Fe^0对土壤中对氯硝基苯和对硝基甲苯的还原

采用零价铁(Fe0)还原技术,在25℃和常压下修复受对氯硝基苯(PCNB)和对硝基甲苯(PNT)混合污染的土壤,研究不同反应条件对还原反应的影响及产物在反应历程中的变化.实验结果表明:零价铁能够有效地将土壤中PCNB和PNT还原为其对应的苯胺化合物.在PCNB和PNT的初始含量约为2.5×106mol·g-1,Fe0加人最为25 mg·g-1,土壤水分含量为0.75 mL·g-1,土壤初始pH值为6.8,于25℃下反应5 h,PCNB和PNT的还原率都可达93%以上.Fe0用量、土壤初始pH值、温度和土壤含水量均对Fe0还原硝基苯类化合物有较明显影响,偏酸性的土壤、较高的温度、增加Fe0用量和饱和的土壤含水量能显著提高还原率.     

Changes in distribution patterns of weed species richness in agricultural lands on Qinghai-Tibet Plateau under climate change北大核心CSCD

农田杂草是阻碍农业生产的主要因素之一.明确农田杂草丰富度分布格局对农业生产管理具有重要意义.以青藏高原农田杂草为研究对象,利用物种分布模型探讨基于县域尺度的农田杂草物种丰富度分布格局及其未来(2050s)的变化,利用逐步回归筛选影响物种丰富度的环境因子,基于传统最小二乘法(OLS)和地理加权回归模型(GWR)分析环境因子对农田杂草物种丰富度的影响,并对两种分析方法进行比较.结果显示:(1)分布在青藏高原的农田主要杂草有51科284种,其中59种单子叶杂草、222种双子叶杂草、135种一年生杂草和149种多年生杂草.青藏高原农田杂草物种丰富度呈由西向东递增的变化规律,物种丰富度中心(丰富度值为167-194)主要集中在一江两河、河湟谷地和川西北等地区;(2)全球气候变化背景下,未来(2050s)青藏高原农田杂草物种丰富度整体呈由东南向西北方向增加的趋势,其中SSP1-2.6情境下最多增加43种,SSP5-8.5情境下最多增加49种;(3)GWR模型优于OLS,其结果表明青藏高原农田杂草物种丰富度的主要驱动因子是最冷季平均温、太阳辐射和最干月降水量,上述变量对杂草丰富度的影响存在明显的空间差异性,其中最冷季平均温由南向北逐渐从负向影响转变为正向影响.太阳辐射整体在青藏高原东部边缘等地区对农田杂草丰富度起正向的影响,在藏东南、青藏高原北部边缘等地区起负向的影响.最干月降水量对整个研究区域起负向影响,并表现出影响力由南向北逐步递增的趋势.上述结果表明青藏高原农田杂草物种丰富度调查不足,实际观测到的丰富度值明显低于当前气候下潜在的丰富度值,存在低估现象.当前气候背景下的农田杂草物种丰富度中心分布地区在未来仍是重点监管对象,且未来青藏高原部分地区作物可能面临新的杂草入侵风险.建议未来研究应注重于青藏高原粮食主产区农田杂草群落结构和功能调查、杂草和作物种间关系、耕地尺度上丰富度驱动因子分析等方面,为区域杂草管理和防治提供充分科学依据.(图6表2参53)     

