Coupling between increased lake color and iron in boreal lakes

Xiao, Yihua; Riise, Gunnhild

doi:10.1016/j.scitotenv.2021.145104

Cited by 26 publications

(10 citation statements)

References 48 publications

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“…A detailed analysis of organic matter trends at the F1 catchment in our dataset (Evans and others in prep.) suggests that visible color may be rising faster than bulk DOC, implying an increased proportion of light-absorbing compounds, and the same finding has been reported for nearby lakes in south-east Norway (Xiao and Riise 2021), as well as more distant locations (for example, lakes in the Northeastern United States, Stetler and others 2021). Although we have no data on organic C composition across the wider dataset, the changes we see in organic C:TON stoichiometry are themselves indicative of fundamental shifts in the composition of organic matter (Wymore and others 2021; Rodrı ´guez-Cardona and others 2022), and so a steady-state in dissolved organic matter composition cannot be assumed.…”

Section: Effects Of Long-term Macronutrient Changessupporting

confidence: 71%

Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast

et al. 2022

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European ecosystems have been subject to extensive shifts in anthropogenic disturbance, primarily through atmospheric deposition, climate change, and land management. These changes have altered the macronutrient composition of aquatic systems, with widespread increases in organic carbon (C), and declines in nitrogen (N) and phosphorus (P). Less well known is how these disturbances have affected nutrient stoichiometry, which may be a more useful metric to evaluate the health of aquatic ecosystems than individual nutrient concentrations. The Swedish west coast has historically experienced moderate to high levels of atmospheric deposition of sulfate and N, and eutrophication. In addition, coastal waters have been darkening with damaging effects on marine flora and fauna. Here, we present three decades of macronutrient data from twenty lakes and watercourses along the Swedish west coast, extending from headwaters to river mouths, across a range of land covers, and with catchments ranging 0.037–40,000 km2. We find a high degree of consistency between these diverse sites, with widespread increasing trends in organic C, and declines in inorganic N and total P. These trends in individual macronutrients translate into large stoichiometric changes, with a doubling in C:P, and increases in C:N and N:P by 50% and 30%, showing that freshwaters are moving further away from the Redfield Ratio, and becoming even more C rich, and depleted in N and P. Although recovery from atmospheric deposition is linked to some of these changes, land cover also appears to have an effect; lakes buffer against C increases, and decreases in inorganic N have been greatest under arable land cover. Our analysis also detects coherently declining P concentrations in small forest lakes; so called (and unexplained) “oligotrophication.” Taken together, our findings show that freshwater macronutrient concentrations and stoichiometry have undergone substantial shifts during the last three decades, and these shifts can potentially explain some of the detrimental changes that adjacent coastal ecosystems are undergoing. Our findings are relevant for all European and North American waters that have experienced historically high levels of atmospheric deposition, and provide a starting point for understanding and mitigating against the trajectories of long-term change in aquatic systems.

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Section: Effects Of Long-term Macronutrient Changessupporting

confidence: 71%

Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast

et al. 2022

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“…Practically all Fe in these generally oxic surface waters is complexed to the DNOM. Typically, the HMW moieties of the DNOM have higher Fe content [44,45]. The role of log(Fe) as an explanatory factor for log(RR) and log(RRn) may thus reflect a covariation to the larger size of the DNOM, and thereby lower biodegradability, as reflected by sUVa (r = 0.3, Figure 6).…”

Section: Priming Effect Boosting the Respiration Ratementioning

confidence: 99%

Factors Governing Biodegradability of Dissolved Natural Organic Matter in Lake Water

Crapart

Andersen

Hessen

et al. 2021

Water

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Dissolved Natural Organic Matter (DNOM) is a heterogeneous mixture of partly degraded, oxidised and resynthesised organic compounds of terrestrial or aquatic origin. In the boreal biome, it plays a central role in element cycling and practically all biogeochemical processes governing the physico-chemistry of surface waters. Because it plays a central role in multiple aquatic processes, especially microbial respiration, an improved understanding of the biodegradability of the DNOM in surface water is needed. Here the current study, we used a relatively cheap and non-laborious analytical method to determine the biodegradability of DNOM, based on the rate and the time lapse at which it is decomposed. This was achieved by monitoring the rate of oxygen consumption during incubation with addition of nutrients. A synoptic method study, using a set of lake water samples from southeast Norway, showed that the maximum respiration rate (RR) and the normalised RR (respiration rate per unit of carbon) of the DNOM in the lakes varied significantly. This RR is conceived as a proxy for the biodegradability of the DNOM. The sUVa of the DNOM and the C:N ratio were the main predictors of the RR. This implies that the biodegradability of DNOM in these predominantly oligotrophic and dystrophic lake waters was mainly governed by their molecular size and aromaticity, in addition to its C:N ratio in the same manner as found for soil organic matter. The normalised RR (independently of the overall concentration of DOC) was predicted by the molecular weight and by the origin of the organic matter. The duration of the first phase of rapid biodegradation of the DNOM (BdgT) was found to be higher in lakes with a mixture of autochthonous and allochthonous DNOM, in addition to the amount of biodegradable DNOM.

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“…2a; Mortimer 1941, Davison 1993, Rysgaard et al 1994, Brothers et al 2014, Krueger et al 2020. Increases in these solutes in the water column can in turn decrease light transparency (Sterner et al 1997, Xiao andRiise 2021), stimulate the growth of algae and cyanobacteria (Elser et al 2007, Trommer et al 2020, Yuan et al 2021, and result in water column concentrations that exceed drinking water safety thresholds (for Fe and Mn; USEPA 2022). Moreover, declining oxygen levels restrict habitat suitability for aerobic organisms, especially fish and benthic macroinvertebrates (Dillon et al 2003, Jiang andPu 2009).…”

Section: Consequences Of Changing Oxygen Dynamics On Lake Ecosystem S...mentioning

confidence: 99%

Causes and consequences of changing oxygen availability in lakes

Carey

2023

Preprint

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Changing oxygen availability in lakes and reservoirs is a fundamental limnological challenge of our time, with massive consequences for freshwater ecosystem functioning and water quality. Cross-lake surveys, paleolimnological studies, and long-term monitoring records indicate that many lakes are exhibiting declines in both surface and bottom-water oxygen availability due to climate and land use change, though a few lakes are exhibiting increases in oxygen. By analyzing time series of oxygen monitoring data from ~400 lakes, I find that some lakes may be experiencing a decoupling of surface and bottom oxygen dynamics: variability in surface oxygen concentrations is decreasing in some lakes while variability in bottom oxygen concentrations is increasing. Changes in both oxygen concentrations and variability have many implications for lake functioning because oxygen concentrations control many ecosystem processes. Consequently, lake ecosystem provisioning and cultural services (e.g., drinking water, fisheries, recreation) will likely be impaired by declining oxygen, whereas the effects of changing oxygen on regulatory and supporting ecosystem services (e.g., nitrate removal through denitrification,

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Coupling between increased lake color and iron in boreal lakes

Cited by 26 publications

References 48 publications

Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast

Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast

Factors Governing Biodegradability of Dissolved Natural Organic Matter in Lake Water

Causes and consequences of changing oxygen availability in lakes

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