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Abstract In ergodic stochastic problems the limit of the value function V λ of the associated discounted cost functional with infinite time horizon is studied, when the discounted factor λ tends to zero. These problems have been well studied in the literature and the used assumptions guarantee that the value function λ V λ converges uniformly to a constant as λ → 0. The objective of this work consists in studying these problems under the assumption, namely, the nonexpansivity assumption, under which the limit function is not necessarily constant. Our discussion goes beyond the case of the stochastic control problem with infinite time horizon and discusses also V λ given by a Hamilton–Jacobi–Bellman equation of second order which is not necessarily associated with a stochastic control problem. On the other hand, the stochastic control case generalizes considerably earlier works by considering cost functionals defined through a backward stochastic differential equation with infinite time horizon and we give an explicit representation formula for the limit of λ V λ , as λ → 0. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Comprehensive contaminant analyses of eight mined landfills. • Identification of contaminant patterns within and between landfills. • Determination of indicator substances for contamination prediction. • Evaluation of limit values with regard to the effectiveness managing substance flows. Abstract Landfill mining is used to close the material loops by recovering recyclables from landfills. Previous research has focused on material composition reporting that, worldwide, landfills mainly consist of soil-like materials ("soils") and combustibles. Although soils have been investigated in a few studies, the results are limited to the presentation of substance concentrations without further analysing the substance patterns (e.g. correlation between substances). This research identifies similarities in substance concentrations within and between landfills, analysing approximately 300 soil samples from eight excavated landfills. Statistical tests enabled the determination of substance variations and correlations. Substance concentration correlations were found between several heavy metals (in particular zinc), sulphate and electrical conductivity, as well as ammonium nitrogen and biodegradability. With regard to contamination prediction, sulphate, pH and total organic carbon proved to be the most efficient indicator elements. Legal limit values have proven to be efficient to manage substance flows in terms of chloride, sulphate, cadmium, lead and zinc, but were ineffective with respect to biodegradability, PCB, benzo[a]pyrene and cyanides. [ABSTRACT FROM AUTHOR]

• Stable residue size increases with litter initial concentrations of N and lignin; • Stable residue size decreases with litter initial Mn concentration; • Stable residue size shows hump-shaped relationships with MAT and latitude; • Stable residue size increases with MAP; • Longer field incubation results in smaller stable residue size. Stable residue from decomposing leaf litter is related to humus buildup in the forest floor and thus to the accumulation of carbon in the soil organic layer (OLC). However, the global pattern and controls of stable residue size remains poorly understood. Herein, the spatial pattern of stable residue size and its association with a series of potential drivers were evaluated by synthesizing available data worldwide. The results showed that stable residue size had a significant and positive correlation with the litter initial nitrogen (N) and lignin concentrations, and a negative correlation with the initial manganese concentration. Larger stable residues were found from decomposing broadleaf litter vs. coniferous litter. The decomposition of green leaf litter produces an equal amount of stable residue as that of brown litter. Stable residue size correlated quadratically with mean annual temperature and latitude, and linearly with mean annual precipitation. Methodological factor also matters, because stable residue size decreased as field incubation time increased. The boosted regression tree model indicated that litter initial traits have the most explanative ability for the variance in stable residue size. We highlighted that litter initial traits exert a predominant role over climate in shaping the stable residue size globally. Our findings are beneficial for a more accurate prediction of global-scale OLC accumulation. [ABSTRACT FROM AUTHOR]

Litter decomposition is a biological process fundamental to element cycling and a main nutrient source within forest meta-ecosystems, but few studies have looked into this process simultaneously in individual ecosystems, where environmental factors can vary substantially. A two-year field study conducted in an alpine forest meta-ecosystem with four litter species (i.e., willow: Salix paraplesia , azalea: Rhododendron lapponicum , cypress: Sabina saltuaria , and larch: Larix mastersiana ) that varied widely in chemical traits showed that both litter species and ecosystem type (i.e., forest floor, stream and riparian zone) are important factors affecting litter decomposition, and their effects can be moderated by local-scale environmental factors such as temperature and nutrient availability. Litter decomposed fastest in the streams followed by the riparian zone and forest floor regardless of species. For a given litter species, both the k value and limit value varied significantly among ecosystems, indicating that the litter decomposition rate and extent (i.e., reaching a limit value) can be substantially affected by ecosystem type and the local-scale environmental factors. Apart from litter initial acid unhydrolyzable residue (AUR) concentration and its ratio to nitrogen concentration (i.e., AUR/N ratio), the initial nutrient concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were also important litter traits that affected decomposition depending on the ecosystem type. [ABSTRACT FROM AUTHOR]

