Photolysis and photooxidation of typical gaseous VOCs by UV Irradiation: Removal performance and mechanisms

UV photodegradation of 27 typical VOCs was systematically investigated. Contribution of photolysis and photooxidation to VOCs removal was identified. Gaseous VOC could be partially converted to particles by 185/254 nm UV irradiation. The mineralization and conversion of 27 VOCs by UV irradiation were reported. Photodegradation by ultraviolet irradiation (UV) is increasingly applied in volatile organic compound (VOC) and odor gas treatments. In this study, 27 typical VOCs, including 11 hydrocarbons and 16 hydrocarbon derivatives, at 150–200 ppm in air and nitrogen gas were treated by a laboratory-scale UV reactor with 185/254 nm irradiation to systematically investigate their removal and conversion by UV irradiation. For the tested 27 VOCs, the VOC removal efficiencies in air were within the range of 13%–97% (with an average of 80%) at a retention time of 53 s, which showed a moderate positive correlation with the molecular weight of the VOCs (R = 0.53). The respective contributions of photolysis and photooxidation to VOC removal were identified for each VOC. According to the CO₂ results, the mineralization rate of the tested VOCs was within the range of 9%–90%, with an average of 41% and were negatively correlated to the molecular weight (R = -0.63). Many of the tested VOCs exhibited high concentration particulate matters in the off-gases with a 3–283 mg/m³ PM₁₀ range and a 2–40 mg/m³ PM_2.5 range. The carbon balance of each VOC during UV irradiation was analyzed based on the VOC, CO₂ and PM₁₀ concentrations. Certain organic intermediates and 23–218 ppm ozone were also identified in the off-gases. Although the UV technique exhibited a high VOC removal efficiency, its drawbacks, specifically low mineralization, particulate matters production, and ozone emission, must be considered prior to its application in VOC gas treatments.     

Vertical ozone distributions observed using tethered ozonesondes in a coastal industrial city, Kaohsiung, in southern Taiwan

This work presents the vertical distributions of ozone and meteorological parameters observed with tethered ozonesondes and meteorological radiosondes in the lower atmosphere during an ozone episode on March 25–27, 2003, in Kaohsiung City in southern Taiwan. Kaohsiung is a coastal industrial city with inland mountain ranges to the east. Extremely complicated ozone structures were identified that spanned day and night during the experimental period. During afternoons, the lower atmosphere was divided into two stratified air layers with substantially different ozone concentrations. On the episode day (March 26), average ozone concentration in the near-ground layer was 85 ppb and the aloft layer was 140 ppb. A very high ozone peak of 199 ppb measured aloft likely resulted from an elevated large point source. Several no-ozone air layers, distributed throughout 400–750 m, were observed to transport onshore during the nigh. As well, elevated ozone layers peaking at 60–90 ppb and 90–160 ppb were detected below and above the no-ozone air layers, respectively. These complicated ozone structures were likely formed through titration of plumes from large point sources and the circulations of sea breezes or combined sea-breeze/mountain flows in the study area.     

外生菌根真菌对五氯芬的耐受性及生理响应

在纯培养条件下,研究了7种外生菌根真菌--美昧牛肝菌(Boletus edulis)、铆钉菇(Gomphidius viscidus)、双色腊蘑(Laccaria bicolor)、褐疣柄牛肝菌(Leccinum 8cabrum)、红绒盖牛肝菌(Xerocomus chrysenteron)、大毒滑锈伞(Heboloma crustulinifoume)和长柄粘滑菇(Hebeloma longicaudum)在不同五氯酚浓度下的生长速度和耐受性,筛选出具有降解五氯酚潜力的3种外生菌根真菌--铆钉菇、双色腊蘑、褐疣柄牛肝菌;考察了这3种外生菌根真菌在五氯酚胁迫下的生长模式,并采用点试方法对真菌氧化还原酶的产生情况进行了检测.结果表明:低浓度(≤10mg·L-1)条件下,五氯酚并没有改变菌种的生长模式,其中铆钉菇表现出了对五氯酚较强的耐受性,而在较高浓度下(15mg·L-1),所有菌种生长均受到抑制.酶点试结果表明,铆钉菇是3种外生菌根真菌中氧化还原酶活性最强且种类较多的菌种,它表现出较高的漆酶、酪氨酸氧化酶和过氧化物酶活性,是一种具有高效降解芳环结构污染物潜力的菌根真菌.     

