珠江河口区翡翠贻贝中有机氯农药和多氯联苯含量及分布

对分布于珠江河口区海域的翡翠贻贝有机氯农药和多氯联苯的含量进行测定 ,结果显示 :HCHs为ND— 1.1ng·g-1,DDTs为 9.5— 191ng·g-1,PCBs为 82 .8— 6 15 .1ng·g-1.尖沙嘴码头 (维多利亚港 )贻贝积累的PCBs浓度最高 ,珠江河口桂山岛和外伶仃岛的贻贝积累的DDTs和PCBs浓度较高 ,而荷包岛 (珠江河口西海区 )的贻贝则检出含量较高的HCHs和DDTs .贻贝选择性积累含 5— 6个氯原子数的PCB异构体 .各采样点贻贝积累的PCBs组成分析表明珠江河口区海域存在两个PCBs污染源     

渤海沿岸底栖贝类体内微污染物残留

依据第二次海洋污染基线调查数据以确定渤海沿岸站位底栖贝类体内重金属和有机污染物含量范围和分布特征.结果表明,沿岸贝类体内Cd的含量普遍较高,而As、Hg和Pb的浓度水平大多较低.辽东湾沿岸贝类体内检测到较高的DDT显示附近区域有新的DDT输入.PCBs的生物残留量以莱州湾近岸为最高,其次是渤海湾近岸;酞酸酯的生物残留主要出现在莱州湾和辽东湾沿岸站位.渤海沿岸大部分站位贝类体内DDTs组份含量已超出相应的USEPA人体健康和野生动物的质量基准,应予以关注.     

Meter-scale variation within a single transect demands attention to taxon accumulation curves in riverine microbiome studies

● Riverine microbiomes exhibited hyperlocal variation within a single transect. ● Certain family-level taxa directionally associated with river center and bank. ● Taxon accumulation curves within a transect urges more nuanced sampling design. Microbial communities inhabiting river ecosystems play crucial roles in global biogeochemical cycling and pollution attenuation. Spatial variations in local microbial assemblages are important for detailed understanding of community assembly and developing robust biodiversity sampling strategies. Here, we intensely analyzed twenty water samples collected from a one-meter spaced transect from the near-shore to the near-center in the Meramec River in eastern Missouri, USA and examined the microbial community composition with 16S rRNA gene amplicon sequencing. Riverine microbiomes across the transect exhibited extremely high similarity, with Pearson’s correlation coefficients above 0.9 for all pairwise community composition comparisons. However, despite the high similarity, PERMANOVA revealed significant spatial differences between near-shore and near-center communities (p = 0.001). Sloan’s neutral model simulations revealed that within-transect community composition variation was largely explained by demographic stochasticity (R² = 0.89). Despite being primarily explained by neutral processes, LefSe analyses also revealed taxa from ten families of which relative abundances differed directionally from the bank to the river center, indicating an additional role of environmental filtering. Notably, the local variations within a river transect can have profound impacts on the documentation of alpha diversity. Taxon-accumulation curves indicated that even twenty samples did not fully saturate the sampling effort at the genus level, yet four, six and seven samples were able to capture 80% of the phylum-level, family-level, and genus-level diversity, respectively. This study for the first time reveals hyperlocal variations in riverine microbiomes and their assembly mechanisms, demanding attention to more robust sampling strategies for documenting microbial diversity in riverine systems.