生态用地分类初步研究

中国现有的土地利用分类体系对土地的生态属性考虑不足,导致生态用地分类缺乏统一的标准,生态用地难以得到有效保护。基于此,该文尝试对生态用地分类体系进行初步研究,以期为生态用地的科学管护,国土空间格局的优化和生态文明建设的推进提供科技支撑。在总结借鉴国内外学者有关生态用地研究成果的基础上,首先对生态用地概念进行了界定,在剔除《第二次全国土地调查技术规程-土地利用现状分类》中的非生态用地基础上,采用“逆向递推”方法将生态用地合并归类：根据生态用地的概念、内涵和划分依据,将剔除非生态用地后的土地利用现状分类中的二级地类归为35个生态用地三级地类;根据人类活动对生态用地影响范围和程度的不同而导致发挥的生态功能强弱的差异,将生态用地三级地类合并归类为14个二级地类;基于“人类活动-生态用地”影响反馈机理,将生态用地分为原生生态用地、半人工生态用地和人工生态用地3个一级地类。随后,为使生态用地分类系统在生态用地管理与生态建设实践中发挥应有的作用,将土地利用现状分类与生态用地分类实现了有效衔接。最后,作者建议借鉴国内外对于生态系统服务功能的相关研究,考虑从生态系统服务价值等视角来建立相关定量化的系统科学的生态用地分类体系。     

不同根瘤菌中突变cysDN基因对硫酸盐同化途径的影响

硫是生物体必须的元素,根瘤菌结瘤因子的硫化修饰与其宿主范围和识别效率有着重要关系,实验室前期研究中突变费氏中华根瘤菌的cys DN基因后,突变体不能利用硫酸盐生长,这与Sinorhizobium sp.BR816的cys D基因突变后的现象不同,两株菌的硫酸盐同化途径中可能存在差异.为探讨不同根瘤菌cys DN基因对硫酸盐同化途径的影响,本研究利用同源交换的方法构建费氏中华根瘤菌WGF03、费氏中华根瘤菌HN01、苜蓿中华根瘤菌14500及大豆慢生根瘤菌15606的cys DN突变体,Δcys DN-WGF03、Δcys DN-HN01、Δcys DN-14500和cys NR-15606,对突变体的硫源利用情况和植株结瘤情况进行研究.结果发现,Δcys DN-WGF03和Δcys DN-HN01失去利用硫酸盐的能力;Δcys DN-14500能微弱地利用硫酸盐生长,生长量约为野生菌株的1/3左右;cys NR-15606对硫酸盐的利用与野生菌株相比无明显差别.植株实验结果显示,Δcys DN-WGF03、Δcys DN-HN01和Δcys DN-14500在平均瘤数、平均瘤重、平均植株干重和固氮酶活性方面均表现出显著降低,而突变体的回补体能够恢复硫酸盐的利用能力及与植株的共生固氮能力.这说明cys DN基因在费氏中华根瘤菌WGF03、费氏中华根瘤菌HN01和苜蓿中华根瘤菌14500硫酸盐同化途径中起着关键影响,而该基因在大豆慢生根瘤菌15606的影响并不明显.本研究表明,cys DN基因在不同根瘤菌中所起的作用不同,不同根瘤菌的硫酸盐同化方式也存在差异.     

食蚊鱼(Gambusia afinis)cat、gapdh和gst基因的克隆及其在生态毒理学中的应用

根据Ensembl、Genbank登录的鱼类cat、gapdh和gst基因的CDS序列设计普通PCR扩增引物,寻找食蚊鱼的cat、gapdh和gst基因的c DNA片段,并根据定量引物设计要求设计出相应的SYBR Green I荧光定量RT-q PCR引物,建立了食蚊鱼cat、gapdh和gst基因的SYBR Green I荧光定量RT-q PCR方法。该方法在104~108数量级范围内有良好线性关系(R=0.999~1.000);熔解曲线显示扩增产物特异性良好,均为单一峰值;质粒标准品最高浓度与最低浓度的批内试验变异系数与批间试验变异系数均低于2%。利用该方法监测和评价环境污染物对水生生物的影响,选择了水体中常见典型药物污染物——双氯芬酸,研究其对食蚊鱼抗氧化基因表达的影响。结果表明,雌性食蚊鱼暴露在不同浓度双氯芬酸钠(0.005、0.05、0.5和5 mg·L-1)24 h后,其肝脏cat、gapdh和gst的mRNA呈现显著变化,相对于对照组,在低浓度0.005 mg·L-1时,cat与gst mRNA的表达量均有极显著上升(p0.01),而其它浓度均极显著下降(p0.01)。试验表明该方法具有快速、精确、灵敏度高的优点,可为利用该类小型鱼类的原位污染物的生物监测和生态毒理评价提供有力的技术支持。     

