Evaluation of calibrated passive sampling for quantifying ammonia emissions in multi-plot field trials with slurry application

Background

There is a great need for simple and inexpensive methods to quantify ammonia emissions in multi-plot field trials. However, methods that meet these criteria have to be thoroughly validated. In the calibrated passive sampling approach, acid traps placed in the center of quadratic plots absorb ammonia, enabling relative comparisons between plots. To quantify ammonia emissions, these acid trap samplings are scaled by means of a transfer coefficient (TC) obtained from simultaneous measurements with the dynamic tube method (DTM). However, dynamic tube measurements are also comparatively costly and time-consuming.

Aims

Our objective was to assess the best practice for using calibrated passive sampling in multi-plot field trials. One particular challenge in such experiments is to evaluate the influence of ammonia drift between plots.

Methods

In a series of eight multi-plot field trials, acid traps and DTM were used simultaneously on all plots to measure ammonia emissions caused by different slurry application techniques. Data obtained by both methods were correlated, and the influence of the ubiquitous ammonia background on both methods was evaluated by comparing net values, including the subtraction of the background with gross values (no background subtraction). Finally, we provide recommendations for calculating a TC for calibrating relative differences between plots, based on simultaneous acid trap and dynamic tube measurements on selected plots.

Results

Treatment mean values obtained by both methods correlated well. For most field trials, R² values between 0.6 and 0.8 were obtained. Ammonia background concentrations affected both methods. Drift between plots contributed to the background for the acid traps, whereas the contamination of the chamber system might have caused the background for the DTM. Treatments with low emissions were comparatively more affected by that background.

Conclusion

For a robust application of calibrated passive sampling, we recommend calculating the TC based on a treatment with high ammonia emissions, reducing the relative influence of the ubiquitous ammonia background.     

Modelling the role of ground-true riparian vegetation for providing regulating services in a Mediterranean watershed

Intensive agricultural and industrial activities are often considered major sources of water contamination. Currently, riparian vegetation (RV) is increasingly being promoted as a solution to balance the potentially adverse effects that agriculture may have on water quality. Nonetheless, existing RV is often overlook in recent modelling efforts, failing to capture the current amount of ecosystem services provide. Here, we used the Soil and Water Assessment Tool ecohydrological model to simulate the influence of ground-true RV on i) nutrient (nitrate and total phosphorus) and sediment exports from agricultural areas and ii) its effect for in-stream concentrations. These results are further compared against a set of hypothetical scenarios of different RV widths and different land-uses. Our results point to a great relevance of existing RV in controlling in-stream concentration of sediments and nutrients where pressure from agriculture is highest, preventing them to surpass limits set in the EU Water Framework Directive. On the other hand, in areas with industry discharges, the role of RV is limited and model results suggest that restoring RV would have limited impacts. We illustrate how existing RV may already provide strong but not acknowledged water quality regulation services, how these services can differ substantially between nearby streams, and that effective strategies to improve water quality using RV must acknowledge existing patterns of vegetation, land use and contamination sources.     

Effect of transdermally administered fentanyl on the minimum alveolar concentration of isoflurane in cats

OBJECTIVE: To determine the effect of two doses of fentanyl, administered transdermally, on the minimum alveolar concentration (MAC) of isoflurane in cats. STUDY DESIGN: Prospective, randomized study. ANIMALS: Five healthy, spayed, female cats. METHODS: Each cat was studied thrice with at least 2 weeks between each study. In study 1, the baseline isoflurane MAC was determined in triplicate for each cat. In studies 2 and 3, isoflurane MAC was determined 24 hours after placement of either a 25 or 50 microg hour(-1) fentanyl patch. In each MAC study, cats were instrumented to allow collection of arterial blood and measurement of arterial blood pressure. Twenty-four hours prior to studies 2 and 3, a catheter was placed and secured in the jugular vein and either a 25 or 50 microg hour(-1) fentanyl patch was placed in random order on the left thorax. Blood samples for plasma fentanyl determination were collected prior to patch placement and at regular intervals up to 144 hours. After determination of MAC in studies 2 and 3, naloxone was administered as a bolus dose (0.1 mg kg(-1)) followed by an infusion (1 mg kg(-1) hour(-1)) and MAC redetermined. RESULTS: The baseline isoflurane MAC was 1.51 +/- 0.21% (mean +/- SD). Fentanyl (25 and 50 micro g hour(-1)) administered transdermally significantly reduced MAC to 1.25 +/- 0.26 and 1.22 +/- 0.16%, respectively. These MAC reductions were not significantly different from each other. Isoflurane MAC determined during administration of fentanyl 25 micro g hour(-1) and naloxone (1.44 +/- 0.16%) and fentanyl 50 micro g hour(-1) and naloxone (1.51 +/- 0.19%) was not significantly different from baseline MAC (1.51 +/- 0.21%). CONCLUSIONS AND CLINICAL RELEVANCE: Fentanyl patches are placed to provide long-lasting analgesia. In order to be effective postoperatively, fentanyl patches must be placed prior to surgery. Plasma fentanyl concentrations achieved intraoperatively decrease the need for potent inhalant anesthetics in cats.     

