World's Largest Lake Research Articles

Satellite data is revealing long time changes in the world largest lakes

Lakes are a crucial source of drinking water, provide ecological services from fisheries and aquaculture to tourism and are also a critical part of the global carbon cycle. Therefore, it is important to understand how lakes are changing over time. The ESA Ocean Colour Climate Change Initiative (OC-CCI) database allows to study changes in the largest lakes over 1997–2023 period. The Caspian Sea and ten next largest lakes were under investigation. Changes in the phytoplankton biomass (Chl-a), the concentration of particulate matter (bbp(555)), the colored dissolved organic matter, CDOM (adg(412)), and the light diffuse attenuation coefficient in water (Kd(490)) were analyzed. Both increasing and decreasing trends (or no significant trend at all) of studied parameters were observed in these lakes over the study period. In some of the Laurentian Great Lakes the changes in CDOM over the study period were found to be in accordance with the lake water level changes i.e. with the inflow from the catchment. There was difference between the trends of Chl-a and bbp(555) in lakes Michigan and Huron indicating that there may have been shift in phytoplankton community that took place around 2005. The study demonstrated that remote sensing products, like the ones created by ESA OC-CCI, are valuable tools to study behavior of large lakes ecosystems over time.

ATTRIBUTION ANALYSIS OF CLIMATE CHANGE AND HUMAN ACTIVITIES TO WATER VOLUME VARIATION IN LARGE LAKES

Abstract. Lakes are important components of the Earth's surface water bodies, and their fluctuating water levels and changing water volumes can have an important impact on ecological processes and landscape patterns within a watershed. Climate change and human activities are the main drivers of water volume changes in lakes. We applied a long time series analysis approach using classical statistics and geographic information system (GIS) technics to quantitatively attribute water volume variations in Lake Victoria from 2000 to 2019. We examined several drivers of lake water volume variations: meteorological factors including regional climate change (precipitation, evaporation) and global climate change (El Niño/Southern Oscillation events), and anthropogenic factors including socio-economic development and land use/cover change. The results show that regional climate change has a greater impact on lake water volume variations than global climate change; among them, the correlation coefficient between precipitation and lake water volume variations is the largest (0.410), with an impact lag of 1 month. For anthropogenic factors, variations in lake water volume are more pronounced in areas with rapid economic development and high population growth, with correlation coefficients greater than 0.440. Different types of land use/cover have varying impacts on Lake Victoria's water volume variations. Overall, the influence of anthropogenic factors is greater than that of meteorological factors. This study results not only provides a scientific basis for exploring the hydrological changes and their drivers in the world's large transboundary lakes, but also be great scientific significance to rational use of water resources and sustainable regional development.

Enhancement of flocculation processes of metals during estuarine mixing by electrodes

Millions of tons of heavy metals enter the ocean through estuaries each year. Estuaries can serve as the interconnection between the sea and the river, preventing the transfer of tons of heavy metals from the river to the sea. These heavy metals are flocculated during the estuarine process, but flocculation process enhancement in estuaries has received limited attention. This study examined the flocculation of dissolved heavy metals in mixtures of freshwater and seawater with varying salinities (0.7 ‰ to 2.49 ‰). The research objectives were first to examine the natural flocculation rate in one of the heavy metals contaminated sites, Namak-abrud River, in the world's largest lake, and then to compare electro-flocculation with self-purification of estuaries using aluminum and graphite electrodes. This multilateral strategy elucidates the practical enhancement of the natural flocculation process in greater detail. The mean removal efficiency of mixtures subjected to natural flocculation at various salinities is as follows: Fe (54.67 %) > Mn (47.82 %). The results indicated that salinity and the mean removal of metals were positively correlated. The most efficient removal of these metals, excluding Cd and Co, generally occurred between 1 and 2 %. Using aluminum electrodes has a negative impact on metal removal rates in comparison to natural flocculation. In contrast, the efficiency of a graphite electrode used for the first time is distinct. Graphite electrodes increased the Co, Cr, and V elimination rates compared to natural flocculation. By eliminating 36 % of metals, nature once again demonstrates its ecological role in estuaries' self-purification.

Satellite-Based Monitoring of Eutrophication in the Earth's Largest Transboundary Lake.

