Plant uptake of aldicarb from contaminated soil and its enhanced degradation in the rhizosphere

Experiments were conducted to investigate the degradation of aldicarb, an oxime carbamate insecticide, in sterile, non-sterile and plant-grown soils, and the capability of different plant species to accumulate the pesticide. The degradation of aldicarb in soil followed first-order kinetics. Half lives (t1/2) of aldicarb in sterile and non-sterile soil were 12.0 and 2.7 days, respectively, which indicated that microorganisms played an important part in the degradation of aldicarb in soil. Aldicarb disappeared more quickly (p< or =0.05) in the soil with the presence of plants, and t1/2 of the pesticide were 1.6, 1.4 and 1.7 days in the soil grown with corn, mung bean and cowpea, respectively. Comparison of plant-promoted degradation and plant uptake showed that the enhanced removal of aldicarb in plant-grown soil was mainly due to plant-promoted degradation in the rhizosphere.     

Characteristics of single atmospheric particles in a heavily polluted urban area of China: size distributions and mixing states

To investigate the chemical composition, size distribution, and mixing state of aerosol particles on heavy pollution days, single-particle aerosol mass spectrometry was conducted during 9–26 October 2015 in Xi’an, China. The measured particles were classified into six major categories: biomass burning (BB) particles, K-secondary particles, elemental carbon (EC)–related particles, metal-containing particles, dust, and organic carbon (OC) particles. BB and EC-related particles were the dominant types during the study period and mainly originated from biomass burning, vehicle emissions, and coal combustion. According to the ambient air quality index, two typical episodes were defined: clean days (CDs) and polluted days (PDs). Accumulation of BB particles and EC-related particles was the main reason for the pollution in Xi’an. Most types of particle size were larger on PDs than CDs. Each particle type was mixed with secondary species to different degrees on CDs and PDs, indicating that atmospheric aging occurred. The mixing state results demonstrated that the primary tracers were oxidized or vanished and that the amount of secondary species was increased on PDs. This study provides valuable information and a dataset to help control air pollution in the urban areas of Xi’an.

Graphical abstract

     

巴氏醋酸杆菌发酵处理甲醇废水合成细菌纤维素的研究

介绍了巴氏醋酸杆菌以甲醇为唯一碳源、以酵母膏或蛋白胨为氮源合成细菌纤维素,同时净化甲醇废水的方法,并对合成细菌纤维素的培养条件进行了研究。试验得出巴氏醋酸杆菌的适宜发酵条件为：发酵培养基中甲醇质量分数为3．5％左右,发酵培养基初始pH为5．0～6．0。接种量为5％,发酵培养温度为30℃,振荡器转速为100r／min。     

皖东地区水资源可持续利用研究

本文分析了皖东地区水资源的基本特点、开发利用现状及其存在的主要问题,并提出了水资源可持续利用的基本对策     

船桥撞击力影响因素有限元仿真模拟分析∗

为了探究船桥碰撞时船撞力的影响因素,选取合适的船撞力为桥梁设计提供参考,采用动力分析软件 LS ? DYNA,结合沪通长江大桥、天生港专用航道桥以及厦漳大桥三座实桥,分别进行了不同船速、不同通航水位、不同基础形式和不同船型等因素对船撞力的影响分析研究。研究结果表明：船撞力峰值和船速正相关;中通行水位时, 船桥撞击动力响应最大;不同桥墩基础和不同船型对船撞力有较大影响。基于中国铁路规范和有限元计算结果, 考虑了船舶类型和基础类型对船撞力的影响,对船撞力计算公式提出改进方法,所得研究结果可为桥梁抗撞设计和研究提供参考。     

