外源Mo降低As(III)和As(V)对水稻的毒性及As的积累

通过溶液培养试验,研究外源添加Mo对2种价态砷(As(III)和As(V))胁迫下水稻吸收积累Mo和As的影响。结果表明,这2种价态的As对水稻生长均有抑制作用,As(III)比As(V)对水稻毒害更明显,添加Mo可缓解As对水稻的毒害。As添加可影响水稻根系和茎叶对Mo的吸收积累,但是不同价态As对Mo积累量的影响不一致。同时,Mo的添加也可以显著地降低水稻根系和茎叶对2个价态As的吸收积累。在100 μmol?L^-1 As(III)处理下,添加0.1和0.5 mg?L^-1的Mo可导致水稻根系As积累量分别比对照处理降低38.8%和52.8%,茎叶As积累量分别降低5.1%和10.6%;当As(V)浓度为100 μmol?L^-1时,添加0.1和0.5 mg?L^-1的Mo可导致水稻根系As积累量分别比对照处理降低15.4%和62.4%,茎叶As积累量分别降低11.9%和23.7%。Mo的添加还能显著地降低2种价态As在水稻根系和茎叶中的富集系数。因此,通过施用适量的Mo肥可以用来防治农田As污染,降低As对人体健康的危害。     

河北平原农田土壤重金属形态分布特征及控制因素研究

土壤重金属污染防治已迫在眉睫,国内外对重金属污染研究热度不减。本文选择河北平原农田为研究区,对采集325个根系土样品中的Cd、Cr、Pb、As、Hg等5种重金属进行了各形态含量统计与分析,并用Arc GIS制作了有效态空间分布图。最后运用相关性分析法探讨了5种重金属各形态与全量及pH值、Fe_2O_3、总有机碳(TOC)、阳离子交换容量(CEC)、粘粒的相关性。研究表明:Cd的有效态(水溶态和离子交换态)含量占全量比重最大,为18.06%,Cr、Pb、As、Hg均低于10%,这4种金属以残渣态为主,占全量的50%以上;As元素各形态与全量、pH值、Fe_2O_3、TOC、CEC、粘粒的相关程度最高,成正相关关系;Cr的3种形态(铁锰氧化态、强有机结合态、残渣态)与Fe_2O_3、TOC、CEC、粘粒呈显著正相关关系,Cr碳酸盐结合态、腐殖酸结合态与pH呈正相关关系,与Fe_2O_3、TOC、CEC、粘粒呈显著负相关关系;5种重金属铁锰氧化态与pH均呈正相关关系。     

The dissipation and risk assessment of 2,4-D sodium,a preharvest anti-fruit-drop plant hormone in bayberries

Preharvest fruit-drop is a challenge to bayberry production. 2,4-D sodium as a commonly used anti-fruit-drop hormone on bayberry can reduce the yield loss caused by preharvest fruit-drop. The persistence and risk assessment of 2,4-D sodium after applying on bayberries were investigated. A method for determining 2,4-D sodium in bayberry was established based on LC-MS-MS. The average recoveries of 2,4-D sodium were at the range of 93.7–95.8% with relative standard deviations (RSDs) ranging from 0.9 to 2.8%. The dissipation rates of 2,4-D sodium were described using first-order kinetics, and its half-life ranged from 11.2 to 13.8 days. A bayberry consumption survey was carried out for Chinese adults for the first time. The safety assessments of 2,4-D sodium were conducted by using field trail data as well as monitoring data. Results showed that the chronic risk quotient and the acute risk quotient were calculated to be 0.23–0.59 and 0.02–0.05%, respectively, for Chinese adults, indicating low dietary risk for adults and children. In the end, the household cleaning steps were compared, and results showed that water rinsing for 1 min can remove 49.9% 2,4-D sodium residue, which provides pesticide removal suggestion for consumers.

     

Detection of phosphorus species in sediments of artificial landscape lakes in China by fractionation and phosphorus-31 nuclear magnetic resonance spectroscopy

Phosphorus (P) pollution in the sediments of seven artificial landscape lakes was studied via fractionation and phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy. The lake sediments accumulated significant amounts of P from supplementation with reclaimed water and from runoff from the golf course lawns. The differences in total sediment P among lakes were correlated to the varied pollution extent from the lawns. One striking feature of the artificial lake sediments was the insufficiency of NaOH-extracted Al, which plays an important role in avoiding internal P release during anoxia. Another characteristic was the dominance of orthophosphate in the NaOH-EDTA extractants of the sediments, due to the heavy external P pollution. Phytate, considered prevalent in many soils and lake sediments, as well as polyphosphates and phosphonates which have appeared in some natural lake sediments, was not detected. The rank order of present biogenic P species was monoester-P>DNA-P>pyrophosphate>lipid-P.     