The world's large lakes and their life-supporting services are rapidly threatened by eutrophication in the warming climate during the Anthropocene. Here, MODIS-Aqua level 3 chlorophyll-a data (2018-2021) were used to monitor trophic state in our planet's largest lake, that is, the Caspian Sea that accounts for approximately 40% of the total lacustrine waters on Earth. We also used the in situ measurements of chlorophyll-a data (2009-2019) to further verify the accuracy of the data derived from the MODIS-Aqua and to explore the deep chlorophyll-a maxima (DCMs) in the south Caspian Sea. Our findings show an acceptable agreement between the chlorophyll-a data derived from the MODIS-Aqua and those measured in situ in the coast of Iran (coefficient of determination=0.71). The oligotrophic, mesotrophic, and eutrophic states cover 66%, 20%, and 13% of the sea surface area, respectively. The DCMs are dominantly regulated by water transparency and they generally observe at depths of less than 20 and 30m during the cold (autumn and winter) and warm (spring and summer) seasons, respectively. Our results suggest an ever-increasing chlorophyll-a in the shallow zones (i.e., coasts) and even in deep regions of the sea, mainly due to nutrient inputs from the Volga river delta. Alarming increase of chlorophyll-a in this transboundary lake can amplify eutrophication under the lens of global warming and further threaten the lake ecosystem's health, where almost all legal agreements have not yet been implemented to protect the lake environment and its rich resources.

Diversification along a benthic to pelagic gradient contributes to fish diversity in the world's largest lake (Lake Baikal, Russia).

Insights into the generation of diversity in both plants and animals have relied heavily on studying speciation in adaptive radiations. Russia's Lake Baikal has facilitated a putative adaptive radiation of cottid fishes (sculpins), some of which are highly specialized to inhabit novel niches created by the lake's unique geology and ecology. Here, we test evolutionary relationships and novel morphological adaptation in a piece of this radiation: the Baikal cottid genus, Cottocomephorus, a morphologically derived benthopelagic genus of three described species. We used a combination of mitochondrial DNA and restriction site associated DNA sequencing from all Cottocomephorus species. Analysis of mitochondrial cytochrome b haplotypes was only able to two resolve two lineages: C.grewingkii and C.comephoroides/inermis. Phylogenetic inference, principal component analysis, and faststructure of genome-wide SNPs uncovered three lineages within Cottocomephorus: C.comephoroides, C.inermis and C.grewingkii. We found recent divergence and admixture between C.comephoroides and C.inermis and deep divergence between these two species and C.grewingkii. Contrasting other fish radiations, we found no evidence of ancient hybridization among Cottocomephorus species. Digital morphology revealed highly derived pelagic phenotypes that reflect divergence by specialization to the benthopelagic niche in Cottocomephorus. Among Cottocomephorus species, we found evidence of ongoing adaptation to the pelagic zone. This pattern highlights the importance of speciation along a benthic-pelagic gradient seen in Cottocomephorus and across other adaptive fish radiations.

Seasonal and Spatial Variability of Dissolved Carbon Concentration and Composition in Lake Michigan Tributaries

AbstractDissolved organic matter (DOM) is a complex mixture of many compounds and its composition dictates numerous reactions in the environment. Large lakes and marine coastlines receive DOM from watersheds that differ widely in their land cover, with potential implications for both the quantity and composition of carbon inputs. Seasonal variation in DOM quantity and composition may also differ among tributaries and be mediated by land cover. Here, we quantify spatially (i.e., among tributary) and seasonal variation in DOM concentration, DOM composition based on ultraviolet‐visible spectroscopy, and alkalinity across 101 tributaries of Lake Michigan, one of the world's largest lakes, using a synoptic sampling approach. Wetland land cover has the largest effect on DOM, producing high concentrations of DOM that are more aromatic and larger in apparent molecular weight. Seasonal variation is also pronounced, with concentrations and aromaticity of DOM peaking in fall across most tributaries. Watershed lithology and land cover both affect alkalinity, with higher values associated with the geography of carbonate bedrock and urbanized watersheds. Watershed land cover has a larger effect than season on all organic carbon parameters. However, seasonal variation is especially important for DOM composition. This disparity suggests that the environmental processing of DOM within river channels mediates its composition more than its concentrations. Considering the wide range of land cover and lithology around Lake Michigan and other large water bodies, accounting for both spatial and seasonal dynamics is essential for understanding controls on DOM delivery.

