Pattern and sources of naturally produced organohalogens in the marine environment: biogenic formation of organohalogens

doi:10.1016/S0045-6535(03)00211-X

Chemosphere

Volume 52, Issue 2, July 2003, Pages 313-324

https://doi.org/10.1016/S0045-6535(03)00211-X Get rights and content

Abstract

The pattern of organohalogens found in the marine environment is complex and includes compounds, only assignable to natural (chloromethane) or anthropogenic (hexachlorobenzene, PCBs) sources as well as compounds of a mixed origin (trichloromethane, halogenated methyl phenyl ether).

The chemistry of the formation of natural organohalogens is summarized. The focus is put on volatile compounds carrying the halogens Cl, Br, and I, respectively. Though marine natural organohalogens are quite numerous as defined components, they are mostly not produced as major compounds. The most relevant in terms of global annual production is chloromethane (methyl chloride). The global atmospheric mixing ratio requires an annual production of 3.5–5 million tons per year. The chemistry of the group of haloperoxidases is discussed. Incubation experiments reveal that a wide spectrum of unknown compounds is formed in side reactions by haloperoxidases in pathways not yet understood.

Introduction

Halogenated compounds found in the environment can be classified as being:

•
biogenic (e.g. CH₃Cl)
•
natural/geogenic (e.g. specific dioxins in clay)
•
having anthropogenic non-halogenated precursors (e.g. halogenated phenols formed from phenol)
•
having anthropogenic halogenated precursors (e.g. chlorophenols formed from chlorobenzenes, pentachlorophenyl methyl ether formed from pentachlorophenol), or
•
anthropogenic (e.g. freons, CH₃CCl₃, PCBs, POPs).

Since the identification of 6,6^′-dibromoindigotin (Tyrian Purple) in marine snails in 1909, a variety of biogenic carbon–halogen compounds has been detected in algae, fungi, plants and biota. The wide spectrum of natural halogenated compounds has been summarized in the past by several authors (Doonan , 1973; Fenical, 1982; Faulkner, 1984; Neidleman and Geigert, 1986; Grimvall and de Leer, 1995; Gribble, 1996, Gribble, 1998, Gribble, 1999).

Recently the group of persistent organic pollutants, the so-called POPs, which are mostly semivolatile chlorinated compounds, have gained wide political visibility thanks to actions of the UN. Ballschmiter summarized the possible spectrum of compounds that have to be discussed in this respect (Ballschmiter et al., 2001).

Polyhalogenated bi-pyrrols identified in the marine environment can be described as natural POPs, persistent organic pollutants. These halogenated 2,2^′-bipyrroles, e.g. C₁₀H₆N₂Br₄Cl₂, a 1,1^′-dimethyl-tetrabromodichloro-2,2^′-bipyrrole accumulate e.g. in fish, birds and marine mammals like the PCBs. (Gribble et al., 1999; Tittlemier et al., 1999, Tittlemier et al., 2002a, Tittlemier et al., 2002b). A C₉H₃N₂Cl₇ compound (Q₁/U₃) has also been identified as a bioaccumulating natural product (Weber and Goerke, 1996; Vetter, 1999; Vetter et al., 1999, Vetter et al., 2000). The compound C₉H₃N₂Cl₇ (Q₁/U₃) is a heptachloro-1^′-methyl-1,2^′-bipyrrole (Wu et al., 2002). A similar global spreading through the marine biosphere as it is observed for the PCBs has not been found yet for this natural heptachlorinated 1,2^′-bipyrrol (Hackenberg et al., 2001). Vetter also reported a mixed halogenated trichlorodibromo-compound in fish and seal (Vetter et al., 2001). It was tentatively assigned to a monoterpene structure.

The occurrence of natural organohalogens resembling the PCB structure, specifically a broad spectrum of volatile and bioaccumulative organohalogens, has stimulated a renewed interest in the chemistry of formation of natural organohalogen compounds under environmentally conditions. It has been known for long that fungi, for example, produce chlorophenols (Turner, 1971). The higher chlorinated compounds of this group are considered as classical anthropogenic compounds found in the environment. Even the natural formation of dioxins of the 2,3,7.8-type has been reported (Svenson et al., 1989; Hoekstra et al., 1999; Ferrario et al., 2000).

Section snippets

Biogenic fluorinated compounds

Biogenic formation of fluoro-organic compounds is mainly of theoretical relevance, though the rare organofluorine compounds are more widely spread in nature than originally presumed. F-metabolites have been discovered in bacteria, fungi (Streptomyces sp.) and higher plants but not yet in algae (Neidleman and Geigert, 1986; O’Hagan and Harper, 1999; O’Hagan et al., 1999). The toxic monofluoroacetate is found in numerous higher plants at the trace level. Ceylon tea may contain 50–160 ng/g

