A 1000-yr record of environmental change in NE China indicated by diatom assemblages from maar lake Erlongwan

AbstractPast environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic species Discostella species occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, including Puncticulata praetermissa and Asterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.

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Global Climate Change, Sustainability, and Some Challenges for Grape and Wine Production

Journal of Wine Economics ◽

10.1017/jwe.2015.31 ◽

2016 ◽

Vol 11 (1) ◽

pp. 181-200 ◽

Cited By ~ 32

Author(s):

Hans R. Schultz

Keyword(s):

Environmental Changes ◽

Global Climate ◽

Regional Climate ◽

Environmental Constraints ◽

Type Number ◽

Wine Production ◽

The Past ◽

Depth Analysis ◽

Sustainable Product ◽

Grape Varieties

AbstractGrapevines are cultivated on six out of seven continents, between latitudes 4° and 51° in the Northern Hemisphere and between latitudes 6° and 45° in the Southern Hemisphere across a large diversity of climates (oceanic, warm oceanic, transition temperate, continental, cold continental, Mediterranean, subtropical, attenuated tropical, and arid climates). Accordingly, the range and magnitude of environmental factors differ considerably from region to region and so do the principal environmental constraints for grape production. The type, number, and magnitude of environmental constraints are currently undergoing changes due to shifts in climate patterns already observed for the past and predicted for the future. These changes are already affecting grape composition with observed changes in sugar and acidity concentrations. As with other components such as polyphenols or aroma compounds, their relationships to environmental changes are more difficult to quantify. In general, one can divide the expected climatic changes during the grape-ripening period into two scenarios: warmer and dryer and warmer and moister, with different responses for red and white grape varieties. The production challenges within this broad separation are vastly different, and the strategies to ensure a sustainable product need to be adapted accordingly. The economic impact of these changes is difficult to assess. An in-depth analysis is necessary to construct relevant scenarios and risk analysis for individual regions and to quantify the costs and/or benefits of regional climate developments. (JEL Classifications: Q1, Q54)

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Holocene Relative Sea Level Changes along the Seattle Fault at Restoration Point, Washington

Quaternary Research ◽

10.1006/qres.2000.2180 ◽

2000 ◽

Vol 54 (3) ◽

pp. 384-393 ◽

Cited By ~ 31

Author(s):

Brian L. Sherrod ◽

Robert C. Bucknam ◽

Estella B. Leopold

Keyword(s):

Sea Level ◽

Environmental Changes ◽

Hanging Wall ◽

Sea Level Changes ◽

Diatom Assemblages ◽

Recent Event ◽

Plant Seed ◽

The Past ◽

The One ◽

Fossil Diatoms

At a marsh on the hanging wall of the Seattle fault, fossil brackish water diatom and plant seed assemblages show that the marsh lay near sea level between ∼7500 and 1000 cal yr B.P. This marsh is uniquely situated for recording environmental changes associated with past earthquakes on the Seattle fault. Since 7500 cal yr B.P., changes in fossil diatoms and seeds record several rapid environmental changes. In the earliest of these, brackish conditions changed to freshwater ∼6900 cal yr B.P., possibly because of coseismic uplift or beach berm accretion. If coseismic uplift produced the freshening ∼6900 cal yr B.P., that uplift probably did not exceed 2 m. During another event about 1700 cal yr B.P., brackish plant and diatom assemblages changed rapidly to a tidal flat assemblage because of either tectonic subsidence or berm erosion. The site then remained a tideflat until the most recent event, when an abrupt shift from tideflat diatoms to freshwater taxa resulted from ∼7 m of uplift during an earthquake on the Seattle fault ∼1000 cal yr B.P. Regardless of the earlier events, no Seattle fault earthquake similar to the one ∼1000 cal yr B.P. occurred at any other time in the past 7500 years.

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Holocene diatom assemblages from Dunderbukhta sediments, West Svalbard

Issues of modern algology (Вопросы современной альгологии) ◽

10.33624/2311-0147-2019-2(20)-242-245 ◽

2019 ◽

pp. 242-245

Author(s):

Ksenya V. Poleshchuk ◽

Zinaida V. Pushina ◽

Sergey R. Verkulich

Keyword(s):

Environmental Changes ◽

Ecological Groups ◽

Diatom Assemblages ◽

Diatom Analysis ◽

Diatom Flora ◽

Sediment Samples ◽

Ecological Zones ◽

Middle Holocene ◽

Temperature Trends

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.