Paleogeography of the Atelian regression in the Caspian Sea (based on drilling data)

The Caspian Sea is the world's largest lake noted for a unique history of its evolution in the past. One of most important events in the Caspian history is the Atelian regression. The purpose of this work is to specify the extent, the time, and environments of the Atelian regression, as well as its correlation with events in the adjacent regions, on the basis of multidisciplinary studies of the Atelian deposits penetrated by engineering boreholes in the Northern Caspian. Processing of two-frequency seismoacoustic profiles permitted to stratify the sequence and to perform a spatial correlation between the determined boundaries of the sedimentary series. The laboratory studies included lithological and geotechnical analysis of the cores, floristic and faunal studies of the organic remains extracted from the cores, as well as analyses of pollen and spores, the isotope and radiocarbon (14C) analysis. In the seismic-acoustic profiles Atelian regression is represented by erosional landforms (incisions) under the reflecting horizon at the base of Khvalynian sediments. The regressive series is noted for inhomogeneous lithology. In depressions they are represented by interlayered clays and clay loams. The elevations between the depressions are composed of loamy sands in association with loams. Plant detritus occur as separate inclusions, or forms layered concentrations; there are also shells of freshwater and terrestrial mollusks. The paleontological material suggests aquatic or wetland environments with freshwater or freshened brackish-water shallow water bodies. The palynological materials provide evidence of diversified landscapes in the northern Caspian Lowland at the time of the Atelian regression – from forests dominated by conifers to periglacial forest-steppe and tundra-forest-steppe, mostly resulting from the climate fluctuations. The redeposited pollen is present in abundance, often well-preserved, indicative of highly active erosion at the time of regression. The Atelian regression maximum and the erosional processes on the northern Caspian Lowland correspond to the maximum cooling of the Kalinin (MIS 4) glacial time. The final stages of the regression fell on the initial phases of the MIS 3 interstadial. As follows from materials obtained by seismic-acoustic profiling and drilling, the Caspian level dropped to −100 m. We attribute the sea level lowering to the Caspian (Hyrcanian) water discharge through the Manych into the Pontian basin and to the specific glacial environment during the Valday (MIS 4) time. The Atelian regression maximum is correlatable with the maximum of the post-Karangatian regression of the Black Sea. It was at the same time that the lacustrine Burtass (Gudilo) series were deposited in the Manych depression. In the stratigraphic scheme of the Caspian Sea the Atelian regressive horizon (as a stratigraphic unit) is positioned between Hyrcanian and the base of Lower Khvalynian deposits. In the Northern Caspian the continental Atelian formation spans a greater chronological interval and should be considered as a suite (or formation) in the regional stratigraphic scheme. A comparison between the position of Atelian deposits in the Pleistocene sequence within the sea basin and on the dry land supports the assumption that the geological records exposed in the coastal zone are incomplete. Only a thorough analysis of the materials obtained from the offshore drilling and from the sequences studied in exposures on land can give a comprehensive picture of the history of regional environments and present them correctly in a stratigraphic scheme.

The Holocene salinity history of Lake Lop Nur (Tarim Basin, NW China) inferred from ostracods, foraminifera, ooids and stable isotope data

Abstract Terminal lakes without outlet respond directly to climate change and human impact, and provide important evidence for environmental conditions prior to times of instrumental monitoring. Lop Nur in northwestern China is a terminal lake which was still one of the world's largest lakes in historical times. Sediments from the excavated section YKD0301 in its presently dry basin were investigated to reconstruct the Holocene salinity history of the lake. Ostracod shells of Cyprideis torosa and Eucypris mareotica, tests of the foraminifer Ammonia tepida, and fruits of Ruppia maritima are abundant in the early Holocene part of the section. Two stratigraphic units in the middle Holocene part of the section contain ostracod shells typical of fresh to mesohaline waters such as Limnocythere inopinata, Cypridopsis vidua, Ilyocypris sp. and Darwinula stevensoni. Three units do not contain fossils or only few remains regarded as allochthonous. Ooids are abundant in the upper half of the section, and are here reported for the sediments of Lop Nur or sub-recent sediments from China for the first time. Ooids from YKD0301 are aragonitic and either subspherical around a detrital nucleus, or elongate and probably formed around fecal pellets of brine shrimps. The recorded fossils from Lop Nur indicate that lake waters were poly- to hyperhaline (20–100‰) at ca. 9.0 ka, oligo- to mesohaline (0.5–18‰) between ca. 8.7–7.5 ka and probably mesohaline (5–18‰) from 6.0–5.0 ka. In the intervening periods and after 5.0 ka, Lop Nur was a hyperhaline (>100‰) lake. The period of freshest conditions of Lop Nur (ca. 8.7–7.5 ka) coincides with wettest Holocene conditions reconstructed from other lake records in the region although a uniform temporal pattern of wettest Holocene climate conditions in NW China and adjacent regions cannot be inferred.