In order to suggest a limit value for gypsum (CaSO 4 ) for the suppression of hydrogen sulfide (H 2 S) generation at an inert solid waste landfill site, the relationship between raw material (SO 4 and organic matter) for H 2 S generation and generated H 2 S concentration, and the balance of raw material (SO 4 ) and product (H 2 S) considering generation and outflow were investigated. SO 4 concentration should be less than approximately 100 mg-SO 4 /L in order to suppress H 2 S generation to below 2000 ppm. Total organic carbon (TOC) concentration should be less than approximately 200 mg-C/L assuming a high SO 4 concentration. The limit value for SO 4 in the ground is 60 mg-SO 4 /kg with 0.011 wt% as gypsum dihydrate, i.e., approximately 1/10 of the limit value in inert waste as defined by the EU Council Decision (560 mg-SO 4 /kg-waste). The limit value for SO 4 in inert waste as defined by the EU Council Decision is high and TOC is strictly excluded. The cumulative amount of SO 4 outflow through the liquid phase is much larger than that through the gas phase. SO 4 concentration in pore water decreases with time, reaching half the initial concentration around day 100. SO 4 reduction by rainfall can be expected in the long term. [ABSTRACT FROM AUTHOR]

This work presents the first comprehensive real-world emissions results from urban buses retrofitted with an optimised low-NO 2 selective catalytic reduction (SCR) system. The SCRT system combines a CRT (Continuously Regenerating Trap) to reduce particle emissions and SCR to reduce NO x emissions. The optimised low-NO 2 SCRT was designed to work under urban conditions where the vehicle exhaust gas temperature is often too low for many SCR systems to work efficiently. The system was extensively tested through on-road and test track measurements using a vehicle emission remote sensing instrument capable of measuring both nitric oxide (NO) and nitrogen dioxide (NO 2 ). Over 700 on-road measurements of the SCRT system were made in London. Compared with identical buses operating under the same conditions fitted with a CRT, NO 2 emissions were reduced by 61% and total NO x by 45%. Under test track conditions reductions in NO x of 77% were observed. The test track results do reveal however that compared with an original Euro III bus without a CRT, the SCRT retrofit bus emissions of NO 2 are 50% higher. Engine-out and tailpipe measurements of several important engine parameters under test track conditions showed the important effect of SCR inlet temperature on NO x conversion efficiency. Overall, we conclude that retrofitting urban buses to use low-NO 2 SCRT systems is an effective method for delivering NO x and NO 2 emissions reduction. [ABSTRACT FROM AUTHOR]

For decomposing foliar litter in forest systems the pattern for accumulated mass loss vs time varies among litter species and environments. Thus, decomposition may be complete (100% accumulated mass loss) or the rate may cease and proceed at such a low rate that a limit value for decomposition may be estimated. Such limit values have been found to range from 42% accumulated mass loss to 100%, resulting in stable fractions of 58 and 0%, respectively. To support a discussion about pattern we need causal relationships and I have used a conceptual model with three decomposition stages as a reference and discuss that in relation to two nutrients that influence the degradation of lignin and lignified tissue. Whereas a high nitrogen (N) concentration may have a stimulating effect on degradation of holocellulose in the early stage the same high N concentration may retard the degradation of lignified tissue in the late stage and the higher the N concentration the stronger the retardation. Through the enzyme manganese peroxidase (MnP), manganese (Mn) stimulates lignin degradation and thus the lignified fraction of litter. A high level of Mn appears to support a further degradation of the lignified tissue and thus results in a high limit value, whereas a high N has been related to a low value. The aim behind this review is to: (i) identify specific factors that may influence the pattern of accumulated mass loss and thus the type of regression model that describes the data; and (ii) present a possible climate influence on decomposition pattern. To this purpose we need to discuss a possible variation in pattern following the variation in concentrations of the two nutrients N and Mn. Concentrations of N and Mn in newly shed litter are both influenced by site climate, with N increasing and Mn decreasing with increasing mean annual temperature (MAT) and increasing annual actual evapotranspiration (AET). Thus, climate becomes at least an indirect regulating factor for decomposition pattern. Two main regression models are used to describe the patterns, namely the single exponential and a function separating a readily decomposed and a stable fraction, by estimating a limit value (asymptotic function). For the discussion on decomposition pattern a model parameter was used, namely estimated limit values with a so far observed range in variation from 42 to 100%. The stabilized litter fraction defined by the limit value may be used for estimating the accumulation rate of stable carbon (C) in soil. [ABSTRACT FROM AUTHOR]

