Vertical Profile of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, Naphthalenes, Biphenyls, Polycyclic Aromatic Hydrocarbons, and Alkylphenols in a Sediment Core from Tokyo Bay, Japan

Abstract

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and nonylphenol (NP) were measured in a dated sediment core collected from Tokyo Bay, Japan, in order to study the history of contaminant inputs and fluxes. Concentrations of organochlorine compounds measured in this study increased gradually from the beginning of the early 1900s, reached a maximum in the early 1980s, and decreased steadily until the 1990s. The profile of isomer/ congener compositions of PCDDs/DFs and PCNs varied with depth, which suggested that the sources of input of these compounds varied at different periods. The possible changing sources of PCDDs/DFs and PCNs to the environment are discussed in the context of the concentration trends and congener-specific data. The composition of PCB congeners was uniform at the top 40 cm, which corresponded to the period of usage of technical PCB mixtures, suggesting that the major single source of PCBs in sediments was technical preparations. All of the above organochlorines were detected in sediment sections collected at 90 cm depth, which corresponded to the early 1900s, suggesting the occurrence of these compounds in pre-industrial sediments. The vertical profile of PAHs was similar to that found for organochlorines with the highest concentrations occurring in the early 1980s. The vertical profile of NP concentrations was different from those observed for restricted compounds such as PCBs and PAHs. NP concentrations were greater in surface sediments (0-12 cm) than those in subsurface sediments (12-30 cm). In general, the profile of residues of organic compounds reflected production and usage trends of the respective compounds, although there was a time lag of a few years between peak periods of usage and deposition in coastal sediments. Improvements in emission controls in the late 1980s and the early 1990s appear to have been effective in reducing the inputs of organic residues to the environment; however, the concentrations of several organochlorines in surface sediments are still greater than those found in sediments from the 1970s.

Polycyclic aromatic hydrocarbons (PAHs) in the water column and sediment core of Deep Bay, South China

“…The sedimentary PAH concentrations displayed a sharp increase in the last 10 years (after 1995), largely due to the rapid economic development in this region, coupled with a rapid increase in vehicle emission and energy consumption. The profile pattern in our study was similar to those reported in the Pearl River estuary (Liu et al, 2005) and in lakes across the US (Van Metre and Mahler, 2005), where an increasing trend of PAH input was observed in recent years, but was different from those in Tokyo Bay where PAH input has significantly declined in recent years (Yamashita et al, 2000). As the average sedimentation flux was 0.28 g cm À2 a À1 in Deep Bay, the sedimentation fluxes of PAHs can be obtained by multiplying the sedimentation rate by PAH concentrations.…”

“…In the water column, PAH tend to associate with suspended particulate matter and are eventually deposited in sediments (Santschi et al, 2001). Since the deposition of sediments continues over time, sediments can act as geochronometers of the contaminant deposition in the environment as well as of general environmental change over time (Hites et al, 1977;Yamashita et al, 2000;Zhang et al, 2002;Luo et al, 2004;Kannan et al, 2005;Van Metre and Mahler, 2005). Studies concerning PAHs in water column and core sediments can lead to better understanding of PAHs cycles in top-to-bottom processes and their historical trend.…”

Occurrence of trace organic contaminants in Bohai Bay and its adjacent Nanpaiwu River, North China

“…The concentration of total PCDDs/DFs in Bohai Bay (C-3) ranged from 430 to 3100 pg/g dry wt (Table 1), which is lower than that reported in Tokyo Bay, where the PCDDs/DFs originated from several independent sources: use of PCP and chloronitrofen (CNP), emission from municipal solid waste incineration (MSWI), municipal sewage sludge, etc (Yamashita et al, 2000). The concentration of PCDDs was over 10 times higher than that of PCDFs.…”

Polychlorinated naphthalenes (PCNs) in riverine and marine sediments of the Laizhou Bay area, North China

“…In another study concerning pollutants from the industrial region of Bitterfeld, a major industrial site of chemical and metallurgical production in Germany in the 19th century, 2540 ng g À1 of PCNs were found in riverine sediments (Brack et al, 2003). By contrast, in the Laizhou Bay area with similar dense industries, it was 4e5 orders of magnitudes lower, despite PCN concentrations in developed countries have undergone a sharp decrease in the last 40 years due to the decline of production and industrial use (Gevao et al, 2000;Meijer et al, 2001;Yamashita et al, 2000b). Thus it was unlikely that technical PCN formulations were widely used in industries in the Laizhou Bay area.…”

“…Pan et al investigated PCN concentrations in sediments collected from Qingdao coast sites with a concentration of 0.2e1.2 ng g À1 dw, similar with the PCN levels in marine sediments of Laizhou Bay found in our study (Pan et al, 2007). Compared to PCN levels in sediments found in other regions (Table 1), such as backgrounds in Sweden (0.14e7.6 ng g À1 dw) (Jaernberg et al, 1993), Venice lagoon (0.03e1.51 ng g À1 dw) (Eljarrat et al, 1999), Gdansk basin of Batic Sea (6.7 ng g À1 dw) (Falandysz et al, 1996), Gulf of Bothnia (0.27e2.8 ng g À1 dw) (Lundgren et al, 2003), coast of Barcelona (0.17e3.27 ng g À1 dw) (Castells et al, 2008), lake Ontario (21e38 ng g À1 dw) (Helm et al, 2008), Tokyo bay (1.81 ng g À1 dw) (Yamashita et al, 2000b), PCN levels in marine sediment of Laizhou Bay were at the lowest end of the range, while the levels in the rivers were similar with many studies in Europe, including the background sites, bays and coastal sites.…”