Determination of cadmium(II), copper(II), manganese(II) and nickel(II) species in Antarctic seawater with complexing resins

The strong species of cadmium(II), copper(II), manganese(II) and nickel(II) in an Antarctic seawater sample are investigated by a method based on the sorption of metal ions on complexing resins. The resins compete with the ligands present in the sample to combine with the metal ions. Two resins with different adsorbing strengths were used. Very stable metal complexes were investigated with the strong sorbent Chelex 100 and weaker species with the less strong resin, Amberlite CG-50. Strong species were detected for three of the considered metal ions, but not for Mn(II). Cu(II) is completely linked to species with a side reaction coefficient as high as log α_M(I) = 11.6 at pH = 7.3. The ligand concentration was found to be similar to that of the metal ion, and the conditional stability constant was around 10²⁰ M^− 1. In the considered sample, only a fraction of the metal ions Cd(II) and Ni(II) is bound to the strong ligands, with side reaction coefficients equal to log α_M(I) = 5.5 and 6.5 at pH = 7.3 for Cd(II) and Ni(II), respectively. These findings were confirmed by the test with the weaker sorbent Amberlite CG-50. It can be calculated from the sorption equilibria that neither Mn(II) nor Ni(II) is adsorbed on Amberlite CG-50 under the considered conditions and, in fact, only a negligible fraction of Mn(II) and Ni(II) was adsorbed. A noticeable fraction of Cd(II) was adsorbed on Amberlite CG-50, meaning that cadmium(II) is partially linked to weak ligands, possibly chloride, while no copper(II) was adsorbed on this resin, confirming that copper(II) is only combined in strong species. These results are similar, but not identical, to those obtained for other seawater samples examined in previous investigations.     

Rectification of nomenclature for Melagraphia aethiops (Gmelin) and Diloma bicanaliculata (Dunker) (Mollusca: Trochidae)

Alterations to nomenclature for two common intertidal New Zealand ‘top shells’ necessitated by re‐examination of type material have been confused by ambiguities in the way the alterations were first presented. We draw attention to recent misinterpretations and clarify the nomenclature. Condensed synonymies that indicate names used for each species during the interregnum are given, allowing papers dealing with these trochids to be read without uncertainty as to which species were really meant by the authors.     

The Biology of Upogebia pusilla (PETAGNA) (Decapoda, Thalassinidea)

Abstract. The distribution of the thalassinidean shrimp Upogebia pusilla was studied at four sites in the North Adriatic Sea: 1) a tidal flat in the lagoon of Grado, 2) a tidal flat at Lido di Staranzano near the mouth of the Isonzo, 3) a mud flat seawards of a salt marsh in a protected bay north of Rovinj, and 4) a sublittoral station in 6m depth near Aurisina. Information on grain size distribution, organic content, amount of debris, redox profiles and pH of sediment as well as temperature and salinity is given. Density, as determined by hole counts and a hole: burrow relationship derived from resin casting, generally increased with increasing water depth in the intertidal. The upper limits ranged between +10cm (Rovinj) and -20cm (Grado); densities between mean water and low water level varied strongly due to microtopography and macrophyte cover. Maximum densities in the intertidal ranged from 189 (Grado) to 2420 (Rovinj, juveniles) animals m². Shrimp density at the sublittoral station ranged between 80 and 230 m"². The zonation of the Upogebiidae and Callianassidae with respect to environmental parameters is discussed.     

The Biology of Upogebia pusilla (PETAGNA) (Decapoda, Thalassinidea)

Abstract. Populations of the thalassinidean shrimp Upogebia pusilla were studied on tidal flats in the Northern Adriatic Sea. Biometric analysis showed a sexual dimorphism, especially in propodus size. Size frequency distributions revealed the presence of large animals during all seasons; recruitment by juveniles occurred in autumn. Moult intervals and moult increments were determined in the laboratory and used to generate growth curves which were compared with those calculated from size frequency distributions. The life span of U, pusilla is over 5 years. Ovigerous females occurred between March and September. Egg numbers were high in spring, lower in summer and increased with body size. The incubation time of embryos was 35 days; a female produces an estimated number of three egg batches during the breeding season. A total annual production of 994 kJ was estimated for a theoretical population of 100 animals; 13.5 % is spent for somatic growth, 31 % for egg production of females, and 55.2% is lost as exuviae. The population structures, growth and breeding patterns, as well as embryonic and larval development within the Upogebiidae and Callianassidae are discussed.     

