Genetic adaptation to heavy metals in aquatic organisms: a review

Natural populations in polluted areas are possibly subjected to selective pressures for an increased resistance to toxicants. This can result in the evolution of resistance, which may have important implications for decisions regarding safe ambient toxicant levels. By reviewing the evolution of resistance to heavy metals in aquatic organisms, we aimed to determine if all populations negatively affected by toxicants do adapt to them. If the published literature accurately represents the situation in polluted areas (i.e. negative results having an equal chance of being published), it can be concluded that most, but not all, populations in polluted areas do have an increased resistance. But it can usually not be determined if such an increased resistance has a genetic basis. There is less evidence for the evolution of resistance in metazoans (especially fish) than in micro-organisms. Additional information strongly indicates that many populations fail to survive in polluted environments. It thus seems dangerous to relax water quality criteria on the assumption that all populations in polluted environments will evolve an increased resistance. But the fact that the evolution of resistance to environmental pollutants does seem to occur in some populations in polluted environments warrants taking that possibility into consideration when evaluating the results of bioassays and monitoring programs.     

Potential effects of UV-B on the chemical environment of marine organisms: a review

An increase in ultraviolet-B (UV-B) due to depletion of stratospheric ozone may affect growth of marine phytoplankton by altering the chemistry of their environment. Production of bioactive free radicals, photodecomposition of organic matter, and availability of trace metals are likely to be altered by increased UV-B flux. Such changes to the chemical environment may be both deleterious and beneficial to marine phytoplankton. Extracellular free radicals such as OH, Br(2)(-), and CO(3)(-) are predicted to have a negligible impact, but superoxide and its decomposition product hydrogen peroxide may react rapidly with cell surfaces and destroy membrane function and integrity. Increased UV-B will enhance the bioavailability of the redox active trace metals Fe and Cu. Thus, in the Fe-limited high latitude ocean, increased Fe availability may promote phytoplankton production, while in other parts of the ocean increased Cu availability may be toxic. Overall, the interdependent direct and indirect effects of UV-B on phytoplankton may compensate for each other and account for the ability of marine ecosystems to be subjected to widely variable UV-B flux without apparent damage.     

Occurrence and seasonal variation of alkylphenols in marine organisms from the coast of Taiwan

The occurrence and distribution of alkylphenols (APs, i.e., 4-tert-octylphenol (4-t-OP) and 4-nonlyphenol isomers (4-NP)) in oysters (Crassostrea gigas), snails (Thais clavigera), coastal water and coastal sediments of the western coast of southern Taiwan are investigated. Alkylphenols were present in all matrices of interest: in water, ranging from 61 to 370 ng/l, in sediments, ranging from 27 to 190 ng/g, and in biota samples (i.e., oyster and snail), ranging from 20 to 5190 ng/g. Statistical analysis indicated that the probability distribution of most determined concentrations in oyster and snail samples was log-normal distribution. The bioaccumulation of APs resulted in a seasonal variation with respect to their compositions and concentrations in oyster and snail samples. For oysters, concentrations of APs in winter exceeded those in summer. In contrast, those in snails in summer exceeded those in winter. Estimated biomagnification factors of APs from snails to oysters ranged from 1.4 to 4.3 in summer, and 0.5 to 0.8 in winter on the dry weight basis. The results suggested that seasonally mediated physiological changes, such as dilution caused by growth, biotransformation and metabolism, may affect the bioaccumulation of APs in according to season and organism.     

Dietary intake of PCDDs, PCDFs and dioxin-like PCBs, due to the consumption of various marine organisms from Korea

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) residues were measured in 70 marine organisms (40 species) from Korean coastal waters. The PCDD/Fs residues in the organisms varied from 0.02 to 4.39 pg WHO-TEQ/g wet weight and the DL-PCBs residues varied from 0.008 to 6.0 pg WHO-TEQ/g wet weight. The levels in fish from Korean coastal waters were comparable to those found in other countries. Comparing organism groups, the highest PCDD/Fs and DL-PCBs residues were recorded in crustaceans, followed by fish, cephalopods, bivalves and gastropods. Although the congener distributions of PCDD/Fs and DL-PCBs in the organism groups were different, the dominant contributors to the total TEQ concentrations in all groups were 2,3,4,7,8-pentachlorinated dibenzofuran (PeCDF), 1,2,3,7,8-pentachlorinated dibenzo-p-dioxin (PeCDD) and PCB 126. The dietary intake of PCDD/Fs and DL-PCBs from the consumption of marine organisms in Korea was estimated to be 0.68 pg WHO-TEQ/kg bodyweight/day. The contribution of DL-PCBs to the total dietary intake from all organisms groups averaged 60%. The relative contribution of each organism group to the total dietary intake was, in descending order: fish, crustaceans, cephalopods, bivalves and gastropods. The current dietary intake was lower than those in countries with a similar dietary pattern to Korea, but higher than those in countries with smaller quantities of seafood consumption.     

