Responses of alkaline phosphatase activity to wind-driven waves in a large, shallow lake: Implications for phosphorus availability and algal blooms

Phosphorus is a vital nutrient for algal growth, thus, a better understanding of phosphorus availability is essential to mitigate harmful algal blooms in lakes. Wind waves are a ubiquitous characteristic of lake ecosystems. However, its effects on the cycling of organic phosphorus and its usage by phytoplankton remain poorly elucidated in shallow eutrophic lakes. A mesocosm experiment was carried out to investigate the responses of alkaline phosphatase activity fractions to wind waves in large, shallow, eutrophic Lake Taihu. Results showed that wind-driven waves induced the release of alkaline phosphatase and phosphorus from the sediment, and dramatically enhanced phytoplanktonic alkaline phosphatase activity. However, compared to the calm conditions, bacterial and dissolved alkaline phosphatase activity decreased in wind-wave conditions. Consistently, the gene copies of Microcystis phoX increased but bacterial phoX decreased under wind-wave conditions. The ecological effects of these waves on phosphorus and phytoplankton likely accelerated the biogeochemical cycling of phosphorus and promoted phytoplankton production in Lake Taihu. This study provides an improved current understanding of phosphorus availability and the phosphorus strategies of plankton in shallow, eutrophic lakes.     

城市污水雌激素活性研究进展——毒性评估、致毒物解析及毒性削减

城市污水成分复杂,含有多种有毒有害物质,使其能对生物体产生各种不良生物效应,其中,内分泌干扰物,尤其是雌激素类物质以及具有雌激素活性的污染物,因能影响生物的生殖系统并造成受纳水体鱼类性别转变等危害而备受关注,城市污水的雌激素活性也一直是污水处理领域的研究热点.当前,城市污水回用是缓解全球水资源危机的重要途径之一,在此背...     

吴哥窟——人间最美的建筑

以雕刻和建筑艺术闻名于世的吴哥文化,是柬埔寨文化乃至世界历史发展上的一个高峰,因此,探访吴哥窟成为当今许多国内外旅游文化人士的梦想,笔者不久前有幸来到柬埔寨,来到吴哥。与中国的万里长城、埃及的金字塔和印度尼西亚的婆罗浮屠并称为东方世界四大奇迹之一的吴哥古迹,位于柬埔寨暹粒省金边湖北面,它包括吴哥主城和吴哥窟古刹,大小奇特的建筑物共有600多座,分布在45平方公里的丛林中,或许没有人想到,这么精致、辉煌的建筑群落,这个世界古代文明璀璨的瑰宝,曾经湮没在荒革中达400年之久。     

怀念逝去的小生命

在你甜甜的睡梦中 有没有你漂亮的玩具？ 在大地抖动的瞬间, 你是否感觉在摇篮里？     

纸船明烛照天烧——沪郊血吸虫病防治纪念章

血吸虫病是一种古老的传染疾病,是人类几千年无法醒来的恶梦,是死神讲述的最惨痛的人间悲剧。新中国成立后,打响了这场现代医学最艰苦的战役,人类与瘟神之间进行着一场无声的较量。1949年,人民解放军以摧枯拉朽之势打过长江,很快解放了上海。为了解放台湾,南下的解放军大批下河学游     

Stabilization of heavy metals in MSWI fly ash using silica fume

The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR (²⁷Al and ²⁹Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.     

Characterization of a fenpropathrin-degrading strain and construction of a genetically engineered microorganism for simultaneous degradation of methyl parathion and fenpropathrin

A gram-negative fenpropathrin-degrading bacterial strain Sphingobium sp. JQL4-5 was isolated from the wastewater treatment sludge of an insecticide factory. Strain JQL4-5 showed the ability to degrade other pyrethroid insecticides, but it was not able to degrade methyl parathion. To enhance its degrading range of substrate, a methyl parathion hydrolase gene (mpd) was successfully introduced into the chromosome of strain JQL4-5 with a mini-Tn-transposon system. A genetically engineered microorganism (GEM) named JQL4-5-mpd resulted, which was capable of simultaneously degrading methyl parathion and fenpropathrin. Soil treatment results indicated that JQL4-5-mpd is a promising multifunctional bacterium in the bioremediation of multiple pesticide-contaminated environments.     

Crystallization and Mechanical Properties of Recycled Poly(ethylene terephthalate) Toughened by Styrene–Ethylene/Butylenes–Styrene Elastomer

Recycled poly(ethylene terephthalate) (R-PET) was blended with 15–30 wt% of styrene–ethylene/butylenes–styrene (SEBS) block copolymer and maleic anhydride grafted SEBS (SEBS-g-MA). Effects of nucleation and toughening of the elastomers were evaluated systematically by study of morphology, crystallization, thermal and mechanical properties of the blend. The addition of 30 wt% SEBS promoted the formation of co-continuous structure of the blend and caused the fracture mechanism to change from strain softening to strain hardening. Addition of SEBS-g-MA resulted in significant modification of phase morphology and obviously improved the impact strength. The compatibilization reaction of PET with SEBS-g-MA accelerated the crystallization of PET and increased the crystallinity. The shifts in glass transition temperature of PET towards that of SEBS-g-MA and the higher modulus for R-PET/SEBS-g-MA (70/30) blend found by DMA are also indications of better interactions under the conditions of compatibilization and interpenetrating structure.     

立式加热炉节能减排可行性研究

大庆油田原稳装置采用立式加热炉,烟气中存在大量的废热。在现有装置运行中,烟气直接排放,浪费了大量的热量。通过在实验装置中可回收废热资源及废热回收技术研究,采用热管技术回收烟气废热,用于预热空气,不仅会节能降耗,给企业创造可观的经济效益,还会减少大气污染,创造良好的社会效益。     

Nitrogen impacts on atrazine-degrading Arthrobacter strain and bacterial community structure in soil microcosms

The objective of this study was to investigate the impacts of exogenous nitrogen on a microbial community inoculated with the atrazine-degrading Arthrobacter sp. in soil amended with a high concentration of atrazine. Inoculated and uninoculated microcosms for biodegradation tests were constructed. Atrazine degradation capacity of the strain DAT1 and the strain's atrazine-metabolic potential and survival were assessed. The relative abundance of the strain DAT1 and the bacterial community structure in soils were characterized using quantitative PCR in combination with terminal restriction fragment length polymorphism. Atrazine degradation by the strain DAT1 and the strain's atrazine-metabolic potential and survival were not affected by addition of a medium level of nitrate, but these processes were inhibited by addition of a high level of nitrate. Microbial community structure changed in both inoculated and uninoculated microcosms, dependent on the level of added nitrate. Bioaugmentation with the strain DAT1 could be a very efficient biotechnology for bioremediation of soils with high concentrations of atrazine.