Growth substrate selection and biodegradation of PCP by New Zealand white-rot fungi

Nine New Zealand native white-rot fungi were studied for their ability to grow and survive on different substrates formulated from bark, wheat straw, sawdust, apple pomace and maize products in order to identify their pentachlorophenol (PCP) biodegradation potential and to select a fungal carrier for bioaugmentation of polluted soils. Isolates were also evaluated to mineralize (14)C-PCP in liquid culture and in soil. The American fungus Phanerochaete chrysosporium outgrew the native fungi on the substrates tested, but the high colonisation did not result in superior PCP dechlorination as measured by chloride release. Whilst Trametes versicolor inocula produced on wheat straw and SCS (sawdust-corn meal-starch-mix) gave the highest chloride release, colonization of these two substrates as measured by biological potential was lower compared to the pomace and pomace-sawdust-mix. Neither lignin peroxidase nor manganese peroxidase production were measured for New Zealand white-rot fungi during the experiments. Laccase was the only enzyme detected. In liquid culture, the mineralisation rate was higher for T. versicolor isolates compared to P. chyrysoporium. Very little to no pentachloroanisole (PCA) was captured in the volatile fraction of T. versicolor isolates, whereas 75% of the volatile fraction of P. chrysosporium consisted of PCA. The soil microcosms studies, using contaminated soil from a timber treatment site, clearly showed that the New Zealand T. versicolor isolates mineralized PCP. Degradation of PCP in non-sterile soil was higher in the presence of white-rot fungi than in soil without white-rot fungus. This demonstrates that viable white-rot fungus is necessary for significant PCP degradation and that T. versicolor isolates showed PCP remediation potential. Wheat straw and SCS could be suitable carriers for New Zealand native T. versicolor isolates for bioremediation of PCP polluted soil sites.     

毛细管气相色谱测定土壤、麦粒和麦秆中燕麦畏残留量

本文用毛细管气相色谱方法测定了燕麦畏在土壤、麦秆和麦粒中的残留量。样品用异辛烷和异丙醇混合溶剂提取，方法的回收率在８２～１０２％之间。相对标准偏差小于７８％。     

利用自养煤矸石砖技术治理铬渣初步研究

本研究通过焙烧试验 ,对利用自养煤矸石砖技术治理铬渣进行了初步研究。结果表明 ,在自养煤矸石砖的焙烧过程中 ,其中炭和自身热量能将铬渣中六价铬还原成 (三价铬 )。本研究确定了该铬渣治理方法工艺简单、成本低、解毒彻底、稳定性强 ,具有广泛的应用前景。     

An evaluation of landfill disposal of asbestos-containing waste and geothermal residues within a risk-assessment framework

 The public perception of risks related to waste disposal facilities appears to reflect general societal anxieties and fears, which may not have a reasonable basis. A three-tier risk assessment study was therefore conducted to evaluate the landfill disposal of asbestos-containing waste (ACW) and geothermal residues. From the tier-1 analysis, the dominant asbestiform phase was identified as chrysotile, that is tightly bound in the matrix of calcite, while arsenic, cadmium, chromium, and lead were identified as the chemicals of potential concern associated with geothermal residues. From the tier-2 analysis, none of the possible exposure pathways associated with the landfill disposal of ACW was found to be potentially significant. On the other hand, there were potentially significant pathways associated with landfill disposal of geothermal residues because of the considerable potential pollution impact of leachate on soil and groundwater quality. From the tier-3 analysis, the health risk associated with landfill disposal of geothermal residues was found to be time-dependent, since the contributions to risk from water-dependent and water-independent pathways occur at different times, as indicated by RESRAD–Chem simulations. Component pathway analyses were performed to identify critical exposure pathways. The results from model sensitivity analysis have identified the input parameters that have the most influence on the time of peak risk, and the cancer risk associated with water-dependent and water-independent pathways. Received: July 9, 2002 / Accepted: October 17, 2002     

残留农膜对土壤性状的影响

残留农膜对土壤性状具有重要影响,如破坏土壤结构、危害作物正常生长发育并造成农作物减产,进而影响到农业环境.通过对临沂市义唐镇农膜残留量不同地块的土壤性状进行对比分析,得出,随着土壤中农膜残留量的增加,土壤团聚体含量、抗蚀指数、团聚度、土壤有机质含量、N、P、K含量、土壤微生物量均表现出下降的趋势,且CK与DK3间差异达到了显著水平(p<0.05),而土壤分散率并没有表现出相同趋势.这种规律在表层土壤(0～20 cm)表现的更为明显.     

垃圾焚烧飞灰中重金属浸出的影响因素

考察不同浸出条件对垃圾焚烧发电厂烟气净化系统飞灰中重金属浸出特性的的影响.研究表明:飞灰浸出时,受飞灰自身性质的影响,翻转式摇床混合和水平振荡摇床混合对飞灰中重金属浸出量的影响不明显;混合8h可使浸出体系达到溶解平衡,16h静置过程对飞灰中重金属溶出的影响不明显;增加浸取剂离子强度对飞灰来说并不会增加重金属元素的溶出;加大液固比(L/S)对飞灰中Pb,Ni和Cd的浸出仅起稀释作用,而Cu,Zn,CT和Hg在L/S<10时浸出液的浓度变化不大,L/S>10时被稀释;在高H 浓度时飞灰中重金属的浸出率大大增加,浸取剂中H 对各元素浸出的影响程度为Pb≈Zn>Cu>Cd>Ni>Cr>As>Hg;在中低H 浓度时,醋酸浸出液中重金属的浓度高于硝酸浸出液,而在>0.2mol·1-1的酸浸取液中,硝酸浸出液中重金属(Hg除外)的浓度大于醋酸浸出液.     