Phosphorus Loadings to the World's Largest Lakes: Sources and Trends

AbstractEutrophication is a major water quality issue in lakes worldwide and is principally caused by the loadings of phosphorus from catchment areas. It follows that to develop strategies to mitigate eutrophication, we must have a good understanding of the amount, sources, and trends of phosphorus pollution. This paper provides the first consistent and harmonious estimates of current phosphorus loadings to the world's largest 100 lakes, along with the sources of these loadings and their trends. These estimates provide a perspective on the extent of lake eutrophication worldwide, as well as potential input to the evaluation and management of eutrophication in these lakes. We take a modeling approach and apply the WorldQual model for these estimates. The advantage of this approach is that it allows us to fill in large gaps in observational data. From the analysis, we find that about 66 of the 100 lakes are located in developing countries and their catchments have a much larger average phosphorus yield than the lake catchments in developed countries (11.1 versus 0.7 kg TP km−2 year−1). Second, the main source of phosphorus to the examined lakes is inorganic fertilizer (47% of total). Third, between 2005–2010 and 1990–1994, phosphorus pollution increased at 50 out of 100 lakes. Sixty percent of lakes with increasing pollution are in developing countries. P pollution changed primarily due to changing P fertilizer use. In conclusion, we show that the risk of P‐stimulated eutrophication is higher in developing countries.

Past and present mercury accumulation in the Lake Baikal seal: Temporal trends, effects of life history, and toxicological implications.

Despite global efforts to reduce anthropogenic mercury (Hg) emissions, the timescale and degree to which Hg concentrations in the environment and biota respond to decreased emissions remain challenging to assess or predict. In the present study we characterize long-term trends and life-history patterns in Hg accumulation and toxicological implications of Hg contamination for a freshwater seal from one of the world's largest lakes (Lake Baikal, Siberia, Russia) using contemporary tissues and archival teeth. Stable isotope analysis and Hg analyses of soft tissues (muscle, liver, kidney, blood, brain, heart) and teeth from 22 contemporary seals revealed rapid changes in diet and Hg accumulation in the first year of life with a stable diet and increase in tissue Hg throughout the rest of life. Although maternal transfer of Hg was an important source of Hg to seal pups, reproduction and lactation by female seals did not appear to result in sex-related differences in Hg concentrations or age-related accumulation in adult seals. Based on Hg analysis of archival teeth (n = 114) and reconstructed values for soft tissues, we also assessed temporal trends in seal Hg between the years 1960 and 2013. Seal Hg concentrations in hard (teeth) and soft (e.g., muscle, liver) tissues were highest in the 1960s and 1970s, followed by a decrease. The decline in seal Hg concentrations in recent decades was most likely driven by a reduction in Hg inputs to the lake, suggesting that global and regional efforts to reduce Hg emissions have been successful at reducing ecosystem and human health risks posed by Hg in Lake Baikal. Environ Toxicol Chem 2018;37:1476-1486. © 2018 SETAC.

Decline of the world's saline lakes

Many of the world's saline lakes have been shrinking due to consumptive water use. The Great Salt Lake, USA, provides an example for how the health of and ecosystem services provided by saline lakes can be sustained. Many of the world's saline lakes are shrinking at alarming rates, reducing waterbird habitat and economic benefits while threatening human health. Saline lakes are long-term basin-wide integrators of climatic conditions that shrink and grow with natural climatic variation. In contrast, water withdrawals for human use exert a sustained reduction in lake inflows and levels. Quantifying the relative contributions of natural variability and human impacts to lake inflows is needed to preserve these lakes. With a credible water balance, causes of lake decline from water diversions or climate variability can be identified and the inflow needed to maintain lake health can be defined. Without a water balance, natural variability can be an excuse for inaction. Here we describe the decline of several of the world's large saline lakes and use a water balance for Great Salt Lake (USA) to demonstrate that consumptive water use rather than long-term climate change has greatly reduced its size. The inflow needed to maintain bird habitat, support lake-related industries and prevent dust storms that threaten human health and agriculture can be identified and provides the information to evaluate the difficult tradeoffs between direct benefits of consumptive water use and ecosystem services provided by saline lakes.