镉胁迫下柳树5个无性系生理特性的变化

柳树(Salix)以其自己特有的生物学特性,对环境Cd污染具有一定的吸收蓄积能力.以5个金丝柳无性系为材料,用盆栽方法研究了镉胁迫对柳树生理特性的影响,以主成分分析法分析7个生理指标的重要性,并以隶属函数法评价了金丝柳5个无性系镉耐性的强弱.研究结果表明,在10～150 mg.kg-1镉胁迫范围内,金丝柳5个无性系生理变化程度不同,但变化规律基本一致.在Cd胁迫下,金丝柳各无性系植株生长受到抑制;叶绿素质量分数降低;叶片细胞膜透性和游离脯氨酸积累量增加,丙二醛和可溶性蛋白质量分数降低.主成分分析表明本试验中选取的5个成分在评价柳树Cd耐性方面有重要作用,它们分别是地径生长率、叶绿素质量分数、MDA质量分数、脯氨酸质量分数和可溶性蛋白质量分数.用隶属函数法以评定金丝柳5个无性系Cd耐性的强弱顺序为4号＞6号＞5号＞7号＞2号.     

Using Citizen Science Programs to Identify Host Resistance in Pest‐Invaded Forests

Abstract: Threats to native forests from non‐native insects and pathogens (pests) are generally addressed with methods such as quarantine, eradication, biological control, and development of resistant stock through hybridization and breeding. In conjunction with such efforts, it may be useful to have citizen scientists locate rare surviving trees that may be naturally pest resistant or tolerant. The degree of resistance of individual trees identified in this way can be tested under controlled conditions, and the most resistant individuals can be integrated into plant breeding programs aimed at developing pest‐resistant native stock. Involving citizen scientists in programs aimed at identifying rare trees that survive colonization by pests provides a low‐cost means of maximizing search efforts across wide geographic regions and may provide an effective supplement to existing management approaches.     

Analysis of tropospheric ozone concentration on a Western Mediterranean site: Castellon (Spain)

Ozone dynamics in our study area (Castellon, Spain) is both strongly bound to the mesoscale circulations that develop under the effect of high insolation (especially in summer) and conditioned by the morphological characteristics of the Western Mediterranean Basin. In this work we present a preliminary analysis of ozone time series on five locations in Castellon for the period 1997–2003. We study their temporal and spatial variations at different scales: daily, weekly, seasonally and interannually. Because both the O₃ concentration and its temporal variation depend on the topographic location of the observing station, they can show large differences within tens of kilometer. We also contrast the variation in the ozone concentration with the variations found for meteorological variables such as radiation, temperature, relative humidity and recirculation of the air mass. The link between elevated ozone concentrations and high values of the recirculation factor (r=0.7–0.9) shown the importance of recirculating flows on the local air pollution episodes.     

Selecting for Tolerance against Pathogens and Herbivores to Enhance Success of Reintroduction and Translocation

Abstract: Some species have insufficient defenses against climate change, emerging infectious diseases, and non‐native species because they have not been exposed to these factors over their evolutionary history, and this can decrease their likelihood of persistence. Captive breeding programs are sometimes used to reintroduce individuals back into the wild; however, successful captive breeding and reintroduction can be difficult because species or populations often cannot coexist with non‐native pathogens and herbivores without artificial selection. In captive breeding programs, breeders can select for host defenses that prevent or reduce pathogen or herbivore burden (i.e., resistance) or traits that limit the effects of parasitism or herbivory on host fitness (i.e., tolerance). We propose that selection for host tolerance may enhance the success of reintroduction or translocation because tolerant hosts generally have neutral effects on introduced pathogens and herbivores. The release of resistant hosts would have detrimental effects on their natural enemies, promoting rapid evolution to circumvent the host resistance that may reduce the long‐term probability of persistence of the reintroduced or translocated species. We examined 2 case studies, one on the pathogenic amphibian chytrid fungus ( Batrachochytrium dendrobatidis [Bd]) and the other on the herbivorous cactus moth ( Cactoblastis cactorum) in the United States, where it is not native. In each case study, we provide recommendations for how captive breeders and managers could go about selecting for host tolerance. Selecting for tolerance may offer a promising tool to rescue hosts species from invasive natural enemies as well as new natural enemies associated with climate change‐induced range shifts.     

