Environmental investigation of bio-modification of steel slag through microbially induced carbonate precipitation

Steel slag (SS) is one of byproduct of steel manufacture industry. The environmental concerns of SS may limit their re-use in different applications. The goal of this study was to investigate the leaching behavior of metals from SS before and after treated by microbially induced carbonate precipitation (MICP). Toxicity characteristic leaching procedure, synthetic precipitation leaching procedure and water leaching tests were performed to evaluate the leaching behavior of major elements (Fe, Mg and Ca) and trace elements (Ba, Cu and Mn) in three scenarios. The concentrations of leaching metals increased with the content of SS. After it reached the peak concentration, the leaching concentration decreased with the content of SS. The leachability of all elements concerned in this study was below 0.5%. The carbonate generated from the MICP process contributed to the low leachability of metals. After bio-modified by MICP process, the leaching concentrations of Ba from TCLP, SPLP and WLT tests were below 2.0 mg/L, which was the limit in drinking water regulated by U.S. EPA. The concentrations of Cu leached out from MICP-treated SS-sand samples were below 1.3 mg/L which is the limit regulated by national secondary drinking water. Compared with the regulations of U.S.EPA and Mississippi Department of Environment Quality (MDEQ), MICP-treated samples were classified as non-hazardous materials with respects to the leaching of metals. Meanwhile, maximum contaminant limits regulated by U.S.EPA states that MICP-treated SS are eco-friendly materials that can be reused as construction materials.     

碳酸钙和硼对棕红壤油菜锰毒缓解作用

对已酸化的棕红壤进行的油菜锰毒缓解研究表明, 施用碳酸钙在提高土壤ｐ Ｈ 和降低土壤交换性锰的基础上, 改善了土壤营养状况, 其中施用０ ． ５ ％ 碳酸钙处理的效果最好, 在这一碳酸钙水平下,土壤硼处于较高的活性, 土壤速效磷钾被油菜幼苗充分利用, 油菜幼苗对营养元素具有最大吸收量,使植株生物学产量达到最大值。酸化的棕红壤只需施用０ ． ５ ％ 的碳酸钙, 其土壤酸碱度便可恢复到正常水平, 如施用更多的碳酸钙, 会造成土壤营养再度失调, 油菜幼苗的生物学产量下降。在施用碳酸钙基础上配施硼素, 可使油菜生物学产量进一步提高, 相应的土壤环境得到更好的改善, 施硼可以降低锰毒植株磷的浓缩效应和提高营养元素的利用效率。因此, 碳酸钙－ 硼配施是缓解棕红壤油菜锰毒的一项重要措施。     

碳酸铅作为铅酸蓄电池电极材料的研究

采用粉末微电极技术和循环伏安法研究了ＰｂＣＯ３转化为铅酸电池电极活性物质的途径以及几种因素对ＰｂＣＯ３转化的ＰｂＳＯ４／ＰＢ电极性能的影响。ＰｂＣＯ３粉末在Ｈ２ＳＯ４溶液中化学转化－电化学活化后,正、负极的伏这行为与文献报道的类似。结果表明,较高扫速活化的ＰｂＳＯ４／Ｐｂ电极性能稳定且活性较高;转化ＰｂＣＯ３的Ｈ２ＳＯ４浓度０．５￣１．０ｍｏｌ·Ｌ＾－１优于２．５￣５．０ｍｏｌ·Ｌ＾－１,３０℃附     

海藻-过渡金属-光三元体系还原转化Se(Ⅵ)研究

以海洋绿藻(Tetraselmis levis,Chlorella autotrophica,Dunaliella salina,Nannochloropsis sp.,Tetraselmis subcordiformis)、硅藻(Phaeodactylum tricornutum)、红藻(Porphyridium purpureum)和过渡金属(铁、锰、铜)构建海藻-光二元体系、过渡金属-光二元体系、海藻-过渡金属-光三元体系,对比分析不同海藻、不同过渡金属、海藻与过渡金属耦合引发光化学过程,对Se(Ⅵ)还原转化的贡献率.二元和三元体系均可光还原转化Se(Ⅵ)为Se(Ⅳ).铁、铜、锰通过自身的光氧化还原过程诱发Se(Ⅵ)/Se(Ⅳ)的氧化还原;海藻的光化学活性首次被证实,表面壁可吸附富集海水中还原性的有机物、Se(Ⅵ)/Se(Ⅳ)和过渡金属,改变其氧化还原电位,提供光反应场所;Se(Ⅵ)的光还原转化率依海藻和过渡金属的种类、浓度不同而异;海藻浓度的提高、海藻与过渡金属的耦合作用有利于光还原转化率的提高.通过三元体系的光还原转化,Se(Ⅵ)/Se(Ⅳ)比值为1.17～2.85,接近海洋真光层Se(Ⅵ)/Se(Ⅳ)实际浓度比,即海藻和过渡金属引发的光化学过程对硒的价态分布起决定性作用.     

