Influence of environmental factors on arsenic accumulation and biotransformation using the aquatic plant species Hydrilla verticillata

Hydrilla verticillata(waterthyme) has been successfully used for phytoremediation in arsenic(As) contaminated water.To evaluate the effects of environmental factors on phytoremediation,this study conducted a series of orthogonal design experiments to determine optimal conditions,including phosphorus(P),nitrogen(N),and arsenate(As(Ⅴ))concentrations and initial pH levels,for As accumulation and biotransformation using this aquatic plant species,while also analyzing As species transformation in culture media after 96-hr exposure.Analysis of variance and the signal-to-noise ratio were used to identify both the effects of these environmental factors and their optimal conditions for this purpose.Results indicated that both N and P significantly impacted accumulation,and N was essential in As species transformation.High N and intermediate P levels were critical to As accumulation and biotransformation by H.verticillata,while high N and low P levels were beneficial to As species transformation in culture media.The highest total arsenic accumulation was(197.2±17.4) μg/g dry weight when As(V) was at level 3(375μg/L),N at level 2(4 mg/L),P at level 1(0.02 mg/L),and pH at level 2(7).Although H.verticillata is highly efficient in removing As(Ⅴ) from aquatic environments,its use could be potentially harmful to both humans and the natural environment due to its release of highly toxic arsenite.For cost-effective and ecofriendly phytoremediation of As-contaminated water,both N and P are helpful in regulating As accumulation and transformation in plants.     

嘉兴地区农村生活污水时空分布及处理设施现状分析

研究选取嘉兴市下辖农村的160座生活污水处理设施进出水为研究对象,分析了区域农村生活污水污染物时空分布特征及其处理设施现状,以期提高处理设施效率。结果表明:嘉兴市农村生活污水中氮、磷污染较有机污染更严重,ρ（COD）、ρ（TP）、ρ（TN）、ρ（NH₄+-N）年均值分别为142.23,4.02,44.19,27.74 mg/L,各污水处理设施处理效果有很大优化空间,COD、TP、TN、NH₄+-N年均去除率分别为50.5%、29.7%、36.8%、51.7%。农村生活污水空间上呈自西向东、由北至南逐渐减小的分布特征,时间上表现为冬季 > 春季 > 秋季 > 夏季。相关性分析表明,COD、TP、TN、NH₄+-N之间呈极显著正相关（P<0.01）,相关系数为0.688±0.946。设施进水C/N、NH₄+-N/TN年均值分别为3.21、68.9%,传统的单一A2/O处理工艺对低碳源污水处理效果不理想,可通过组合工艺设计、规范运营管理、加强后期监测等有效措施来进一步加强污水处理设施处理效果。     

以牺牲阳极强化的电化学联用方法修复铬污染土壤

为解决重金属污染土在电动法修复过程中存在的聚焦效应问题,提出了牺牲铁阳极的电化学联用修复技术。在传统电动修复方法基础上增加电解液净化循环装置,优化Cr（Ⅵ）还原及沉淀所需技术参数,并与传统电动修复技术进行对比,探讨其修复效果及适用性。结果表明:迁出的Cr（Ⅵ）可在Fe2+作用下被还原为Cr（Ⅲ）并沉淀,pH、电压梯度、电流密度、电极面积均会影响其反应速率,电极距离对反应速率无直接影响,主要影响电解功率。Cr（Ⅵ）还原-沉淀反应的最佳技术参数为:pH值5~6.5,电压梯度0.8 V/cm,电流密度>6.67 mA/cm2,电极面积90 cm2,电极距离15 cm;较传统电动修复技术,以牺牲阳极强化铬污染土的电化学联用修复技术中,土壤室不同点位的去除率波动范围在10%,最高点位的去除率提高近24%,达93.4%。靠近阳极附近土体中Cr（Ⅵ）去除率从0.24%提高到80.38%。以牺牲阳极强化污染土的电化学联用修复方法不仅有效解决了重金属迁移的聚焦问题,而且有助于促进土中重金属污染物的整体性迁出。     

