Bioaccessibility and human health implications of heavy metals in different trophic level marine organisms: A case study of the South China Sea.

This study investigated the total concentrations and bioaccessibility of heavy metals in edible tissues and trophic levels of 12 marine organism species in the South China Sea. The results were used to estimate health risks to humans. Of the heavy metals detected, nickel (Ni) was present at the highest concentrations, followed in descending, order by iron (Fe), zinc (Zn), manganese (Mn), chromium (Cr), copper (Cu), cadmium (Cd) and lead (Pb). Cd had the highest percentage bioaccessibility (61.91%). There were no correlations between log-transformed total metal concentrations and trophic level values, nor between log-transformed bioaccessibility metal concentrations and trophic level values. This indicates there is no biomagnification among these trace metals. The carcinogenic risk probabilities for Pb and Cr to urban and rural residents were below the acceptable level (< 1â€¯× 10-4). The target hazard quotient (THQ) value for each metal and the total THQ values for all metals studied indicated no significant risk of non-carcinogenic effects to urban and rural residents from consuming marine organisms from the South China Sea.

Distribution and sources of organic carbon, nitrogen and their isotopes in surface sediments from the largest mariculture zone of the eastern Guangdong coast, South China.

China is the world's largest mariculture producer. However, there is limited detailed information on organic matter distribution generated by mariculture in China. This study assessed the total organic carbon (TOC), total nitrogen (TN), and isotopic composition (δ13C and δ15N) in surface sediments from Zhelin Bay in South China. TOC, TN, δ13C and δ15N ranged from 0.46-1.23%, 0.08-0.20%, -22.07 to -21.13‰ and 5.28-7.14‰, respectively, and followed similar spatial patterns. The C/N ratio coupled with isotopic composition (δ13C and δ15N), indicates that the TOC originated from both terrestrial and marine sources. In general, surface sediments of Zhelin Bay were dominated by marine derived organic carbon; this form of carbon was separately calculated based on δ13C-based two end-member mixing and C/N ratio models.

Changes of the Macrobenthic Faunal Community with Stand Age of a Non-native Mangrove Species in Futian Mangrove National Nature Reserve, Guangdong, China.

Ya-Fang Li, Fei-Yan Du, Yang-Guang Gu, Jia-Jia Ning, and Liang-Gen Wang (2017) Sonneratia apetala, a non-native superior rapidly growing mangrove species with wide environmental tolerance, has been introduced to Futian National Nature Reserve in Shenzhen, Guangdong, China, for mangrove restoration since 1993. However, the community structure of the associated macrobenthic fauna, a vital component of energy ow and nutrient recycling, remains obscure. The present study analyzed the macrobenthic faunal community, associated habitat characteristics and physico-chemical properties of sediment in rehabilitated S. apetala forests at stand ages of 8, 9, 14, 16 and 20 years from November 2014 to May 2015. Habitat complexity and stand structural heterogeneity varied with stand age. Sediment physico-chemical properties were similar for all stands analyzed, although soil organic matter (SOM) content was significantly higher in the 20-year-old stand than in others. Shannon-Weaver (H') and Pielou's evenness (J) indices of macrobenthic fauna were highest in 14- and 16-year- old stands, respectively, and lowest in 8-year-old stands. In contrast, abundance and biomass peaked in 8-year- old stands and were lowest in 16-year-old stands. Multivariate analysis (cluster, ANOSIM and SIMPER) showed that the macrobenthic faunal community in the 20-year-old stand was different from other stand ages because of a greater abundance of small-sized mollusks and opportunistic species. Spearman correlation analysis showed that H' was positively correlated with salinity. The distance-based linear model suggested that SOM was a significant predictor variable correlated with the macrobenthic faunal community. However, SOM was the only significant predictor variable explaining 12.7% of the total variation; this implies that the spatial variation of the macrobenthic faunal community here was mostly independent of the sediment properties measured. Therefore, we conclude that habitat characteristics such as vegetation characteristics can potentially explain the majority of the variation.

Heavy metals in fish tissues/stomach contents in four marine wild commercially valuable fish species from the western continental shelf of South China Sea.

The concentrations of heavy metals (Cd, Pb, Cr, Ni, Cu and Zn) were determined in four commercially valuable fish species (Thunnus obesus, Decapterus lajang, Cubiceps squamiceps and Priacanthus macracanthus), collected in the western continental shelf of the South China Sea. Concentrations of Cd, Pb, Cr, Ni, Cu, and Zn in fish muscles were 0.006-0.050, 0.13-0.68, 0.18-0.85, 0.11-0.25, 0.12-0.77, and 2.41-4.73µg/g, wet weight, respectively. Concentrations of heavy metals in all species were below their acceptable daily upper limit, suggesting human consumption of these wild fish species may be safe, with health risk assessment based on the target hazard quotients (THQ) and total THQ, indicating no significant adverse health effects with consumption. The average concentrations of Zn were higher in gills than in stomach contents, backbones or muscle, while conversely, the other heavy metals had higher concentrations in stomach contents than in other tissues.

Fuzzy comprehensive assessment of heavy metals and Pb isotopic signature in surface sediments from a bay under serious anthropogenic influences: Daya Bay, China.

The fuzzy comprehensive assessment was undertaken to evaluate the marine sediment quality in Daya Bay, China based on the monitoring data of 2015 and China National Standard for Marine Sediment Quality (GB 18668-2002). The results demonstrated that the average metal concentrations (mg/kg) were 0.08 (Cd), 51.30 (Pb), 91.30 (Cr), 29.63 (Cu), 143.42 (Zn), 0.03 (Hg), and 7.31 (As), which were clearly higher with respect to their corresponding background values. Cr was the major pollutant based weight matrices calculated. Taken as whole, the membership degree of class I was a range from 0.65 to 1, suggesting that the marine sediment quality in Daya Bay belongs to class I. Pb stable isotopic analysis coupled with geographic information system (GIS) approach showed the sedimentary Pb mainly originated from petrochemical industry at northwest coast of Daya Bay.

Speciation and risk of heavy metals in sediments and human health implications of heavy metals in edible nekton in Beibu Gulf, China: A case study of Qinzhou Bay.

We investigated the total concentrations of heavy metals in surface sediments and nekton, along with sediment metal chemical partitioning in Qinzhou Bay of the Beibu Gulf. Cd was preferentially associated with the acid-soluble fraction and Pb mainly with the reducible fraction, whereas a major portion of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. A principal component analysis (PCA) in sediment metal speciation revealed three groupings (Cd; Pb; Cr, Ni, Cu, and Zn) that mainly resulted from different distributions of the metals in the various fractions. The Cr concentrations in nekton species were higher than maximum Cr concentrations permitted by the Chinese National Standard (GB 2762-2012). Taking as a whole, surface sediments of Qinzhou Bay had a 21% incidence calculation of adverse biological effects, based on the mean probable-effects-levels quotient. A human health risk assessment indicated no significant adverse health effects from consumption of nekton.