Epidemiological derivation of fl ux-based critical levels for visible ozone injury in European forests

The European MOTTLES project set-up a newgeneration network for ozone(O 3)monitoring in 17 plots in France,Italy and Romania.These monitoring stations allowed:(1)estimating the accumulated exposure AOT40 and stomatal O 3 fl uxes(PODY)with an hourly threshold of uptake(Y)to represent the detoxifi cation capacity of trees(POD1,with Y=1 nmol O 3 m^−2 s^−1 per leaf area);and(2)collecting data of forest-response indicators,i.e.crown defoliation and visible foliar O 3-like injury over the time period 2017–2019.The soil water content was the most important parameter aff ecting crown defoliation and was a key factor aff ecting the severity of visible foliar O 3-like injury on the dominant tree species in a plot.The soil water content is thus an essential parameter in the PODY estimation,particularly for water-limited environments.An assessment based on stomatal fl ux-based standard and on real plant symptoms is more appropriated than the exposure-based method for protecting vegetation.From fl ux-eff ect relationships,we derived fl ux-based critical levels(CLef)for forest protection against visible foliar O 3-like injury.We recommend CLef of 5 and 12 mmol m^−2 POD1 for broadleaved species and conifers,respectively.Before using PODY as legislative standard in Europe,we recommend using the CLec for≥25%of crown defoliation in a plot:17,000 and 19,000 nmol mol^−1 h AOT40 for conifers and broadleaved species,respectively.

Slope stability of reclaimed coal mines through a new water filling index

A common reclamation practice for closed coal surface mines is filling them with water to form pit lakes.The creation and sustainability of these lakes are significantly affected by the stability of the corresponding slopes.The present study provides a general framework for analyzing the water filling’s effect on slope stability based on a new water filling index,which can indirectly consider the factors affecting the process and efficiently quantify the filling speed’s influence.The assumptions of the proposed approach are thoroughly discussed,and the range of the water filling index is identified.Furthermore,the safety factor is calculated using the finite element method with the shear strength reduction technique during the filling process for various conditions(soil properties,slope geometry,hydraulic conditions,and water filling speed).Results are presented as normalized stability charts for practical use.During the water filling,the stability gradually decreases until the reservoir reaches a critical level of 10%e40%of the total height;it then increases to even more stable conditions than the initial one.Overall,the present analysis allows for the preliminary stability evaluation of a coal mine during the formation of a pit lake and the appropriate quantification of the water filling’s effect.

Critical Soil Phosphorus Values for Yield Reduction in Intensive Agricultural Systems

Phosphorus(P)is an essential element for agricultural production.Over-fertilization during decades caused an accumulation of P in soils leading to eutrophication in regions characterized by intensive agriculture.These environmental concerns together with the non-renewability of P resources have led to a more sustainable P use.Knowledge about the P need of crops is essential for a sustainable agriculture thereby minimizing P losses to the environment without lowering the yield substantially.Therefore,in this study,critical soil P values for yield reduction(PCrit)were determined based on fertilizer trials conducted between 1970 and 1988 and more recent fertilizer trials(2016-2017).At rotational level a common PCrit value of 109 mg P/kg dry soil(in an ammonium lactate and acetate extract)was determined.Crop specific PCrit values were also determined for seven crops(potato,winter wheat,barley,rye,maize,sugar beet and temporary grassland).These critical values ranged from 59 mg P/kg dry soil to 164 mg P/kg dry soil with winter wheat the least and maize the most sensitive towards P deficiency.The diversity in PCrit values among crops can mainly be explained by the root intensity but also rooting depth,exudation of organic acids and phosphatases may influence the PCrit value.The soil pH also influenced the P availability significantly.Soils with a favorable pH had a significantly higher availability(i.e.,lower PCrit value)for all crops compared to soils with a suboptimal pH.Critical soil P values might help to set up new or to evaluate current soil P in target zones used for P fertilizer recommendations.

isoAOT40:An improved ozone exposure index based on the Annual Ozone Spectrum Profile(AO3SP)

Abstarct In recognition of the rising threats of groundlevel ozone(O_(3))pollution to forests,agricultural crops,and other types of vegetation,accurate and realistic risk assessment is urgently needed.The accumulated O_(3)exposure over a concentration threshold of 40 nmol mol-1(AOT40)is the most commonly used metric to investigate O3 exposure and its effects on vegetation and to conduct vegetation risk assessment.It is also used by international regulatory authorities for deriving critical levels and setting standards to protect vegetation against surface O_(3).However,fixed periods of the growing season are used universally,yet growing seasons vary with latitudes and elevations,and the periods of plant lifespan also differ among annual species.Here,we propose the concept of the Annual O_(3)Spectrum Profile(AO_(3)SP)and apply it to calculate the profile of AOT40 throughout the year(AAOT40SP,Annual AOT40 Spectrum Profile)using the International Organization for Standardization(ISO)weeks as a shorter window ISO-based accumulated exposure.Using moving time periods of three(for crops)or six(for forests)months,the i so AOT40 behavior throughout the year can be examined as a diagnostic tool for O_(3)risks in the short-or long-term during the lifecycle of local vegetation.From this analysis,AOT40(i so AOT40)that is most representative for the local conditions and specific situations can be identified,depending on the exact growing season and lifecycle of the target vegetation.We applied this novel approach to data from five background monitoring stations located at different elevations in Cyprus.Our results show that the AAOT40SP approach can be used for improved and more realistic assessment of O3 risks to vegetation.The AO_(3)SP approach can also be applied using metrics other than AOT40(exposure-or flux-based),adding a new dimension to the way O_(3)risk to vegetation is assessed.

Experimental Investigation of Flow Patterns in a Pump Intake with Different CWL(Critical Water Level)and Back-Wall Clearance

In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different cases.The statistical data show that CWL for a two-phase flow is lower than that in the case of a single-phase flow at a relatively low flow rate,and as the flow rate increases,this trend turns out to be completely reversed.Fine experimental data obtained under conditions of subcritical,critical and supercritical flow rates have revealed that the larger the back-wall clearance is,the more vortices exist and the higher the vorticity of free-surface vortices is.For the smallest back-wall clearance,the flow coming through the inlet occupies most space under the pipe bell,and both this flow and the inflow coming from the back wall are asymmetric relative to a certain vertical line other than the axis.For the larger and the largest back-wall clearances,the flows coming from the inlet and from the back wall are almost symmetrical relative to the vertical axis of the pipe bell.The velocity distributions on two PIV measurement lines for different back-wall clearance magnitudes indicate that the smallest back-wall clearance influences the flow around the pipe bell.

A Predictive,Two-Parameter Model for the Movement of Reservoir Landslides

Monitoring data show that many landslides in the Three Gorges region,China,undergo step-like displacements in response to the managed,quasi-sinusoidal annual variations in reservoir level.This behavior is consistent with motion initiating when the reservoir water level falls below a critical level that is intrinsic to each landslide,with the subsequent displacement rate of the landslide being proportional to the water depth below that critical level.Most motion terminates when the water level rises back above the critical level,so the annual step size is the time integral of the instantaneous displacement rate.These responses are incorporated into a differential equation that is easily calibrated with monitoring data,allowing prediction of landslide movement from actual or anticipated reservoir level changes.Model successes include(1)initiation and termination of the annual sliding steps at the critical reservoir level,producing a series of steps;(2)prediction of variable step size,year to year;and(3)approximate prediction of the shape and size of each annual step.Annual rainfall correlates poorly with step size,probably because its effect on groundwater levels is dwarfed by the 30 m annual variations in the level of the Three Gorges Reservoir.Viscous landslide behavior is suggested.