Name: nitrogen in soil and living things
Uploaded: 2019-03-11T09:21:40.000Z
Duration: 1 min 49 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Biology

ecosystems-interactions-energy-and-dynamics

Ecosystems- Interactions, Energy, and Dynamics

LS.Bio.4.1

The Nitrogen Cycle

מחזור החנקן כרוך במעבר אטומי החנקן בין מרכיבים ביוטיים ואביוטיים במערכת האקולוגית. מרבית החנקן שבמערכת האקולוגית נאגר N2 באטמוספירה כגז, אבל רק חיידקים מכילים אנזימים הנחוצים כדי להמיר גז חנקן לצורה שימושית עבור אורגניזמים אחרים, מושג הנקרא קיבוע חנקן. לפיכך, חנקן הוא חומר מזין מוגבל מאוד במערכת האקולוגית.ברגע שחיידקים באדמה ממירים את הגז לאמוניה, צמחים יכולים אז להמיר את החנקן לחלבונים, לדנ"א, ולמולקולות אורגניות אחרות, אשר אז נצרכים על ידי אוכלי עשב ומפורקים לחומצות אמינו. ניתן להרכיבן מחדש לחלבונים המשמשים לגדילה והתפתחות, ולתזונה עבור צרכנים. במקביל, אוכלי עשב וצרכנים מחזירים חלק מהחנקן חזרה לאדמה בתור תוצרי פסולת.גם אורגניזמים מתים וגם תוצרי פסולת מכילים חנקן בצורת החלבון, השתנן וחומצת השתן. מפרקים כגון חיידקים ופטריות, מסוגלים לפרק מולקולות אלו ולשחרר אמוניה בחזרה לאדמה, שאז יכולה להיספג על ידי צמחים, או להיות מומרת לחנקה על ידי חיידקים מחנקנים. חנקות אלו יכולות גם להיספג על ידי צמחים או, בהיעדר חמצן, להיות מומרות לגז חנקן על ידי חיידקים מבטלי חנקון.בני אדם גם כן משחררים חנקן לתוך המערכת האקולוגית באמצעות שימוש בדשנים חקלאיים. אולם, כאשר משתמשים בהם בזמן הלא נכון, או בכמויות גדולות, עודף חנקן יכול לזרום לתוך מערכות אקולוגיות מימיות ולהגביר גידול חיידקים, אצות וצמחי מים, תהליך המכונה איטרופיקציה.

Ramakrishnan VV, Ghaly AE. "מקורות חנקן ורכיבה על אופניים במערכת האקולוגית ותפקידה בזיהום אוויר, מים וקרקע: סקירה ביקורתית". כתב העת של השפעות זיהום ובקרה 03, מס '02 (2015). [<a href="https://doi.org/10.4172/2375-4397.1000136" target="__blank">מקור</a>]