共存阳离子对砷、硒和钒毒性效应的影响及预测模型研究

为探明并量化共存阳离子存在下含氧阴离子型金属在生物体中的毒性效应,以模式植物小麦(Triticum aestivumL.)为研究对象,通过单一变量控制实验,探究了4种阳离子(Ca⁽²⁺⁾、Mg(2+)、Mg⁽²⁺⁾、Na(2+)、Na⁺和K+和K⁺)对3种典型含氧阴离子型金属(AsO_4+)对3种典型含氧阴离子型金属(AsO_4^(3-)、SeO_3(3-)、SeO_3^(2-)和VO_4(2-)和VO_4^(3-))毒性的影响,并构建了静电作用模型来预测和评估As、Se和V的生态毒性效应与风险。结果表明,Ca(3-))毒性的影响,并构建了静电作用模型来预测和评估As、Se和V的生态毒性效应与风险。结果表明,Ca⁽²⁺⁾对As、Se和V毒性的影响呈现出3种不同的趋势：在相同设计浓度范围内Ca(2+)对As、Se和V毒性的影响呈现出3种不同的趋势：在相同设计浓度范围内Ca⁽²⁺⁾的增加显著引起了As毒性的减弱(Adj.R(2+)的增加显著引起了As毒性的减弱(Adj.R²=0.76,P<0.05)、V毒性的加剧(Adj.R2=0.76,P<0.05)、V毒性的加剧(Adj.R²=0.81,P<0.05),而对Se毒性却没有显著影响。当Mg2=0.81,P<0.05),而对Se毒性却没有显著影响。当Mg⁽²⁺⁾从0.20 mmol·L(2+)从0.20 mmol·L^(-1)增加到2.73 mmol·L(-1)增加到2.73 mmol·L^(-1)时,Se主导形态的半数有效活度值(EC_(50){HSeO+3(-1)时,Se主导形态的半数有效活度值(EC_(50){HSeO+3^-})从40.40 μmol·L-})从40.40 μmol·L^(-1)显著下降为27.98 μmol·L(-1)显著下降为27.98 μmol·L^(-1),即Se毒性增强到原来的1.44倍(Adj.R(-1),即Se毒性增强到原来的1.44倍(Adj.R²=0.79,P<0.05)。静电作用理论能够很好地解释Ca2=0.79,P<0.05)。静电作用理论能够很好地解释Ca⁽²⁺⁾(或Mg(2+)(或Mg⁽²⁺⁾)在显著增强V(或Se)毒性中发挥的作用,将这种静电作用影响纳入考虑成功构建了可以定量预测V(Adj.R(2+))在显著增强V(或Se)毒性中发挥的作用,将这种静电作用影响纳入考虑成功构建了可以定量预测V(Adj.R²=0.88)和Se(Adj.R2=0.88)和Se(Adj.R²=0.95)毒性的静电作用模型。研究结果弥补了目前含氧阴离子型金属生态毒性研究的不足,为含氧阴离子型金属的土壤污染生态风险评估提供了指导与参考。     

黄、渤海恶劣天气影响船舶安全的风险预估技术初探

在黄渤海船舶类型调查和事故调查的基础上,将船舶航行作为由人-船-环境组成的多因素复杂系统,将气象海况条件作为操船环境因素之一,依据风险决策ALARP准则,调查得到黄海、渤海海区大风浪条件下5 000 t以下货船和客滚轮的不同风险等级标准,具有一定的可操作性。依托精细化的数值预报产品,建立气象保障支持系统,并加工不同船舶的风险预估产品。对实际出现的海难事故进行风险预估,证明了方法的可用性。还需要研究更多船型的风险预估方法和黄海、渤海海区航行船舶的风险区划;已有方法也有待深化。     

Poultry litter-based activated carbon for removing heavy metal ions in water

Utilization of poultry litter as a precursor material to manufacture activated carbon for treating heavy metal-contaminated water is a value-added strategy for recycling the organic waste. Batch adsorption experiments were conducted to investigate kinetics, isotherms, and capacity of poultry litter-based activated carbon for removing heavy metal ions in water. It was revealed that poultry litter-based activated carbon possessed significantly higher adsorption affinity and capacity for heavy metals than commercial activated carbons derived from bituminous coal and coconut shell. Adsorption of metal ions onto poultry litter-based carbon was rapid and followed Sigmoidal Chapman patterns as a function of contact time. Adsorption isotherms could be described by different models such as Langmuir and Freundlich equations, depending on the metal species and the coexistence of other metal ions. Potentially 404 mmol of Cu²⁺, 945 mmol of Pb²⁺, 236 mmol of Zn²⁺, and 250–300 mmol of Cd²⁺ would be adsorbed per kg of poultry litter-derived activated carbon. Releases of nutrients and metal ions from litter-derived carbon did not pose secondary water contamination risks. The study suggests that poultry litter can be utilized as a precursor material for economically manufacturing granular activated carbon that is to be used in wastewater treatment for removing heavy metals.     

