Are oil spills an important source of heavy metal contamination in the Bohai Sea, China?

Accurate evaluation of the heavy metal contamination caused by oil spills is more urgent than that of organic pollution since heavy metals are toxic and persistent. This study applies bulk geochemical parameters and hydrocarbon compositions to explore heavy metal contamination caused by oil spills. The contents of six heavy metals (Cu, Pb, Zn, Cr, Ni, and Co), total organic carbon, aliphatic hydrocarbons, and grain size were measured in 50 subsurface sediment samples obtained from an area affected by oil spills in the Bohai Sea. The values of the contamination factor (CF), the geo-accumulation index (Igeo), and the enrichment factor (EF) indicate moderate contamination with the six investigated heavy metals at most of the sampling sites. Riverine inputs, oil spills, and airborne dust are the three main sources of the heavy metals, and oil spills are the significant source of heavy metal contamination in the areas. The distributions of the mean grain size (Mz) and the contents of unresolved complex mixture (UCM) and Cr suggest that crude oil migrates from deep hydrocarbon reservoirs through geological faults and seeps through coarse-grained sediments until it reaches fine-grained sediments. The spilled oil contributes appreciable amounts of heavy metals to the sediments at the oil-contaminated sites. At these sites, the heavy metals from oil spills overprinted on those contributed by terrigenous materials, which are the predominant source of metals in the subsurface sediments in the areas affected by oil spills.

An analysis of organic matter sources for surface sediments in the central South Yellow Sea, China: evidence based on macroelements and n-alkanes.

By analyzing the composition of n-alkane and macroelements in the surface sediments of the central South Yellow Sea of China, we evaluated the influencing factors on the distribution of organic matter. The analysis indicates that the distribution of total organic carbon (TOC) was low in the west and high in the east, and TOC was more related to Al2O3 content than medium diameter (MD). The composition of n-alkanes indicated the organic matter was mainly derived from terrestrial higher plants. Contributions from herbaceous plants and woody plants were comparable. The comprehensive analysis of the parameters of macroelements and n-alkanes showed the terrestrial organic matter in the central South Yellow Sea was mainly from the input of the modern Yellow River and old Yellow River. However, some samples exhibited evident input characteristics from petroleum sources, which changed the original n-alkanes of organic matter in sediments.

miRNAs: biogenesis, origin and evolution, functions on virus-host interaction.

MicroRNAs (miRNAs) are small endogenous non-coding functional RNAs. They can play vital roles in post-transcriptional regulating mRNAs transcripts in nearly all biological processes. More and more reports on miRNAs come from different species (animal, plant, bacteria, virus) in the researches in development, immunity, apoptosis, tumor, virus-host interaction. These recent findings provide new insights into the roles of miRNAs as well as their function. This review outlines the ever-deepening understanding of miRNAs (biogenesis, origin, evolution), and discusses functions from host and viral miRNAs in the context of virus-host interaction.

[Diurnal dynamics of photosynthetic and transpiration rates of alfalfa under dry farming and their relationships with environmental factors].

In this paper, the diurnal dynamics of photosynthetic rate (Pn) and transpiration rate ( Tr) of four years planted alfalfa under dry farming, as well as those of photosynthetic active radiation (PAR) , CO2 concentration in field ( Ca ) , relative humidity (RH) and air temperature ( Ta) were measured, and the relationships between the diurnal dynamics of Pn, Tr and climatic factors were analyzed by correlation coefficient, path coefficient, and decision coefficient analyses. The results showed that T. had the greatest effect on the diurnal dynamics of Pn , while RH, PAR and C, affected P,, mainly through their acting on Ta PAR had the greatest effect on the diurnal changes of Tr, and RH, Ta and Ca affected Tr indirectly by acting on PAR. For the characteristics of photosynthesis and transpiration, PAR was the primary determining factor, and Ta was the main limiting factor.