Bangqi Hu

Distribution, enrichment and source of heavy metals in surface sediments of the eastern Beibu Bay, South China Sea

Sixty-nine samples of surface sediments (0-5 cm) recovered from the eastern Beibu Bay were analyzed for TOC and heavy metals to examine the element distribution pattern and potential pollutant sources. The sediments in the study area are characterized by variable heavy metal concentrations that are comparable with those of the surrounding regions. Obvious positive correlations were observed amongst the concentrations of Zn, Cr, Pb, Cd, Cu and the clay contents, suggesting that fine clay particles are important carriers of trace metals in the sediments. Hg and As show a considerable/low positive correlation with TOC, indicating that organic matter may play a discernible role in the sediment chemistry. Cd contamination was detected in the north of the study area primarily due to the input of phosphate fertilizers carried by rivers. In comparison, Zn, Cr, Pb, and partly Cu are predominantly sourced from lithogenic components, and Hg and As are mainly from organic matter related to anthropogenic input.

Heavy metals distribution and contamination in surface sediments of the coastal Shandong Peninsula (Yellow Sea)

Selected heavy metals (Cr, Cu, Ni, Pb and Zn) in surface sediments from the coastal Shandong Peninsula (Yellow Sea) have been determined to evaluate the spatial distribution and potential ecological risk. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality. However, both the enrichment factor (EF) and geoaccumulation index (Igeo) values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cr, Cu and Ni were likely to pose environment risks. Spatial distribution of ecotoxicological index (mean-PEL-quotient) suggested that most of the surface sediments have a 21% probability of being toxic. Similar results were also obtained by pollution load index (PLI). The spatial distribution pattern of heavy metal in surface sediments is a basis for undertaking appropriate action to protect marine sediment quality.

Spatial distribution and pollution assessment of heavy metals in the surface sediments of the Bohai and Yellow Seas

A total of 141 surface sediments were collected and analyzed for their geochemistry, total organic carbon, and grain size to assess the heavy metal pollution in the Bohai and Yellow Seas. The enrichment factor (EF) and geoaccumulation index (Igeo) of Cu, Pb, Zn, Cr, Cd, Ni, As, and Hg were calculated to assess anthropogenic contamination, and the results suggest that moderate Pb, Cd, and As contamination occurs in the study area. Sediment quality guidelines were applied to assess the adverse biological effects of these metals. The spatial distribution of the mean Effects Range-Median quotient for the vast majority of the study area is between 0.1 and 0.5, indicating low impact and potential negative biological effects. Multivariate analysis indicates that Cu, Pb, Zn, Cr, and Ni resulted primarily from lithogenic sources, whereas As, Cd, and Hg were mainly attributed to anthropogenic sources.

Seasonal variability and flux of particulate trace elements from the Yellow River: Impacts of the anthropogenic flood event

In this study, the suspended particulate matter (SPM) of the Yellow River (Huanghe) was collected biweekly at the outlet and analyzed for particulate trace element contents. The seasonal variations of the trace elements were primarily controlled by hydrological processes, which determined different sources of the SPM. Moreover, As, Co, Cr, and Ni primarily originated from lithogenic sources, whereas Cd, Cu, Pb and Zn were influenced by anthropogenic activities. The Yellow River has suffered moderate to considerable ecological risk during the late stage of Water and Sediment Regulation (WSR). Using the discharge-weighted contents method, the annual trace element fluxes were estimated, with ca. 30% of the annual fluxes occurring within the short WSR period (6% of one year). More specifically, 75% of the Cd flux was from an anthropogenic source, which likely posed a significant threat to the estuary and the adjacent coastal ecosystems.

One hundred-year sedimentary record of heavy metal accumulation in the southeastern Liaodong Bay of China

Integrated analyses of grain size, 210Pb stable isotope, and heavy metals were performed to characterize the sedimentary core LDC30 collected from the southeastern Liaodong Bay of China and investigate the 100-year history of heavy metal accumulation. The aluminum-normalized enrichment factors and the excess metal fluxes (MFxs) indicated that the metal accumulation in the southeastern Liaodong Bay occurred in three stages: a pre-industrial stage (prior to 1960s) with natural accumulation, an initial industrial stage (1960–1990) with slowly elevated accumulation, and an industrialized stage (post-1990s) with accelerated accumulation. A moderate enrichment of Cd and Pb (up to 4.1- and 2.6-fold over the baseline, respectively) and a slight enrichment of Cr, Cu, Ni, and Zn (up to 1.3-fold) were measured in the recent sediments. Multivariate analysis demonstrated that the Cr, Cu, Ni, and Zn were from the natural origin, whereas Cd and Pb from the anthropogenic origin. The MFxs of Cd and Pb showed a drastically increasing trend since 1990s, which could result from the intensive application of fertilizers and combustion of fossil fuels.

Prehistoric heavy metal pollution on the continental shelf off Hainan Island, South China Sea: From natural to anthropogenic impacts around 4.0 kyr BP:

Human–environment interactions across historical periods in China have been well reconstructed over the past decade; however, few studies have focused on southern China, particularly Hainan Island. This study investigated two sediment cores (cores X1 and X2) collected from the continental shelf off Hainan Island in the northern South China Sea. Combined with geochemical compositions (Al, Ni, Cu, Zn, Cd, and Pb), Sr-Nd isotopes, grain size, and AMS 14C ages, our results showed that Cd and Cu in core X1 and Cd and Pb in core X2 have been mainly influenced by anthropogenic activities since ~4.0 kyr BP. The enrichment factors showed obvious increases starting at ~4.0 kyr BP and were in good accordance with the appearance of abundant archeological sites on Hainan Island. Significant climatic changes (i.e. decreases in the East Asian summer monsoon and increases in El Niño–Southern Oscillation activities) at ~4.0 kyr BP likely promoted more intense, localized human activities, which in turn enhanced heavy metal accumulation in the continental shelf sediments. These results provide new insights into the history of human activities on Hainan Island and indicate that the geochemical compositions of continental shelf sediments have the potential for broadening our knowledge of the human activities and cultural development in tropical areas.

Distribution pattern and controlling factors of heavy mineral assemblages in surficial seafloor sediments offshore of the Eastern Shandong Peninsula (Yellow Sea)

The source and processes controlling the deposition of the sand fraction of muddy seafloor sediments remain poorly understood. Surficial seafloor sediments were collected offshore of the Eastern Shandong Peninsula and were analyzed regarding their detrital heavy mineral constituents and grain size distributions to determine their spatial distribution patterns, sand fraction provenance, and transport pathways. Five sediment types were identified in the study area: clayey silt, silt, sandy silt, silty sand, and sand. Each of these sediment types displayed distinct grain size parameters of their corresponding sand fractions. Moreover, three statistical clusters of sand grains were identified, suggesting variations in provenances and sedimentary processes from one cluster to the next. Twenty-five species of detrital heavy minerals in the sand fraction were identified and then assigned to four categories based on their mineral stability (i.e., ultrastable, stable, moderately stable, and unstable). The sandy sediments were enriched in ultrastable and stable heavy minerals, indicating that these sand grains mostly originated from coastal erosion of granitic and/or metamorphic rocks. In contrast, the muddy sediments were characterized by unstable heavy minerals dominated by hornblende and epidote. The results of principal component analysis further suggested that these sand grains are similar in terms of their provenance (coastal erosion) but have undergone complex sedimentary processes. Relative sea level changes during the late Quaternary caused shifts in the sediment sources and supplies, which were the primary factors controlling the grain sizes of the sand fractions and heavy mineral assemblages in the surficial sediments of the study area.