Plastics and microplastics,effects on marine coastal areas: a review

Environmental Science and Pollution Research - Plastics have become strong environmental stressors of coastal marine ecosystems. Their introduction into the marine ecosystem is subjected to...     

Pesticide residues in freshwater and marine zooplankton: a review

A review of the scientific literature on pesticide residues in freshwater and marine zooplankton indicates that despite the great number of pesticides in current use, only residues of the persistent organochlorine insecticides, many of which have been restricted or removed from general use in North America, have been determined. Much of this information is outdated. In addition, with the exception of the Great Lakes on which limited information is available, reports on residues in freshwater zooplankton are rare. Information on residues of the newer, less persistent but heavily used pesticides is lacking. As an alternative to field sampling and chemical analysis of endemic populations of zooplankton, scientists have modeled the bioaccumulation of pesticides in zooplankton using either laboratory microcosms or mathematical equations. However, the extent and importance of trophic transfer to higher food levels through this intermediary group of organisms is still controversial. In addition, the relationship between accumulation of pesticides and toxicity to zooplankton remains unresolved.     

Dynamics of trace metals in organisms and ecosystems: prediction of metal bioconcentration in different organisms and estimation of exposure risks

Metal ions interact with biological materials and their decomposition products by ligation (coordination complex-formation with certain moieties containing O, N, S, etc.). The extent of this interaction depends on the identities of both ligand and metal ion and can be described by some equation derived from perturbation theory. Uptake of metal ions - including highly toxic ones - from soils is controlled by a competition between root exudate components and soil organic matter (SOM) for the ions. SOM consists of a variety of potential ligands which evolve during humification towards more efficient binding (retention) of metals such as Cu, Ni, Cr but also of toxicants like U, Cd. The actual way of interaction can be inferred from stoichiometry of the involved compounds and the C/N ratio in the soil, providing predictions as to which metals will be most efficiently shuttled into green plants or fungi, respectively. The latter, selective process is crucial for closing nutrient cycles and sensitively depends on C/N ratio and the extent of "forcing" by onfalling leaf or needle litter. Therefore, analytical data on the soil can be used to predict possible risks of exposition to toxic metals also for human consumption of plant parts.     

Occurrence of PPCPs in the marine environment: a review

Little research has been conducted on the occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment despite being increasingly impacted by these contaminants. This article reviews data on the occurrence of PPCPs in seawater, sediment, and organisms in the marine environment. Data pertaining to 196 pharmaceuticals and 37 personal care products reported from more than 50 marine sites are analyzed while taking sampling strategies and analytical methods into account. Particular attention is focused on the most frequently detected substances at highest concentrations. A snapshot of the most impacted marine sites is provided by comparing the highest concentrations reported for quantified substances. The present review reveals that: (i) PPCPs are widespread in seawater, particularly at sites impacted by anthropogenic activities, and (ii) the most frequently investigated and detected molecules in seawater and sediments are antibiotics, such as erythromycin. Moreover, this review points out other PPCPs of concern, such as ultraviolet filters, and underlines the scarcity of data on those substances despite recent evidence on their occurrence in marine organisms. The exposure of marine organisms in regard to these insufficient data is discussed.     

Nanoscale zero-valent metals: a review of synthesis,characterization, and applications to environmental remediation

Engineered nanoscale zero-valent metals (NZVMs) representing the forefront of technologies have been considered as promising materials for environmental remediation and antimicrobial effect, due to their high reducibility and strong adsorption capability. This review is focused on the methodology for synthesis of bare NZVMs, supported NZVMs, modified NZVMs, and bimetallic systems with both traditional and green methods. Recent studies have demonstrated that self-assembly methods can play an important role for obtaining ordered, controllable, and tunable NZVMs. In addition to common characterization methods, the state-of-the-art methods have been developed to obtain the properties of NZVMs (e.g., granularity, size distribution, specific surface area, shape, crystal form, and chemical bond) with the resolution down to subnanometer scale. These methods include spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), electron energy-loss spectroscopy (EELS), and near edge X-ray absorption fine structure (NEXAFS). A growing body of experimental data has proven that nanoscale zero-valent iron (NZVI) is highly effective and versatile. This article discusses the applications of NZVMs to treatment of heavy metals, halogenated organic compounds, polycyclic aromatic hydrocarbons, nutrients, radioelements, and microorganisms, using both ex situ and in situ methods. Furthermore, this paper briefly describes the ecotoxicological effects for NZVMs and the research prospects related to their synthesis, modification, characterization, and applications.     

