Long‐term (18‐year) changes in sulphate concentrations in two Ontario headwater lakes and their inflows in response to decreasing deposition and climate variations

Eimers, M. Catherine; Dillon, Peter J.; Watmough, Shaun A.

doi:10.1002/hyp.5570

Cited by 45 publications

(34 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Elevated SO 4 2-concentrations following rewetting have been observed in similar studies, and are the result of oxidation of insoluble FeS x from the sediment during desiccation (Lucassen et al, 2005;Fernandez-Alaez and Fernadez-Alaez, 2010). The decrease in pH values follows the oxidation of SO 4 2-, which is mobilised as H 2 SO 4 during rewetting (Eimers et al, 2004). The decrease in SO 4 2-following Day 11 may have indicated the onset of sulfate reduction, although this is not consistent with the observed increase in NO 2 -+ NO 3 -at around the same time, which suggested the onset of nitrification under aerobic conditions.…”

Section: Figure 4 Mean (± Se; N = 5) P Released In Water Where Sedimementioning

confidence: 88%

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

Dabrowski

Baldwin

Hill

et al. 2017

WSA

View full text Add to dashboard Cite

South Africa is prone to droughts and is heavily dependent on stored water resources. Few studies in South Africa have investigated the impact of drought on water quality when rainfall resumes and reservoir sediments are rewet. Other research has shown that several negative impacts may occur with rewetting, including eutrophication, and acidification with increased metal solubility. In this study, the impact of drying and rewetting sediments on the mobility of nutrients and metals is explored using sediments from Loskop Reservoir. Rarely exposed sediments were collected from three sites, dried at 35°C for 36 days, and then rewet under aerobic conditions. Filtered water samples were collected on Days 1, 2 ,4, 7, 11 and 16 following rewetting, and analysed for , and were compared to reference (non-drought) treatments that were maintained under saturated conditions. Acute toxicity tests were performed using Daphnia magna to establish if toxic effects were associated with changes in water quality following sediment rewetting. Following rewetting, elevated SO 4 2-indicated the mobilisation of acid from sulfide oxidation, with an associated reduction in pH. Nitrification was evident as high quantities of organic N and NH 4 + were initially released, followed by increases in NO 2 -+ NO 3 -. Total P increased, but PO 4 3-reduced. This was attributed to complexes formed between PO 4 3-and Fe (FePO 4 ) and Al (AlPO 4 ). Amounts of Fe and Al released were lower following rewetting due to the formation of relatively immobile (hydr)oxides. In contrast, Mn increased substantially reaching maximum values > 2 300 mg/m 2 (14 000 µg/L). There were no acute toxic effects observed to D. magna. This study highlights the potential for acidification, mobilisation of nutrients, SO 4 2-, and Mn following rewetting of reservoir sediments under aerobic conditions. This information may be incorporated into reservoir and catchment management plans in the form of revised water quality guidelines and a better ability to predict how drought impacts water quality in our stored water resources.

show abstract

Section: Figure 4 Mean (± Se; N = 5) P Released In Water Where Sedimementioning

confidence: 88%

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

Dabrowski

Baldwin

Hill

et al. 2017

WSA

View full text Add to dashboard Cite

show abstract

“…There was no significant decrease at Moose Pit Brook and at 2 sites (Plastic, Chub) in Muskoka-Haliburton in central Ontario. In central Ontario, this is likely due to the strong influence that climatic variations, and in particular summer droughts have on SO 4 export in the region (Eimers and Dillon 2002;Eimers et al, 2004). Sulphate release from Muskoka-Haliburton (MUS-HAL) catchments increases dramatically following TABLE VI Significant trends (values are in mg L −1 yr −1 ) in stream chemistry and the percentage of acid anions (SO 4 + NO 3 -N) trend balanced by base cations (Ca + Mg + K) at the 17 study catchments with more than 9 years of data (using the entire data period presented in Table I prolonged summer droughts (Eimers and Dillon, 2002), and a major drought event (peak) occurred in 1998/1999 at the end of the period considered in this study.…”