圆红冬孢酵母利用生物柴油副产物粗甘油产油脂的影响因素分析

以餐饮废油制备生物柴油的副产物粗甘油为碳源,采用圆红冬孢酵母发酵生产微生物油脂。通过对发酵影响因素的优化,确定了最适发酵条件为:种子复苏时长24 h、富集时长10 h、接种量为6%、初始粗甘油浓度为60 g/L、C/N为60、有机氮占总氮比例为75%、发酵体积为100 mL、发酵温度为30 ℃、发酵时间为6 d,在此条件下,获得总产油量为10.56 g/L,油脂产率为0.229。与无机氮源硫酸铵相比,有机氮源蛋白胨的添加显著提高了油脂含量和总产油量。通过测定油脂的脂肪酸成分并利用Hoekman方程估算所得生物柴油的性能指标,表明其符合中国、美国及欧盟标准。该方法既为粗甘油的再利用提供了一条新途径,又为生物柴油的生产提供了廉价的原材料。     

亚铁添加条件下潜流湿地中氮和化学需氧量的去除效应

为了强化水平潜流人工湿地脱氮和去除化学需氧量的效果,文章利用模拟实验开展了不同浓度的亚铁(Fe~(2+))添加对其去除效果的影响研究,并初步探讨了其作用机理。研究结果表明,添加Fe~(2+)影响了水平潜流人工湿地脱氮和去除化学需氧量的能力,而且各形态的氮素和化学需氧量的去除率随水力停留时间的延长而增大。添加高浓度Fe~(2+)(≥50 mg/L)促进了湿地系统总氮和硝态氮的去除,其去除率分别超过67.7%和72.6%;而对铵态氮去除效果的影响不明显;添加低浓度Fe~(2+)(≤10 mg/L)限制了硝态氮和铵态氮的去除,而对总氮的去除效果的影响较弱。添加高浓度Fe~(2+)(≥50 mg/L)显著促进水平潜流人工湿地化学需氧量的去除,水力停留时间为24 h,其去除率均高于91%,而添加低浓度Fe~(2+)(≤10 mg/L)对促进化学需氧量的去除效果不明显,但其去除率略高于对照组,表明添加Fe~(2+)可以提高水中易降解有机物的去除能力。Fe~(2+)进入湿地系统后,水中可溶性总铁、Fe~(2+)和Fe3+浓度迅速下降,5 h后基本保持平稳,其中可溶性总铁浓度低于3.2 mg/L。添加Fe~(2+)明显降低了人工湿地出水的pH和氧化还原电位,并发生了显著变化。因此,添加适宜浓度Fe~(2+)(50 mg/L)可促进水平潜流湿地对氮素和化学需氧量的去除,可以为人工湿地强化技术研发提供理论依据。     

Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols(BSOA) derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau(a continental background site) and five cities of China were measured using gas chromatography/mass spectrometry(GC/MS). Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations(R2= 0.44–0.90) between BSOA and sulfate were found at the six sites,suggesting that anthropogenic pollution(i.e., sulfate) could enhance SOA formation,because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode( 3.3 μm) except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse( 3.3 μm) modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.     

南通市冬季PM2.5中水溶性离子污染特征

根据南通市2016和2017年冬季大气多参数站自动监测PM2.5数据和在线离子色谱分析仪Marga监测的PM2.5中水溶性离子数据,分析了南通市冬季PM2.5中水溶性离子污染特征。结果表明,南通市2016和2017年冬季,ρ(PM2.5)分别为58和54μg/m 3,均高出其年均值(14μg/m^3);ρ(水溶性离子)总占ρ(PM2.5)百分比分别为74.5%和74.3%;二次离子ρ(NO3^-、SO4^2-和NH4^+)占ρ(PM2.5)百分比分别为66.8%和66.6%;各水溶性离子占比大小依次为:NO3^-、SO4^2-、NH4^+、Cl^-、K^+、Na^+、Ca^2+、Mg^2+。对ρ(NO3^-)/ρ(SO 4^2-)分析表明,移动源已经成为南通市冬季的主要污染源,且呈逐年增强趋势。对氯氧化率和硫氧化率的分析表明,南通市冬季存在较明显的二次污染,SO2的转化程度大于NO2。除Na^+和Mg^2+外,其他离子与PM2.5均呈显著相关性,NO3^-、SO4^2-与NH4^+之间的相关系数最高,Cl^-与除Na^+外的所有阳离子均呈显著相关性。     

滨州沿海湿地生物多样性保护探讨

重点研究了该区域海洋生物多样性、淡水生物多样性、陆生和海岛等高等植物多样性、陆栖动物多样性与特点。分析了其破坏现状及原因，提出了生物多样性保护对策和可持续利用途径。