Abstract: Long-term studies of Common beech litter decomposition are scarce and the relationship of its limit values to nutrients/heavy metals dynamics has not been sufficiently studied. The present study is a rare case in which beech litter decomposes almost entirely and enables analyses of the impacts of nutrients and heavy metals on litter decomposition. The aim of the present paper is to (i) determine a decomposition pattern of leaf litter and estimate the limit values and to (ii) determine the dynamics of the main nutrients and heavy metals (concentration and net amounts, based on ash-free litter) in an unpolluted stand of Common beech. Common beech (Fagus sylvatica L.) leaf litter was incubated in polyester litterbags (1.5mm mesh size) and 41 samplings were made over a period of 6.5 years until a mass loss of 88.9% was achieved. Carbon (C) plus 12 more nutrients and heavy metals were analyzed. Mass losses of both whole litter and of C were used in order to estimate the limit values as well as to determine significant differences between the two approaches. An asymptotic function gave significant limit values that were close to 100% (p <0.0001). These results were also supported by a single exponential function (p <0.0001). The initial increase in concentrations of nutrients was followed by a decrease of N, P, K, Ca, Na and Mn. A similar pattern was observed for some of the heavy metals (Cu, Cd and Fe) while Zn concentrations decreased continuously. A net release (e.g. a decrease in the net amounts) was observed for all nutrients and heavy metals except for Cd. The litter fraction did not leave any stable residues (i.e. limit values were close to 100%), which was at least partly due to the low initial N and very high Mn concentration (20 times higher than in other studies). [Copyright &y& Elsevier]

Highlights: [•] Food chain models were edited to get a region-specific PCDD/F deposition limit. [•] The calculation started from the local diet and the WHO’s Tolerable Daily Intake. [•] The case-study refers to an Alpine valley where a steel producing plant is present. [•] Dairy products are of primary importance in the PCDD/F intake. [•] PCDD/F deposition was measured for one year and was lower than the limit value. [Copyright &y& Elsevier]