Determinations of dimethylsulphoniopropionate (DMSP) lyase activity using headspace analysis of dimethylsulphide (DMS)

The osmolyte dimethylsulphoniopropionate (DMSP) can be enzymatically cleaved to dimethylsulphide (DMS), acrylate and a proton. The enzyme involved in this reaction is dimethylpropiothetin dethiomethylase (DMSP lyase; enzyme classification number 4.4.1.3.). Although the importance of this reaction for the global sulphur cycle, the influence of DMS on atmospheric acidity and the possible effect on climate regulation have been widely recognised, our knowledge of DMSP lyases is limited to just a few studies. Activity measurements of DMSP lyases offer an important step towards a better understanding of the conditions under which DMS is produced. In the available published data somewhat similar methods have been used before, but a critical examination of the method limitations has not been reported. To encourage further research on this enzyme, we suggest and detail two protocols for measurements of DMSP lyase activity: An in vitro assay for crude cell extracts or purified enzyme and an in vivo method for whole cells, which we recently started to use. After addition of DMSP, samples incubated in a gas tight vial may produce DMS from enzymatic cleavage under suitable conditions, and a DMS production rate can be estimated from time-series measurements of DMS in the headspace of the vial. Headspace analysis of DMS is a useful and rapid technique to estimate and compare DMSP lyase activities from different sources. The relative rates of DMS production in the liquid and of the gas transfer between liquid and headspace, determine the rate of DMS production measured via headspace analysis. If DMS production in the liquid is higher than the rate of transfer, headspace measurements will not reflect the actual amount of DMS produced in the liquid. In this case, extracts have to be diluted to a level that ensures linearity between dilution factor and reduction of enzyme activity. Additionally, incubation volumes and vials should be selected to provide a high surface-to-volume ratio to ensure maximum flux of DMS from the aqueous phase into the headspace. The methods can be adapted to further investigate species- and strain-specific activities, biogeographical distribution, cellular location and biochemical properties of various DMSP lyases.     

东山湾海水中Fe(II)和Fe(III)相互转化围隔实验研究

根据2008 年8 月与11 月在东山湾海域获得的调查资料对表层水中溶解态Fe(II)和Fe(III)含量、浮游植物叶绿素a、营养元素及其浓度等环境参数进行分析。结果表明, 夏、秋季海水中Fe(II)浓度及其在总溶解铁中所占比例均与浮游植物叶绿素a 呈正相关, 其相关系数分别为0.7959、0.9219。现场围隔实验表明, 海水中总溶解态Fe 含量在24 h 内有较大的变化, 最大减少量达到17.4%。DS2 站点海水中Fe(II)浓度及其在总溶解铁中所占比例随光照强度增加而增加。最高值与初始值相比较, 叶绿素a 较高的DS2 站点海水中Fe(II)浓度增加较叶绿素a 较低的DS5 号站点高0.053μg/L。Fe(II)和Fe(III)加富实验研究了溶解态的Fe(II)和Fe(III)在海水中相互转化。高浓度的Fe(II)在海水中被氧化成Fe(III),海水中浮游植物也会引发光还原作用使Fe(III)还原成Fe(II)。     

Juvenile form of the New Zealand turbot Colistium nudipinnis (Waite) (Pisces: Heterosomata: Rhombosoleinae) (note)

A juvenile (26 mm) specimen of the New Zealand turbot Colistium nudipinnis (Waite) is figured and described. Differences between the juvenile and adult forms, and characters distinguishing juvenile C. nudipinnis from the young of other New Zealand species of flatfish, are noted.     