Volatile organohalogens in the marine environment

For natural organohalogen compounds found in the marine environment Br mostly dominates over Cl, while for natural organohalogens found in the terrestrial environment Cl dominates over Br. The volatile organohalogens like the methane derivatives CH₃Cl, CH₃Br, CH₃I, CH₂Cl₂, CH₂Br₂, CH₂I₂, CH₂ClBr, CH₂ClI, CHCl₃, CHBr₃, CHBrCl₂, CHBr₂Cl, several halogenated ethanes and acetones, and even halogenated methyl-phenyl ethers (anisoles, X_zC₆H_5−z–(OCH₃), (X=Br, Cl) can be found worldwide in the marine

Methylation reaction

CH₃Cl is by far the most abundant volatile, naturally formed organohalogen. The global atmospheric mixing ratio requires an annual production of 3.5–5 million tons per year of chloromethane (Khalil et al., 1999; Khalil and Rasmussen, 1999a, Khalil and Rasmussen, 1999b; Harper, 2000). The global atmospheric mixing ratio of methyl bromide is substantially lower (Khalil et al., 1993) (Table 2).

The formation of CH₃Cl, CH₃Br and CH₃I is mainly through biomethylation of the respective Cl⁻, Br⁻ and I⁻

In vitro incubations with chloroperoxidase (CPO)

To evaluate the possible formation of volatile halogenated C₁/C₂-hydrocarbons several in vitro incubations with chloroperoxidase (CPO) and horseradish peroxidase (HRP) were carried out with substrate molecules that are common in biochemistry and which possess a carbonyl-activated site (Walter and Ballschmiter, 1991a, Walter and Ballschmiter, 1991b).

The pattern of compounds detected by high resolution capillary gas chromatography and ECD detection is surprisingly high and variable that is formed

Water chlorination chemistry

The similarity of the chemistry discussed above with the basic chemistry of the products formed in water chlorination should be pointed out. In water chlorination as well as in the reaction pathways involving the haloperoxidases, the active species is thought to be HOX (X=Cl, Br, I).

Haloperoxidase reaction: formation of Cl⁺ $H_{2} O_{2} + Cl^{−} → H_{2} O + OCl^{−}$ $OCl^{−} + H^{+} → HOCl$ $HOCl → HO^{−} +(Cl^{+})$ $RH +n(Cl^{+})→ RCl n+ H^{+} (n=2,3)$ Water chlorination: formation of Cl⁺ $Cl_{2} + NaOH → HCl + NaOCl$ $NaOCl + H_{2} O → Na^{+} + OCl^{−}$ $OCl^{−} + H^{+} → HOCl$ $HOCl → HO^{−} +(Cl^{+})$ The

Marine areas of high primary production release halomethanes in the Atlantic and the Indian Ocean

Among the volatile halocarbons in the atmosphere the methylhalides CH₃Cl, CH₃Br and CH₃J are known to be mainly of natural origin (Khalil et al., 1993; Khalil and Rasmussen, 1999a, Khalil and Rasmussen, 1999b). The current knowledge of identity and source strength including terrestrian sources explaining the atmospheric concentration of chloromethane has recently been reviewed by Harper (2000).

There has been a long-standing discussion whether CHCl₃ besides its anthropogenic sources, which are

Pattern of global occurrence of halogenated phenyl methyl ether (HMPEs; halogenated anisols) in the marine atmosphere

Chlorophenols are normally considered as anthropogenic compounds. Chlorophenols however have been detected in fungi and soil (Hoekstra et al., 1999). The biosynthesis of chloro-metabolites by fungi has been extensively reviewed by Turner (1971).

Bromophenols are quite often found as chemical repellants in marine biota. Methylation of phenols leads to the quite volatile anisols that can be detected in the marine atmosphere on a global scale (Table 4) (Walter and Ballschmiter, 1991a, Walter and

Polychlorinated long chain (C₂₂/C₂₄) hydrocarbons

Unusual hexachlorinated aliphatic C₂₂ and C₂₄ compounds (sulfolipids) are found in phytoflagellatae. They contain two CH–OSO₃– groups, and one CH₂–CCl₂–CH₂ moiety, one CH₂–CHCl–CHCl–CH₂ moiety, and one CH₂–CHCl–CH₂–CHCl–CH₂ moiety (Mercer and Davies, 1979). No biochemical pathway of formation of the different (C–Cl) moieties of these polychlorinated C₂₂–C₂₄ sulfolipids can be given yet.

Formation of halo n-(C₁–C₃) alkanes by abiotic Fe³⁺ oxidation of organic matter––a non-biogenic natural process

Phenolic moeities of natural organic matter containing alkoxy groups can be oxidized without microbial mediation in the presence of Fe³⁺ that is reduced to Fe²⁺. During this process halides are C₁–C₃ alkylated. Methoxy-, ethoxy-, and propoxy groups of phenolic structures apparently lead to the corresponding methyl-, ethyl-, and n-propyl halides (Cl, Br, I) (Keppler et al., 2000). Details of the reaction mechanism are still open.

Classical anthropogenics as naturally produced organohalogens?

