Driving factors influencing spatiotemporal variation of natural organic chlorine in Shennongjia forest soil.

Studying the geochemical behavior of chlorine is the basis of understanding the chlorine cycle in nature. To explore the spatiotemporal distribution of natural organic chlorine (Clorg), L layer (litter fall), F-H layer (humification zone), topsoil layer (0-20 cm), and deep soil layer (20-40 cm) samples were collected from 18 sampling sites at different altitudes (851-2918 m) in Shennongjia Forest in May, August, and December. Clorg content was analyzed, and the Clorg stocks were calculated. The major factors affecting the distribution of Clorg were explored. The results revealed that the sum of Clorg content in four layers varied from 7.958 to 184.686 mg/kg, and the highest value was observed in August. Clorg accounted for 46%-77% of total chlorine, with the highest mean ratio in soil layer (0-20 cm). Clorg content exhibited the following trend: F-H layer > L layer > topsoil layer (0-20 cm) > deep soil layer (20-40 cm). The seasonal patterns of Clorg in soil layers were different from that in L and F-H layers, which were mainly controlled by the content and humification degree of organic matter. Clorg storage was much higher in soil layers (61-246 kg/ha) than those in F-H layer (1.1-7.1 kg/ha) and in L layer (0.1-0.8 kg/ha) because of the large thickness of the soil layers. Overall, the Clorg content exhibited an increasing trend with altitude, except at an altitude of approximately 1800 m. Clorg content in L and F-H layers varied more obviously with altitude than that in soil layers. When inorganic chlorine (Clin) was not a limiting factor for the chlorination process, Clorg content in L and F-H layers was significantly affected by climate and organic matter controlled by altitude, while Clorg content in soil layers was also mediated by metal ions and pH, and soil particle size. This study could provide a scientific basis for assessing the chlorine cycle in nature.

High genetic diversity and frequent genetic reassortment of avian influenza A(H9N2) viruses along the East Asian-Australian migratory flyway.

To understand the molecular epidemiology and evolution of avian influenza viruses (AIV) along the East Asian-Australian migration flyway, we collected faecal samples (n=2859) between November 2014 and March 2015 from poultry, environmental sources and wild birds in Dongying, Shandong province and Yancheng, Jiangsu province in eastern China. The presence of AIV RNA was evaluated by real-time PCR and the positivity rate ranged from 0 to 29.3%. In both Dongying and Yancheng, samples collected from live poultry markets had the highest positivity rate for AIV RNA. AIV whole genomes were generated and phylogenetically analysed. Our results demonstrate that most of the viruses belonged to the H9N2 subtype, and could be classified into nine novel genotypes based on the phylogenetic analysis of the eight gene segments of the AIV genomes. This revealed a high genetic diversity of H9N2 in this region and suggested that they might have undergone frequent genetic reassortment. In addition, the internal genes (PB2, etc.) of two viruses from wild birds and several viruses from poultry belonged to the same gene constellation, suggesting a potential inter-host transmission of AIV between wild birds and poultry in live markets along routes of migratory flyways. Our results highlight the high genetic diversity of AIV along the East Asian-Australian migration flyway and the need for more extensive AIV surveillance in eastern China.