Zn（OH）42-在针铁矿（010）晶面上化学吸附结构和稳定性的理论研究

采用周期性边界条件的密度泛函理论研究Zn(OH)42-在针铁矿(010)晶面的吸附结构和稳定性,得到了Zn(OH)42-吸附前后键长的变化规律。计算结果表明:当Zn(OH)42-通过共用O原子在针铁矿表面发生吸附时,平均ZnbridgeO键长较自由Zn(OH)42-的平均Zn-O键长有增长趋势,而平均Zn-O键长则有缩短趋势;Zn(OH)42-在针铁矿(010)晶面进行化学吸附时,双角DC2吸附方式为优势吸附物种。各吸附构型的稳定性顺序为DC2>SE1>DC1>SC1>SC2。     

重金属离子(Cu~(2 )、Pb~(2 )、Hg~(2 )、Cd~(2 ))对日本鳃丝和肝胰脏显微结构的影响

在实验生态条件下研究了重金属离子(Cu2 、Pb2 、Hg2 、Cd2 )对日本鳃丝和肝胰脏显微结构(15d)的影响。观察结果表明:在2 mg/L Cu2 处理组,日本鳃叶不规则增厚,鳃腔相对扩大,其中血细胞明显增多;上皮层出现破坏:角质膜(CU)呈波状拱起,部分上皮细胞脱离角质膜形成大的空泡(VA);上皮细胞排列不规则,并与数目众多的血细胞充挤于血腔;肝胰脏中构成肝管的细胞发生严重崩解,只残留包被在外周的一层结缔组织的被膜。10mg/L Pb2 处理组鳃丝角质膜明显呈波状突起;肝管结构紊乱,开始出现大量空泡(VA)。0.1 mg/L Hg2 暴露下,鳃丝上皮层偶有溶解现象;肝胰脏肝细胞空泡化(VA)现象更为严重,细胞间界限不明显,肝细胞溶解,有些细胞核固缩;被膜中的结缔组织充血,出现血细胞浸润现象。1 mg/L Cd2 暴露下,鳃丝上皮层严重解体,只剩一层角质层,鳃腔相对扩大,部分区域有充血现象;肝胰脏出现细胞质溶解,细胞间界限不明显,血细胞浸润等现象。     

多棘海盘车对太平洋牡蛎、紫贻贝、菲律宾蛤仔摄食选择性的研究

以多棘海盘车(Asterias amurensis)为试验对象,研究了多棘海盘车对3种双壳贝类的摄食选择性、摄食过程中用于搜寻和处理饵料生物的时间分配以及摄食机制等。试验以选择指数、捕食速率、日平均摄食率对多棘海盘车的摄食行为及搜寻和处理时间比进行了描述和统计。结果表明:各处理组多棘海盘车对菲律宾蛤仔的选择指数均为最高,占3种饵料生物的70%以上,显著高于太平洋牡蛎和紫贻贝(P<0.05),而各处理组对太平洋牡蛎的选择性均最低。多棘海盘车对菲律宾蛤仔的捕食速率和日平均摄食率显著高于太平洋牡蛎和紫贻贝。研究发现,在各处理组中多棘海盘车用于搜寻饵料生物的时间无显著差异,但随饵料密度的增加,用于处理饵料的时间逐渐减少。     

Reactivity of various types of iron(III) (hydr)oxides towards light-induced dissolution