Section: Trends In Runoffmentioning

confidence: 99%

Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe

Watmough

Aherne

Alewell

et al. 2005

Environ Monit Assess

180

127

View full text Add to dashboard Cite

To assess the concern over declining base cation levels in forest soils caused by acid deposition, input-output budgets (1990s average) for sulphate (SO(4)), inorganic nitrogen (NO(3)-N; NH(4)-N), calcium (Ca), magnesium (Mg) and potassium (K) were synthesised for 21 forested catchments from 17 regions in Canada, the United States and Europe. Trend analysis was conducted on monthly ion concentrations in deposition and runoff when more than 9 years of data were available (14 regions, 17 sites). Annual average SO(4) deposition during the 1990s ranged between 7.3 and 28.4 kg ha(-1) per year, and inorganic nitrogen (N) deposition was between 2.8 and 13.8 kg ha(-1) per year, of which 41-67% was nitrate (NO(3)-N). Over the period of record, SO(4) concentration in deposition decreased in 13/14 (13 out of 14 total) regions and SO(4) in runoff decreased at 14/17 catchments. In contrast, NO(3)-N concentrations in deposition decreased in only 1/14 regions, while NH(4)-N concentration patterns varied; increasing at 3/14 regions and decreasing at 2/14 regions. Nitrate concentrations in runoff decreased at 4/17 catchments and increased at only 1 site, whereas runoff levels of NH(4)-N increased at 5/17 catchments. Decreasing trends in deposition were also recorded for Ca, Mg, and K at many of the catchments and on an equivalent basis, accounted for up to 131% (median 22%) of the decrease in acid anion deposition. Base cation concentrations in streams generally declined over time, with significant decreases in Ca, Mg and K occurring at 8, 9 and 7 of 17 sites respectively, which accounted for up to 133% (median 48%) of the decrease in acid anion concentration. Sulphate export exceeded input at 18/21 catchments, likely due to dry deposition and/or internal sources. The majority of N in deposition (31-100%; median 94%) was retained in the catchments, although there was a tendency for greater NO(3)-N leaching at sites receiving higher (<7 kg ha(-1) per year) bulk inorganic N deposition. Mass balance calculations show that export of Ca and Mg in runoff exceeds input at all 21 catchments, but K export only exceeds input at 16/21 sites. Estimates of base cation weathering were available for 18 sites. When included in the mass balance calculation, Ca, Mg and K exports exceeded inputs at 14, 10 and 2 sites respectively. Annual Ca and Mg losses represent appreciable proportions of the current exchangeable soil Ca and Mg pools, although losses at some of the sites likely occur from weathering reactions beneath the rooting zone and there is considerable uncertainty associated with mineral weathering estimates. Critical loads for sulphur (S) and N, using a critical base cation to aluminium ratio of 10 in soil solution, are currently exceeded at 7 of the 18 sites with base cation weathering estimates. Despite reductions in SO(4) and H(+) deposition, mass balance estimates indicate that acid deposition continues to acidify soils in many regions with losses of Ca and Mg of primary concern.

show abstract

“…have demonstrated that long-term or multi-season droughtinduced SO 4 mobilization retards general recovery from acidification (Eimers et al, 2004b;Jeffries et al, 2002). Hence, a possible explanation for the strong correlation between low antecedent runoff and the anthropogenically driven ANC (poll) found in this study is that a temporary lowering of the ground water level can result in a transformation of immobile sulfides to readily mobile sulfates that can be washed out during subsequent hydrological episodes.…”

Section: Discussionmentioning

confidence: 99%

Recovery from episodic acidification delayed by drought and high sea salt deposition

Laudon¹

2008

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. For the prediction of episodic acidification large uncertainties are connected to climatic variability and its effect on drought conditions and sea-salt episodes. In this study data on 342 hydrological episodes in 25 Swedish streams, sampled over 10 years, have been analyzed using a recently developed episode model. The results demonstrate that drought is the most important factor modulating the magnitude of the anthropogenic influence on pH and ANC during episodes. These modulating effects are especially pronounced in southern and central Sweden, where the historically high acid deposition has resulted in significant S pools in catchment soils. The results also suggest that the effects of episodic acidification are becoming less severe in many streams, but this amelioration is less clear in coastal streams subject to high levels of sea-salt deposition. Concurrently with the amelioration of the effects of episodic acidification, regional climate models predict that temperatures will increase in Sweden during the coming decades, accompanied by reductions in summer precipitation and more frequent storms during fall and winter in large areas of the country. If these predictions are realized delays in streams' recovery from episodic acidification events can be expected.

show abstract

Long‐term (18‐year) changes in sulphate concentrations in two Ontario headwater lakes and their inflows in response to decreasing deposition and climate variations

Cited by 45 publications

References 47 publications

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe

Recovery from episodic acidification delayed by drought and high sea salt deposition

Contact Info

Product

Resources

About