acid rain: rain or any other form of precipitation that is unusually acidic (i.e. below pH 5.7) and often has negative ecological impacts.
algal bloom: a loose term referring to a rapid increase in the algal density of an aquatic system.
alpha dating: chronological dating techniques based on the measurement of alpha particles (i.e. helium nuclei) emitted from a radioisotope.
Ambrosia: a genus of flowering plants within the Asteraceae family commonly referred to as “ragweed”. In eastern North America, an Ambrosia rise in the pollen record can be used as an indicator for the time of European settlement.
bioindicator: species or communities that are so closely associated with particular environmental conditions that their presence can be used to infer the presence of those conditions.
brominated flame retardants: a group of organobromine compounds commonly used to reduce the flammability of consumer products. Long-term changes in their concentrations within lake sediments can be used as a chemical paleoindicator.
C2: a Microsoft Windows program for the analysis and visualisation of ecological and palaeoenvironmental data (the most recent release can be found here).
calibration set: also known as a training set is a set of surface sediment samples used to identify the optima and tolerances to environmental conditions of a particular indicator group, often used to develop a transfer function.
Canoco: a Microsoft Windows program for multivariate statistical analysis using ordination methods (the most recent release can be found here).
carbon-14 (14C): also known as radiocarbon is a naturally occurring radioisotope of carbon that has a half-life of ~5700 years. Used in paleolimnology to date biological materials that are less than ~50, 000 years old.
cesium-137 (137Cs): a radioisotope with a half-life of ~30 years that is associated with the fallout from nuclear weapons testing.
Chaoborus: a genus of small flies commonly referred to as “phantom midges”. The chitinized mandibles of Chaoborus‘ aquatic larval stages preserve well in sediments and are used in paleolimnology as a bioindicator of historical fish populations and/or deepwater oxygen conditions.
charcoal: a lightweight black carbon residue usually produced through the heating of wood or other organic materials in the absence of oxygen. Charcoal is used in paleolimnology as an indicator of regional fire history.
chironomids: members of the Chironomidae, a family of flies with aquatic larval stages whose chitinized remains preserve well in lake sediments. Chironomids are used in paleolimnology as a bioindicator for several environmental variables including deepwater oxygen conditions.
chronology: the science of locating events in time. In paleolimnology a chronology typically refers to the age-depth relationship of the sediments over the time period represented by the sediment core. See dating.
chrysophytes: members of the Chrysophyceae a large group of algae found mostly in freshwater. The siliceous scales and cysts of some chrysophyte taxa are used as an indicator of pH and nutrient conditions.
citation: a reference to a published source in order to acknowledge the relevance of prior work to the topic of discussion.
climate change: the ongoing rise of the average temperature of the Earth, and the related changes to climate and weather patterns.
diatoms: members of the Bacillariophyceae, a class of algae with cell walls made of silica that preserve well in lake sediments. Diatoms are a commonly used bioindicator for a variety of environmental variables including pH and nutrient conditions.
environmental DNA (eDNA): DNA collected from environmental samples rather than directly from an individual organism. In paleolimnology, this typically refers to DNA isolated from sediment samples.
extrusion: the process of forcing a material through an opening. In paleolimnology, extruding typically refers to the sectioning of a continuous sediment core by pushing it out of a coring tube at discrete intervals.
high-performance liquid chromatography (HPLC): an analytical chemistry technique used to separate, identify, and quantify the components of a mixture.
Intergovernmental Panel on Climate Change (IPCC): the United Nations body for assessing the science related to climate change (more info can be found here).
internal loading: the release of phosphorus from lake sediments back into the water column under anoxic conditions.
International Paleolimnology Association (IPA): organization dedicated to the advancement of the science of paleolimnology and its applications, while also promoting the interests of paleolimnology globally (more info can be found here).
Journal of Paleolimnology (JOPL): academic journal dedicated to paleoenvironmental studies of river, wetland, peatland and estuary systems.(more info can be found here).
lead-210 (210Pb): a radioisotope with a half-life of ~22 years that occurs naturally as part of the uranium-238 decay series. Used in paleolimnology to date sediments that are less than ~150 years old.
loss-on-ignition (LOI): the weight loss of dried sediment after ~2h at ~550℃, used to estimate the amount of organic matter present in the sediment.
Ontario-Québec Paleolimnology Symposium (PALS): an annual student-run conference for the discussion of ongoing studies and research within paleolimnology.
optima: the most favourable value of an environmental condition for the growth and reproduction of an organism. Differences in optima withing indicator groups are used to build transfer functions.
ostracods: members of the Ostracoda, a class of small aquatic crustaceans with calcareous carapaces that can preserve in lake sediments. The stable isotope composition of ostracod remains can be used to infer information about paleoclimatic and paleohydrological conditions.
paleolimnology: the interdisciplinary science that reconstructs the paleoenvironments of inland waters.
persistent organic pollutants (POPs): are organic compounds that are resistant to environmental degradation. Due to their longevity, they can bioaccumulate with harmful ecological impacts.
pH: a (logarithmic) scale used to describe the acidity (or basicity) of an aqueous solution.
polychlorinated biphenyl (PCB): an organic chlorine compound once widely used as a dielectric and coolant fluid. PCBs are now classified as a POP and probable human carcinogen.
postdoctoral researcher (postdoc): an individual who continues to conduct research professionally after their doctoral studies.
R: a programming language and free software environment for statistical computing and graphics (the most recent release can be found here).
radioisotope: also known as a radionuclide is an atom that is unstable due to excess nuclear energy, that is released through radioactive decay. In paleolimnology, known half-lives of specific radioisotopes (e.g. carbon-14, cesium-137, lead-210) are often used to develop age-depth models for sediment cores.
rioja: an R package for the analysis of Quaternary science data. It contains functions for constrained clustering, transfer functions, and plotting stratigraphic data.
space for time
Tilia: a Microsoft Windows program designed for managing and graphing paleontological data and metadata, especially stratigraphic data. (the most recent release can be found here).
tolerance: the range of values of an environmental condition where an organism is able to grow and reproduce. Differences in tolerances within indicator groups are used to build transfer functions.
training set: see calibration set.
transfer function: an inference model to describe the relationship between an indicator group and an environmental variable. Used to infer past values of the environmental variable from indicator assemblages preserved in deeper sediments.
varve: an annual pattern (composed of two sub-layers, one coarse and one fine) that can form in lake sediments as particles deposited in the spring are coarser (due to greater flow strength) than those deposited later in the year. Varves are sometimes visible to the naked eye, and can be used to develop chronologies for sediment cores.
vegan: an R package for ordination methods, diversity analysis and other functions for community and vegetation ecologists.
visible reflectance spectroscopy (VRS): measurement of absorption or reflectance at wavelengths visible to the human eye (between 380 and 740nm). Paleolimnological applications of these techniques include using the absorbance peak between 650 and 700nm to infer chlorophyll a concentrations in sediments.
X-ray fluorescence (XRF): an analytical technique that uses emission of “secondary” (or fluorescent) X-rays from a material bombarded with high-energy X-rays or gamma rays to obtain elemental/chemical information.