Laboratory experiments were conducted on the light-induced dissolution of three well defined Fe(III) (hydr)oxide phases (γ-FeOOH, α-FeOOH, and α-Fe₂O₃) with oxalate as reductant/ligand. Upon irradiation of an aerated γ-FeOOH suspension of pH 3, photooxidation of oxalate and photochemical formation of dissolved Fe(II) occurred according to a 1:1 stoichiometry. This was not observed with aerated α-FeOOH and α-Fe₂O₃ suspensions of pH 3, where photooxidation of oxalate was not accompanied by formation of appreciable concentrations of dissolved Fe(II). We hypothesize that in aerated α-FeOOH and α-Fe₂O₃ suspensions, oxidation of surface Fe(II) outcompetes its detachment from the crystal lattice. Also in deaerated suspensions, α-FeOOH and α-Fe₂O₃ behaved differently from γ-FeOOH with regard to light-induced dissolution. We interpret our results by assuming that light-induced dissolution of α-FeOOH and α-Fe₂O₃ in deaerated suspensions of pH 3 occurred mainly through Fe(II)-catalyzed thermal dissolution of the solid phases, where Fe(II) was initially formed by photoreductive dissolution and then predominantly via photolysis of dissolved Fe(III) oxalate complexes. With γ-FeOOH, on the other hand, dissolved Fe(II) formation occurred probably mainly through photochemical reductive dissolution under photooxidation of adsorbed oxalate. From our results we conclude that the efficiency of detachment of reduced surface iron is a key parameter of the overall kinetics of photoreductive dissolution of Fe(III) (hydr)oxides in aquatic systems, and that thermodynamically stable phases such as α-FeOOH and α-Fe₂O₃ are not readily dissolved in the presence of O₂, even at low pH-values and in the presence of light and reductants like oxalate. We propose that redox cycling of iron at the surface of crystalline Fe(III) (hydr)oxide phases, i.e. reduction and oxidation of surface iron without transfer into solution, may be an important pathway of transformation of thermodynamically stable atmospheric Fe(III) (hydr)oxides into less stable and thus more soluble phases.     

Arnoglossus boops (hector): A synonym of a. scapha (schneider) (pisces: Heterosomata: Bothidae)

The unique holotype of Arnoglossus boops Hector is compared with specimens of Arnoglossus scapha (Schneider). It is concluded that the two species are identical, and that A. boops is therefore a junior synonym of A. scapha.     

Effect of siderophores on the light-induced dissolution of colloidal iron(III) (hydr)oxides

Siderophores play an important role in biological iron acquisition in iron-limited aquatic systems. While it is widely accepted that the solubilization of iron-bearing mineral phases is a key function of siderophores, the mechanism of siderophore-promoted mineral dissolution in aquatic systems is largely unknown. In this study, we investigated the effect of siderophores (desferrioxamine B (DFOB) and aerobactin) on light-induced dissolution of goethite and lepidocrocite in the presence or absence of oxalate in aerated and deaerated suspensions at pH 6. For the irradiated two-ligand system (oxalate/siderophore), the experimental results suggest that oxalate acts as the electron donor for the formation of surface Fe(II), and the siderophore acts as an efficient shuttle for the transfer of surface Fe(II) into solution. Furthermore, even in the absence of an electron donor such as oxalate, both DFOB and aerobactin accelerated the light-induced dissolution of lepidocrocite as compared to the thermal dissolution. Experiments with dissolved Fe(III)–DFOB and Fe(III)–aerobactin complexes suggest that this enhancing effect is not due to photolysis of corresponding surface complexes but to efficient transfer of reduced surface Fe(II) into solution, where surface Fe(II) may be formed, e.g., through photolysis of surface Fe(III)–hydroxo groups. Based on this study, we conclude that the interplay of light and siderophores may play a key role in the dissolution of colloidal iron(III) (hydr)oxides in marine systems, particularly in the presence of efficient electron donors.     

波令-阿勒罗德间冰期时期西南印度夏季季风降雨的变化性

北方春季时期印度次大陆和西藏高原的差异性增热吸引了印度洋的潮湿空气穿越印度大陆,产生了世界上最显著的西南印度夏季季风(ISM)体系(Webster,1987)。世界上大约25%的人口受到这种季节降雨的影响。20世纪60年代末期,印度约150万人死于连续3年的季风失常(重大灾害数据库,2005)