מחזור החנקן

<div style="direction:rtl">אטומי חנקן, הקיימים בכל החלבונים וה-DNA, ממוחזרים בין רכיבים אביוטיים וביוטיים של המערכת האקולוגית. עם זאת, הצורה העיקרית של חנקן על פני כדור הארץ היא גז חנקן, שאינו יכול לשמש את רוב בעלי החיים והצמחים. לפיכך, גז חנקן חייב להיות מומר תחילה לצורה שמישה על ידי חיידקים מקבעים חנקן לפני שניתן יהיה להעביר אותו דרך אורגניזמים חיים אחרים. השימוש בדשנים המכילים חנקן ובמוצרי פסולת מן החי בחקלאות האנושית השפיע רבות על מחזור החנקן הטבעי. <h4>מחזור חנקן ביולוגי</h4> כ-78% מהאוויר שאנו נושמים הוא גז חנקן. עם זאת, בצורה זו, N2, מעט אורגניזמים מסוגלים להשתמש בו. חנקן מרכיב מולקולות חיוניות בכל האורגניזמים, כמו חלבונים ו-DNA. לא מסוגלים להשתמש בצורה האטמוספרית של חנקן, רוב האורגניזמים משתמשים בתוצרי הלוואי של פרוקריוטים מקבעים וחנקן. קיבוע חנקן הופך גז חנקן (N2) לאמוניה (NH3), ואילו ניטריפיקציה הופכת את NH3 לניטריטים (NO2-) ולניטרטים (NO3-). צמחים יכולים להשתמש ישירות באמוניה ובחנקות, ואורגניזמים אוכלי צמחים משיגים חנקן על ידי בליעת צמחים. כאשר אורגניזמים אלו מתים, חיידקים באדמה מסוגלים להמיר את החנקן האורגני לאמוניה בתהליך הנקרא אמוניפיקציה. באמצעות דניטריפציה, חיידקים אירוביים יכולים להמיר אמוניה לגז חנקן המשתחרר בחזרה לאטמוספירה, ומשלים את המחזור. <h4>שקעי חנקן</h4> המאגר העיקרי לאגירת חנקן לטווח ארוך הוא גז חנקן באטמוספרה. עם זאת, ישנם שקעי חנקן אחרים, קטנים יותר במערכת האקולוגית. ניתן לקשור חנקן לפרקי זמן ארוכים יחסית בביצות, משקעים ימיים וסלע משקע. עם זאת, מכיוון שתרכובות חנקן מסיסות מאוד במים, בליה של סלע משקע יכול לשחרר חנקן בחזרה למערכת האקולוגית. <h4>השפעות האדם על מחזור החנקן</h4> מכיוון שחנקן הוא לעתים קרובות גורם מגביל לגידול צמחים בסביבות טבעיות, חקלאים מוסיפים חנקן לאדמה כדשן כדי להגדיל את התשואה החקלאית. נגר חקלאי למערכות אקולוגיות מימיות עלול לגרום לאאוטרופיקציה ולצמיחה מהירה באופן לא טבעי של מיני אצות רעילות. גידול מספר רב של בעלי חיים יכול גם להגדיל את כמות הפסולת החנקתית בקרקע ובמקורות המים המקומיים.</div>

אטומי חנקן, הנמצאים בכל החלבונים והדנ"א, ממוחזרים בין רכיבים אביוטיים וביוטיים של המערכת האקולוגית. עם זאת, הצורה העיקרית של ...

Education

JoVE Core

ביולוגיה

Ecology

אקולוגיה

Ecosystems

מערכות אקולוגיות

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

nitrogen in soil and living things

Nitrogen in soil and living things moves through ecosystems in several forms. Nitrogen atoms are found in proteins and DNA. Most animals and plants cannot use nitrogen gas, which is the main form of nitrogen on Earth. Nitrogen must first be changed into a usable form by nitrogen-fixing bacteria before it can move through food webs.

About 78% of the air we breathe is nitrogen gas, but few organisms can use it in that form. Nitrogen fixation changes nitrogen gas (N2) into ammonia (NH3). Nitrification then changes ammonia into nitrites (NO2-) and nitrates (NO3-). Plants can use ammonia and nitrates directly. Plant-eating organisms get nitrogen by eating plants.

When organisms die, soil bacteria break down organic nitrogen and convert it into ammonia. This process is called ammonification. Aerobic bacteria can then carry out denitrification and convert ammonia into nitrogen gas that returns to the atmosphere. That return of nitrogen gas completes the cycle.

The main long-term reservoir for nitrogen is nitrogen gas in the atmosphere. Smaller nitrogen sinks also store nitrogen for long periods. These include swamps, marine sediments, and sedimentary rock. Because nitrogen compounds dissolve easily in water, weathering of sedimentary rock can release nitrogen back into the ecosystem.

