The potential effect of differential ambient and deployment chamber temperatures on PRC derived sampling rates with polyurethane foam (PUF) passive air samplers

Performance reference compound (PRC) derived sampling rates were determined for polyurethane foam (PUF) passive air samplers in both sub-tropical and temperate locations across Australia. These estimates were on average a factor of 2.7 times higher in summer than winter. The known effects of wind speed and temperature on mass transfer coefficients could not account for this observation. Sampling rates are often derived using ambient temperatures, not the actual temperatures within deployment chambers. If deployment chamber temperatures are in fact higher than ambient temperatures, estimated sampler-air partition coefficients would be greater than actual partition coefficients resulting in an overestimation of PRC derived sampling rates. Sampling rates determined under measured ambient temperatures and estimated deployment chamber temperatures in summer ranged from 7.1 to 10 m³ day⁻¹ and 2.2-6.8 m³ day⁻¹ respectively. These results suggest that potential differences between ambient and deployment chamber temperatures should be considered when deriving PRC-based sampling rates.     

Biodegradation kinetics of selected brominated flame retardants in aerobic and anaerobic soil

The purpose of the present study was to investigate the biodegradation kinetics in aerobic and anaerobic soil of the following brominated flame retardants: 2,4,4′-tribromodiphenyl ether (BDE 28), decabromodiphenyl ether (BDE 209), tetrabromobisphenol A (TBBPA), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 2,4,6-tribromophenol (246BrPh), and hexabromobenzene (HxBrBz). For comparison, the biodegradation of the chlorinated compounds 2,4,4′-trichlorodiphenyl ether (CDE 28), 2,4,6-trichlorophenol (246ClPh), hexachlorobenzene (HxClBz), and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) was also assessed. In aerobic soil, BDE 209 showed no significant degradation during the test period, but concentrations of the other BFRs declined, with half-lives decreasing in the following order: BDE 28 > TBBPA > TBECH > HxBrBz > 246BrPh. Declines in almost the same order were observed in anaerobic soil: BDE 28, BDE 209 > TBBPA > HxBrBz > TBECH >246BrPh.     

低温低浓度下城市污水活性污泥自然培养和驯化

介绍了交互式物化/生化反应器处理城市污水的工艺流程和特点。研究了交互式物化/生化反应器中试系统在低温低进水浓度(水温13℃~17℃,平均CODcr为144mg/L)和自然不接种的情况下,利用生态絮凝剂聚硅硫酸铁和助凝剂聚丙烯酸进行活性污泥培养和成长的过程规律,并在自然状态下(水温17℃~23℃,平均CODcr为117mg/L)对生成的活性污泥进行驯化。     

DGGE/TGGE方法在土壤微生物群落研究中的应用

变性梯度凝胶电泳(DGGE)或温度梯度凝胶电泳(TGGE)已成为环境微生物学领城比较微生物群落多样性和检测种群动力学的重要分子手段,本文介绍了DGGE/TGGE方法在土壤微生物群落研究中的应用进展及存在的缺陷,并提出了改进建议.     

预测流速法在炼厂高温高压烟道烟尘浓度采样分析中的应用与探讨

对预测流速法用于炼厂高温高压烟道采样分析的可行性进行了探讨，介绍了针对高温高压烟道烟尘采样分析特点进行的技术改进，指出该方法存在的问题和保证分析准确度应采取的措施。     

燃气火焰中热力型NOx的生成与控制

燃气火焰中热力型ＮＯｘ以ＮＯ为主，以ＮＯ为主，燃烧温度对ＮＯ生成起决定作用，空气系数也主要通过改变燃烧温度影响ＮＯｘ生成。燃烧温度大于１８００Ｋ时，有较多ＮＯ生成。降低燃烧温度与保持高效燃烧相协调是控制ＮＯｘ生成的关键。     

Evidence of temperature-controlled dissolved inorganic nitrogen distribution in a shallow lake

Dissolved inorganic nitrogen (DIN) plays an important role in aquatic ecosystems as an available source of nitrogen (N). Despite recent advances in our understanding of the effects of climate change on DIN in coastal waters, shallow high-latitude lakes exposed to large seasonal temperature differences have received limited research attention. Therefore, in the present study, Baiyangdian Lake (BYDL) was selected as the study area, as a typical high latitude shallow lake in North China. Based on water and sediment samples collected in spring, summer and winter seasons, DIN accumulation in sedimentary pore water and DIN diffusion fluxes at the sediment-water interface were quantified under different temperature conditions. Correlation analysis was used to establish the effects of temperature on DIN concentration and diffusion in different media. Results show that the diffusion of DIN at the lake sediment-water interface exhibited a strongly positive relationship with temperature, suggesting that high temperature conditions lead to greater DIN release from sediments. Cold temperatures cause DIN accumulation in sedimentary pore water, providing sufficient substrate for N-related bacteria in the sediment under cold temperature conditions. Temperature controls the vertical distribution of DIN by affecting its migratory diffusion and transformation at the sediment-water interface. These findings are valuable for understanding the impact of climate change on the distribution of N in inland shallow lakes, especially in high latitude shallow lakes subjected to large seasonal temperature differences throughout the year.     

堆肥式生态厕所处理人类排泄物变化规律研究

选用秸秆和木屑的混合物作为生态厕所反应基质,采用日本研制生产的s-15型生态厕所为实验装置,通过好氧微生物的氧化分解,将粪便转化为无臭味的水、二氧化碳和较干燥的有机肥.实验模拟实际生活,通过5～6人正常使用方式投加物料,旨在研究生态厕所在现实生活中处理人类排泄物的变化规律.通过分析实验过程中的物料投加量、使用周期、温度、含水率等指标的变化.发现生态厕所使用的第5～12周,温度在50℃左右,含水率稳定在50%～60%之间时生态厕所减量化效果最为理想.     

带肋薄壁方钢管混凝土柱温度场试验研究与分析

为研究带肋薄壁钢管混凝土柱在火灾下的温度分布,进行3根足尺带肋薄壁方钢管混凝土柱升温试验。建立方钢管混凝土柱温度场有限元模型,模型计算结果与实验结果符合较好。利用模型分析了典型的温度场分布规律,并研究了各参数对构件温度场的影响规律。结果表明:构件截面温度场在四面受火状态下呈双轴对称分布,且角部温度较高。加劲肋对构件温度场的影响仅限于焊接点附近,加劲肋间距和含钢率对构件整体温度场影响微小;截面边长、受火时间和受火方式是影响构件温度场的主要因素。     

温度三区间理论评价气候变化对作物产量影响

传统平均温度法往往无法表征极端温度事件对作物产量的作用,导致气候变化对产量影响的评估结果与实际情况存在较大偏差.鉴于此,论文提出了温度三区间理论.该理论基于作物生长发育各阶段的生物量指标以及最终产量随温度变化呈现出三区间的响应关系,分别评价正常温度、极端低温以及极端高温对产量的影响.为了验证温度三区间理论的科学性和可行性,论文以黑龙江省玉米为例,通过构建包括三区间积温指标和降水量指标的统计模型来评价气候变化对玉米单产的影响,并将此结果和平均温度法相比较,研究发现温度三区间评价法更能客观全面地评价气候变化对作物产量的影响,为这方面的研究提供了新思路.