Multiresidue determination and potential risks of emerging pesticides in aquatic products from Northeast China by LC–MS/MS

A simple method for determining 33 pesticides with a wide polarity range(log Kow0.6-4.5) in aquatic products was developed based on LC–MS/MS. The target analytes included three types of widely used pesticides: insecticides, fungicides and herbicides. Based on the optimization of ultrasonic assisted extraction and GPC clean-up procedures, the matrix effect, extraction recoveries and LOD were improved distinctively. LOQ of this method was below 0.5 ng/g for all pesticides, which is superior to values in the literature, and the matrix effect was reduced effectively(-14.7% to 7.5%). The method was successfully applied to investigate the pesticide residue levels of twenty-five samples including seven common kinds of fishes from Northeast China. The results showed that all targeted pesticides were present in the fish samples; however, their levels were low, except for atrazine, linuron,ethoprophos, tetrachlorvinphos, acetochlor and fenthion. Atrazine and linuron caught our attention because the concentrations of atrazine in fish samples from Liaoning province were in the range of 0.5-8 ng/g(w/w) with mean concentration of 2.3 ng/g, which were far above those of other pesticides. The levels of linuron were in the range of 0.6-6 ng/g(mean concentration 2.8 ng/g), which were the highest among all targeted pesticides in the Inner Mongolia. This is the first systematic investigation on the characteristics and levels of these pesticides in aquatic products from northeast China. Considering their toxicity and bioaccumulation, the potential risk of atrazine and linuron from consuming aquatic products should be paid more attention.     

Effects of tourmaline on nitrogen removal performance and biofilm structures in the sequencing batch biofilm reactor

The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors(SBBRs)(denoted SBBR1 and SBBR2) at different nitrogen loading rates(NLRs) varying from(0.24 ± 0.01) to(1.26 ± 0.02) g N/(L·day). SBBR1 was operated in parallel with SBBR2, but SBBR1 was filled with polyurethane foam loaded tourmaline(TPU) carriers and another(SBBR2) filled with polyurethane foam(PU) carriers. Results obtained from this study showed that the excellent and stable performance of SBBR1 was obtained. Ammonia nitrogen removal and total nitrogen removal were higher in SBBR1 than that in SBBR2 with increase of NLR. At an NLR of(0.24 ± 0.01) g N/(L·day), the majority of the spherical and elliptical bacteria were surrounded by the extracellular polymeric substance(EPS) and bacillus or filamentous bacteria in two SBBRs biofilms. When NLR increased to(1.26 ± 0.02) g N/(L·day), the clusters were more obvious in the SBBR1 biofilm than that in the SBBR2 biofilm. Bacteria in SBBR1 were inclined to synthesis more EPS, and the formed EPS could protect the bacteria from free ammonia(FA) under extreme condition NLR(1.26 ± 0.02) g N/(L·day). The results of polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial community similarity in SBBR2 decreased more obviously than that in SBBR1 with the increase of NLR, which the microbial community in SBBR1 was relatively stable.     

Assessment of column aerosol optical properties using ground-based sun-photometer at urban Harbin, Northeast China

Aerosol plays a key role in determining radiative balance, regional climate and human health. Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects caused by excessive aerosols. In this study, column aerosol measurements over urban Harbin, a metropolis located at the highest latitude in Northeast China, during May 2016 to March 2017 were conducted using a CIMEL sun-photometer to analyze local aerosol properties and its variation from different aspects. According to the observations, aerosol optical depth at 440 nm (AOD₄₄₀) ranges from 0.07 up to 1.54, and the large variability in both AOD₄₄₀ and Angstrom Exponent (AE_440–870) indicates the frequent change of aerosol types due of different emission sources. Coarse mode particles dominated Harbin during the studying period because of the long-range transported dust and probably the suspended snow crystals in winter. As the wavelength increases, relatively consistent decrease trends of single scattering albedo (SSA) and asymmetry factor (ASY) were observed in spring, autumn, and winter, indicating the presence of absorbing polluted aerosols. Mixed type (MIX) aerosol dominated the study region with a total percentage of 34%, and biomass burning and urban industry (BB/UI), clean continental (CC), and desert dust (DD) aerosols were found to be 31%, 27%, and 8%, respectively. The current work fills up the optical characteristics of aerosols in Harbin, and will contribute to the in-depth understanding of local aerosol variation and regional climate change over Northeast China.     