医疗垃圾焚烧飞灰重金属形态分析

利用原子吸收光谱仪分别对医疗垃圾焚烧飞灰重金属含量和重金属形态及其随颗粒度分布特性进行了分析,结果表明,飞灰中Cd、Zn、Pb等的浸出浓度远超标与这些重金属的可交换态和碳酸盐态含量较高有关;飞灰颗粒度主要在96 μm以下,96～150 μm的颗粒中Cd、Pb含量最高,且Zn、Cd的形态以可交换态为主.     

杭州城市可吸入颗粒物污染与气象条件关系的分级评价和BP神经网络评估

为了解杭州城市环境空气质量与气象条件之间的关系,利用杭州市区2003-2007年的可吸入颗粒物(PM10)浓度数据和气象资料,通过分级评价的方法和基于BP神经网络的污染物浓度评估模型,得到PM10浓度与气象条件的对应关系.结果表明,随着日降水量的增大,PM10浓度减小;风速与PM10浓度呈明显的负相关,随着风速的增大,PM10浓度明显减小;气象因素与PM10浓度之间呈非线性关系,大气能见度对PM10和相对湿度的变化极为敏感.随着PM10浓度的增大,大气能见度迅速降低,相对湿度越高,大气能见度则越低;近几年杭州市气象条件不利于大气污染物的扩散和清洗,是杭州城市环境空气质量上升缓慢的主要原因之一.     

水泥窑共处置污染土壤的污染排放研究

以被DDT和六六六污染的土壤为研究对象,开展了利用水泥窑进行共处置的工程试验研究,分析了共处置过程对尾气排放的影响。结果表明,水泥窑共处置对农药污染物的焚毁去除率很高,DDT达到99.99991%,六六六达到99.99964%,均高于我国危险废物焚烧炉规定99.99％的焚烧效率;与空白处理相比,尾气排放中有机污染物（包括二恶英/呋喃,简称PCDD/F、多氯联苯PCB、六氯苯HCB、挥发性有机物VOC）、酸性气体和重金属的排放在共处置过程中没有显著增加,且都低于相应的规定限值。试验结果表明,水泥窑共处置固体废物不会导致污染负荷的增加。     

混合固定化硝化菌和好氧反硝化菌处理焦化废水

对传统的聚乙烯醇(PVA)固定化方法进行了改进,试制了加入麦秸粉末的固定化球和以活性炭纤维膜为载体膜固定化细胞产品。混合固定化硝化细菌和好氧反硝化细菌对经过厌氧折流板反应器酸化后的焦化废水进行脱氮,焦化废水在厌氧折流板反应器中经过18 h的酸化后,pH在8.0左右,开始进入好氧槽进行脱氮。在有效容积为5 L好氧槽中经过12 h的曝气处理,加入麦秸粉末的固定化球对氨氮的去除率高达94.3%;纤维膜固定化细胞产品对氨氮的去除率为85%。整个脱氮过程无NO^-₂-N和NO^-₂-N的积累,实现了好氧条件下的同时硝化和反硝化。     

锰矿尾渣改性壳聚糖对Pb2+的吸附

将工业废弃物锰矿尾渣与壳聚糖混合制得一种高效吸附剂,并应用扫描电镜、X射线衍射对其结构进行了表征。采用正交表设计试验,分别考察了pH值、吸附时间、温度、复合吸附剂的投加量等4个影响因素对Pb²⁺吸附的影响,最佳吸附条件为：pH值为7,吸附时间为40 min,温度为20℃,复合吸附剂的投加量为0.10 g。处理后的水符合国家污水综合排放标准（GB8978-1996）中的一级标准。复合吸附剂对Pb2+的吸附符合Langmuir和Freundlich吸附等温方程。     

活性炭三维电极流化床处理洗车废水的研究

以经吸附处理的活性炭为填充粒子,对三维电极流化床反应器处理洗车废水进行了静态条件实验研究。结果表明：三维电极流化床处理洗车废水的效果明显好于三维电极固定床和单纯的活性炭吸附。在槽电压为30 V,通气量为3 L/min, 通电时间为30 min,活性炭用量为50 g时,COD去除率最高。