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An Assessment of Environmental Changes in Three Lakes from King's County (Nova Scotia, Canada) Using Diatom-Based Paleolimnological Techniques

Water Quality Research Journal ◽

10.2166/wqrj.2008.012 ◽

2008 ◽

Vol 43 (2-3) ◽

pp. 85-98 ◽

Cited By ~ 10

Author(s):

Joshua R. Thienpont ◽

Brian K. Ginn ◽

Brian F. Cumming ◽

John P. Smol

Keyword(s):

Nova Scotia ◽

Environmental Changes ◽

Sediment Cores ◽

Lake Management ◽

River System ◽

210Pb Dating ◽

Hydroelectric Power ◽

Diatom Assemblages ◽

Shoreline Development ◽

Before And After

Abstract Paleolimnological approaches using sedimentary diatom assemblages were used to assess water quality changes over the last approximately 200 years in three lakes from King's County, Nova Scotia. In particular, the role of recent shoreline development in accelerating eutrophication in these systems was assessed. Sediment cores collected from each lake were analyzed for their diatom assemblages at approximately 5-year intervals, as determined by 210Pb dating. Analyses showed that each system has changed, but tracked different ecosystem changes. Tupper and George lakes recorded shifts, which are likely primarily related to climatic warming, with diatom assemblages changing from a preindustrial dominance by Aulacoseira spp. to present-day dominance by Cyclotella stelligera. In addition to the recent climatic-related changes, further diatom changes in the Tupper Lake core between approximately 1820 and 1970 were coincident with watershed disturbances (farming, forestry, and construction of hydroelectric power infrastructure). Black River Lake has recorded an increase in diatom-inferred total phosphorus since about 1950, likely due to impoundment of the Black River system for hydroelectric generation and subsequent changes in land runoff. Before-and-after (i.e., top-bottom) sediment analyses of six other lakes from King's County provided further evidence that the region is being influenced by climatic change (decreases in Aulacoseira spp., increases in planktonic diatom taxa), as well as showing other environmental stressors (e.g., acidification). However, we recorded no marked increase in diatom-inferred nutrient levels coincident with shoreline cottage development in any of the nine study lakes. Paleolimnological studies such as these allow lake managers to place the current limnological conditions into a long-term context, and thereby provide important background data for effective lake management.

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HOLOCENE REGIONAL CLIMATE INFERRED FROM DIATOM ASSEMBLAGES OF YELLOWSTONE LAKE

10.1130/abs/2018nc-312845 ◽

2018 ◽

Author(s):

Sabrina R. Brown ◽

◽

Sherilyn C. Fritz

Keyword(s):

Regional Climate ◽

Diatom Assemblages ◽

Yellowstone Lake

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Late-Holocene diatom community response to climate driven chemical changes in a small, subarctic lake, Northwest Territories, Canada

The Holocene ◽

10.1177/09596836211003214 ◽

2021 ◽

pp. 095968362110032

Author(s):

Paul B Hamilton ◽

Scott J Hutchinson ◽

R Timothy Patterson ◽

Jennifer M Galloway ◽

Nawaf A Nasser ◽

...

Keyword(s):

Iron Age ◽

Biological Diversity ◽

Regional Climate ◽

Natural Aging ◽

Community Response ◽

Warm Period ◽

Ice Age ◽

Diatom Assemblages ◽

Subarctic Lake ◽

Over Time

The paleolimnological record of diatoms and climate, spanning the last 2800 years, was investigated in a small subarctic lake (Pocket Lake) that from AD 1948 to 2004 was contaminated by gold smelting waste. An age-depth model was constructed using a combination of 210Pb, 14C, and tephra to determine a 2800 year history of lake ontogeny (natural aging), biological diversity, and regional climate variability. Diatoms form six strong paleoecological assemblages over time in response to changes in local hydrological and sedimentological conditions (including metals). Selected environmental variables explained 28.8% of the variance in the diatom assemblages, with Fe, Ca, and sediment end member distribution being important indicators. The diatom assemblages correlated to the Iron Age Cold Epoch (2800–2300 cal BP), Roman Warm Period (2250–1610 cal BP), Dark Age Cold Period (1500–1050 cal BP), Medieval Climate Anomaly (ca. 1100–800 cal BP), and the Little Ice Age (800–200 cal BP). The disappearance of Staurosira venter highlights the change from the Iron Age Cold Epoch to the Roman Warm Period. After deposition of the White River Ash (833–850 CE; 1117–1100 cal BP), transition to circumneutral conditions was followed in tandem by a transition to planktic influenced communities. Ten discrete peaks of Cu, Pb, and Zn were observed and attributed to soluble mobility from catchment soils through enhanced seepage and spring snowmelt. The prominent metal spikes were aligned with increases in Brachysira neoexilis. Downward mobilization of arsenic and antimony from contaminated surficial sediments highlight the problem of post depositional industrial contamination of paleosediments. Results demonstrate that paleoclimatic changes in the region, modulated by solar radiation, impacted temperature and precipitation in the lake catchment, influencing temporal shifts in diatom ecology. Changes in diatom taxa richness provided valuable information on the relative influence of water quality (planktic taxa) and sediment input (benthic taxa). The diatom assemblage succession also provides evidence that natural aging over time has played a role in the ecological evolution of the lake.

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