Long-Term and Ontogenetic Patterns of Heavy Metal Contamination in Lake Baikal Seals (Pusa sibirica).

Little is known about the history of heavy metal pollution of Russia's Lake Baikal, one of the world's largest lakes and a home to numerous endemic species, including the Baikal Seal, Pusa sibirica. We investigated the history of heavy metal (V, Cu, Zn, Cd, Hg, Tl, Pb, U) pollution in Lake Baikal seals over the past 8 decades. C and N stable isotope analysis (SIA) and laser-ablation ICP-MS of seal teeth were used to examine changes in feeding ecology, heavy metal levels associated with life history events and long-term variation in metal exposure. SIA did not suggest large changes in the feeding ecology of Baikal seals over the past 80 years. LA-ICP-MS analyses revealed element-specific ontogenetic variability in metal concentrations, likely related to maternal transfer, changes in food sources and starvation. Hg and Cd levels in seals varied significantly across the time series, with concentrations peaking in the 1960s - 1970s but then declining to contemporary levels similar to those observed in the 1930s and 1940s. Trends in atmospheric emissions of Hg suggest that local sources as well as emissions from eastern Russia and Europe may be important contributors of Hg to Lake Baikal and that, despite the size of Lake Baikal, its food web appears to respond rapidly to changing inputs of contaminants.

Institute Profile: The Large Lakes Observatory and the Scientific Study of the Large Lakes of Earth

Institute Profile: The Large Lakes Observatory and the Scientific Study of the Large Lakes of Earth

Predicting a Great Lake's Response to a Warm Winter

The Superior Challenge Summit: Forecasting El Niño's Impact on the World's Largest Lake; Ann Arbor, Michigan, 17–19 May 2016

Monitoring: safeguarding the world's largest lake.

Monitoring: safeguarding the world's largest lake.

Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

The transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9-15° S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world's largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ∼800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species.

National getaways for the weary trauma surgeon; part 2: the northern provinces.

National getaways for the weary trauma surgeon; part 2: the northern provinces.

Diversity of Lake Ladoga (Russia) bacterial plankton inferred from 16S rRNA gene pyrosequencing: An emphasis on picocyanobacteria

We report the first insight, using 454 pyrosequencing, into the diversity of bacterial plankton from Lake Lagoda (Russia), one of the world's largest lakes and the largest European lake. The majority of 16S rRNA sequences recovered from the lake epilimnion belonged to the phyla Proteobacteria, Actinobacteria, Bacteroidetes, Verrucomicrobia and Cyanobacteria. Proteobacterial pyrotags were mainly from the classes Betaproteobacteria and Alphaproteobacteria. These data, supplemented with clone assignment to the freshwater bacterial clades, demonstrate that the diversity of Lake Ladoga bacterial plankton is similar to other large freshwater lakes. At the same time, the cyanobacterial sequence abundance was low, with 2.5% of the universal primer-based amplicons derived from DNA templates sampled at three hydrographic stations. Similar to the communities in other large lakes, 85% of group-specific primer based sequences corresponded to Synechococcus. Most of the abundant (n>5 per library) Synechococcus sequences comprising operational taxonomic units (OTUs) I − XVIII belonged to the widely distributed clusters MH305 and LB03 (47% and 12.6% of sequences, respectively). OTUs I–IV (19%) comprised a putative assemblage termed Group LL. A small proportion of Synechococcus sequences (~4%), with n≤5 per library, belonged to low-abundance OTUs 1′42′. Five phycoerythrin-lacking Synechococcus strains were cultured; four of them clustered with Synechococcus Group A, whereas the fifth strain which did not match any pyrotag clustered with Synechococcus Group I. Group LL representatives were not cultured successfully. In conclusion, Lake Ladoga bacterial plankton shares common features with that in other (large) lakes and has obtained some specificity probably under low temperature selection.

