The environmental impacts of regional disparity in population and wealth distribution in Nigeria

The disparity in both population and wealth distribution in Nigeria by geo-political zones is well recognized. There is also the recognition that some of the environmental problems in certain sections of the country can be attributed to the imbalance in both population and wealth distribution. Hence the various agitations for environmental resource control in the country. What is lacking however is the research that shows the magnitude of the linkages between the disparity and the environmental degradation in regional context. This provides the basis for this research. To achieve the aim of the research, a STIRPAT model was employed as an analytical tool. The findings show that the southern geopolitical zones are generally more densely populated and wealthier than the northern zones. The south is also experiencing a higher degree of environmental resource degradation attributable to anthropogenic factors. Thus, there is congruence between population density, wealth distribution and environmental degradation in Nigeria. Therefore the achievement of sustainable environment and development in Nigeria requires deliberate policies to mitigate the impact of population concentration and wealth creation on the environment. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

The Swedish System for Quality Assessment of Agricultural Soils

Soil quality assessment is based on the concept of soilfunctions. The performances of three soil functions, cropproduction, biological decomposition and matter exchange withthe atmosphere and groundwater, are used as quality criteria.Soil properties that can be used as indicators for the degreeof functional performance were identified. Each soil propertyselected was graded into five classes – from best (class 1) toworst (class 5). Grading was based biological on boundaryconditions as well as on statistical distribution. The systemoutlined can be used to interpret the quality state ofagricultural soils, provides for a relative comparison betweensoils, and may be helpful in an environmental monitoringprogram to assess trends in data.     

Photochemical degradation of methylparathion in the presence of humic acid

Photochemical degradation of methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorothioate) in the presence of humic acid between pH 2 and 7 was monitored by differential pulse polarography. Humic acid was not electro-active under the experimental conditions used in this study. Only the pesticide and its main degradation product at pH 2 exhibited polarographic signals. Photolysis of methylparathion in acid media was sensitized by humic acid since the pesticide did not degrade in the absence of this compound. Methylparathion degradation in the presence of humic acid was observed at each of the studied pHs. The reaction was first-order with rate constant values ranging from 2 × 10^?3 to 6.3 × 10^?3 min^?1.     

H4SiW12O40/TiO2/beads光催化降解亚甲基蓝的研究

以钛酸四丁酯为原料,空心微珠为载体,采用溶胶-凝胶法制备TiO2/beads光催化剂载体,然后浸渍法制备出H4SiW12O40/TiO2/beads表面负载修饰型复合光催化剂,并运用SEM、XRD、FT-IR和DRS对催化剂进行表征和分析。研究了H4SiW12O40/TiO2/beads对亚甲基蓝降解的光催化活性,考察了光强度、pH值、曝气量、底物浓度和催化剂用量等对催化效率的影响。实验结果表明,在中性条件下,H4SiW12O40/TiO2/beads催化剂的投加量为0.25 g/L,浓度为7.5 mg/L的亚甲基蓝溶液在250 W的紫外灯和600 W的可见光灯下光照60 min降解率分别可达到94.5%和55%。     

球形红细菌好氧降解氯代苯研究

采用光合细菌球形红细菌在好氧条件下对氯代苯进行生物降解.结果表明,氯代苯不能作为球形红细菌生长的惟一碳源和能源,球形红细菌好氧降解氯代苯是在适宜碳源存在下以共代谢的方式进行;根据分析细胞提取液中双加氧酶活性和代谢中间产物,推断出其降解机制为邻位裂解途径,按先开环再脱氯过程进行,邻苯二酚1,2-双加氧酶的活性可以通过氯代...     

不同前处理方式对铁屑还原降解土壤中对硝基苯酚的影响

为推动铁屑在治理受硝基酚类化合物污染土壤中的实际应用,常温(25±1℃)常压下,利用不同前处理方式处理的铁屑、还原铁粉对土壤中的对硝基苯酚(p-NP)进行了还原降解研究;分析了土壤部分理化性质对p-NP还原效果的影响;并对反应时间、铁屑用量和土壤含水量3个人工易控因素作了最优化选择。结果表明:铁屑和铁粉对p-NP还原降解效果影响的大小顺序为:酸洗铁屑还原铁粉水洗铁屑碱洗铁屑;适中的土壤含水量、偏酸性的土壤初始pH值及较高的土壤有机质含量均可显著提高铁屑对p-NP的还原率;正交实验结果显示反应时间对p-NP还原效果影响最大,铁屑用量次之,土壤含水量最小;处理1.5 g p-NP浓度约为1.3×10-5mol/g的模拟污染土壤的反应最优化条件为:酸洗铁屑用量26 mg,土壤含水量0.35 mL,反应时间130 m in,还原率可达到96.4%。     

用Fe3+掺杂锐钛矿型TiO2光催化剂降解孔雀石绿

以硫酸钛为原料,用水热法制备了Fe3+掺杂锐钛矿型TiO2(Fe3+ - TiO2)粉末,用扫描电子显微镜测定了试样的形貌.研究了自制的Fe3+ - TiO,光催化剂对孔雀石绿的光催化降解作用.实验结果表明,在孔雀石绿溶液质量浓度为2 mg/L、Fe3+ - TiO2加入量为1.616 g/L、Fe3+-TiO2中Fe...     