围生期毒死蜱暴露致子代8周雄鼠睾丸组织的氧化损伤

毒死蜱是目前全世界使用和销售量最大的有机磷杀虫剂之一。为探讨围生期毒死蜱暴露致8周雄性子鼠睾丸组织的氧化损伤,选择健康Wistar妊娠母鼠于妊娠期(gestation days,GD)第6天至子鼠出生后(postnatal days,PND)21天通过灌胃染毒0、0.75、1.35和2.70 mg·kg~(-1)剂量的毒死蜱,待雄性子鼠8周龄取左侧睾丸实施组织病理学检查,右侧睾丸用以检测丙二醛(maleic dialdehyde,MDA)的含量和谷胱甘肽S转移酶(glutathione S transferases,GST)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)、总超氧化物歧化酶(total superoxide dismutase,T-SOD)的活力。结果表明,与对照组比较,随着染毒剂量的增加子鼠体重和睾丸、附睾脏器系数有下降的趋势(P0.05);而MDA呈升高趋势(P0.05)。各组T-SOD和1.35、2.70 mg·kg~(-1)剂量组GSH-Px活力的下降及2.70 mg·kg~(-1)剂量组GST活力的升高均有统计学意义(P0.05)。睾丸组织病理学检查结果可见2.70mg·kg~(-1)剂量组睾丸组织有明显的损伤,管腔中精液量减少,生精细胞脱落增多。上述研究结果提示母鼠于围生期暴露于毒死蜱,可通过氧化损伤诱导子代雄性大鼠睾丸的毒性作用。     

全氟及多氟类化合物在人体分布及其毒性研究进展

全氟和多氟烷酸类化合物(perfluoroalkyl and polyfluoroalkyl substances, PFASs)是一类新型持久性有机污染物,目前其在民用和工业产品中得到广泛应用。在环境样品、野生动物以及人类体内都检测到了这类物质。PFASs对哺乳动物和水生生物具有广泛的毒性,其对生态环境和人体健康的影响受到公众关注。目前,PFASs对人类健康的研究还多停留在流行病学研究和体外细胞毒性研究方面,由于人类有复杂的免疫和代谢系统,因此PPASs对人类健康影响的具体机制和安全剂量仍然需要进一步研究。本文针对PFASs在人体的分布、流行病学研究、毒理学效应和作用机制等热点问题进行了总结,并对目前PFASs研究存在的问题及今后的研究方向进行讨论和展望。     

Exogenously applied oxalic acid assists in the phytoremediation of Mn by Polygonum pubescens Blume cultivated in three Mn-contaminated soils

• The OA supply significantly increased the water-extractable Mn in all soils. • All OA supply levels promoted plant growth in unexplored soil. • Low OA supply level promoted plant growth in explored and tailing soils. • OA amendment increased the Mn concentrations and total Mn in P. pubescens. • P. pubescens experienced less Mn stress in unexplored soil than in the other two soils. The current study evaluated the effects of oxalic acid (OA) application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese (Mn)-contaminated soils sampled from an unexplored area (US), an explored area (ES) and a tailing area (TS) of the Ertang Mn mine, South China. The supplied levels of OA were 0 (control), 1 (low level), 3 (medium level), and 9 (high level) mmol/kg, referred to as CK, OA1, OA3 and OA9, respectively. The results revealed that the average water-extractable Mn concentrations US, ES and TS amended with OA increased by 214.13, 363.77 and 266.85%, respectively. All OA supply levels increased plant growth and Mn concentrations in US. The low OA supply level increased plant growth in ES and TS; however, contrasting results were found for the medium and high OA supply levels. Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels. Total Mn in the aerial parts increased by 81.18, 44.17 and 83.17% in US, ES and TS, respectively; the corresponding percentages for the whole plants were 81.53, 108.98 and 77.91%, respectively. The rate of ·O₂⁻ production and malondialdehyde (MDA) concentrations increased in response to OA amendment, especially the medium and high OA supply levels in ES and TS. In general, antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US, while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.     

HNO_3─KI─MIBK萃取／原子吸收光谱法测定固体废物浸提液中的微量银

采用选择性较好的ＨＮＯ３—ＫＩ—ＭＩＢＫ萃取体系对铋渣和尾矿渣浸出液中的痕量银进行预分离富集后，用火焰原子吸收法（ＡＡＳ）进行测定。此法不仅变异系数小（约为３．１％），而且检出限比直接火焰ＡＡＳ法降低两个数量级，达０．５ｎｇ／ｍｌ．另外，还就作品细度对银测定结果的影响原因做了初步探讨。     

水中氨氮挥发影响因素探讨

本文介绍了水中氨氮挥发的影响因素。水中氨氮挥发速率常数随水的ｐＨ值和水温升高而增加，水面风速大则常数值也大，大气压高的地区的挥发速率常数小于大气压低者。与蒸馏水体系相比，在实验条件相同时滇胡水中氨氮挥发速率常数小。