Late Pleistocene and Holocene palaeoenvironments in and around the middle Caspian basin as reconstructed from a deep-sea core

Late Pleistocene and/or Holocene high-resolution palynological studies are available for the south basin of the Caspian Sea (CS), the world's largest lake. However, the north and middle basins have not been the object of high-resolution palynological reconstructions. This new study presents the pollen, spores and dinoflagellate cysts records obtained from a 10 m-long sediment core recovered in the middle basin, which currently has brackish waters and is surrounded by arid and semi-arid vegetation.An age–depth model built based on six radiocarbon dates on ostracod shells indicates that the sequence spans the period from 14.47 to 2.43 cal. ka BP. The present palaeoenvironmental study focuses on the top 666 cm, or from 12.44 to 2.43 cal. ka BP.At the vegetation level, the Younger Dryas is characterised by an open landscape dominated by desert vegetation composed by Amaranthaceae with shrubs and salt-tolerant plants. However, although the Early Holocene is also characterised by desert vegetation, it is enriched in various shrubs such as Ephedra and Calligonum, but tree expansion is not important at the Holocene onset. After a major shift at 8.19 cal. ka BP, the Middle Holocene displays now both the character of desert and of steppe, although some trees such as Quercus and Corylus slightly spread. The Late Holocene records steppe vegetation as dominant, with more tree diversity.Regarding the lacustrine signal, the dinocyst assemblage record fluctuates between slightly brackish conditions highlighted by Pyxidinopsis psilata and Spiniferites cruciformis, and more brackish ones – similar to the present day – with the dominance of Impagidinium caspienense. The Late Pleistocene is characterised by low salinities, related to the Khvalynian highstand. From 11.56 cal. ka BP, slightly more saline waters are reconstructed with an increase of I. caspienense for a period of 1000 years, which could be attributed to the Mangyshlak lowstand. From 10.55 cal. ka BP, low salinity conditions return with remains such as Anabaena and Botryococcus abundant until 8.83 cal. ka BP, followed by a slow, progressive decrease of P. psilata and S. cruciformis until 4.11 cal. ka BP, which is the main assemblage change at lacustrine scale. Since then, higher salinities, similar to the present one, are reconstructed. Finally, Lingulodinium machaerophorum starts its development only at 2.75 cal. ka BP, in the Late Holocene.The present research revealed fundamental differences from previously published sea-level curves, in that a 6000 yr-long highstand suggested by low salinities is shown between 10.55 and 4.11 cal. ka BP. Amongst other arguments, using a comparison to a similar palynological regard but in the south basin, a N–S salinity gradient that is the reverse of the present one across the CS, suggests that the Amu Darya was flowing in the CS. Hence the CS levels during the Late Pleistocene and Holocene were influenced by a combination of precipitation over the high European latitudes and the indirect influence of the Indian summer monsoon over the Pamirs.

Water quality trading in the Lake Winnipeg Basin: A multilevel architecture

Excess nutrients or eutrophication are degrading freshwater bodies worldwide which is undermining human wellbeing. Some of the world's large lakes, such as Lake Victoria, Lake Tai and Lake Winnipeg, have become eutrophic due to excess nutrients from point and non-point sources. Novel approaches that can prevent excess nutrients from over fertilizing surface water bodies are required. Water quality trading (WQT) is a market mechanism that could cost-effectively provide a means to remediate eutrophication by reducing nutrient loads from point and non-point sources. This paper provides WQT design considerations to remediate water quality within large multi-jurisdictional basins by examining Lake Winnipeg which has become the most eutrophied large lake in the world due to excessive phosphorus loads. The multilevel architecture proposed is designed to simultaneously remediate water quality and encourage integrated water resource management. Inter-sub-basin trading allows for meeting a phosphorus load target for the lake while intra-sub-basin trading allows for meeting phosphorus load targets at the sub-basin outflows. The paper also provides regulatory frameworks (Boundary Waters Treaty, United States Clean Water Act, the Canadian Environmental Protection and the Canada Water Acts) and institutional support (International Joint Commission, United States Environmental Protection Agency and Environment Canada) required to manage an international WQT system within the Lake Winnipeg Basin. To reduce transaction costs a composite market with clearing house and exchange characteristics is likely best suited. By providing design considerations in the form of a multilevel WQT system, this paper makes a contribution towards WQT research within large multi-jurisdictional basins.