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EC number: 231-104-6 | CAS number: 7439-95-4
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Field studies
Administrative data
- Endpoint:
- field studies
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: handbook with reliable values
Data source
Reference
- Reference Type:
- review article or handbook
- Title:
- The chemical composition of seawater
- Author:
- J Floor Anthoni
- Year:
- 2 006
- Bibliographic source:
- www.seafriends.org.nz/oceano/seawater.htm
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- GLP compliance:
- not specified
- Type of measurement:
- concentration of Magnesium ion Mg in seawater
- Media:
- seawater
Test material
- Reference substance name:
- Magnesium
- EC Number:
- 231-104-6
- EC Name:
- Magnesium
- Cas Number:
- 7439-95-4
- Molecular formula:
- Mg
- IUPAC Name:
- magnesium
- Test material form:
- solid: compact
Constituent 1
Results and discussion
Any other information on results incl. tables
Detailed
composition of seawater
at
3.5% salinity
Element |
At.weight |
ppm |
|
Element |
At.weight |
ppm |
Helium He |
4.0026 |
0.0000072 |
|
Tellurium Te |
127.6 |
. |
Copper Cu |
63.54 |
0.0009 |
|
Tantalum Ta |
180.948 |
<0.0000025 |
Note! ppm= parts per million = mg/litre = 0.001g/kg.
Salinity and the main salt ions
The salinity of sea water (usually 3.5%) is made up by all the
dissolved salts shown in the above table. Interestingly, their
proportions are always the same, which can be understood if salinity
differences are caused by either evaporating fresh water or adding fresh
water from rivers. Freezing and thawing also matter.
Salinity affects marine organisms because the process of osmosis transports water towards a higher concentration through cell walls. A fish with a cellular salinity of 1.8% will swell in fresh water and dehydrate in salt water. So, saltwater fish drink water copiously while excreting excess salts through their gills. Freshwater fish do the opposite by not drinking but excreting copious amounts of urine while losing little of their body salts.
Marine plants (seaweeds) and many lower organisms have no mechanism to control osmosis, which makes them very sensitive to the salinity of the water in which they live.
The main nutrients for plant growth are nitrogen (N as in nitrate NO3-, nitrite NO2-, ammonia NH4+), phosporus (P as phosphate PO43-) and potassium (K) followed by Sulfur (S), Magnesium (Mg) and Calcium (Ca). Iron (Fe) is an essential component of enzymes and is copiously available in soil, but not in sea water (0.0034ppm). This makes iron an essential nutrient for plankton growth. Plankton organisms (like diatoms) that make shells of silicon compounds furthermore need dissolved silicon salts (SiO2) which at 3ppm can be rather limiting.
The main salt ions that make up 99.9% are the following:
chemical ion |
valence |
concentration |
part of |
molecular |
mmol/ |
Chloride Cl |
-1 |
19345 |
55.03 |
35.453 |
546 |
Sodium Na |
+1 |
10752 |
30.59 |
22.990 |
468 |
Sulfate SO4 |
-2 |
2701 |
7.68 |
96.062 |
28.1 |
Magnesium Mg |
+2 |
1295 |
3.68 |
24.305 |
53.3 |
Calcium Ca |
+2 |
416 |
1.18 |
40.078 |
10.4 |
Potassium K |
+1 |
390 |
1.11 |
39.098 |
9.97 |
Bicarbonate HCO3 |
-1 |
145 |
0.41 |
61.016 |
2.34 |
Bromide Br |
-1 |
66 |
0.19 |
79.904 |
0.83 |
Borate BO3 |
-3 |
27 |
0.08 |
58.808 |
0.46 |
Strontium Sr |
+2 |
13 |
0.04 |
87.620 |
0.091 |
Fluoride F |
-1 |
1 |
0.003 |
18.998 |
0.068 |
By adding the µmol in last column up, multiplied by respective valences,
like: -546 +468 -56.2 +106.6 + .... one ends up with almost 0,
suggesting that the above values are about right. During the Challenger
Expedition of the 1870s, it was discovered that the ratios between
elements is nearly constant although salinity (the amount of H2O) may
vary. Note that the figures above differ slightly in differing
publications. Also landlocked seas like the Black Sea and the Baltic
Sea, have differing concentrations.
This world map shows how the salinity of the oceans changes slightly from around 32ppt (3.2%) to 40ppt (4.0%). Low salinity is found in cold seas, particularly during the summer season when ice melts. High salinity is found in the ocean 'deserts' in a band coinciding with the continental deserts. Due to cool dry air descending and warming up, these desert zones have very little rainfall, and high evaporation. The Red Sea located in the desert region but almost completely closed, shows the highest salinity of all (40ppt) but the Mediterranean Sea follows as a close second (38ppt). Lowest salinity is found in the upper reaches of the Baltic Sea (0.5%). The Dead Sea is 24% saline, containing mainly magnesium chloride MgCl2. Shallow coastal areas are 2.6-3.0% saline and estuaries 0-3%.
Applicant's summary and conclusion
- Conclusions:
- Due to magnesium ion's high solubility in water, it is the third most abundant element dissolved in seawater.
The average concentration of Magnesium ion Mg in seawater is 1295 mg/l.
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