In marine and freshwater ecology

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

, a particle is a small object. Particles can remain in suspension in the ocean or freshwater, however they eventually settle (rate determined by Stokes' law

Stokes' law

In 1851, George Gabriel Stokes derived an expression, now known as Stokes' law, for the frictional force – also called drag force – exerted on spherical objects with very small Reynolds numbers in a continuous viscous fluid...

) and accumulate as sediment. Some can enter the atmosphere

Earth's atmosphere

The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 through wave action where they can act as cloud condensation nuclei

Cloud condensation nuclei

Cloud condensation nuclei or CCNs are small particles typically 0.2 µm, or 1/100 th the size of a cloud droplet ) about which cloud droplets coalesce. Water requires a non-gaseous surface to make the transition from a vapour to a liquid. In the atmosphere, this surface presents itself as tiny...

 (CCN). Many organisms filter

Filter (chemistry)

In chemistry and common usage, a filter is a device that is designed to physically block certain objects or substances while letting others through. Filters are often used to remove solid substances suspended in fluids, for example to remove air pollution, to make water drinkable, and to prepare...

 particles out of the water with unique filtration mechanisms (filter feeder

Filter feeder

Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...

s). Particles are often associated with high loads of toxin

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

s which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation

Bioaccumulation

Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost...

). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and can cause the water to become hypoxic

Hypoxia (environmental)

Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...

.

Particle analysis

Particle levels in water (or air) can be measured with a turbidity

Turbidity

Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....

 meter and analyzed with a particle counter

Particle counter

A particle counter is an instrument that detects and counts particles. By its very nature a particle counter is a single particle counter, meaning it detects and counts particles one at a time. The nature of particle counting is based upon either light scattering or light obscuration...

. They can also be scanned with an underwater microscope, such as ecoSCOPE

EcoSCOPE

The ecoSCOPE is an optical sensor system, deployed from a small remotely operated vehicle or fibre optic cable, to investigate behavior and microdistribution of small organisms in the ocean.-Deployment:...

. Collected particles of size 20 - 200 micrometers hovering in the free water in the vicinity of a harbor

Harbor

A harbor or harbour , or haven, is a place where ships, boats, and barges can seek shelter from stormy weather, or else are stored for future use. Harbors can be natural or artificial...

 had the following contaminant levels (table). Many of those contaminants are carcinogenic.

Particles in the vicinity of a harbor

Contaminant	Mass of contaminant relative to total particle dry weight
Arsenic Arsenic Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...	8.17 mg/kg
Lead Lead Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...	80.1 mg/kg
Cadmium Cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...	0.61 mg/kg
Chromium Chromium Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...	31.2 mg/kg
Copper Copper Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...	44 mg/kg
Nickel Nickel Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...	20.6 mg/kg
mercury Mercury (element) Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...	0.86 mg/kg
Zinc Zinc Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...	156 mg/kg
EOX	0.79 mg/kg
Anthracene Anthracene Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a component of coal-tar. Anthracene is used in the production of the red dye alizarin and other dyes...	602 µg/kg
Fluoranthene Fluoranthene Fluoranthene is a polycyclic aromatic hydrocarbon consisting of a naphthalene and a benzene unit connected by a five-membered ring. It is a member of the class of PAHs known as non-alternant PAHs because it has rings other than those with six carbon atoms. It is a structural isomer of the...	5947 µg/kg
Pyrene Pyrene Pyrene is a polycyclic aromatic hydrocarbon consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is . This colourless solid is the smallest peri-fused PAH...	5549 µg/kg
Benzo(a)anthracene	5296 µg/kg
Benzo(b)fluoranthene	2499 µg/kg
Benzo(k)fluoranthene	1652 µg/kg
Benzo(a)pyrene	1895 µg/kg
Dibenzo(ah)anthracene	200 µg/kg
Benzo(ghi)perylene Perylene Perylene or perilene is a polycyclic aromatic hydrocarbon with the chemical formula C20H12, occurring as a brown solid. It or its derivatives may be carcinogenic, and it is considered to be a hazardous pollutant. In cell membrane cytochemistry, perylene is used as a fluorescent lipid probe...	1533 µg/kg
Dichloromethane Dichloromethane Dichloromethane is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents...	66 µg/kg
Chloroform Chloroform Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...	11 µg/kg
Carbon tetrachloride Carbon tetrachloride Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...	5 µg/kg
1,1,1-Trichloroethane 1,1,1-Trichloroethane The organic compound 1,1,1-trichloroethane, also known as methyl chloroform, is a chloroalkane. This colourless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent...	4 µg/kg
Pentachlorophenol Pentachlorophenol Pentachlorophenol is an organochlorine compound used as a pesticide and a disinfectant. First produced in the 1930s, it is marketed under many trade names...	22 µg/kg
1,2,3-Trichlorobenzene	0.4 µg/kg
1,3,5-Trichlorobenzene	0.4 µg/kg
1,2,4-Trichlorobenzene	1.4 µg/kg
1,2,3/4,5-Tetrachlorobenzene	1.2 µg/kg
1,2,3,4-Tetrachlorobenzene	0.4 µg/kg
Pentachlorobenzene Pentachlorobenzene Pentachlorobenzene is a chemical compound with the molecular formula C6HCl5 which is a chlorinated aromatic hydrocarbon. It consists of a benzene ring substituted with five chlorine atoms...	0.8 µg/kg
Hexachlorobenzene Hexachlorobenzene Hexachlorobenzene, or perchlorobenzene, is a chlorocarbon with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt...	3.9 µg/kg
Total PCBs Polychlorinated biphenyl Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...	2205 µg/kg
PCB 28	598 µg/kg
PCB 52	331 µg/kg
PCB 101	205 µg/kg
PCB 138	414 µg/kg
PCB 153	432 µg/kg
PCB 180	225 µg/kg
Benzene Benzene Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....	108 µg/kg
Toluene Toluene Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...	655 µg/kg
o,-m,-p-Xylene Xylene Xylene encompasses three isomers of dimethylbenzene. The isomers are distinguished by the designations ortho- , meta- , and para- , which specify to which carbon atoms the two methyl groups are attached...	247 µg/kg
2,3,7,8-TCDF (dioxin)	0.8 ng/kg

