RESUMO
Persistent organic pollutants (POPs) in the environment have the characteristics of persistence, bioaccumulation, teratogenicity, carcinogenicity, and mutagenicity. Long-term exposure of low-content POPs will also have a certain impact on marine ecosystems and human beings. The contents of three typical persistent organic pollutants[polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polycyclic biphenyls (PCBs)] of surface sediments were analyzed using gas chromatography and mass spectrometry (GC-MS) to assess the pollution characteristics of persistent organic pollutants in Boao coastal waters. The distribution and source of persistent organic pollutants were analyzed in this study, and the ecological risk was assessed using three different methods:the effect interval low/median method (ERL/ERM), mean effect interval median quotient method (M-ERM-Q), and mean potential impact concentration quotient method (M-PEC-Q). The results indicated that the contents (measured by dry weight) of ΣPAHs, ΣOCPs, and ΣPCBs in the study area were 4.5-367.50, 3.99-175.30, and ND-2.89 ng·g-1, respectively, which were at a low level, and the overall distribution showed a trend of gradually increasing toward the sea. The results of POPs source analysis showed that the PAHs in the study area were mainly from the combustion of wood and coal. Among OCPs, the HCH was mainly from lindane, the historical land-based input had been completely degraded, and the DDT was mainly the traditional DDTs pesticides, with additional continuous DDT input. The PCBs were primarily pentachlorobiphenyls, which might have come from the release of paint on the bottom of the hull in the early stage of shipping and the peeling off of paint from old ships. The ecological risk assessment results showed that there was little difference among the assessment results of the three methods, which showed that only phenanthrene monomer of PAHs in the study area had a slight negative impact, and the DDT and the γ-HCH among PAHs would cause great ecological risk, whereas PCBs and other pollutants would not cause ecological risk. On the whole, the possibility of comprehensive ecological risk caused by the three pollutants was very small.
RESUMO
In the title compound, catena-poly[[trisilver(I)-tri-mu3-N,N-diethyldithiocarbamato-3'kappaS:1kappaS':2kappaS;1kappaS:2kappaS':3kappaS;2kappaS:3kappa2S,S':1'kappaS'], [Ag3(C5H10NS2)3]n, the trigonally and tetrahedrally coordinated Ag atoms are mu3-bridged by kappa3- and kappa4-S2CNEt2 ligands to form a ribbon structure along the c axis. There is a twofold axis parallel to the b axis and passing through the tetrahedrally coordinated Ag atom. The S2CNEt2 ligands coordinate the Ag atoms in eta1,eta2- and eta2,eta2-fashions, depending on the bridging S atoms. The distances between the trigonal Ag and S atoms are 2.4915 (11)-2.6205 (11) A, while those between the tetrahedral Ag and S atoms are 2.5457 (11) and 2.7145 (10) A. The shortest Ag...Ag distance between trigonal Ag atoms is 2.8336 (7) A, which indicates a weak Ag...Ag interaction, whereas the shortest distance between trigonal and tetrahedral Ag atoms is 3.463 (6) A, which is considered as non-bonding.