Abstract: Litter quality is an important determinant of soil organic matter formation. Changes of organic components were investigated along decomposition of black locust (Robinia pseudoacacia L.) leaf litter and black pine (Pinus nigra Arn.) needle litter in the native adjacent coeval forest stands. To this purpose, data from proximate analyses were compared with those from CPMAS 13C NMR. Newly shed leaf litter of black locust had significantly higher concentrations of ADSS (acid detergent soluble substances) as well as lower concentrations of cellulose and AUR (acid unhydrolyzable residues that include lignin) and higher AUR-to-Cellulose ratio than that of black pine. The 13C CPMAS NMR spectra of newly shed leaf litter of black locust and black pine revealed that O-Alkyl-C components (including cellulose and hemicelluloses) accounted, respectively, for 53.8% and 61.4% of the total area of the spectra. All other C fractions were relatively more abundant in black locust than in black pine. Within individual sampling periods, relationships between residual litter mass and concentrations of ADSS, cellulose and AUR were examined, as were relationships between residual litter C and NMR fractions. Four periods were defined based on the slopes of the decomposition curve, with the length of period I defined by the start of a net decrease of AUR. Proximate analyses and NMR data showed changes in chemical composition over the decomposition process, as well as changes in decay rates of the residues, following different paths in the two litters. ADSS decayed faster in black locust litter; in contrast cellulose and AUR decayed faster in that of black pine. AUR concentration increased in both litters during decomposition; however, compared to black pine, the remaining litter of black locust was richer in AUR, despite the lower initial concentration, and had a higher AUR-to-Cellulose ratio. Phenol-C and Aryl-C decayed faster in black locust litter, while Alkyl-C decayed faster in that of black pine. In both litters, mass loss in periods was negatively correlated to concentration of AUR at the start of the periods. C loss in periods was negatively correlated to the concentration at the start of the periods of MC-to-PC (an index of lignin content) in black locust litter and positively correlated to Alkyl-C and O-Alkyl-C in that of black pine. Phenol-C, O-Alkyl-C and Aryl-C were the most decomposable C fractions in black locust. O-Alkyl-C and Alkyl-C were the most decomposable C fractions in black pine. Limit value was lower in black pine than in black locust. Consequently the different pattern of litter decomposition can affect the size of C sequestration in the forest floor and the quality of accumulated organic carbon. [Copyright &y& Elsevier]

Abstract: The objective of this study was to describe the ambient levels of particulate matter (PM) and its influence to air quality situation on the dry Mediterranean island of Cyprus. From October 2002 to August 2003 PM10 and PM2.5 samples were collected at 31 different sampling sites in Cyprus. In addition, continuous measurements of PM10 were carried out from 2003 to 2007 at a traffic and a rural site. It can be recognised that at all traffic and at some residential and urban background sites, the actual EU limit values have been exceeded. Special events e.g. long-range transport of Sahara dust storms were recorded over urban as well as rural areas in the order of 6–8 events per year, with a major frequency in summer and spring periods. The comparison of the PM10 concentrations in Cyprus cities with values of other European cities demonstrates the PM10 problem in Cyprus, especially in the dry summer season, when no rain is cleaning the air and the dry surfaces. This underlines the necessity of PM abatement strategies. [Copyright &y& Elsevier]

Abstract: Proposals from the European Commission have raised the possibility that Member States may be able to subtract the concentrations of natural components of airborne particulate matter from measured concentrations when evaluating compliance with EU Limit Values. By applying the pragmatic mass closure model [. A pragmatic mass closure model for airborne particulate matter at urban background and roadside sites. Atmospheric Environment 37, 4927–4933] to chemical composition data for PM10, it has been possible to estimate the concentrations of natural sea salt, strongly bound water and secondary organic carbon (which is assumed wholly biogenic) to the measured mass of PM10. Because of the difficulty in distinguishing between natural and anthropogenic crustal dusts, the contribution of natural windblown dust and soil has not been accounted for. When the natural components are estimated for two urban and one rural site in the UK, the long-term mean PM10 concentration is reduced by between 5.2 and 7.3μgm−3. The number of exceedences of the 50μgm−3 24-h limit value falls dramatically from 54 to 21 (from a total of 291 days) at an urban street canyon site, 7 to 3 ( days) at an urban background site and from 8 to 0 ( days) at a rural site when using gravimetric PM10 concentrations. The calculations have also been performed using PM10 concentrations measured by TEOM increased by a factor of 1.3 as recommended by the European Commission as an interim means of estimating gravimetric equivalency, and the number of exceedences of the 24-h limit value fell from 92 to 47 (from a total of 291 days) at the urban street canyon site, from 11 to 3 ( days) at the urban background site and from 6 to 3 () at the rural site. Clearly, therefore, application of this proposed measure would make a very major difference to the likelihood of compliance or otherwise with the 24-h limit value for PM10. [Copyright &y& Elsevier]