Human activity can change the nitrogen cycle. Farmers add nitrogen to soil as fertilizer because nitrogen is often a limiting factor for plant growth in natural environments. This can increase agricultural yield. However, runoff from farms can enter aquatic ecosystems and cause eutrophication, which leads to unnaturally rapid growth of toxic algae species. Large numbers of livestock can also increase the amount of nitric waste in soil and local water sources.

Nitrogen in Soil and Living Things

what is an ecosystem?

Ecosystem Zones and Climate

Ecosystems are shaped by living and nonliving parts of an environment, and they can be grouped as terrestrial or aquatic. Terrestrial ecosystems depend on climate. Aquatic ecosystems are divided into freshwater and marine systems, and depth affects water temperature and how much sunlight reaches the water. Terrestrial ecosystems are called biomes. A biome is defined by climate and by the organisms that live there. Near the equator, rainforests have high, aseasonal temperatures and high annual...

trophic levels

Food Chains and Energy Flow

Food chains show how energy and nutrients move through an ecosystem. Each organism holds a trophic level, or a specific place in that chain. The lowest level includes primary producers, which make their own food using energy from the sun or from chemicals. Organisms at the next levels are heterotrophs, which get energy from other organisms below them. Primary consumers are herbivores, and they feed on autotrophs, also called primary producers. Secondary and tertiary consumers are carnivores...

primary production

GPP, NPP, and Ecosystem Energy

Gross primary production and net primary production describe how energy enters and moves through ecosystems. Primary producers, or autotrophs, make their own food. They can do this by photosynthesis or chemosynthesis, and they can also gain energy by consuming other organisms. The rate at which producers capture and store this energy is called gross primary production, or GPP. Not all of the energy in GPP stays available to the rest of the ecosystem. Primary producers use some energy for...

production efficiency

Energy Transfer as Biomass Efficiency

Net production efficiency shows how much energy organisms turn into biomass for the next trophic level. It focuses on the usable energy stored in body tissue, not the energy lost as heat or excreted wastes. This makes it a key idea for understanding energy flow through ecosystems. As energy moves from one organism to the next, only biomass can serve as food for the next trophic level. The rest of the energy is used in metabolism and is lost over time. Net production efficiency, or NPE, is the...

trophic efficiency

Energy Loss in Food Chains

Trophic level transfer efficiency describes how much energy moves from one level of a food chain to the next. It shows why energy drops sharply as organisms eat and are eaten. In most ecosystems, only about 10% of the energy passes on. This energy loss follows the second law of thermodynamics. In living systems, much of the energy is lost as metabolic heat during respiration. Trophic level transfer efficiency, or TLTE, measures this transfer by comparing the energy produced at one trophic...

what are biogeochemical cycles?

Nutrient Recycling in Ecosystems

Nutrient recycling in ecosystems keeps the elements needed for life moving through living and nonliving parts of the environment. Elements such as water, carbon, nitrogen, sulfur, and phosphorus are present in limited amounts, so they must be conserved and reused. These movements are called biogeochemical cycles. These nutrients can exist in several chemical forms. They may spend long periods in the atmosphere, on land, under the land, or in aquatic environments. Decomposition is a key part of...

the water cycle

Water Movement Through Earth Systems

Water movement through Earth systems connects the hydrosphere, the atmosphere, the land, and living things. The hydrosphere includes every place where water is stored or moves. Because water supports living processes, its movement is important for ecosystem dynamics. The cycle starts when the sun warms surface water on land and in the oceans. That water evaporates and enters the atmosphere as vapor. Water can also move into the air by sublimation, which is ice changing directly into vapor, and...

the carbon cycle

Carbon Movement in Living Systems

Carbon moves through living systems and Earth over short and long time scales. It is the basis of all organic matter on Earth, and it cycles through ecosystems by passing between organisms and by moving through rocks, oceans, and the atmosphere. Human activities, including farming and burning fossil fuels, have changed this balance. In the biological carbon cycle, carbon dioxide in the atmosphere reacts with water to form bicarbonate. Primary producers, or autotrophs, use carbon dioxide and...

