基于诊断色素分析的胶州湾浮游藻功能类群研究

分析了2003年12月至2004年10月胶州湾18个站位7个航次的浮游藻色素组成(包括叶绿素和类胡萝卜素)。使用岩藻黄素、多甲藻黄素、色素组合(别黄素+19'-丁酰氧基岩藻黄素+19'-己酰氧基岩藻黄素+青绿藻黄素)和玉米黄素作为特定功能类群的诊断色素指标定义了四个浮游藻功能类群(PFTs), 即硅藻、甲藻、微型鞭毛藻和蓝细菌, 并根据各浮游藻功能类群的诊断色素(组合)占诊断色素总量的比例研究了各功能类群在胶州湾的时空分布特点, 结果表明硅藻是胶州湾的优势类群(平均占65.8%), 微型鞭毛藻次之(26.0%), 甲藻和蓝细菌最低(分别为6.3%和1.9%)。基于诊断色素指标的浮游藻功能类群分析是一种简便的判断优势浮游藻类群组成和丰度的方法。     

Differences in SEM-AVS and ERM-ERL predictions of sediment impacts from metals in two US Virgin Islands marinas

Two US Virgin Islands marinas were examined for potential metal impacts by comparing sediment chemistry data with two sediment quality guideline (SQG) values: the ratio of simultaneously extractable metals to acid volatile sulfides (SEM-AVS), and effects range-low and -mean (ERL-ERM) values. ERL-ERMs predicted the marina/boatyard complex (IBY: 2118 microg/g dry weight total metals, two exceeded ERMs) would have greater impacts than the marina with no boatyard (CBM: 231 microg/g dry weight total metals, no ERMs exceeded). The AVS-SEM method predicted IBY would have fewer effects due to high AVS-forming metal sulfide complexes, reducing trace metal bioavailability. These contradictory predictions demonstrate the importance of validating the results of either of these methods with other toxicity measures before making any management or regulatory decisions regarding boating and marina impacts. This is especially important in non-temperate areas where sediment quality guidelines have not been validated.     

IPCC确定的几种未来大气CO_2浓度水平对人为CO_2排放的限制

用三维海洋碳循环模式和一个简单的陆地生物圈模式计算了ＩＰＣＣ（政府间气候变化委员会）未来大气ＣＯ２情景中海洋和生物圈的吸收，并结合上地变化的资料得出燃料的排放值。结果表明：尽管在所有的构想下，为了使大气中ＣＯ２浓度达到稳定必须减少排放，但对应不同的ＩＰＣＣ未来大气ＣＯ２情景，对人为ＣＯ２排放的限制是很不相同的。     

Biomagnification in marine systems: the perspective of an ecologist

Biomagnification is the process where xenobiotic substances are transferred from food to an organism resulting in higher concentrations compared with the source. It is widely believed that this is a general phenomenon for marine food webs. An analysis of 148 papers with biomagnification in the title shows that under half show biomagnification. Of studies on metals only organic mercury shows biomagnification and most metals are regulated and excreted and do not biomagnify. Of the studies on organic compounds 67% claimed to show biomagnification. However, bioconcentration (uptake from the surrounding water) is the most usual way that organic compounds are accumulated in organisms from invertebrates to and including fish. Only in sea-birds and marine mammals is food intake the major route and where biomagnification can be clearly shown. Body concentrations of organic compounds vary with lipid content and thus in order to compare across species normalisation to uniform lipid content should be done. Yet often this is not done so data purporting to show biomagnification merely relate to differing lipid content in the different species studied. Finally suggestions are made as to how data can be collected to better interpret the process of biomagnification in marine food webs.     

