Effect of mercuric chloride on terrestrial slug Semperula maculata and histopathology of reproductive organs: a comprehensive study

Since the last few decades, terrestrial diversity is found to be under stress due to the contamination by various chemicals and gases of aquatic and agricultural media. The bioaccumulation of these compounds at certain concentrations in different tissues produces histopathological changes leading to behavioral changes in target animals. This study focused on terrestrial molluscan slug, Semperula maculata, against lethal concentrations of mercury chloride (HgCl₂). Bioaccumulation of Hg was highest in ovotestis, while lowest in the molluscan penis. Histopathological changes were observed in the cellular arrangement of reproductive organs. Alterations in the penis and the dart gland included dilated unicellular, multicellular glands, and muscular dystrophy, dilated peripheral glandular cells, respectively; dilation being maximal in the prostate gland. Ovotestis showed depleted number of gametocytes. Vacoulized pre-vitellogenic oocytes with early vitellogenic oocytes were noted under light microscopy. Mercury produced toxicity on secretory functions and lowered the rate of reproduction in animals. Evidence indicates that Hg produced gamete degeneration, impacted reproductive capacity and survival of this species in the ecosystem.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in invertebrate animals from a rural beach in Japan

PCDDs and PCDFs were analyzed by high resolution GC MS in several invertebrate animals collected from a rural beach in Japan. PCDDs and PCDFs were detected in all samples. Total concentration of PCDDs and PCDFs ranged 8.8–120 pg g⁻¹ wet and 3.5–38 pg g⁻¹ wet, respectively. TEQs of invertebrate animals examined ranged from 0.048 pg g⁻¹ wet in sea slug to 0.91 pg g⁻¹ wet in mussel. Isomer profiles in all samples were similar to each other despite of variety of species. Their major sources are estimated to be herbicides such as CNP and PCP, and combustion by using a statistical analysis of isomer profiles.     

曝气方式对MBR平板膜组件流体力学特征的影响

以实际平板膜生物反应器为研究对象,以自由曝气为对照,考察了在不同曝气强度(0.625,1.25,2.5,5L/min)和不同曝气频率(0.17,0.33,0.42,0.56,0.83Hz)下,活塞流曝气对膜表面压力及其变化系数的影响.结果表明,在试验所设范围内,当曝气频率一定时,活塞流曝气引起的平板膜表面压力变化与强度有关;在相同曝气强度下,存在一个最佳的曝气频率范围,使活塞流曝气引起的膜表面压力最大.在相同曝气强度下,可控制的活塞流曝气可以获得比自由曝气更佳的压力变化效果.当曝气量为2.5L/min时,曝气频率0.33Hz的活塞流曝气所带来的压力系数变化高于曝气量为5.0L/min的自由曝气.