3 research outputs found
Organochlorine Pesticides in Sediments around Chaohu Lake: Concentration Levels and Vertical Distribution
<p>Eighteen organochlorine pesticides (OCPs) were investigated in surface sediments from the Nanfei River and in four sediment cores from the primary estuaries of Chaohu Lake, Eastern China. The results indicate that the OCP concentrations in the surface and core sediments around Chaohu Lake were 3.48–121.08 (with a mean of 34.93) ng/g and 0.60–39.28 (7.07) ng/g, respectively. Significantly higher concentrations of ΣOCPs were observed in sediment samples from the Nanfei River and its estuary. The three important OCP contributors around Chaohu Lake were dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB), which originated primarily from the historical use of technical DDTs and HCHs. A principal component analysis (PCA) suggests that HCB and lindane may originate from the same sources, and DDTs were greatly influenced by organic carbon from the soil environment and the impact of urbanization processes.</p
Sediment Records of Polycyclic Aromatic Hydrocarbons (PAHs) in the Continental Shelf of China: Implications for Evolving Anthropogenic Impacts
Sources, compositions, and historical records of polycyclic
aromatic
hydrocarbons (PAHs) in sediment cores collected from the Yellow Sea
and the South China Sea were analyzed to investigate the influence
of anthropogenic activities. The occurrence of PAHs was mainly derived
from various combustion sources, especially the combustion of biomass
and domestic coal. Uniform composition of sedimentary PAHs (52–62%
of phenanthrene, benzoÂ[<i>b</i>]Âfluoranthene, indenoÂ[1,2,3-<i>cd</i>]Âpyrene, and benzoÂ[<i>g,h,i</i>]Âperylene) suggested
air-borne mixtures intractable to degradation. The concentrations
of the sum of 15 PAHs (16 priority pollutants designed by the United
States Environmental Protection Agency minus naphthalene; designed
as Σ<sub>15</sub>PAH) in Yellow Sea sediment cores were generally
higher than those in the South China Sea. The profiles of Σ<sub>15</sub>PAH concentrations recorded in the sediment cores closely
followed historical socioeconomic development in China. In general,
Σ<sub>15</sub>PAH concentrations started to increase from the
background pollution level posed by agricultural economy at the turn
of 20th century. In addition, a Σ<sub>15</sub>PAH concentration
reduction was observed during the Chinese Civil War (1946–1949)
and Great Cultural Revolution (1966–1976), suggesting them
as setbacks for economic development in Chinese history. Increasing
PAH emissions as a result of increasing coal combustion associated
with the rapid urbanization and industrialization since the implementation
of the Reform and Open Policy (since 1978) accounted for the fast
growth of Σ<sub>15</sub>PAH concentrations in sediment cores.
The decline of Σ<sub>15</sub>PAH concentrations from subsurface
maximum until sampling time was inconsistent with current-day economic
development in China, and may possibly suggest emission reductions
due to decreasing proportional use of domestic coal and increasing
consumption of cleaner energies (natural gas and liquefied petroleum
gas)
Anthropogenic Activities Have Contributed Moderately to Increased Inputs of Organic Materials in Marginal Seas off China
Sediment has been recognized as a
gigantic sink of organic materials
and therefore can record temporal input trends. To examine the impact
of anthropogenic activities on the marginal seas off China, sediment
cores were collected from the Yellow Sea, the inner shelf of the East
China Sea (ECS), and the South China Sea (SCS) to investigate the
sources and spatial and temporal variations of organic materials,
i.e., total organic carbon (TOC) and aliphatic hydrocarbons. The concentration
ranges of TOC were 0.5–1.29, 0.63–0.83, and 0.33–0.85%,
while those of Σ<i>n</i>-C<sub>14–35</sub> (sum
of <i>n</i>-alkanes with carbon numbers of 14–35)
were 0.08–1.5, 0.13–1.97, and 0.35–0.96 μg/g
dry weight in sediment cores from the Yellow Sea, ECS inner shelf,
and the SCS, respectively. Terrestrial higher plants were an important
source of aliphatic hydrocarbons in marine sediments off China. The
spatial distribution of Σ<i>n</i>-C<sub>14–35</sub> concentrations and source diagnostic ratios suggested a greater
load of terrestrial organic materials in the Yellow Sea than in the
ECS and SCS. Temporally, TOC and Σ<i>n</i>-C<sub>14–35</sub> concentrations increased with time and peaked at either the surface
or immediate subsurface layers. This increase was probably reflective
of elevated inputs of organic materials to marginal seas off China
in recent years, and attributed partly to the impacts of intensified
anthropogenic activities in mainland China. Source diagnostics also
suggested that aliphatic hydrocarbons were mainly derived from biogenic
sources, with a minority in surface sediment layers from petroleum
sources, consistent with the above-mentioned postulation