1.3 Common Heavy Metals in the Marine Environment
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1.3 Common Heavy Metals in the Marine Environment
Heavy metals are eminent marine pollutants; naturally occurring as well as anthropogenically introduced into the marine environment. Continental runoff and atmospheric deposition are the primary natural inputs of trace elements in the marine
environments while the major anthropogenic sources include mining and smelting
(Richir and Gobert 2016).
Al-Rousan et al. (2007) further elaborates that natural and anthropogenic sources
of heavy metals in the marine environment include terrigenous input during flash
floods that transport terrestrial material, ground water input, agricultural activities,
increase in land traffic, sedimentation caused by filling and coastal construction and
dredging, oil spills and discharges, industrial discharges (fertilizers, plastic stabilizers), ship-based sewage and solid waste, soft waste dumping (alloys, dyes, automobile tyres, antifouling paints and galvanizing materials), and shipment of mineral
products (mainly phosphates).
The transportation of heavy metals to the marine environment is through natural
and anthropogenic induced process as dissolved species in water or in association
with suspended sediments probably affecting the primary productivity and coral
growth (Al-Rousan 2012). Heavy metals also enter the marine environment through
atmospheric deposition, which is also regarded as an important exposure pathway.
Sedimentation contributes significant amount of heavy metals to the marine environment especially during heavy rainfall resulting in flash flooding and dust storms.
The sediments can be of terrestrial origin such as run-off from logging catchments,
or coastal development, or from poor farming practices or of riverine inputs. Sediments are composed of oxides of Fe and Mn (manganese), minerals, terragenic
materials and organic matter (Rodrigo 1989). In marine environments adjacent to
arid landmasses where fringing reefs usually occur, aeolian transport of fine particles can be the primary source of heavy metals (Esslemont 1998). Once in the water
column, heavy metals are associated with sediment as well as particulate organic
matter (Bastidas et al. 1999). Heavy metals can contribute to degradation of marine
ecosystems by reducing species diversity and abundance and through accumulation
of metals in living organisms and food chains (Hosono et al. 2011; Naser 2013).
Described below are some common heavy metals present in the marine environment. The major sources of these metals to the marine environment; roles
of these metals in aquatic environment (if any) and their bioaccumulation and
biomagnification properties are deliberated here.
First, a brief note on the definitions of bioaccumulation and biomagnification
as used in the context of this monograph. Bioaccumulation is a good integrative
indicator of chemical exposures of organisms in polluted ecosystems (Philips and
Rainbow, 1994).
Bioaccumulation is the process of the intake of a chemical and its concentration
in the organism by all potential means such as contact, respiration and ingestion
(Alexander 1999) relative to that in the environment. The uptake of the chemical
occurs either directly from exposure to a contaminated medium or by consumption
5
1.3 Common Heavy Metals in the Marine Environment
Heavy metals are eminent marine pollutants; naturally occurring as well as anthropogenically introduced into the marine environment. Continental runoff and atmospheric deposition are the primary natural inputs of trace elements in the marine
environments while the major anthropogenic sources include mining and smelting
(Richir and Gobert 2016).
Al-Rousan et al. (2007) further elaborates that natural and anthropogenic sources
of heavy metals in the marine environment include terrigenous input during flash
floods that transport terrestrial material, ground water input, agricultural activities,
increase in land traffic, sedimentation caused by filling and coastal construction and
dredging, oil spills and discharges, industrial discharges (fertilizers, plastic stabilizers), ship-based sewage and solid waste, soft waste dumping (alloys, dyes, automobile tyres, antifouling paints and galvanizing materials), and shipment of mineral
products (mainly phosphates).
The transportation of heavy metals to the marine environment is through natural
and anthropogenic induced process as dissolved species in water or in association
with suspended sediments probably affecting the primary productivity and coral
growth (Al-Rousan 2012). Heavy metals also enter the marine environment through
atmospheric deposition, which is also regarded as an important exposure pathway.
Sedimentation contributes significant amount of heavy metals to the marine environment especially during heavy rainfall resulting in flash flooding and dust storms.
The sediments can be of terrestrial origin such as run-off from logging catchments,
or coastal development, or from poor farming practices or of riverine inputs. Sediments are composed of oxides of Fe and Mn (manganese), minerals, terragenic
materials and organic matter (Rodrigo 1989). In marine environments adjacent to
arid landmasses where fringing reefs usually occur, aeolian transport of fine particles can be the primary source of heavy metals (Esslemont 1998). Once in the water
column, heavy metals are associated with sediment as well as particulate organic
matter (Bastidas et al. 1999). Heavy metals can contribute to degradation of marine
ecosystems by reducing species diversity and abundance and through accumulation
of metals in living organisms and food chains (Hosono et al. 2011; Naser 2013).
Described below are some common heavy metals present in the marine environment. The major sources of these metals to the marine environment; roles
of these metals in aquatic environment (if any) and their bioaccumulation and
biomagnification properties are deliberated here.
First, a brief note on the definitions of bioaccumulation and biomagnification
as used in the context of this monograph. Bioaccumulation is a good integrative
indicator of chemical exposures of organisms in polluted ecosystems (Philips and
Rainbow, 1994).
Bioaccumulation is the process of the intake of a chemical and its concentration
in the organism by all potential means such as contact, respiration and ingestion
(Alexander 1999) relative to that in the environment. The uptake of the chemical
occurs either directly from exposure to a contaminated medium or by consumption