我国海洋环境保护的法律原则和政策措施

通过对近年来我国海洋环境保护法律法规和一些政策措施的分析,论述了基本的法律原则和当前所采取的污染防治和生态保护措施,结果表明,国家通过加强立法、增加投入,实施重点污染物总量控制、加强海洋生态保护和实施重点流域污染防治计划、重点海域碧海行动计划等措施,在一定程度上减缓了沿海经济建设和海洋产业开发给海洋环境带来的压力,近岸海域环境污染加剧的趋势得到初步控制,局部海域的环境质量有所改善。指出了当前存在的主要问题是城市环境基础没施建设滞后、工业污染防治水平不高、海上污染事故应急能力不足等,并提出了相应的建议。     

Marine Bacteria and Viruses in the Water and Bottom Sediments of Sevastopol Bays

Russian Journal of Ecology -     

Implications of Heterogeneous Chemistry of Nitric Acid for Nitrogen Deposition to Marine Ecosystems: Observations and Modeling

Size resolved particle composition and nitric acid (HNO₃)measurements from the ASEPS'98 experiment conducted in the BalticSea are used to provide observational evidence of substantialgas-particle transfer of oxidized nitrogen (N) compounds in themarine boundary layer. We then focus on the importance ofHNO₃ reactions on sea salt particles in determining spatio-temporal patterns of N dry deposition to marine ecosystems.Modelling results obtained assuming no kinetic or chemical limiton HNO₃ uptake and horizontally homogeneous conditions withnear-neutral stability, indicate that for wind speeds 3.5 – 10 ms^-1 transfer of HNO₃ to the particle phase to formparticle nitrate (NO₃ ^-) may decrease the N depositionvelocity by 50%. We extend this research using the CHEM-COASTmodel to demonstrate that, in a sulphur poor environment undermoderate wind speeds with HNO₃ concentrations representativeof those found in the marine boundary layer, inclusion ofheterogeneous reactions on sea spray significantly reducesmodelled NO₃ ^- deposition in the near coastal zone.     

海洋环境对直升机基础产品腐蚀行为影响研究

目的 研究螺栓、卡箍等直升机基础产品在海洋大气环境下腐蚀和力学性能随时间的变化规律,采用结构模拟连接件,验证直升机防护体系对基础产品的防护效果。方法 通过将螺栓、卡箍和连接件在外场暴露不同时间,在此期间定期对试验件表面状态和力学性能进行测试,分析海洋环境对直升机基础差的影响和机上防护方法的可靠性。结果 经过2a腐蚀后,螺栓表面发生了明显的腐蚀,但是腐蚀深度不大,抗拉强度维持在18.3 MPa,剪切强度从27.99 MPa下降到26.52 MPa。卡箍发生了腐蚀,橡胶材料老化严重,推出力降低80%,基本丧失锁紧性能。有涂层保护的典型连接件,表面厚度为66 mm,色差为0.3,光泽度变化1%,各项参数与未暴露时相比变化不大。结论 在海洋大气环境下,螺栓、卡箍等在未采取防护措施的情况下不建议使用,机上采用的防护措施有效,可对基体起到很好的保护作用。     

海洋大气环境对封套防护材料性能影响

目的 探究铝塑型封套防护材料在湿热海洋大气自然环境贮存条件下性能衰退规律。方法 通过优化铺层结构,采用SiO_x蒸镀双向拉伸聚酯膜作为外增强层,PA6共挤EVOH双向拉伸膜作为内增强层制备新型封套防护材料。在海洋大气环境试验站库内、棚下2种贮存条件下开展贮存试验,跟踪测试水蒸气透过率、氧气透过率、剥离力、拉断力和表面电阻率等关键性能,建立时间-性能影响曲线,同时记录材料内部湿度曲线和内置的金属圆片的锈蚀状态,以此评价海洋大气环境对铝塑型封套防护材料性能影响趋势。结果 在经过180 d的贮存后,水蒸气透过率仍小于0.3 g/(cm²·24 h),自研的新型封套防护材料在库内和棚下贮存环境下的阻湿能力分别提高了29.8%和31.5%,且剥离力和拉断力未发生明显降低,表面电阻率处于10⁹～10¹¹?。结论 通过降低水分子与外增强层分子的相互作用,可有效提高封套防护材料的阻隔能力,验证了多级防潮理念的科学性。     

建立我国污水海洋处置管理信息系统

根据“八五”国家科技攻关课题的研究成果,建立了我国污水海洋处置管理信息系统。该系统界面十分清晰、直观,便于操作,有助于海域环境管理的快速决策,可用于我国沿海城市进行污水海洋处置工程规划建设和运行时的查询检索或跟踪监测海域的环境状况,并可对海域环境质量进行评价、预测及污水海洋处置规划。可确定出污水出水点近区浓度场及初始稀释度等各类污水排放参数,对当地海域环境管理及重大战略决策起到很好的技术支持作用