The chemistry of the marine environment is a complex aspect of the world er

Seawater chemically interacts with atmosphere, the organisms, and the sediment on the bottom. The chemistry of the marine environment is a complex aspect of the world ocean. It is important to understand the chemical composition of seawater

1. Chemical composition of seawater

2. Seawater chemically interacts with atmosphere, the organisms, and the sediment on the bottom The chemistry of the marine environment is a complex aspect of the world ocean It is important to understand the chemical composition of seawater Introduction

3. Elements with concentration at least one percent Initially come from volcanic activity and/or the weathering of minerals in igneous (magmatic) rocks Plu s Bicarbonate (HCO 3 − )  0.14 g/kg (0.4% by weight) Major elements

4. three main rock types Igneous rock is formed through the cooling and solidification of magma or lava (ex. Granite), Sedimentary rocks , formed from the products of weathering through cementation or precipitation on the Earth's surface (ex. Dolomites) and. Metamorphic rocks , formed by temperature and pressure changes inside the Earth (ex. Marble) magmatic rock

5. Ex : Salinity of 35 ‰ 3.5 % of chemical elements 95 % consists of macro elements 5 % consists of micro elements 96,5 % of water

6. It is vary in abundance with concentration less than one percent Important to the overall chemical scheme in the oceans Some are economic importance (gold, zinc, aluminum, and iron), others are critical to various organisms in the sea (oxygen, nitrogen, and silicon) Minor elements

7. Many are nutrients and required to sustain life (e.g. P, N, Fe, Cu) Others are toxic (e.g. Cu, Hg) Some are tracers for redox conditions (chromium (Cr); Iodine (I); rhenium (Re), molybdenum (Mo); vanadium (V); Uranium (U); Pb (lead)) Some form economic deposits such as manganese nodules (e.g. Cu, Co, Ni, Cd) Some are tracer s of pollution (e.g. Pb , Pu , Ag) The importance of minor elements

8. always found in constant proportions to one another and to salinity in the open sea, even though salinity varies; constant with depth and in the different oceans (uniformly distributed) Not affected by chemical or biological processes in seawater All the major ions in seawater, excep t for bicarbonate , are included in this group Na, K, SO4, Br, B and F have constant ratios to Cl and each other, everywhere in the ocean. Conservative elements

9. are not in constant proportions The concentrations are altered by chemical reactions that occur faster than the physical processes responsible for water movement Most substances in seawater are non-conservative , but they collectively comprise only a small fraction of the total mass of solutes and solids in the ocean Examples : C, P, N Non-conservative elements

10. Present primarily as complexes (with others element ) & at very low concentrations ( less than 1 pp m (mg/kg)) It does not contribute to the salinity concentrations range down to picomoles per litre ( pmol 1 -1 ) and even lower. Such small concentrations pose extreme analytical problems , and it is only recently that these have been fully overcome Essential trace elements of the human body include zinc (Zn), copper (Cu), selenium (Se), chromium (Cr), cobalt (Co), iodine (I), manganese (Mn), and molybdenum (Mo). Trace element

11. Allothoneous  denoting sediment or rock that originated at a distance from its present position Weathering Volcano eruption Anthropogenics Autothoneous  f ormed or originating in the place where found Advection  transfer by flow/fluid Mixing/up welling Biodegradation Dissolution suspension, Underwater eruption /explosion Hydrothermal vent Sources of major components of seawater

12. Sources of Salt in Seawater Weathering and erosion of rocks on land Rate of supply of salts from rivers: 10 15 grams/year !

13. The Ocean DOES NOT get saltier at least during the past 1.5 billion years The " steady state " results from the removal rate of salts from the ocean being equal to the input rate This balance holds because the removal rate of salts is related to their concentration, and increases when their concentration increases Surprisingly,

14. The average length of time that the element or ion stays in solution or remains in the ocean before it is removed It is varies greatly for each dissolved elemen t Each element has its own residence time depending on how reactive the element is in the marine environment Some have long residence times (sodium, magnesium, and potassium), and others have short residence time (iron and aluminum) Residence time

15. different processes remove different ele ments HCO 3 and Ca are used biologically very rapidly (non-conservative) Na and Cl are removed very slowly, by absorption on clay particles (conservative) Elements have different residence times, determine by reactive speed and demanding by ocean biota Removal Processing

16. Conservativ e constituents of seawater occur in constant proportions Conservativ e elements have long residence times and are the most abundant dissolved salts in the ocean Non-conservative constituents have short residence times , and are usually associated with seasona l, biological or short geological cycles Conservative and Non-conservative Constituents

17. calculated by The residence time of any element depends on its chemical activities The average molecule of water spends 3800 years in the ocean before being removed, mostly via the process of evaporation Residence Time

18. Elements that are believed to be limiting to plant growth in the surface ocean Although they are not among the most abundant element in the ocean, they are among the most important because of their role in the organic cycle and essential nutrient elements for living organisms  needed to synthesis macromolecules such as lipids, proteins and carbohydrate They present in various states and concentrations Phosphorus, nitrate and silica are the important macronutrient Macronutrients

19. Extracted from surface water by photosynthesizin g phytoplankton May become totally depleted in surface waters where biological production is high ( bio-limiting constituents ) When the organisms are consumed or they died and decompose, the nutrients are returned to the water column ( re-mineralization ) Macronutrients

20. Marine nitrogen cycle http://wordsinmocean.com/2012/02/21/the-marine-nitrogen-cycle/ diazotroph dinitrogen Ammonium Nitrogen dioxide

21. http://www.marlborough.govt.nz/Environment/Rivers-and-Wetlands/River-Water-Quality/Quality.aspx ( Various natural & human sources)

22. Vertical profiles of nutrients http://www.waterencyclopedia.com/Mi-Oc/Ocean-Biogeochemistry.html

23. Any questions?