Effects of As levels on radial oxygen loss and As speciation in rice

Greenhouse experiment was conducted to examine effects of arsenic (As) on iron plaque formation, radial oxygen loss, As accumulation, and speciation in rice. Three genotypes were grown in soil with three different concentrations of As. The stress of As caused a slight increase of iron plaque formation (P?>?0.05) and a decrease in the rates of radial oxygen loss (ROL; P?<?0.01). The results of As speciation showed that the percentages of DMA increased from 19–28 % to 53–58 %, while the percentages of inorganic As decreased from 53–58 % to 36–42 % with the increasing soil As concentrations, indicating a strong environmental influence on As species in rice grain. The present study showed that elevated soil As may induce As toxicity towards rice plants, leading to the decrease of ROL; environmental factors could influence As methylation or As species transportation. Our study provided useful information on As tolerance and accumulation in rice which may contribute to reducing the health risk posed by As contamination in rice.     

Effects of alkaline and bioorganic amendments on cadmium,lead, zinc,and nutrient accumulation in brown rice and grain yield in acidic paddy fields contaminated with a mixture of heavy metals

Paddy soils and rice (Oryza sativa L.) contaminated by mixed heavy metals have given rise to great concern. Field experiments were conducted over two cultivation seasons to study the effects of steel slag (SS), fly ash (FA), limestone (LS), bioorganic fertilizer (BF), and the combination of SS and BF (SSBF) on rice grain yield, Cd, Pb, and Zn and nutrient accumulation in brown rice, bioavailability of Cd, Pb, and Zn in soil as well as soil properties (pH and catalase), at two acidic paddy fields contaminated with mixed heavy metals (Cd, Pb, and Zn). Compared to the controls, SS, LS, and SSBF at both low and high additions significantly elevated soil pH over both cultivation seasons. The high treatments of SS and SSBF markedly increased grain yields, the accumulation of P and Ca in brown rice and soil catalase activities in the first cultivation season. The most striking result was from SS application (4.0 t ha^?1) that consistently and significantly reduced the soil bioavailability of Cd, Pb, and Zn by 38.5–91.2 % and the concentrations of Cd and Pb in brown rice by 20.9–50.9 % in the two soils over both cultivation seasons. LS addition (4.0 t ha^?1) also markedly reduced the bioavailable Cd, Pb, and Zn in soil and the Cd concentrations in brown rice. BF remobilized soil Cd and Pb leading to more accumulation of these metals in brown rice. The results showed that steel slag was most effective in the remediation of acidic paddy soils contaminated with mixed heavy metals.     

模糊评价因子的熵权法赋权及其在水质评价中的应用

针对模糊综合评价方法中对多因子赋权时计算繁琐、工作量大、未考虑多个评价对象间联系等缺陷，提出利用熵权法对多评价目标因子赋权的新思路．利用三峡库区城市江段13个监测断面的水质监测数据，比较了利用熵权法与传统的评价因子赋权的差异．结果表明，当涉及多个评价对象时，采用熵权法对各因子赋权，只需1次计算即可，无需对每个监测点进行权重计算，从而使模糊评价过程大大简化，评价的结果客观、合理．     

毛皮加工清洁生产的白皮鞣制技术

研究了改性有机磷化合物在毛皮鞣制过程中的应用技术(白皮鞣制技术),替代了传统的甲醛或铬类鞣剂进行的毛皮加工生产,减少了毛皮产品及生产废液中有害物质的含量,达到了欧盟规定的技术要求,实现了环保型加工。     

生物反硝化去除地下水中硝酸盐的混合碳源研究

选取麦秸、锯末、乙醇为碳源,比较了这3种物质单独或两两组合作为碳源的情况下,生物反硝化去除模拟地下水中硝酸盐的效果.结果表明,以麦秸为碳源的反应体系具有较好的反硝化效果,但反应器出水具有颜色和异味;锯末+乙醇作为混合碳源的反应体系比单独添加锯末或乙醇反应体系的脱氮效果好;碳氮比(C/N)为40的混合碳源用量有利于硝酸盐...     