The decomposition dynamics of four types of needle litter and three types of leaf litter were followed for 3 years at two very contrasting coniferous forest systems, a nutrient-rich silver fir (Abies alba Mill.) forest in south Italy (Monte Taburno) and a nutrient-poor Scots pine (Pinus sylvestris L.) forest in central Sweden (Ja¨draa˚s). Decomposition of the same litter type at the two sites did not differ in the early stages but proceeded further at the nutrient-rich forest site than at the nutrient-poor one. Limit values for decomposition were calculated and the differences for the same litter type between the two contrasting coniferous systems were investigated. At both sites six of the seven litter types gave significant (asymptotic) limit values for decomposition, which varied with litter type. For four litter types out of six the limit values differed significantly between the two sites and were always higher at the nutrient-rich site (Monte Taburno). Using all available data for litters incubated at the two sites revealed that at the nutrient-poor site (Ja¨draa˚s) there was a significant negative relationship between litter N levels and limit values and there was also a significant negative relationship between initial concentrations of heavy metals (e.g. Zn, Cd, Cu) and limit values. In contrast, at the site Monte Taburno, rich in nutrients and in heavy metals, there was no such relationship. [Copyright &y& Elsevier]

Construction activities such as blasting, piling, compaction, excavations, and construction traffic can produce vibrations of sufficient strength to cause damage to neighbouring buildings and structures. Therefore, many countries have national limit values for construction vibration in standards. However, building damages assumed to originate from vibrations are seldom observed. This may indicate that today's limit values are unnecessarily strict. In this field little newer research has been undertaken to scientifically observe the onset of cracking, and there is a particular lack of information about which role the frequency content of the vibration plays. In this study the onset of blast induced cracking was observed in two instrumented test structures located in a rock quarry. Two buildings were constructed, one in cast-in-place concrete without reinforcement and one made of lightweight construction blocks in expanded clay aggregate (LECA). The buildings were instrumented with geophones and Fiber Bragg Grating Sensors (strain sensors). In addition, vibrations on the ground surface and air blast overpressure were measured. Test blasts were designed to produce increasing vibration values, starting with peak particle velocities (PPVs) around 20 mm/s and ending with PPVs above 250 mm/s. No visible cracks were found on any of the two buildings. However, the last blast, which produced PPVs above 260 mm/s, resulted in a residual displacement of 0.05 mm across the 110 mm strain gage length above the door of the concrete building. The results of the test indicate that the limit values of most national standards include a large safety margin for buildings founded on rock. Further, the dominant frequency was determined by different methods and the results show a considerable deviation, with a distinct difference between methods which determine the frequency in a short time interval around the highest peak and methods which are using the entire vibration time series. In addition, methods which determines the frequency in short time intervals show a large spread in the frequency between the different vibration cycles. • An instrumented blast study was performed on two buildings in different materials. • The buildings were exposed to vibration velocities from 20 mm/s to above 250 mm/s. • No visible damages were found, but strain measurements showed residual displacement. • Vibration limits seem to include large safety margins for buildings founded on rock. • Different methods for determining dominant frequency result in deviations in results. [ABSTRACT FROM AUTHOR]

Raw salmon is commonly used in sushi and sashimi, indicating that fresh salmon may be considered as a ready-to-eat product. Listeria monocytogenes is occasionally present in fresh salmon, but studies of prevalence and growth of the bacterium in this matrix have been few. In the present study, salmon from a company where L. monocytogenes is present in low levels has been investigated in order to develop performance objectives for L. monocytogenes in fresh salmon intended for use in ready-to-eat products as sushi and sashimi. According to the European Food Law, the maximum level of L. monocytogenes on the last day of shelf life is 100cfu/g. The variations between and within eight batches have been determined, and the results were used to estimate limit values for L. monocytogenes in salmon and develop a tentative sampling plan for the processing day. Various time-temperature scenarios for storage until the fish is consumed as sushi, sashimi or native fillets have been taken into account. The results indicate that limit values in the range from 0.5 to 10cfu/g are sufficient to ensure that the regulatory limit of <100cfu/g of L. monocytogenes on the last day of shelf life is not exceeded, provided that the recommended time-temperature conditions are respected. For instance, if the fish is intended for processing into sushi within one week of storage at 4°C after filleting, no samples should have higher levels of L. monocytogenes than 2cfu/g at the day of filleting. [ABSTRACT FROM AUTHOR]