铜陵新桥矿区土壤中耐Cu微生物的筛选研究

选择安徽铜陵新桥矿区富Cu的污染土壤,充分利用微生物受自然环境重金属胁迫而产生耐性这一特点,进行土壤中耐Cu微生物的筛选研究。实验过程中分别配制三种不同的培养基,细菌、真菌和放线菌培养基。在水浴恒温振荡器中对土壤中耐受重金属的微生物进行驯化,将得到的对cu2＋耐受性最高的液体培养基作为菌源,在琼脂平板培养基上进行划线分离,并将得到的纯菌株在光学显微镜下进行形态观察,菌种经试管斜面富集培养后保存在4℃冰箱中以便后续使用。研究发现,土样中细菌和真菌对cu的耐受性低,最高耐受质量浓度分别只达到500mg·L-1和1100mg·L-1。而放线菌表现出cu高耐受性,分离得到的放线菌耐受Cu的质量浓度最高达到10000mg·L-1,初步鉴定该放线菌株为链霉菌属。该放线菌菌种可能同时对Cu有吸附降解特性,具有成为污染土壤生物治理的高效耐受吸附菌种的潜力巨大。     

基于环境腐蚀损伤的某型飞机日历寿命的确定

目的基于腐蚀的观点,确定基于环境区域腐蚀损伤的某型飞机结构的日历寿命。方法通过试验确定各级温湿度下飞机结构常用铝合金材料2Al2-T3腐蚀至任意损伤值的时间曲线(T-H曲线),并根据某型飞机的服役环境谱以及对应的腐蚀损伤容限D_c确定该型飞机的日历寿命。结果试验确定出不同湿度下的T-H曲线,引入海南陵水机场的温湿度环境谱,将数据带入计算模型,所得结果比较合理。结论该模型可以合理地求得腐蚀环境下飞机结构的日历寿命,获得的2Al2-T3铝合金腐蚀损伤时间曲线具有普适性。     

铜绿假单胞菌ZGKD2的重金属耐性机制研究

从煤矸石中分离的耐Cd2+铜绿假单胞菌(Pseudomonas aeruginosa)ZGKD2具有多种重金属耐性,研究其铁载体产生特征和重金属耐性机制对于开发土壤重金属污染修复技术具有重要意义.在牛肉膏蛋白胨培养基中分别添加200～3 000μmol.L-1的Cd2+、Cu2+、Zn2+、Ni2+、Pb2+或Mn2+等重金属,ZGKD2菌株的最大生长量随着重金属浓度的增加而降低,不同浓度重金属对ZGKD2菌株产碱能力无明显影响.ZGKD2菌株生长进入稳定期时,用0、200、600、1 000μmol.L-1的Cd2+、Cu2+、Zn2+、Ni2+或0、1 000、2 000、3 000μmol.L-1的Pb2+、Mn2+处理2 h,SOD和CAT活性随重金属浓度增加而增加.ZGKD2菌株在MSA培养基中能产生铁载体,200～1 000μmol.L-1的重金属Cd2+或Zn2+可显著诱导铁载体的产生,Ni2+和Mn2+的作用较小,Cu2+则抑制;ZGKD2菌株的产铁载体能力与重金属耐性能力相关.这些结果表明ZGKD2菌株的产碱、产铁载体特性以及抗氧化酶活性提高可能是其耐重金属的主要机制.