Time discounting and the decision to protect areas that are near and threatened or remote and cheap to acquire

Should conservation organizations focus on protecting habitats that are at imminent risk of being converted but are expensive or more remote areas that are less immediately threatened but where a large amount of land can be set aside? Variants of this trade‐off commonly arise in spatial planning. I used models of land‐use change near a deforestation frontier to examine this trade‐off. The optimal choice of where to protect was determined by how decisions taken today accounted for ecological benefits and economic costs of conservation actions that would occur sometime in the future. I used an ecological and economic discount rate to weight these benefits and costs. A large economic discount rate favored protecting more remote areas, whereas a large, positive ecological discount rate favored protecting habitat near the current deforestation frontier. The decision over where to protect was also affected by the influence economic factors had on landowners' decisions, the rate of technological change, and ecological heterogeneity of the landscape. How benefits and costs through time are accounted for warrants careful consideration when specifying conservation objectives. It may provide a niche axis along which conservation organizations differentiate themselves when competing for donor funding or other support.     

南通平原河网地区典型农田系统地下水硝态氮污染调查

针对平原河网地区典型农田系统灌溉施肥带来的地下水环境污染问题,采集南通地区蔬菜地、水稻-小麦轮作地、水稻-油菜轮作地和桑地地下水样品,分析了不同农田种植体系下的地下水污染程度。结果表明,蔬菜、桑地、水稻-油菜轮作、水稻-小麦轮作地地下水的硝态氮(N)平均值分别为12.2,9.53,7.95和6.12 mg/L,与氮肥用量呈显著的正相关关系;研究区域地下水硝态氮超Ⅲ类标准率(20 mg/L)的为4.8%,表明地下水已部分受到硝态氮污染。     

臭氧二级传递标准量值传递技术

臭氧(O_3)二级传递标准对O_3三级传递标准进行量值传递,开展了对分析类型、发生类型等不同类型O_3三级传递标准的量值传递实验。分析类型O_3三级传递标准6组校准斜率的相对标准偏差Sm为0.19%、截距的标准偏差SI为0.25 nmol/mol;发生类型O_3三级传递标准6组校准的Sm为0.67%、SI为0.20 nmol/mol,均符合美国环保局O_3二级传递标准量值传递的评价指标:6组多点校准斜率的相对标准偏差Sm≤3.7%,截距的标准偏差SI≤1.5 nmol/mol。进一步对分析类型、发生类型O_3三级传递标准分别进行了6个月的量值传递时间稳定性考察,O_3三级传递标准新的斜率与最近6组斜率均值的比值为0.965~1.037,且新计算的斜率的相对标准偏差Sm为0.37%~1.87%,截距的标准偏差SI为0.20~0.52 nmol/mol,均符合美国环保局量值传递评价指标的要求,建议至少每6个月采用O_3二级传递标准开展一次量值传递。     

2008-2017年苏州沿江三市主要入江支流水质变化特征

采用单因子评价法和Spearman秩相关系数评价法，对2008—2017年苏州沿江三市（张家港、常熟、太仓）主要入江支流水质变化特征进行分析。结果表明，苏州沿江三市的入江支流水质总体好转，张家港市入江支流水质明显好转，太仓市入江支流水质有所好转，常熟市入江支流水质总体保持稳定；NH₃-N、COD和BOD₅是影响入江支流水质的主要污染指标；主要污染指标优Ⅲ类比例总体呈上升趋势，但2014—2016年有所下降。2017年沿江三市入江支流水质总体处于Ⅲ类水平。     

Effects of glucose dehydrogenase gene knock-out in Acetobacter sp. On the metabolism of carbon sources and the synthesis of 3-hydroxypropionic acid北大核心CSCD

3-Hydroxypropionic acid (3-HP) is an emerging platform chemical with a high added-value. Resting cells of Acetobacter sp. can efficiently catalyze 1,3-propanediol (1,3-PDO) to 3-HP. Glucose is oxidized by the membrane-bound dehydrogenase, resulting in an acidic environment that inhibits cell growth and reduces the biomass. We deleted the gdh gene for glucose dehydrogenase (GDH), and investigated the effects on cell growth, carbon metabolism, and 3-HP production. The gdh gene knocked-out showed a 1.72-fold increase in biomass in the mixed medium containing glucose and glycerol. A carbon flux analysis showed that glucose was converted to gluconic acid by GDH, followed by an oxidation to 2-ketogluconic acid. In addition, a small percentage of the gluconic acid was degraded via the pentose phosphate pathway. Glycerol was phosphorylated and entered the central pathway (gluconeogenesis). Results indicate that the deletion of gdh can effectively promote higher cell densities and improve the catalytic performance for the production of 3-HP, and thus provide a theoretical reference for improving the carbon source utilization and the catalytic performance of acetic acid bacteria. © 2018 Science Press. All rights reserved.     