载Ca磁性碳纳米管对水中腐殖酸的去除

采用化学共沉淀一步法以钙盐和铁盐对多壁碳纳米管（MWCNTs）改性以制备具有去除水中微污染物腐殖酸的磁性碳纳米管复合材料。X射线能谱分析表明改性MWCNTs上载有Ca和Fe元素。通过振动样品磁强计测得该复合材料具有较强磁性。改性后的MWCNTs 30 min对水中腐殖酸的去除率由改性前的63.89%提高到90.27%。研究了改性MWCNTs投加量、腐殖酸初始浓度、吸附时间、振荡速度、pH及温度对水中腐殖酸去除的影响。结果表明,腐殖酸去除率随着载Ca磁性MWCNTs投加量增大而提高。吸附量随着腐殖酸初始浓度的增大而增加,但去除率却减小。吸附初期腐殖酸去除速率快,0.5 g·L-1的载Ca磁性多壁碳纳米管在腐殖酸初始浓度为20 mg·L-1时,5 h达到吸附平衡,平衡吸附量为39.41 mg·g-1。腐殖酸去除率随着振荡速度的增大而增大,在225 r·min-1时达最大,随后随着振荡速度的增大而缓慢下降。在弱酸性下,腐殖酸去除率较高,当pH为5时,腐殖酸去除率达到92.24%;当pH5时,腐殖酸去除率随pH增大呈下降趋势。腐殖酸去除率随着温度的升高而降低。     

生物滞留系统处理水产养殖尾水的效能和机制

为探究生物滞留系统(bioretention system,BS)对水产养殖尾水的处理效能,设计并构建倒置(inverted bioretention system,IBS)和正置(control bioretention system,CBS)2组生物滞留系统,在不同进水条件下比较了2种BS构建方式的运行效能,通过胞外聚合物(EPS)、三维荧光光谱和电子传递活性(ETSA)等方法阐述了不同构建方式下BS的脱氮机制。结果表明：在不同进水条件下IBS的处理效能优于CBS,当运行间隔周期为1 d时,IBS的TN和NO₃⁻-N去除率分别达到71.79%~82.00%和68.70%~85.84%,平均去除率比CBS分别高出10.65%和15.89%。CBS和IBS的TN和NO₃⁻-N去除率随进水负荷的增加呈先升高后稳定的趋势,TP波动最小,去除率均稳定在97.04%~99.22%。构建方式对EPS的组分无明显影响,但对EPS含量和ETSA影响显著。IBS的构建方式可促进微生物分泌更多的EPS,其中EPS的多糖(PS)和蛋白质(PN)含量分别比CBS高出66.89 ug·g⁻¹和603.24 ug·g⁻¹,并且IBS的酪氨酸、色氨酸和微生物代谢产物明显高于CBS;此外,与CBS的ETSA为(0.47±0.07) ug·(g·min)⁻¹,相比IBS提高了0.35 ug·(g·min)⁻¹。以上研究结果为应用生物滞留系统技术处理养殖尾水提供参考。     

印染废水处理厂二级出水的硫自养反硝化脱氮工艺

采用硫/白云石自养反硝化脱氮工艺处理印染废水处理厂二级出水,考察不同污泥接种方式、水力停留时间（HRT）、温度及进水负荷对系统脱氮效果的影响。结果表明：反应器在3 d内即可完成快速启动,工程应用中可不接种污泥;反应器最佳HRT为20 min,TN去除率为40.2%,但反冲洗频率加快;温度、进水负荷对系统脱氮效果影响较大,当温度在25~30 ℃之间,TN平均去除率为43.8%;当进水负荷为（1.37±0.15）kg·（m3·d）-1,TN平均去除率为37.1%,反应器具有较强的抗冲击负荷能力。     

改性凹凸棒土的优化定向制备及对腐殖酸的吸附效果

以天然凹凸棒土为原料,以去除以腐殖酸为代表的天然有机物为目的,研究酸活化、热处理和十八烷基三甲基氯化铵(OTAC)有机改性3种改性方法,进行定向筛选。进一步比较3种方法联合改性凹土后对腐殖酸的吸附效果,确定最优定向改性方法。结果表明,先酸处理后OTAC改性凹土对腐殖酸的吸附效果最好,改性凹土投药量为0.7 g/L时,腐殖酸的去除率可达97%。利用正交实验确定凹土改性的最佳工艺条件、钠化时间和有机改性剂的用量对改性凹土吸附腐殖酸的能力影响显著。改性的最佳工艺条件为:酸浓度3 mol/L,氯化钠浓度0.5 mol/L,钠化时间2 h,改性剂用量为凹土质量的3%,微波改性时间为9 min。单独投加改性凹土时pH值对腐殖酸的吸附效果有重要影响。该方法制备的改性凹土在水处理工艺有良好的应用前景。