Tetrachloromethane, as well as tri- and tetrachloroethene, and hexachloroethane are normally considered as classical man-made organic atmospheric pollutants (e.g. Singh et al., 1976; Kirschmer et al., 1983; Fogelqvist, 1985; Class and Ballschmiter, 1986, Class and Ballschmiter, 1987a, Class and Ballschmiter, 1987b; Wiedmann et al., 1994; Weifl, 1996; Kleiman and Prinn, 2000). The possible natural formation of tetrahalomethanes may involve a radical mechanism (Gribble, 1996; Urhahn and

Conclusions

The spectrum of natural volatile organohalogens seems rather well established in its qualitative aspects, though single new compounds may be found in the future. It is surprising that the detailed reaction pathways of the formation of quite simple volatile organohalogens often are not known. On the other side, the chemistry of the group of haloperoxidases as seen in incubation experiments reveals that a wide spectrum of unknown compounds is formed in side reactions in pathways not yet

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ReviewPattern and sources of naturally produced organohalogens in the marine environment: biogenic formation of organohalogens

Abstract

Introduction

Section snippets

Biogenic fluorinated compounds

Volatile organohalogens in the marine environment

Methylation reaction

In vitro incubations with chloroperoxidase (CPO)

Water chlorination chemistry

Marine areas of high primary production release halomethanes in the Atlantic and the Indian Ocean

Pattern of global occurrence of halogenated phenyl methyl ether (HMPEs; halogenated anisols) in the marine atmosphere

Polychlorinated long chain (C22/C24) hydrocarbons

Formation of halo n-(C1–C3) alkanes by abiotic Fe3+ oxidation of organic matter––a non-biogenic natural process

Classical anthropogenics as naturally produced organohalogens?

Conclusions

Phytochemistry

Soil Biology Biochemistry

Enzyme and Microbial Technology

Coordination Chemistry Reviews

Chemosphere

Chemosphere

Atmospheric Environment

Catalysis Today

Atmospheric Environment

Chemosphere

Atmospheric Environment

Atmospheric Environment

Atmospheric Environment

Chemosphere

Current Opinion in Chemical Biology

Phytochemistry

Journal of Fluorine Chemistry

Water Research

Archives of Biochemistry and Biophysics

Chemosphere

Environmental Pollution

Chemosphere

Biotechnology Advances

Analytica Chimica Acta

Environmental Pollution

Formation and distribution of halogenated volatile organics in sea water

The natural formation of trichloroethylene and perchloroethylene in sea water

Alkyl nitrates, nonmethane hydrocarbons, and halocarbons gases over the equatorial Pacific Ocean during SAGA-3

Journal of Geophysical Research

Transport and fate of organic compounds in the global environment

Angewandte Chemie Int Ed Engl

Man-made chemicals found in remote areas of the world: The experimental definition for POPs

ESPR––Environ Science & Pollution Research

Ozone destruction and photochemical reactions at polar sunrise in the lower Antarctic atmosphere

Nature

Dihaloacetonitriles in chlorinated natural waters

Volatile halogen compounds in the alga Asparagopsis Taxiformis

Journal Food Chemistry

Marine haloperoxidases

Chemical Reviews

Evidence of natural marine sources for chloroform in regions of high primary production

Fresenius Zeitschrift für Analytische Chemie

Fresenius Zeitschrift für Analytische Chemie

Sources and distribution of bromo- and bromochloromethanes in marine air and surface water of the Atlantic Ocean

Journal of Atmospheric Chemistry

A Functional model for vanadium, haloperoxidase

Journal of the American Chemical Society

Functional models for vanadium haloperoxidase––reacitvity and mechanism of halide oxidation

Journal of the American Chemical Society

Halomethane: bisulfide/halide ion methyltransferase, an unusual corrinoid enzyme of environmental significance isolated from an aerobic methylotroph using chloromethane as the sole carbon source

Applied and Environmental Microbiology

The biochemistry of carbon-halogen compounds

Marine natural products: Metabolites of marine algae

Natural Products Reports

Natural products chemistry in the marine environment

Science

2,3,7,8-dibenzo-p-dioxins in mined clay products from the United States: Evidence for possible natural origin

Environmental Science & Technology

Carbon tetrachloride, tetrachloroethylene, 1,1,1-trichloro-ethane and bromoform in Arctic seawater

Journal of Geophysical Research

Halogenation and oxidation reactions with haloperoxidases

Biocatalysis

Bromochloro methoxybenzenes in the marine troposphere of the Atlantic Ocean: A group of organohalogens with mixed biogenic and anthropogenic origin

Environmental Science & Technology

Determination of biogenic halogenated methyl-phenyl-ethers (halogenated anisols) in the picogram m−3 range in air

Review
Pattern and sources of naturally produced organohalogens in the marine environment: biogenic formation of organohalogens

Polychlorinated long chain (C₂₂/C₂₄) hydrocarbons

Formation of halo n-(C₁–C₃) alkanes by abiotic Fe³⁺ oxidation of organic matter––a non-biogenic natural process

Determination of biogenic halogenated methyl-phenyl-ethers (halogenated anisols) in the picogram m⁻³ range in air

Analysis of halogenated methoxybenzenes and hexachlorobenzene (HCB) in marine air in the picogram/m³ range