UV/H2O2氧化降解克拉霉素的反应动力学及影响因素

克拉霉素用量大、检出频率高、生态风险大,已被欧盟列为优先监测污染物.针对传统污水处理厂难以完全去除克拉霉素的问题,主要研究了UV/H_2O_2降解克拉霉素的效果和反应动力学,探讨了pH、天然有机质(NOM)和水中共存阴、阳离子对UV/H_2O_2降解克拉霉素的影响.结果表明:单一UV对克拉霉素的光降解符合准一级反应动力学模型,其反应速率常数为0.0016 min~(-1).UV/H_2O_2对克拉霉素的降解符合准一级反应动力学模型,且克拉霉素的降解速率随H_2O_2浓度的增大而增大,在H_2O_2浓度为40 mmol·L~(-1)时,克拉霉素降解的反应速率常数为0.0284min~(-1).克拉霉素与·OH的二级反应速率常数为(2.36±0.20)×10~(10)L·mol~(-1)·s~(-1).碱性条件有利于克拉霉素的降解;NOM(2~10 mg·L~(-1))会抑制克拉霉素的降解,且随NOM浓度增大而增大;共存阴离子CO_3~(2-)对克拉霉素降解无影响,HCO_3~-、NO_3~-、Cl~-会抑制克拉霉素的降解,抑制程度的大小顺序为NO_3~-HCO_3~-Cl~-;共存阳离子Ca~(2+)、Mg2+、Cu~(2+)、Fe~(3+)会抑制克拉霉素的降解,抑制程度的大小顺序为Fe~(3+)Cu~(2+)Mg2+Ca~(2+).     

Coupled effects of methane monooxygenase and nitrogen source on growth and poly-β-hydroxybutyrate (PHB) production of Methylosinus trichosporium OB3b

The coupled effects of nitrogen source and methane monooxygenase(MMO) on the growth and poly-β-hydroxybutyrate(PHB) accumulation capacity of methanotrophs were explored.The ammonia-supplied methanotrophs expressing soluble MMO(s MMO) grew at the highest rate, while N_2-fixing bacteria expressing particulate MMO(p MMO) grew at the lowest rate. Further study showed that more hydroxylamine and nitrite was formed by ammonia-supplied bacteria containing p MMO, which might cause their slightly lower growth rate. The highest PHB content(51.0%) was obtained under nitrogen-limiting conditions with the inoculation of nitrate-supplied bacteria containing p MMO. Ammoniasupplied bacteria also accumulated a higher content of PHB(45.2%) with the expression of p MMO, while N_2-fixing bacteria containing p MMO only showed low PHB production capacity(32.1%). The maximal PHB contents of bacteria expressing s MMO were low, with no significant change under different nitrogen source conditions. The low MMO activity,low cell growth rate and low PHB production capacity of methanotrophs continuously cultivated with N_2 with the expression of p MMO were greatly improved in the cyclic NO_3-N_2 cultivation regime, indicating that long-term deficiency of nitrogen sources was detrimental to the activity of methanotrophs expressing p MMO.     