Microplastic pollution,a threat to marine ecosystem and human health: a short review

Human populations are using oceans as their household dustbins, and microplastic is one of the components which are not only polluting shorelines but also freshwater bodies globally. Microplastics are generally referred to particles with a size lower than 5 mm. These microplastics are tiny plastic granules and used as scrubbers in cosmetics, hand cleansers, air-blasting. These contaminants are omnipresent within almost all marine environments at present. The durability of plastics makes it highly resistant to degradation and through indiscriminate disposal they enter in the aquatic environment. Today, it is an issue of increasing scientific concern because these microparticles due to their small size are easily accessible to a wide range of aquatic organisms and ultimately transferred along food web. The chronic biological effects in marine organisms results due to accumulation of microplastics in their cells and tissues. The potential hazardous effects on humans by alternate ingestion of microparticles can cause alteration in chromosomes which lead to infertility, obesity, and cancer. Because of the recent threat of microplastics to marine biota as well as on human health, it is important to control excessive use of plastic additives and to introduce certain legislations and policies to regulate the sources of plastic litter. By setup various plastic recycling process or promoting plastic awareness programmes through different social and information media, we will be able to clean our sea dustbin in future.     

The content of metals in organisms of various trophic levels in freshwater and brackish lakes on the coast of the sea of Japan

Environmental Science and Pollution Research - The content of trace metals (Pb, Zn, Cd, Cu) was examined in water—in the suspended and dissolved forms, in the suspended material and organisms...     

A review of mesocosm experiments on heavy metals in marine environment and related issues of emerging concerns

Environmental Science and Pollution Research - Mesocosms are real-world environmental science tools for bridging the gap between laboratory-scale experiments and actual habitat studies on ecosystem...     

Distribution and accumulation of heavy metals in the sediments of Kaohsiung Harbor, Taiwan

The distribution, enrichment, and accumulation of heavy metals in the sediments, especially those at the vicinity of tributary estuaries of Kaohsiung Harbor, Taiwan were investigated. Sediment samples from six locations in the Kaohsiung Harbor were collected quarterly in the period from 2002 to 2005 and characterized for metal content (e.g., Hg, Pb, Cd, Cr, Cu, Zn and Al), water content, organic matter, total nitrogen, total phosphorous, total grease, and grain size. Results showed that metal concentrations varied from 0.58 mg kg(-1) for Cd to 596 mg kg(-1) for Zn. Metal concentrations at the vicinity of river mouths were higher than those at other locations. All heavy metals studied, except Cr, had relatively high enrichment factors and geo-accumulation indices in the estuaries. Moreover, metal concentrations correlated closely to the physical-chemical properties of the sediments, which strongly suggested the influence of industrial and municipal wastewaters discharged from the neighboring industrial parks and river basins. Results would help develop strategies for pollution control and sediment remediation of Kaohsiung Harbor.     

Polychlorinated dibenzofurans/dibenzo-p-dioxins (PCDF/PCDDs) and other dioxin-like substances in marine organisms from the Grenland fjords,S. Norway, 1975-2001: present contamination levels,trends and species specific accumulation of PCDF/PCDD congeners

Discharge of WHO toxicity equivalents (TEQs) of PCDF/PCDDs to Frierfjorden, Norway has been reduced from an estimated sum of 50-100 kg in the period 1951-1975 to about 6-7 kg in 1976-1990, and further to about 20 g for 1991-2000. In accordance with this, the yearly monitoring since 1987 has shown considerably decreasing contamination in organisms, first highly significant in all indicator species from 1990 to 1991, then levelling off. Present concentrations thus are still high. Compared with estimated "high background" (reference) concentrations of 10 ng TEQ(PCDF/PCDD)/kg w.w. in liver of cod and in hepatopancreas ("brown meat") of crabs, Frierfjord samples in 2001 were about 60 and 70 times higher, respectively. With considerable uncertainty due to large fluctuations, the rate of yearly decrease for TEQ(PCDF/PCDD) in cod liver 1991-2001 has been calculated to 10-12%. A hypothetic target value of 50 ng TEQ/kg w.w. will not be reached until 2015-2020, possibly even later. Including contributions from dioxin-like PCBs and PCNs, the weekly maximum tolerable amount of cod liver and crab hepatopancreas from Frierfjorden in 2001 were about 2-3 g. Multivariate analysis of PCDF/PCDD congener profiles in four fish species, mussels and crabs resulted in five distinct groups, separating four of the species and grouping the remaining two together, hence demonstrating examples of species specific accumulation characteristics.     