Contaminant kinetics

It takes a few days until plankton

Plankton

Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

 organisms have filtered the particles and incorporated the toxins into their body fat and tissue

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

: In the southwards flow of the waters of the Hudson off the coast of New Jersey

New Jersey

New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

, the highest levels of mercury in copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s have not been found directly in front of the river off New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 but 150 km south, off Atlantic City.

Many copepods are then captured by mysidae

Mysidae

Mysidae is a family of crustaceans in the order Mysida or mysid shrimps. Six sub-families are recognised:* Boreomysinae Holt & W. M. Tattersall, 1905a* Siriellinae Norman, 1892* Rhopalophthalminae Hansen, 1910* Gastrosaccinae Norman, 1892...

, krill

Krill

Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

 and smallest fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 like the juveniles of atlantic herring

Atlantic herring

Atlantic herring is a fish in the family Clupeidae. It is one of the most abundant fish species on earth. Herring can be found on both sides of the Atlantic Ocean, congregating in large schools. They can grow up to in length and weigh more than...

 - and in each step of the foodchain the toxin concentrations increase by the factor of 10. The milk of mothers (Homo sapiens) consuming fish and related products like margerine and eggs in such areas have so high toxin levels that it would be impossible to sell such milk on markets - their babies have much more birth-defects and/or retarded brains and have later difficulties to learn and/or reproduce. Many die at an early age.



Filter of krill

Krill

Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

: The first degree filter setae carry in v-form two rows of second degree setae, pointing towards the inside of the feeding basket. The purple ball is one micrometer in size. To display the total area of this fascinating particle filtration structure one would have to tile 7500 times this image.



Filter basket of a mysid. These 3 cm long animals live close to shore and hover above the sea floor, constantly collecting particles. Mysids are an important food source for herring

Atlantic herring

Atlantic herring is a fish in the family Clupeidae. It is one of the most abundant fish species on earth. Herring can be found on both sides of the Atlantic Ocean, congregating in large schools. They can grow up to in length and weigh more than...

, cod

Cod

Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...

, flounder

Flounder

The flounder is an ocean-dwelling flatfish species that is found in coastal lagoons and estuaries of the Northern Atlantic and Pacific Oceans.-Taxonomy:There are a number of geographical and taxonomical species to which flounder belong.*Western Atlantic...

, striped bass

Striped bass

The striped bass is the state fish of Maryland, Rhode Island, South Carolina, and the state saltwater fish of New York, Virginia, and New Hampshire...

. In polluted areas they have high toxin levelsin their tissue but they are very robust and take a lot of poison before they die. Such filter feeding organisms are the reason that much of the materials we throw in the oceans comes back to us in our food.