陇东黄土高原地区石油污泥原位修复过程中土壤主要肥力指标动态变化分析

为了分析陇东黄土高原地区石油污泥在原位修复过程中土壤主要肥力指标的变化情况,对长庆油田第二采油厂的石油污泥进行为期105 d的原位修复,采用常规方法测定了土壤有机质、pH、总石油烃含量(TPHs)、含盐率、碱解氮、速效磷、速效钾、土壤脲酶、脱氢酶、多酚氧化酶、过氧化氢酶等土壤肥力指标;通过PCR-DGGE技术分析了土壤微生物群落的功能多样性,并采用主成分分析法对供试石油污泥的土壤肥力进行评价.结果显示:随着原位修复的时间的延长,土壤碱解氮、速效磷含量呈显著增加趋势;有机质、pH、含盐率、TPHs含量显著降低,而速效钾含量呈逐步增加趋势.土壤脲酶及脱氢酶活性增加,多酚氧化酶及过氧化氢酶活性降低.土壤微生物群落遗传多样性结果显示,ShannonWiener多样性指数、Patrick丰富度指数及Pielou均匀度指数均呈增加的趋势.经过105 d的原位修复土壤肥力显著提升,各阶段土壤肥力得分为105 d80 d60 d45 d25 d.上述实验结果有助于掌握石油污泥原位修复中土壤肥力动态变化趋势,并为土壤石油烃污染的综合治理提供基础依据和数据参考.     

CeO_2-TiO_2复合纳米纤维光催化降解醛酮类污染物的研究

采用同轴静电纺丝法制备了CeO2-TiO2复合纳米纤维,并用X射线衍射仪、扫描电子显微镜、程序升温脱附仪和紫外-可见光谱能谱(UVVis)仪表征了CeO2-TiO2纳米纤维的相组成和微观形貌,分析了CeO2-TiO2纳米纤维对醛酮的吸附强度与光电化学特性.同时,研究了CeO2配比量、光源条件和重复使用性对降解甲醛污染物的影响规律.结果表明,CeO2质量配比为50%的CeO2-TiO2催化剂对甲醛降解效率最高;在无光和可见光条件下,CeO2-TiO2催化剂对甲醛的降解效率分别为13.5%和25.3%,在紫外光下CeO2-TiO2催化剂对甲醛的降解效率为92.5%;随着光催化循环次数的增加,可见光下CeO2-TiO2催化剂对甲醛的降解效率逐渐增高,紫外光下CeO2-TiO2催化剂对甲醛的降解效率维持在92.5%左右.利用催化剂样品CT50对柴油机尾气中醛酮类排放污染物进行光催化降解的应用发现,CeO2-TiO2催化剂对醛类污染物的降解效率为85.4%,酮类污染物的降解效率为81.3%,苯甲醛和甲基苯甲醛的降解效率分别为80.4%和80.3%.表明CeO2-TiO2催化剂具有较强的光催化降解醛酮类污染物的能力.     

泰乐菌素的微生物降解途径及其降解产物研究

研究了越南伯克霍尔德氏菌(Burkholderia vietnamiensis)对泰乐菌素的降解能力,并通过对降解产物的分析,推测了泰乐菌素的微生物降解途径.在自主筛选驯化分离到1株泰乐菌素高效降解菌B.vietnamiensis的基础上,采用高效液相色谱法测定其在不同条件下降解泰乐菌素的能力,并利用制备液相色谱分离纯化降解产物,质谱鉴定其结构.实验结果表明:B.vietnamiensis能高度耐受并快速降解泰乐菌素,用B.vietnamiensis处理初始浓度为50、100、200、300、400或500 mg·L-1的泰乐菌素培养基7 d,泰乐菌素的降解率均达到99%以上.B.vietnamiensis降解泰乐菌素的可能途径是:泰乐菌素A首先脱去碳霉糖转化为泰乐菌素B,然后分子中内酯键和醛基再经水解和还原生成2个新的降解产物.研究结果为泰乐菌素微生物降解机制的研究以及在此基础上降解酶的确定提供有价值的技术参考.