Environmental assessment of trace element bioaccumulation in sipunculan from seagrass and wetland sediments

This study is the first measurement of trace elements in sipunculan and their surrounding sediments. The bioaccumulation characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) were analyzed and compared in two sipunculan species, Sipuncula nudus and Siphonosoma vastum, which were collected from seagrass beds and wetlands in Taiwan. The sipunculan and sediment samples were analyzed using an inductively coupled plasma mass spectrometer. Both sipunculan in the wetlands and seagrass beds had a high Cu bioaccumulation mechanism. Multivariate analysis, principle component analysis, and partial least squares for discriminant analysis of trace element levels and bioaccumulation factors were used to distinguish the element distributions that corresponded to the two habitats (seagrass beds and wetlands). Different levels of certain trace elements in these two sipunculan species may result not only from the environmental factors of various habitats but also from the accumulation characteristics of various species. The As, Cd, Cr, Cu, Hg, and Zn concentrations were markedly lower in sipunculan than in other invertebrates from the adjacent polluted regions. The public health issues regarding the consumption of sipunculan are also discussed.     

Melt Flow Behavior and Processability of Polylactic Acid/Polystyrene (PLA/PS) Polymer Blends

The present investigation dealt with the flow behavior and processability of polylactic acid/polystyrene (PLA/PS) polymer blends using a capillary rheometer. For this purpose, PLA/PS blends with different ratios of the concentrations were prepared using a single screw extruder. The shear viscosity, shear stress, shear rate, power-law index, viscous activation energy at a constant shear stress, and elongational stress were determined. PLA/PS blends exhibited a typical shear-thinning behavior over the entire range of shear rates tested, and the viscosity values of the blends would tend to decrease with increasing amount of PLA. In addition, the polymer blend of 70 % PLA and 30 % PS was found to be relatively less sensitive to the processing temperature, implying that the extrusion process was more desirable for fabrication of PLA/PS polymer blend than the injection process.     

Evaluation of the potential methane yield of industrial wastewaters used in bioreactor landfills

To increase the moisture content of waste disposed in a bioreactor landfill, it is critical to secure the moisture source. In this study, industrial wastewater was evaluated as a potential moisture source for a bioreactor landfill with respect to the impact on methane generation. Industrial wastewater samples were collected from fishery, brewery and dairy industries. These samples were tested for basic water chemistry parameters, heavy metals, and methane generation using the regular and modified biochemical methane potential (BMP) assays. Despite high sodium and total phosphate concentrations in the fishery wastewater, a significant methane yield was observed (0.313?m³ CH₄/kg COD). However, a relatively large amount of fishery wastewater added at the phase of methane generation acceleration adversely affected microbial activity. Samples from the brewery and dairy wastewater did not indicate significant inhibitory effects on methane generation in either the regular or the modified BMP assay. This study demonstrates the utility of wastewater as an alternative to traditional moisture sources when used to enhance methane production in a bioreactor landfill.     

Case study of landfill leachate recirculation using small-diameter vertical wells

A case study of landfill liquids addition using small diameter (5 cm) vertical wells is reported. More than 25,000 m³ of leachate was added via 134 vertical wells installed 3 m, 12 m, and 18 m deep over five years in a landfill in Florida, US. Liquids addition performance (flow rate per unit screen length per unit liquid head) ranged from 5.6 × 10^?8 to 3.6 × 10^?6 m³ s^?1 per m screen length per m liquid head. The estimated radial hydraulic conductivity ranged from 3.5 × 10^?6 to 4.2 × 10^?4 m s^?1. The extent of lateral moisture movement ranged from 8 to 10 m based on the responses of moisture sensors installed around vertical well clusters, and surface seeps were found to limit the achievable liquids addition rates, despite the use of concrete collars under a pressurized liquids addition scenario. The average moisture content before (51 samples) and after (272 samples) the recirculation experiments were 23% (wet weight basis) and 45% (wet weight basis), respectively, and biochemical methane potential measurements of excavated waste indicated significant (p < 0.025) decomposition.     

市政污泥热解过程颗粒物中重金属分布

以深圳市某污水处理厂的污泥为原料,研究了污泥热解过程产生的颗粒物及其中8种重金属的分布规律.结果表明,颗粒物的生成速率分别在400~600℃和1000℃保温30min的两个区间内达到峰值.8种重金属的热挥发性由大到小依次为Cd > Zn > As > Pb > Mn > Ni > Cu > Cr,而其在颗粒物中富集能力大小顺序为Pb > As > Mn > Zn > Cd > Ni > Cr > Cu.颗粒物重金属在热解气中的体积浓度随热解过程呈上升趋势,Zn和Cd则在升温阶段（1000℃以前）达到峰值后开始降低.研究表明,污泥热解颗粒物富集的重金属超标,因而污泥热解尾气颗粒物的去除装置十分必要.     

Quantifying the efficiency of soil sampling designs: A multivariate approach

The objective of this paper is to quantify and compare the loss functions of the standard two-stage design and its composite sample alternative in the context of multivariate soil sampling. The loss function is defined (conceptually) as the ratio of cost over information and measures design inefficiency. The efficiency of the design is the reciprocal of the loss function. The focus of this paper is twofold: (a) we define a measure of multivariate information using the Kullback–Leibler distance, and (b) we derive the variance-covariance structure for two soil sampling designs: a standard two-stage design and its composite sample counterpart. Randomness in the mass of soil samples is taken into account in both designs. A pilot study in Slovenia is used to demonstrate the calculations of the loss function and to compare the efficiency of the two designs. The results show that the composite sample design is more efficient than the two-stage design. The efficiency ratio is 1.3 for pH, 2.0 for C, 2.1 for N, and 2.5 for CEC. The multivariate efficiency ratio is 2.3. These ratios primarily reflect cost ratios; influence of the information is small.     

Prenatal diagnosis of 46, XX/47, XXY mosaicism: A case report

A case of 46,XX/47,XXY mosaicism was diagnosed at 22 gestational weeks by amniocentesis and fetal blood sampling. After genetic counselling, the couple elected to have the pregnancy terminated. Culture of the fetal skin and both gonads confirmed the prenatal diagnosis. In external appearance, the abortus had no remarkable findings except hypospadia. Histology of both gonads showed testicular tissue without evidence of ovarian components.