煤粉燃烧器氮氧化污染物减排方法研究

煤粉燃烧会产生大量的氮氧化污染物,对环境造成巨大污染,煤粉燃烧分解中,采用煤焦脱硝的机理能有效降低氮氧化物的排放量,结合煤焦表面化学吸附方法,提高煤粉的燃烧值,采用催化还原法进行煤粉燃烧的还原脱销,在脱硝过程中不用加入催化剂,采取多点BET法降低O2对碳的消耗,结合烟道的火焰控制方法精确控制煤粉燃烧器的进气浓度,降低C-NO起始反应温度,抑制氮氧化污染物的产生,促进烟煤焦脱硝过程中C对NO的化合反应,通过恒温稳态反应方法,进行NO出口浓度控制,从而有效实现污染物的减排处理。     

A Century of Plant Species Loss from an Isolated Fragment of Lowland Tropical Rain Forest

An isolated 4-ha fragment of lowland tropical rain forest has been preserved in the Singapore Botanic Gardens since their founding in 1859. The Botanic Gardens'Jungle has recently had enumerated all woody stems 5 cm diameter at breast height (dbh) and larger and the complete vascular plant flora inventoried. This inventory can be compared with the historic record of the flora of the Gardens'Jungle obtained from the extensive collection of herbarium specimens dating back to the 1890s. Of the 448 historically recorded native species, 220 are still present. Ninety-four native species for which there were no historic records and 80 introduced species were also recorded in the recent inventory. The 50.9% loss of plant species richness over approximately the last century has not been distributed uniformly across plant life-form groups. Tree species have been less likely to go extinct than shrubs, climbers, or epiphytes. But half of the tree species present in 1994 were represented by only one or two individuals ≥ 5 cm dbh and larger. Individual longevity may be the major correlate with persistence of plant species in isolated forest fragments. Shade-tolerant understory shrubs (mostly Rubiaceae ) and rattans ( Palmae ) have been particularly prone to extinction. Some species have probably proliferated during the period of isolation. The tree Calophyllum ferrugineum currently constitutes one quarter of all woody stems. A group of climbers has become very common and covers large areas, probably inhibiting tree regeneration. We conclude that tiny fragments will act as refuges for tropical rain-forest plant species for decades, possibly even centuries after isolation but on their own they will not provide a permanent guarantee of the conservation of tropical biodiversity.     

扑草净降解菌降解特性、降解基因保守序列的扩增及同源性分析

从受污染农田中分离到一株补草净降解菌FR，经鉴定属于假单胞菌，考察了温度及pH对其降解能力的影响，确定pH7.0,32℃为最适作用条件；设计引物，通过PCR扩增到一条长度约为500bp的降解基因保守片段，通过对该片段部分序列测定及同源性搜索，证实该片段与atzA,triA等均三嗪化合物水解酶基因具有很高的同源性。     

有机锡化合物对水生无脊椎动物的毒性研究

通过不同层次水生无脊椎动物的毒理学研究，能更好地反映有机化合物的生态效应，以氯化三丁基锡（ＴＢＴＣｌ）为例，结果表明，ＴＢＴＣｌ对原生动物等５种水生无脊椎动物的半致死浓度（ＬＣ５０）为２５．６５－３５５．６３ｐｐｂ，有明显的种特异性，ＴＢＴＣｌ对河口轮虫种群净生殖率ＥＣ５０为１０ｐｐｂ，影响平均寿命ＥＣ５０为２２ｐｐｂ，根据浓度Ｃ及原生动物平衡种类数Ｓｅｑ进行回归，得方程Ｓｅｑ＝１１．８７－１．８     

低贵金属含稀土复合型汽车排气净化催化剂研究

研究了３种低钯含稀土复合型汽车排气净化催化剂的制备工艺条件、活性和热稳定性。结果表明：所研制的催化剂对ＣＯ、ＨＣ的起燃温度分别在１８２℃～２１０℃之间；完全氧化温度在２３０℃～２５０℃之间。具有起燃温度低、活性高的特性。高温处理后，Ｔ５０％和Ｔ１００％仅上升了８℃～２４℃，说明热稳定性良好。少量贵金属Ｐｄ分浸法以及在活性氧化铝涂层上使用无机胶粘剂的制备工艺能提高催化剂的热稳定性     

Study on the response of wheat to lead, cadmium and zinc

Ｓｔｕｄｙｏｎｔｈｅｒｅｓｐｏｎｓｅｏｆｗｈｅａｔｔｏｌｅａｄ，ｃａｄｍｉｕｍａｎｄｚｉｎｃＭｅｎｇＬｉｎｇ，ＴａｎＤｅｙｏｎｇ，ＷａｎｇＨｕａｎｘｉａｏ，ＤｕａｎＣｈａｎｇｑｕｎ，ＤｕａｎＰｅｉｓｈａｎｇ，ＧａｏＳｈａｎｇｙｉＤｅｐａｒ...     

湿法烟气脱硫法鼓泡反应器的气液传质建模

利用双膜理论对湿法烟气脱硫法鼓泡反应器气液传质建立数学模型。通过鼓泡反应的钠碱脱硫实验来验证模型，得到的模型计算结果和实验相吻合。利用模型，通过改变的初始参数来研究对传质的影响。结果表明，提高气流速度、进气浓度、吸收液柱高度和吸收液浓度，有利于传质吸收，提高鼓泡反应器的传质系数和脱硫效率。