the nitrogen cycle

Nitrogen in soil and living things moves through ecosystems in several forms. Nitrogen atoms are found in proteins and DNA. Most animals and plants cannot use nitrogen gas, which is the main form of nitrogen on Earth. Nitrogen must first be changed into a usable form by nitrogen-fixing bacteria before it can move through food webs. About 78% of the air we breathe is nitrogen gas, but few organisms can use it in that form. Nitrogen fixation changes nitrogen gas (N2) into ammonia (NH3).

the phosphorus cycle

Phosphorus Movement in Soil and Water

Phosphorus moves through ecosystems mostly as phosphate ions in soil, water, sediment, and rocks. Unlike carbon, water, and nitrogen, it is not found in the atmosphere as a gas. It is also often a limiting nutrient, which means it is in short supply in many environments. Phosphorus is important in DNA, cell membranes, bones, and teeth. It is found in minerals, sediment, volcanic ash, and aerosols. As rocks and sediment weather over time, they release inorganic phosphate. That phosphate then...

the sulfur cycle

Sulfur in Ecosystems and Acid Rain

Sulfur moves through ecosystems as part of the chemical cycle that supports life. It is an important element in proteins and in amino acids such as cysteine, which helps give proteins their structure. On land, sulfur reaches ecosystems in several ways. Weak sulfuric acid can fall with precipitation, sulfur can drop directly from the atmosphere, rocks can weather and release sulfur, and geothermal vents can add it as well. Plants and microorganisms take sulfur up from the soil and change it...

bioremediation

Bioremediation in Soil and Oil Cleanup

Bioremediation uses prokaryotes, fungi, or plants to remove pollutants from the environment. It is a practical way to reduce harmful chemicals in contaminated soil and water. In agriculture, fertilizers and pesticides can leach into groundwater, streams, and lakes. Microbes and bacteria can help break down these toxins. One example is atrazine, an environmental toxin found in many fertilizers, which can be removed from soils by the bacterial species Rhizobium and Tricoderma sp. Bioremediation...

key terms and concepts

Follow nitrogen as it moves from air to soil, plants, and animals, and see how bacteria, fertilizers, and runoff shape the cycle in ecosystems.

Nitrogen in Soil and Living Things | JoVE K12

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Ecosystems: Interactions, Energy And Dynamics

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Ohio’s Learning Standards and Model Curriculum

Diversity And Interdependence Of Life

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112.49.c.12.

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What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

The Water Cycle

The Earth&rsquo;s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, ...

The Carbon Cycle

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of ...

The Phosphorus Cycle

Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, ...

The Sulfur Cycle

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the ...

Use models to illustrate how processes in organisms contribute to the flow of energy and the cycling of matter within an ecosystem.

What are Populations and Communities?

Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting ...

Distribution and Dispersion

Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species ...

Life Histories

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented ...

Energy Budgets and Reproductive Strategies

Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of ...

Population Growth

Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with ...

Use models to explain the relationship between the flow of energy and cycling of matter among organisms in an ecosystem.

LS.Bio.4.2

Ecological Niches

All organisms have a position within an ecosystem. The complete set of living and nonliving factors&#x2014;including food resources, climate, and ...

Ecological Succession

Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species ...

Keystone Species

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ...

Symbiosis

Symbiotic relationships are long-term, close interactions between individuals of different species that affect the distribution and abundance of those ...

Competition

When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction. ...

Predator-Prey Interactions

Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction ...

Ecological Disturbance

An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced ...

Use mathematics and computational thinking to explain how interactions between organisms (predator/prey, competition) affect carrying capacity and maintain stability in an ecosystem.

LS.Bio.5.1

What is Biodiversity?

Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity ...

Engage in argument from evidence to evaluate various solutions to reduce the impact of human activities on biodiversity and ecosystem health.

LS.Bio.5.2

Analyze the relationships between matter and energy within ecosystems.

Nitrogen in Soil and Living Things

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