|
Eutrophication
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplankton productivity". Water bodies with very low nutrient levels are termed oligotrophic and those with moderate nutrient levels are termed mesotrophic. Advanced eutrophication may also be referred to as dystrophic and hypertrophic conditions. Eutrophication can affect freshwater or salt water systems. In freshwater ecosystems it is almost always caused by excess phosphorus. In coastal waters on the other hand, the main contributing nutrient is more likely to be nitrogen, or nitrogen and phosphorus together. This depends on the location and other factors. When occurring naturally, eutrophication is a very slow process in which nutrients, especially phosphorus compounds and organic matter, accumulate in water bodies. These nutrients deri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Cycle
The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth. The production of phosphine gas occurs in only specialized, local conditions. Therefore, the phosphorus cycle should be viewed from whole Earth system and then specifically focused on the cycle in terrestrial and aquatic systems. Living organisms require phosphorus, a vital component of DNA, RNA, ATP, etc, for their proper functioning. Plants assimilate phosphorus as phosphate and incorporate it into organic compounds and in animals, phosphorus is a key component of bones, teeth, etc. On the land, phosphorus gradually becomes less available to plants over thousands of years, since it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmful Algal Bloom
A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural phycotoxin, algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen saturation, oxygen levels in natural waters, killing organisms in marine habitats, marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microorganism, microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone (ecology), dead zone" which can cause fish kill, fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides". It is sometimes unclear what causes specific HABs as their occurrence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nutrient Pollution
Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. Sources of nutrient pollution include surface runoff from farm fields and pastures, discharges from septic tanks and feedlots, and emissions from combustion. Raw sewage is a large contributor to cultural eutrophication since sewage is high in nutrients. Releasing raw sewage into a large water body is referred to as sewage dumping, and still occurs all over the world. Excess reactive nitrogen compounds in the environment are associated with many large-scale environmental concerns. These include eutrophication of surface waters, harmful algal blooms, hypoxia, acid rain, nitrogen saturation in forests, and climate change. Since the agricultural boom in the 1910s and again in the 1940s to match the incre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Pollution
Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants are introduced into these water bodies. Water pollution can be attributed to one of four sources: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. It can be grouped into surface water pollution (either fresh water pollution or marine pollution) or groundwater pollution. For example, releasing inadequately treated wastewater into natural waters can lead to degradation of these aquatic ecosystems. Water pollution can also lead to water-borne diseases for people using polluted water for drinking, bathing, washing or irrigation. Water pollution reduces the ability of the body of water to provide the ecosystem services (such as drinking wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen Cycle
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmospheric nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonpoint Source Pollution
Nonpoint source (NPS) pollution refers to diffuse contamination (or pollution) of water or air that does not originate from a single discrete source. This type of pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. It is in contrast to point source pollution which results from a single source. Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrological modification (rainfall and snowmelt) where tracing pollution back to a single source is difficult. Nonpoint source water pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Nonpoint source air pollution affects air quality, from sources such as smokestacks or car tailpipes. Although these pollutants have originated from a point source, the long-range transport ability and multiple sources of the pollut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coastal Waters
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes, mangroves or seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g. mussels, starfish, barnacles) and various kinds of seaweeds. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of . According to a United Nations atlas, 44% of all people live within 5 km (3.3mi) of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilizer
A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment or hand-tool methods. Historically fertilization came from natural or organic sources: compost, animal manure, human manure, harvested minerals, crop rotations and byproducts of human-nature industries (i.e. fish processing waste, or bloodmeal fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algal Bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. ''Algal bloom'' commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest. Algal blooms are the result of a nutrient, like nitrogen or phosphorus from various sources (for example fertilizer runoff or other forms of nutrient pollution), entering the aquatic system and causing excessive growth of algae. An algal bloom affects the whole ecosystem. Consequences range from the benign feeding of higher trophic levels to more harmful effects like blocking sunlight from reaching other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophic State Index
The Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed. The TSI of a water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: * oligotrophic (TSI 0–40, having the least amount of biological productivity, "good" water quality); * mesotrophic (TSI 40–60, having a moderate level of biological productivity, "fair" water quality); or * eutrophic to hypereutrophic (TSI 60–100, having the highest amount of biological productivity, "poor" water quality). The quantities of nitrogen, phosphorus, and other biologically useful nutrients are the primary determinants of a water body's TSI. Nutrients such as nitrogen and phosphorus tend to be limiting resources in standing water bodies, so increased concentrations tend to result in increased p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dystrophic Lake
Dystrophic lakes, also known as humic lakes, are lakes that contain high amounts of humic substances and organic acids. The presence of these substances causes the water to be brown in colour and have a generally low pH of around 4.0-6.0. Due to these acidic conditions, there is little biodiversity able to survive, consisting mostly of algae, phytoplankton, picoplankton, and bacteria.Drzymulska, D., Fiłoc, M., Kupryjanowicz, M., Szeroczyńska, K., & Zieliński, P. 2015. Postglacial shifts in lake trophic status based on a multiproxy study of a humic lake. Holocene, 25(3), 495-507.Jasser, I. 1997. The dynamics and importance of picoplankton in shallow, dystrophic lake in comparison with surface waters of two deep lakes with contrasting trophic status. Hydrobiologia, 342/343(1), 87-93. Ample research has been performed on the many dystrophic lakes located in Eastern Poland, but dystrophic lakes can be found in many areas of the world.Kostrzewska-Szlakowska, I. 2017. Microbial B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia (environmental)
Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm or 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface (if there is more oxygen in the air, it will diffuse across the partial pressure gradient). Atmospheric hypoxia Atmospheric hypoxia occurs naturally at high altitudes. Total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen, which is defined as hypobaric hypoxia. Oxygen remains at 20.9% of the total gas mixture, differing from hypoxic hypoxia, where the percentage of oxygen in the air (or blood) is decreased. This is common in the sealed burrows of some subterranean animals, such as blesmols. Atmospheric hypoxia is also the basis of altitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