氮肥和秸秆还田方式对麦玉轮作土壤N2O排放的影响

为探究氮肥和秸秆还田方式对N₂O排放的影响,本研究在关中地区冬小麦-夏玉米轮作模式下,采用双因素裂区设计,主区为常规施氮（G）和减量施氮（70% G）;副区为秸秆不还田（N）、秸秆还田（S）和秸秆还田+生物炭（SB）,分析对N₂O排放和产量的影响及与相关影响因子间的关系.结果表明,小麦季和玉米季各处理在施肥后第5~16d内相继出现N₂O排放高峰,在降雨后也出现N₂O排放峰值.N₂O通量和土壤温度、NH₄⁺-N含量呈显著正相关.在同等施氮水平下,S处理增加了N₂O排放量,SB处理可降低N₂O排放量,S和SB处理均能显著增加作物产量,且SB增产幅度更大;70% G水平的N₂O年排放量较G水平减少了40%~48%,而产量并没有明显减少.综合考虑,在常规施氮基础上减氮30%配合秸秆+生物炭,在保证作物高产的同时,N₂O减排效果最好.     

我国典型秸秆露天燃烧黑碳的高时间分辨率排放特征及其排放清单

农作物秸秆燃烧是大气中黑碳(black carbon,BC)气溶胶的主要来源之一。目前农作物秸秆燃烧排放黑碳的研究主要集中在通过离线样品分析获得的BC排放特征,缺少实时在线排放特征的研究。本研究收集了我国具有代表性的4种农作物秸秆(小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆),通过在实验室燃烧平台模拟农作物秸秆露天燃烧的过程,利用黑碳仪获得农作物秸秆燃烧过程中BC的实时浓度排放变化;利用质量重建,获得BC在线排放因子。结果表明:农作物秸秆在明燃过程中BC的排放因子较为稳定。通过平均排放因子的计算,获得小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆的BC排放因子分别为(0.32±0.05) g?kg~(-1)、(0.31±0.13) g?kg~(-1)、(0.31±0.09) g?kg~(-1)和(0.44±0.01) g?kg~(-1)。在排放因子的基础上,结合我国农作物秸秆露天燃烧量,最终建立了2015年我国省级(不含港澳台地区)典型农作物秸秆燃烧的BC排放清单。     

有机负荷对醋糟厌氧消化系统启动的影响

本研究通过醋糟的中温产甲烷潜力测试实验,考察了有机负荷对醋糟厌氧消化反应器启动的影响.并通过对不同有机负荷条件下的甲烷产量、液相组分的对比分析,结合热重、X射线衍射和红外光谱学方法进行差异表征,结果发现:1较低的有机负荷有利于缓解醋糟中有机物水解酸化过程中VFAs的积累和pH的下降,保证产甲烷过程的稳定进行.当接种物与基质VS比为1∶1[即有机负荷(以VS计)为1.78 g·(L·d)~(-1),pH=7.60]时的累积甲烷产量最高,达2 249.7 m L.随着有机负荷的提高,VFAs的累积浓度随之升高,使产甲烷过程受到不同程度的抑制并相继终止,且在接种物与基质VS比为1∶4时[即有机负荷为7.12 g·(L·d)~(-1),pH=5.52]实现了乙酸和乳酸的同步发酵(分别可达到8 000 mg·L~(-1)和2 650 mg·L~(-1)).2醋糟中木质纤维素类物质为短程有序的微晶结构或非晶结构,与富含纤维素类晶体结构物质的玉米秸秆等相比,其VS的降解率更高.醋糟中的木质素、纤维素、半纤维素的降解率随着有机负荷的降低而逐渐升高.     

Using pruning residues as mulch: analysis of its adoption and process of diffusion in Southern Spain olive orchards

This paper analyses both the processes of adoption and diffusion of the practice of using the chopped residues of pruning as mulch in the olive orchards of the Southern Spanish province of Granada, one of the major olive-producing areas in the world. Many olive groves in the area are located on steep areas where the risk of soil erosion is high. A majority of farmers have adopted no tillage, as an alternative to traditional tillage, combined with either vegetation soil covers or, more frequently, using the chopped pruning residues as mulch. The data used comes from a survey carried out in 2005 to 215 olive farmers. From farmers' responses we estimate a binomial probit model to identify some socio-economic and institutional factors related to the decision to use the practice of mulching on a regular basis. We also estimate several diffusion models that describe the spatial and temporal spread of mulching among farmers. Our results show that mulching using the pruning residues is adopted by 43% of the surveyed farmers. The diffusion process of this practice has been very intense since the middle nineties, and seems to have been based on the interactions among farmers in the area of study rather than in other external source of information. Some of the relevant identified factors that affect the probability of adoption of this practice are farmer's experience, the level of soil degradation in the farm or the continuity of farming by some relative.