3/1/2023 0 Comments Secchi disk graphTransparency can serve as an early warning that activities on the land are having an effect on a lake. If transparency is measured through the season and from year to year, trends in transparency may be observed. Transparency is an indicator of the impact of human activity on the land surrounding the lake. Suspended sediments often come from sources such as resuspension from the lake bottom, construction sites, agricultural fields, and urban storm runoff. Clearer water is a sign of less algae and sediment in your lake. Transparency can therefore be affected by the amount of plant nutrients coming into the lake from sources such as sewage treatment plants, septic tanks, and lawn and agricultural fertilizer. A deep Secchi disk reading, represented by a longer bar on the graph below, means clearer water. Algae are small, green aquatic plants whose abundance is related to the amount of plant nutrients, especially phosphorus and nitrogen. In bogs and some lakes the brown stain can make the water the color of strong tea. Water is often stained yellow or brown by decaying plant matter. Transparency can be affected by the color of the water, algae, and suspended sediments. This depth of disappearance, called the Secchi depth, is a measure of the transparency of the water. It is lowered into the water of a lake until it can no longer be seen by the observer. ![]() Transparency decreases as color, suspended sediments, or algal abundance increases. A Secchi disk is an 8-inch (20 cm) disk with alternating black and white quadrants. Data are used for environmental status monitoring and assessment of eutrophication in the Baltic Sea and Gulf of Riga.A Secchi disk is an 8-inch (20 cm) disk with alternating black and white quadrants. Use the accompanying graph to relate depth to NTUs (nephelometric turbidity. Measurements were done onboard research or naval vessels or self-propelled boats during daylight hours. Objective: Learn how to use a Secchi disk to determine water turbidity. Includes attached sinker and rot-proof polymer line on a polymer foam bobbin. Constructed of robust white plastic disk with permanent screen printed black sectors. Graph 2, the Secchi depth increased in the post-invasion samples, and the phosphorus and. Measurements were performed by personnel from the Baltic Research Institute of Fishery of Latvia (BaltNIIRH) (1973 - 1989), Riga Hydrometeorological Centre of Latvia (1989 - 1995) and Latvian Institute of Aquatic Ecology (since 1995). Good quality and inexpensive Secchi Disk for water clarity measurements. resulted in increasing Secchi depth 10,8. ![]() Additional existing data from monitoring and public projects are incorporated into this dataset. The majority of the dataset consists of measurements from the Marine Monitoring Program since 1973. The Secchi disk (Figure 1) is a reflective white disk that is attached to a rope and lowered down the water column until it goes out of sight from above the surface. This dataset contains information on water transparency, as measured by Secchi disk, in the territorial and economic waters of Latvia and Estonia in the Baltic Sea and Gulf of Riga. Territorial and economic waters of Latvia in the Baltic Sea and Gulf of Riga A few stations in territorial and economic waters of Estonia in the Baltic sea and Gulf of Riga Ongoing monitoring measurement of transparency by Secchi disk Effect of climate change on aquatic ecosystems in Latvia(KALME) LIMOD(LIMOD) Implementation of innovative ecotoxicological methods for identification of natural and anthropogenic pollution impact on Latvian territorial waters(HIDROTOX) Innovative approaches for marine biodiversity monitoring and assessment of conservation status of nature values in the Baltic Sea(MARMONI)
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