOC, and Zn in the wet monsoon season are similar to those observed in the tropics. The role of long-term cultivation without chemical fertilizers in ions supply to streams is less than in other headwater areas of the tropical zone. Strong control of water chemistry in densely populated built-up areas is analogous to both tropical and temperate regions. Population density or a built-up area may be used as a proxy for the reconstruction or prediction of the anthropogenic impact on stream water chemistry in similar subtropical elevated shields.

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Long-term responses in soil solution and stream-water chemistry at Hubbard Brook after experimental addition of wollastonite

Environmental Chemistry ◽

10.1071/en15113 ◽

2016 ◽

Vol 13 (3) ◽

pp. 528 ◽

Cited By ~ 12

Author(s):

Shuai Shao ◽

Charles T. Driscoll ◽

Chris E. Johnson ◽

Timothy J. Fahey ◽

John J. Battles ◽

...

Keyword(s):

Soil Solution ◽

New Hampshire ◽

Stream Water ◽

Mineral Soil ◽

Forest Health ◽

Aluminium Toxicity ◽

Hubbard Brook Experimental Forest ◽

Acid Base ◽

Hubbard Brook ◽

Acid Base Status

Environmental context Calcium silicate was added to a forest watershed in New Hampshire, USA, to accelerate its recovery from acid rain. The acid–base status of soil and stream quality improved over the 12-year study, with the most pronounced response in the upper elevation and the upper soil of the watershed. A total of 95% of the added calcium and 87% of the added silica were retained in the watershed over the study period. Abstract In October 1999, 3450kgha–1 of wollastonite (CaSiO3) was applied to Watershed 1 at the Hubbard Brook Experimental Forest in New Hampshire, USA, with the objective of restoring calcium that had been depleted from soil-exchange sites by chronic inputs of acid deposition. After the treatment, the concentrations and fluxes of calcium and dissolved silica significantly increased in both soil solution and stream water throughout Watershed 1, as did the acid-neutralising capacity. The concentrations and fluxes of inorganic monomeric aluminium significantly decreased. The treatment improved the acid–base status and decreased the potential for aluminium toxicity in stream water, especially in the lower reaches of the watershed. Approximately 4.7% of the added calcium and 17% of the added silica from the wollastonite treatment was exported from Watershed 1 in stream water by the end of 2010. Meanwhile, ~1825mmolm–2 of the added calcium and 2125mmolm–2 of the added silica were either transported to lower mineral soil horizons – as particulate wollastonite, or as dissolved solutes (calcium 77.6mmolm–2; silica 592.2mmolm–2), thus contributing to increases in soil pools – or were taken up by vegetation and incorporated into internal calcium and silica cycles of the watershed ecosystem. This experimental wollastonite addition was an effective tool for mitigating the acidification of the ecosystem and restoring the calcium status and forest health of this base-poor watershed.

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