中华鳖致病性嗜水气单胞菌分离鉴定与药敏试验

为了探求中华鳖致病性菌株的药物体外抗菌效果,在江西进贤某中华鳖养殖场对病死中华鳖进行细菌分离,并对细菌进行形态特征、培养特性、生化鉴定、毒力因子检测试验、小白鼠毒力试验和人工感染等试验;采用K-B法药敏试验和96孔微型板二倍稀释法测定9种抗菌药物对该菌的最低抑菌浓度(MIC)来分析抗菌效果.结果表明:中华鳖为致病性嗜水...     

兼顾排涝标准与水质净化要求的农业圩区最优水面率确定

针对农业圩区的排涝以及水环境问题,该研究以江苏里下河地区为研究对象,以满足里下河圩区设计排涝标准与水质净化要求为目标,构建农业圩区坑塘-排水沟道湿地系统最优水面率数学模型.模型以工程系统总费用现值最小为目标函数,以泵站涝水外排能力与圩内水面率、水面率上下限、水环境容量与圩内坑塘与排水沟道系统的关系(主要包括圩内坑塘沟道...     

蝴蝶兰丛生芽快繁体系的建立

以蝴蝶兰花梗腋芽为外植体,对消毒方法、培养基种类、激素浓度、褐化控制等因素进行研究,结果表明:花梗切为2～3 cm带腋芽段,预处理后用0.1%升汞灭菌15 min,灭菌成功率达90%;花梗腋芽最适诱导培养基为MS或1/2MS+6-BA 3.0 mg/L;丛生芽诱导最适培养基为1/2MS+6-BA 7.5 mg/L+NAA 1.0 mg/L;生根最适培养基为1/2MS+NAA 1.0 mg/L+AC 1.0 g/L+香蕉泥60 mg/L。建立了一套通过诱导丛生芽进行蝴蝶兰快繁的有效途径。     

大麦籽粒蛋白质含量的QTL定位分析

通过栽培大麦Karl与Lewis杂交构建的重组自交系F10代60个骨干家系,种植于贵州高海拔地区,并对其F11代籽粒蛋白质含量(GPC)进行测定及其QTL分析后,发现2个单一QTL(GPC1和GPC2),LOD值分别为3.63和2.93,贡献率分别为49％和26％,加性效应分别为+2.9％和+1.9％.在自交系群体中发现极端表现型家系,分别为高GPC的R9、R 15、R32、R7及低GPC的R121、R 34、R 110、R 136,两极端表现型家系GPC相差高达10％.以上结果均为大麦GPC基因研究及品种改良提供了极具价值的依据和材料.     

Distribution and Sources of Polycyclic Aromatic Hydrocarbons in Suspended Particle Mater in Rainy Season from Jialing River in Chongqing

16 polycyclic aromatic hydrocarbons (PAHs) were measured by GC-MS for 13 suspended particle matter samples collected from Jialing River in Chongqing in rainy season. The results showed that the total concentrations of 16 PAHs ranged from 447.47 ng/g to 1 344.92 ng/g, with a mean value of 927.48 ng/g. The concentration of total PAHs in suspended particle matter showed the trend of“up-down-up-down”in spatial distribution in the 13 sampling sites. The predominant PAHs in suspended particle matter were 4 ring PAHs, which accounting for 41.87% of the tatal PAHs. The ratio analysis and principle factor analysis-multiple linear regression(PCA-MLR) indicated that the major source of PAHs was the engine combustion source, in which the proportion of gasoline combustion and diesel combustion were 37.79% and 29.97%, respectively. The ecological risk of PAHs was evaluated by the effects range median values (ERM) and the effects range low values (ERL). The results illustrated that Acy, Ace, Fl and DahA had certain ecological risks, while the ERL values of other12 PAHs in all suspended particle matter samples were lower than the ERL guideline value,namely, PAHs in Jialing River in Chongqing could not cause obvious ecological risk.     

Effects of fuel injection and intake parameters on low temperature combustion

The effects of fuel injection and intake parameters on low temperature combustion are investigated using CFD modeling in the present study. With the increase of injection pressure or decrease of nozzle hole diameter:the maximum in-cylinder pressure and temperature increase. Heat release from premixed combustion increases at the same oxygen concentration and oxygen concentration that obvious premixed combustion appears increases. As to emissions, soot emission decreases because of the improvement of mixing of fuel and air and NOx emission increases because the increase of local temperature in the cylinder. With the increase of intake pressure:the maximum cylinder pressure increases but the maximum cylinder temperature decreases. The ignition timing advances at the same oxygen concentration. The combustion efficiency increases. As to emissions, both soot and NOx emissions decrease.     

水质生物毒性在线监测的必要性和常用方法探讨

指出了水环境污染事故的不断发生,严重威胁着人们正常的生产和生活秩序,为了预警重特大水质污染事故的发生,及时采取有效措施降低损失,提出了引入新的监测技术,开展水质生物毒性在线监洌l工作成为水质在线监测工作的必然,探讨了生物毒性在线监测的常用方法。