Effects of the 1995–1997 drought on nitrate leaching in lowland England

Morecroft, Michael D.; Burt, Tim; Taylor, M.; Rowland, A. P.

doi:10.1111/j.1475-2743.2000.tb00186.x

Cited by 45 publications

(34 citation statements)

References 17 publications

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“…Because point sources were absent, these results suggested reduced input from non‐point sources during low‐flow periods. Evidence for reduced loads during low‐flow due to changed water origin compared to normal conditions was also found elsewhere (Baures et al, ; Burt & Worrall, ; Burt, Worrall, Howden, & Anderson, ; Foster & Walling, ; Morecroft, Burt, Taylor, & Rowland, ; Zielinski, Gorniak, & Piekarski, ).…”

Section: Introductionsupporting

confidence: 67%

Patterns in the linkage of water quantity and quality during low‐flows

Hellwig

Stahl

Lange

2017

Hydrological Processes

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This study investigates 72 catchments across the federal state of Baden‐Wuerttemberg, Germany, for changes in water quality during low‐flow events. Data from the state's water quality monitoring network provided seven water quality parameters (water temperature, electrical conductivity, concentrations of chloride, sodium, sulfate, nitrate, and phosphate), which were statistically related to streamflow variability. Water temperature changes during low‐flow showed seasonal dependence. Nitrate concentrations revealed high spatial heterogeneity with about one third of the stations showing decreasing values during low discharge. For most other parameters, concentrations increased during low‐flow. Despite consistent trend directions, the magnitudes of changes with streamflow differed markedly across the state. Both multiple linear regression and a multiple analysis of variances were applied to explain these differences with the help of catchment characteristics. Results indicated that for sulfate and conductivity, geology of the catchments was the most important control, whereas for chloride, sodium, and nitrate, sewage treatment plants had the largest influence. For phosphate, no clear control could be identified. Independent from the applied method, land use was a less important control on river water quality during low‐flow than geology or inflow from sewage treatment plants. These results show that the effects of diffuse and point sources, as well as those of natural and anthropogenic sources differ for different water quality parameters. Overall, a high diversity of potential water quality deterioration signals needs to be considered when the ecological status of rivers is to be protected during low‐flow events.

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Section: Introductionsupporting

confidence: 67%

Patterns in the linkage of water quantity and quality during low‐flows

Hellwig

Stahl

Lange

2017

Hydrological Processes

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“…Although the annual memory effect does not appear to be statistically significant at the 0.2 level (Figure 1a), many previous observational studies demonstrated that just one year or even shorter dry periods followed by high rainfalls can lead to high DN-load anomalies and eutrophication, such as marked rises of river nitrate-N concentrations or loads [e.g., Foster and Walling, 1978;Morecroft et al, 2000;Kaushal et al, 2008] and phytoplankton production [e.g., Acker et al, 2005]. Furthermore, the statistical significance may be low due to the short-term ) N data availability, which excludes historically the most dry (1960s) and wet (1970s) periods.…”

Section: The Influence Of Climate Variability On River Dn-load Anomaliesmentioning

confidence: 87%

Climate variability and extremes, interacting with nitrogen storage, amplify eutrophication risk

Lee

Shevliakova

Malyshev

et al. 2016

Geophysical Research Letters

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Despite 30 years of basin‐wide nutrient‐reduction efforts, severe hypoxia continues to be observed in the Chesapeake Bay. Here we demonstrate the critical influence of climate variability, interacting with accumulated nitrogen (N) over multidecades, on Susquehanna River dissolved nitrogen (DN) loads, known precursors of the hypoxia in the Bay. We used the process model LM3‐TAN (Terrestrial and Aquatic Nitrogen), which is capable of capturing both seasonal and decadal‐to‐century changes in vegetation‐soil‐river N storage, and produced nine scenarios of DN‐load distributions under different short‐term scenarios of climate variability and extremes. We illustrate that after 1 to 3 yearlong dry spells, the likelihood of exceeding a threshold DN load (56 kt yr−1) increases by 40 to 65% due to flushing of N accumulated throughout the dry spells and altered microbial processes. Our analyses suggest that possible future increases in climate variability/extremes—specifically, high precipitation occurring after multiyear dry spells—could likely lead to high DN‐load anomalies and hypoxia.

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“…The effects of drought can be different if drought increases in a currently dry area or in an area that is not currently water limited and if drought does not cause drastic changes in these situations. Drought tends to increase mineralization and nitrification in the UK, probably because of an increase of oxygen in soils and because of increases in nitrate loads in runoff (Morecroft et al, 2000). The most frequent effect observed after droughts in temperate forests is an increase of nitrate concentrations in runoff after the first rain following a drought, with the nitrates coming mainly from superficial runoff, but from subsurface runoff after subsequent rainfall (Lange and Haensler, 2012).…”

Section: Climate Changementioning

confidence: 99%

Hydraulic redistribution by plants and nutrient stoichiometry: Shifts under global change

Sardans

Peñuelas²

2014

Ecohydrology

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Hydraulic lift, water movement from deep to upper soil layers by roots, is a widespread process in temperate and semi-arid environments. It can contribute 17-81% of total water transpired and favour the uptake of nutrients available mainly from soil organic matter decomposition (e.g. N). Downward siphoning, water movement from upper to deep soil layers, can represent 10-60% of total transpired water, favouring the uptake of nutrients supplied mainly from the leaching of bedrock minerals (e.g. P and K). These vertical water movements also can affect the N : P ratio of runoff waters when, in the case of hydraulic lift, they open the possibility for a given pulse of water to circulate multiple times across the N-rich upper soil layers. Plants, thus, affect the stoichiometry of nutrients in soils and groundwater not only through the physical protection of the soil and through the water uptake but also through water redistribution. Soil water redistribution can also play an outstanding role in the ecosystem responses to global change drivers. The increase in soil patchiness in current and future arid lands modifies runoff fluxes, hydraulic lift and downward siphoning, allowing plants to dispose of higher water and nutrient availabilities. The higher use of hydraulic lift and/or downward siphoning by alien species is a possible cause of alien plant success. Further mechanistic and quantitative research is thus warranted to discern the plant role in water and nutrient cycling and in the responses to global change.

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Effects of the 1995–1997 drought on nitrate leaching in lowland England

Cited by 45 publications

References 17 publications

Patterns in the linkage of water quantity and quality during low‐flows

Patterns in the linkage of water quantity and quality during low‐flows

Climate variability and extremes, interacting with nitrogen storage, amplify eutrophication risk

Hydraulic redistribution by plants and nutrient stoichiometry: Shifts under global change

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