花椰菜基生物炭对水中Pb (II)的吸附性能

以农业废弃物花椰菜的根和叶为原材料,采用限氧裂解法在500℃条件下制备花椰菜根基生物炭(BCR)和叶基生物炭(BCL),探究了吸附时间、温度、Pb(Ⅱ)初始浓度、pH及不同共存离子对2种生物炭吸附性能的影响,并通过扫描电镜(SEM)、能谱分析(EDS)、红外光谱(FTIR)及比表面积测定(BET)等手段对生物炭的结构和性质进行了表征,初步探讨了吸附机理.结果表明,2种生物炭对Pb(Ⅱ)的吸附符合准二级动力学和颗粒内扩散模型,BCR和BCL对Pb(Ⅱ)的吸附分别在3 h和6 h达到吸附平衡;2种生物炭对不同浓度下Pb(Ⅱ)的吸附符合Langmuir和Freundlich等温吸附模型;在25℃条件下,BCR和BCL对Pb(Ⅱ)的最大吸附量分别达到454.55和434.78 mg·g~(-1),BCR和BCL具有良好的吸附效果,可作为优良的生物质基吸附材料.     

采油废水处理技术研究

采油废水含有大量聚合物,成分复杂,粘度大,且乳化严重极难处理,目前已有部分相关的研究报道.文中关注了近十年各种处理技术的研究成果,着重介绍了传统工艺和膜处理技术在采油废水领域的应用与研究以及存在的主要问题,虽然膜处理存在污染问题,但大量研究结果表明传统处理技术与膜处理技术的有效组合是达到油田回注水标准的有效途径.     

Evaluating biotoxicity variations of landfill leachate as penetrating through the soil column

Recent studies of leachate-induced ecotoxicity have focused on crude samples, while little attention has been given to changes in biotoxicity resulting from the environmental behavior of landfill leachate. Therefore, we set up a soil column to simulate the underground penetration of leachate into the soil layer, define the rules of migration and transformation of leachate pollutants, and determine the variation in toxicity of landfill leachate during penetration. The results demonstrated that: (1) landfill leachate inhibited the growth and chlorophyll levels, elevated the levels of lipid peroxidation and protein oxidation, and stimulated the antioxidant enzyme activities of barley seedlings. The effects generally displayed a peak value at 12–24 cm, slowly declined at 36–48 cm, and then rapidly decreased with penetrating distance in the column. (2) Statistical correlation analysis of the properties of leachate and the observed biotoxic effects revealed that COD, conductivity and heavy metals (esp. Ni, Mn, Cd) were positively correlated with variations in biotoxicity. (3) The microbial activity of outflowing leachate sampled from the 48 cm port was significantly higher than the activity from succedent ports, and the types of contaminants increased in the leachate outflowing from the same port, implying that microbial behaviors near the 48 cm port could be used to partially evaluate variations in the composition and biotoxicity of landfill leachate. Taken together, the above results illustrate the polluting characteristics of landfill leachate when penetrating a soil column and provide guidance for pollution control and risk assessment of landfill leachate.     

Changes of DOM and its correlation with internal nutrient release during cyanobacterial growth and decline in Lake Chaohu, China

The seasonal changes in dissolved organic matter (DOM), and its correlation with the release of internal nutrients during the annual cycle of cyanobacteria in the eutrophic Lake Chaohu, China, were investigated from four sampling periods between November 2020 and July 2021. The DOM fluorescence components were identified as protein-like C1, microbial humic-like C2, and terrestrial humic-like C3. The highest total fluorescence intensity (F_T) of DOM in sediments during the incubation stage is due to the decomposition and degradation of cyanobacteria remains. The lowest humification of DOM and the highest proportion of C1 in waters during the initial cyanobacterial growth indicate that fresh algae are the main source. The highest molecular weight of DOM and F_T of the C2 in sediments during cyanobacterial outbreaks indicate the concurrent deposition of undegraded cyanobacterial remains and microbial degradation. The components of DOM are affected mainly by the dissolved total phosphorus in waters, while the temperature drives the annual cycle of cyanobacteria. The decreasing C1 in sediments and increasing nutrients in waters from the cyanobacterial incubation to outbreak indicate that mineralization of algal organic matter contributes importantly to the release of internal nutrients, with the strongest release of phosphorus observed during the early growth of cyanobacteria. The humic-like C2 and C3 components could also affect the dynamics of internal phosphorus through the formation of organic colloids and organic–inorganic ligands. The results show that the degradation of DOM leads to nutrients release and thus supports the continuous growth of cyanobacteria in eutrophic Lake Chaohu.