Characteristics of culturable endophytic bacteria of Xanthoceras sorbifolia Bunge with tumor roots北大核心CSCD

Xanthoceras sorbifolia Bunge with tumor roots was discovered, and the endophytic bacteria that were isolated from the tumor roots were purified and identified. This paper aimed to study the characteristics of endophytic bacteria. The CAS detection plate, Salkowski colorimetry, phosphate solubilizing circle, and molybdenum antimony spectrophotometry were used to analyze endophytic bacteria ability, which produced siderophores, secreted indole-3-acetic acid (IAA), and dissolved phosphorus. Strains were isolated from the tumor roots through morphological and molecular identification, and they were named XSB1-XSB9, of which 6 strains belonged to Bacillus sp., 2 strains belonged to Brevibacillus sp., and 1 strain belonged to Pseudomonas sp. All 9 strains produced siderophores; strains XSB3, XSB4, XSB8, and XSB9 were extremely high yielding, and strains XSB5 and XSB6 were high yielding. The strains with high yields were XSB3, XSB4, XSB5, XSB6, XSB8, and XSB9 and accounted for 66.7% of the tested strains. Nine strains secreted IAA; the concentration of IAA secreted by the strains that contained tryptophan was between 15-50 mg/L, and the concentration of IAA secreted by the one strain without tryptophan was between 10-35 mg/L. The IAA ability of the XSB2, XSB3, XSB4, XSB5, and XSB9 strains were significantly different (P < 0.05) after adding tryptophan. These results indicate that the synthesis of IAA may be the tryptophan synthesis pathway where tryptophan is used as a precursor. All 9 strains had some ability to dissolve phosphorus. The concentration of phosphate in the solubilizing strains, XSB1, XSB2, XSB4, and XSB5, were significantly higher than that in the other strains (P < 0.01), and the concentration of phosphate solubilizing was between 50-90 mg/L; the ability to dissolve phosphate was increased by 19-29 times. The XSB4 and XSB5 strains, which produced siderophores, secreted IAA and had a strong capacity to dissolve phosphorus, may be candidate strains for promoting growth. This research provides the foundation for the development and utilization of rhizosphere microbes to understand the resistance mechanisms and cultivation level of X. sorbifolia. © 2018 Science Press. All rights reserved.     

Endocrine modulation and toxic effects of two commonly used UV screens on the aquatic invertebrates Potamopyrgus antipodarum and Lumbriculus variegatus

The two UV screens 3-benzylidene-camphor (3-BC) and 3-(4'-methylbenzylidene)-camphor (4-MBC) were tested regarding their toxicity and estrogenic activity. The Yeast Estrogen Screen (YES) and two sediment assays with the freshwater invertebrates Lumbriculus variegatus and Potamopyrgus antipodarum were performed. In the YES, both substances activated the human estrogen receptor alpha with EC50 values of 44.2 microM for 3-BC and 44.3 microM for 4-MBC, whereby 4-MBC attained only 8% of the maximal response of 17beta-estradiol. For P. antipodarum embryo production increased after exposure to both substances (EC50 of 4.60 microM 4-MBC=1.17 mg kg(-1)dw) while mortality increased at high concentrations. The reproduction of L. variegatus was decreased by 3-BC with an EC50 of 5.95 microM (=1.43 mg kg(-1)dw) and also by 4-MBC, where no EC50 could be calculated. While reproduction decreased, the worms' weight increased after exposure to 3-BC with an EC50 of 26.9 microM (=6.46 mg kg(-1) dw), hence the total biomass remained unaffected.     

Suitability of Nicotiana tabacum 'Bel W3' for biomonitoring ozone in São Paulo, Brazil

Nicotiana tabacum 'Bel W3' is a widely used sensitive bioindicator for ambient ozone, but it is rarely used in tropical countries. Our goal was to determine the suitability of this plant for biomonitoring ozone in the city of S?o Paulo by evaluating the relationships between leaf necroses and ozone under field conditions and measurements of chlorophyll a fluorescence and antioxidants in plants exposed to different concentrations of ozone in closed chambers. While a weak linear relationship between leaf injury and ozone concentrations (R(2)=0.10) was determined in the field, a strong linear relationship was observed in the chamber experiments. Maximum leaf injury was observed in plants submitted to 40 ppb, which coincided with a significant decrease in fluorescence and total ascorbic acid. The relationship between leaf damage observed in the field and ozone was improved when the concentrations were limited to 40 ppb (R(2)=0.28).     

热化学清洗法洗涤油泥-回收石油的工艺条件研究

以辽河油田落地油泥为样品,采用热化学清洗法洗涤油泥,净化土壤,回收石油,并获取工程所需的必要参数.通过筛选、复配,确定十二烷基苯磺酸钠(LAS):NazSiO3=1:2(质量比)为最佳清洗剂配比.考察了清洗温度、清洗液pH、液固比(即清洗剂与落地油泥的质量比)和清洗剂投加量等因素对清洗效率的影响,通过正交实验优化工艺参数,实验表明,当清洗时间为30min、清洗温度为75℃、搅拌器转速为200 r/min、液固比为8:1、清洗液pH为11、LAS Na2SiO3投加量为2.8 g/L时,含油率为21.2%(质量分数)的落地油泥样品经一级清洗,油泥残油率降为0.8%(质量分数,下同);经二级清洗,油泥残油率降为0.3%.清洗后,石油浮于水面,无明显乳化,易于分离.     

石化污水厂二级出水溶解性有机物分级解析研究

以某石化污水处理厂二级出水为研究对象,采用大孔吸附树脂将污水中溶解性有机物分离成亲水性物质、疏水酸性物质、疏水中性物质和疏水碱性物质4个组分,分析了各组分的有机物的组成特征、三维荧光光谱特征及红外光谱特征.结果表明,亲水性物质和疏水酸性物质分别占水样中溶解性有机碳的49%和29%,是该石化污水厂二级出水中的主要物质类别.亲水性物质中含有较多的生物源腐殖质类物质,疏水中性物质含有较多的芳香族蛋白质和溶解性微生物代谢产物类物质.4种组分的红外光谱图中600~1200cm-1波数的指纹区波峰数量最多,多为芳香类同分异构体化合物.