Thermal Properties and Crystallization Behavior of Novel Biodegradable Poly(hexamethylene succinate-<Emphasis Type="Italic">co</Emphasis>-6 mol% butylene succinate) and Poly(hexamethylene succinate)

In this research, the thermal properties and crystallization behavior of novel poly(hexamethylene succinate-co-6 mol% butylene succinate) (PHBS) and its homopolymer poly(hexamethylene succinate) (PHS) were extensively studied. With respect to PHS, the introduction of a small content of butylene succinate (BS) unit slightly reduces the melting point and equilibrium melting point but hardly influences the glass transition temperature of PHBS. Despite crystallization temperature, PHS and PHBS crystallize through the same crystallization mechanism. At the same crystallization temperature, PHBS crystallizes more slowly than PHS; furthermore, lowering crystallization temperature enhances the crystallization rates of PHBS and PHS. The spherulites morphologies were observed for both of them, with the spherulites nucleation density of the copolymer being smaller than that of the homopolymer. PHBS and PHS share the same crystal structures, indicative of the location of BS unit in the amorphous region.     

锌粉对1,2,4-三氯苯的脱氯性能

采用锌粉对1,2,4-三氯苯（1,2,4-TCB）进行了脱氯的研究。实验结果表明,在40mL质量浓度为22.94m g/L的1,2,4-TCB水溶液中加入1.0g锌粉,反应24h时,1,2,4-TCB的还原率可达94.6%;反应16h时,试样中的Cl-浓度约为1,2,4-TCB完全脱氯所得Cl-理论浓度的30%;锌粉还原1,2,4-TCB的反应能在较宽的pH范围内进行,弱碱性条件下的脱氯效果最好,1,2,4-TCB的还原率达70%。     

Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate/Fe(II)/formic acid system in aqueous solution

Complete CT degradation was achieved by SPC/Fe(II)/FA system.Formic acid established the reductive circumstance by producing CO₂·^–.CO₂·^– was the dominant active species responsible for CT degradation.CT degradation was favorable in the pH range from 3.0 to 9.0.SPC/Fe(II)/FA system may be suitable for CT remediation in contaminated groundwater.The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CT could be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO2·^–) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl^– and HCO₃^– of high concentration showed negative impact on CT removal. Cl^– released from CT was detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.     

酸沉降临界负荷计算模式的修正

酸沉降临界负荷是酸沉降水平的函数,不同酸沉降水平下,矿物风化速率有数量级差别,在因此,酸沉降临界负荷的计算应先使用判别方程计算平衡ＰＨ值,然后确定采用何种方法计算,在欧洲可以直接采用动态模式计算临界负荷,是因为其酸沉水平能满足判别方程成立,但在中国大多数情况下不成立。     

改进式曝气生物滤池处理高氨氮废水的研究

针对化肥氨氮废水排放量大、氨氮浓度高、C/N低等特点,通过实验研究探讨了添加高效菌种后采用改进式曝气生物滤池对化肥氨氮废水的处理性能、机理及实用性,并与SBR、普通BAF(Biofor)工艺和未添加高效菌种的改进式曝气生物滤池进行了对比。实验结果表明,添加高效菌种后改进式曝气生物滤池可以将氨氮≤200 mg/L,COD≤150 mg/L的化肥废水有效地处理至氨氮≤5 mg/L,COD≤50 mg/L,同时对总氮去除率达60%以上。