Arsenic and metal contamination of water resources from mining wastes in Korea

 Water resources near a gold-mine waste site were studied for the distribution and contents of contaminants, and their behavior in the surface and groundwater systems. Arsenic, cadmium, and manganese were identified with levels exceeding the drinking water guidelines of WHO (World Health Organization), and their distribution depended upon the differences in source materials and in spatial pH variations. Originating from arsenopyrite, concentrations of dissolved arsenic were controlled by sorption with amorphous iron (Fe(OH)₃) and carbonate minerals. Cadmium and manganese were derived from the mineral phase including sphalerite (ZnS), otavite (CdCO₃), and rhodochrosite (MnCO₃); their concentrations in water resources were limited by the solubility of mineral phases. All of these processes are significantly pH-dependent, implying that a small decline in pH could result in a drastic increase in contaminant concentrations and become a pollution threat to the water resources of the Gubong area. Received: 13 December 1999 · Accepted: 21 March 2000     

Electrochemical Evidence for Pentasulfide Complexes with Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+

A series of stable pentasulfide complexes of the common base metals, Mn, Fe, Co, Ni, Cu and Zn exist in aqueous solutions at ambient temperatures. Pure sodium pentasulfide was prepared and reacted with the divalent cations of Mn, Fe, Co, Ni, Cu and Zn in aqueous solution at ambient temperature. The S52- complexes were found to exist as determined by voltammetric methods.Pentasulfide complexes with compositions assigned as [M(1-S5)] and [M2(- S5)]2+ occur for Mn, Fe, Co and Ni where only one terminal S atom in the S52- binds to one metal (1 = mono-dentate ligand or M-S-S-S-S-S, = ligand bridging two metal centers or M-S-S-S-S-S-M). Conditional stability constants are similar for all four metals with log 1 between 5.3 and 5.7 and log 2 between 11.0 and 11.6. The constants for these pentasulfide complexes are similar to the tetrasulfide complexes and are approximately 0.4–0.8 log units higher than for comparable bisulfide complexes [M(SH)]+ as expected based on the higher nucleophilicity of S52- compared to HS-. Voltammetric results indicate that these are labile complexes.As with the bisulfide and tetrasulfide complexes, Zn(II) and Cu(II) are chemically distinct from the other metals. Zn(II) reacts with pentasulfide to form a stable monomeric pentasulfide chelate, [Zn(1-S5)] with log = 8.7. Cu(II) reacts with pentasulfide to form a complex with the probable stoichiometry [Cu(S5)]2 with log estimated to be 20.2. As with the other four metals, these complexes are comparable with the tetrasulfide complexes. Discrete voltammetric peaks are observed for these complexes and indicate they are electrochemically inert to dissociation. Reactions of Zn(II) and Cu(II) also lead to significant breakup of the polysulfide.The relative strength of the complexes is Cu > Zn > Mn, Fe, Co, Ni. Cu displaces Zn from [Zn(1- S5)] and both Cu and Zn displace Mn, Fe, Co and Ni from their pentasulfide complexes.     

Comparing water use patterns of sand-binding species in an alpine semi-arid desert

The processes of species obtaining water resources are crucial to evaluate the adaptability of plantations, which can affect the establishment and survival of restored ecosystems and functions of water-limited ecosystems. However, there are still limitations in understanding water use patterns of different four plantations (Populus sylvestris, Salix cheliophe, Hippophae rhamnoides and Artemisia ordosica) in the Qinghai Lake basin. Stable isotopes of xylem water of four individual species were analysed at different dunes located at the eastern shore of Qinghai Lake in 2018 and 2019. The purpose of this study was to explore potential water sources used by different life form plants, to identify whether the soil moisture content and root distribution determined the plants water use patterns. Results from the Bayesian mixing model MixSIAR showed that all species mainly uses three levels of soil water, but they extracted soil water from different layers in different growing seasons among species. All species primarily depended on water from upper soil layers at the early growing stage, but P. sylvestris and S. cheliophe also absorbed much proportion middle and deep soil layers' water in dry year of 2019. All four species shift to use middle or deep soil layer water rather than shallow water in July with the most rainfall and soil water content (SWC). However, it was only used by P. sylvestris and H. rhamnoides in 2018. In all, seasonal water use pattern of different species was affected by SWC, soil texture and root distribution. Compared with moratorium plantations such as S. cheliophe, mixed afforestation of P. sylvestris and H. rhamnoides maximized of soil water sources absorbed by the plants. The study can shed light on plant–water relationships to facilitate the woody species for afforestation and desertification restoration management in the semi-arid desert ecosystem.