Concentrations of chlorobenzenes, hexachlorobutadiene and heavy metals in surficial sediments of Kaohsiung coast, Taiwan

This work analyzes surface sediment samples collected from 40 stations along the Kaohsiung coast in southern Taiwan for chlorobenzenes (CBs), hexachlorobutadiene (HCBD) and heavy metals (Cu, Zn, Pb, Cd, Ni, Fe, Mn and Cr). The highest CBs concentrations are recorded in station T7-15 (about 10 km west off the outlet of Da-lin-pu ocean outfall pipe), with total di-, tri-, tetra-, penta- and hexa-chlorobenzenes concentrations of 290.5, 117.1, 64.5, 15.7 and 22.3 ng/g, respectively. The major pollution source of HCBD is most likely located in the Tso-yin ocean outfall field; while the Dah-lin-pu ocean outfall field and Kao-ping Chi estuary, located in the southern portion of Kaohsiung coast, are the major contributors of hexachlorobenzene. The concentration of CBs congeners correlate fairly well with each other, as do metals. However, concentrations of organics (CBs and HCBD) did not correlate with metals. This finding implies that the pollution characteristics of organics and heavy metals in this highly utilized coastal zone markedly differ from each other.     

Hexabromocyclododecanes in limnic and marine organisms and terrestrial plants from Tianjin,China: Diastereomer- and enantiomer-specific profiles,biomagnification, and human exposure

To interpret the distribution of hexabromocyclododecanes (HBCDs) in various organisms, we measured the concentrations and diastereomer and enantiomer profiles of HBCDs in 21 different species of limnic and marine cohorts from Tianjin, China. The concentration ranges of HBCDs in limnic and marine organisms were 64.3–1111 ng g⁻¹ lw and 85.5–989 ng g⁻¹ lw, respectively. Living habitat and feeding habits had important impacts on HBCD diastereomer distribution. Most of the species appeared to preferentially select (+)-α-, (−)-β- and (−)-γ-HBCD. There is a tendency that the total and α-HBCDs were magnified as trophic level increased with trophic magnification factors (TMFs) around 2. The concentrations of HBCDs in the limnic and marine fishes were highest in the liver, followed by the gill, skin, and muscle. In terrestrial plants, the highest concentrations of HBCDs were observed in the leaf, followed by the root and the rhizosphere soil. Plants showed enantioselectivity for HBCD enantiomers, which varied with plant species and organs (leaf vs. root) of the same plant. Higher estimated daily intakes (EDIs) of HBCDs were observed from fish than from wheat.     

National status and trends mussel watch program: chlordane-related compounds in Gulf of Mexico oysters, 1986-1990

The National Oceanic and Atmospheric Administration's National Status and Trends (NS&T) Program has been monitoring the chemical contamination in bivalve tissues from the US coastal waters since 1986. alpha-Chlordane, trans-nonachlor, heptachlor and heptachlor epoxide, components of technical chlordane, are among the chlorinated pesticides measured. The geographical distribution of these chlordane compounds in oyster samples from the US Gulf of Mexico is well-established. For example, highest residue levels, predominantly alpha-chlordane and trans-nonachlor, were encountered in samples collected near highly populated areas in contrast with the concentrations measured in predominantly agricultural areas. Data collected during 5 years of bivalve sampling are used to evaluate temporal trends in residue concentrations at most NS&T sites. Minor decreases can be observed in the concentrations of alpha-chlordane and trans-nonachlor. Heptachlor and its epoxide concentrations, in contrast, have been increasing since 1987.     

Bioremediation perspectives and progress in petroleum pollution in the marine environment: a review

Environmental Science and Pollution Research - The marine environment is often affected by petroleum hydrocarbon pollution due to industrial activities and petroleum accidents. This pollution has...