Representative locations from time series of soil water content using time stability and wavelet analysis

The concept of time stability has been widely used in the design and assessment of monitoring networks of soil moisture, as well as in hydrological studies, because it is as a technique that allows identifying of particular locations having the property of representing mean values of soil moisture in the field. In this work, we assess the effect of time stability calculations as new information is added and how time stability calculations are affected at shorter periods, subsampled from the original time series, containing different amounts of precipitation. In doing so, we defined two experiments to explore the time stability behavior. The first experiment sequentially adds new data to the previous time series to investigate the long-term influence of new data in the results. The second experiment applies a windowing approach, taking sequential subsamples from the entire time series to investigate the influence of short-term changes associated with the precipitation in each window. Our results from an operating network (seven monitoring points equipped with four sensors each in a 2-ha blueberry field) show that as information is added to the time series, there are changes in the location of the most stable point (MSP), and that taking the moving 21-day windows, it is clear that most of the variability of soil water content changes is associated with both the amount and intensity of rainfall. The changes of the MSP over each window depend on the amount of water entering the soil and the previous state of the soil water content. For our case study, the upper strata are proxies for hourly to daily changes in soil water content, while the deeper strata are proxies for medium-range stored water. Thus, different locations and depths are representative of processes at different time scales. This situation must be taken into account when water management depends on soil water content values from fixed locations.     

Environmental impact of flood: the study of arsenic speciation in exchangeable fraction of flood deposits of Warta river (Poland) in determination of "finger prints" of the pollutants origin and the ways of the migration

The paper presents the application of the hyphenated technique - high-performance liquid chromatography with atomic absorption spectrometry detection with hydride generation (HPLC-HG-AAS) - in the determinations of inorganic forms of arsenic: As(III) and As(V) in the exchangeable fraction of flood deposits. The separation of analytical signals of the determined arsenic forms was obtained using an ion-exchange column in a chromatographic system with the atomic absorption spectrometer as a detector, at the determination limits of 5 ng g⁻¹ for As(III) and 10 ng g⁻¹ for As(V). Flood deposits were collected after big flood event in valley of the Warta river which took place in summer 2010. Samples of overbank deposits were taken in Poznań agglomeration and vicinity (NW Poland). The results of determinations of arsenic forms in the exchangeable fraction of flood deposits allowed indication of a hypothetical path of deposits migration transported by a river during flood and environmental threats posed by their deposition by flood.     

Monitoring of heavy metal concentrations in home outdoor air using moss bags

One monitoring station is insufficient to characterize the high spatial variation of traffic-related heavy metals within cities. We tested moss bags (Hylocomium splendens), deployed in a dense network, for the monitoring of metals in outdoor air and characterized metals’ long-term spatial distribution and its determinants in Girona, Spain. Mosses were exposed outside 23 homes for two months; NO₂ was monitored for comparison. Metals were not highly correlated with NO₂ and showed higher spatial variation than NO₂. Regression models explained 61-85% of Cu, Cr, Mo, Pb, Sb, Sn, and Zn and 72% of NO₂ variability. Metals were strongly associated with the number of bus lines in the nearest street. Heavy metals are an alternative traffic-marker to NO₂ given their toxicological relevance, stronger association with local traffic and higher spatial variability. Monitoring heavy metals with mosses is appealing, particularly for long-term exposure assessment, as mosses can remain on site many months without maintenance.     

Landscape-Based Assessment of Human Disturbance for Michigan Lakes

Assessment of lake impairment status and identification of threats’ type and source is essential for protection of intact, enhancement of modified, and restoration of impaired lakes. For regions in which large numbers of lakes occur, such assessment has usually been done for only small fractions of lakes due to resource and time limitation. This study describes a process for assessing lake impairment status and identifying which human disturbances have the greatest impact on each lake for all lakes that are 2 ha or larger in the state of Michigan using readily available, georeferenced natural and human disturbance databases. In-lake indicators of impairment are available for only a small subset of lakes in Michigan. Using statistical relationships between the in-lake indicators and landscape natural and human-induced measures from the subset lakes, we assessed the likely human impairment condition of lakes for which in-lake indicator data were unavailable using landscape natural and human disturbance measures. Approximately 92% of lakes in Michigan were identified as being least to marginally impacted and about 8% were moderately to heavily impacted by landscape human disturbances. Among lakes that were heavily impacted, more inline lakes (92%) were impacted by human disturbances than disconnected (6%) or headwater lakes (2%). More small lakes were impacted than medium to large lakes. For inline lakes, 90% of the heavily impacted lakes were less than 40 ha, 10% were between 40 and 405 ha, and 1% was greater than 405 ha. For disconnected and headwater lakes, all of the heavily impacted lakes were less than 40 ha. Among the anthropogenic disturbances that contributed the most to lake disturbance index scores, nutrient yields and farm animal density affected the highest number of lakes, agricultural land use affected a moderate number of lakes, and point-source pollution and road measures affected least number of lakes. Our process for assessing lake condition represents a significant advantage over other routinely used methods. It permits the evaluation of lake condition across large regions and yields an overall disturbance index that is a physicochemical and biological indicator weighted sum of multiple disturbance factors. The robustness of our approach can be improved with increased availability of high-resolution disturbance datasets.     

Characterization of particle number concentrations and PM<Subscript>2.5</Subscript> in a school: influence of outdoor air pollution on indoor air

Background, Aim and Scope  

The impact of air pollution on school children’s health is currently one of the key foci of international and national agencies. Of particular concern are ultrafine particles which are emitted in large quantities, contain large concentrations of toxins and are deposited deeply in the respiratory tract.     

Spatial configuration of land-use/land-cover in the Pujal-Coy project area, Huasteca Potosina region, Mexico

This article analyzes the relationship between the configuration and spatial reorganization of land-use and land-cover in the Pujal-Coy project area, Huasteca Potosina region, eastern San Luis Potosí, Mexico, as well as the relationship between these changes and the environmental conditions prevailing in the area. Land-use and land-cover changes were determined through the analysis and interpretation of satellite images from different dates. The changes identified in the different study periods were correlated with the prevailing physical factors. The results show that the spatial configuration of farming activities, initially induced by the implementation of a regional development project, is highly correlated to the presence of limiting factors such as soil type, slope, and climate. Particularly, the former represents the element that has led to the establishment of the current distribution pattern of farming activities.     

Evaluation of the Spanish hot dip galvanising sector as a source of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans

A survey to estimate the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) emissions of Spanish hot dip galvanising sector was carried out during 2002. This investigation is the first presenting Spanish experimental data related to this industrial sector. Three different matrices: flue gas, ash and filter dust were tested to quantify the PCDD/Fs generated during the galvanising process. The organic source of PCDD/F formation could be from the insufficient degreasing o from inhibitors or additives used in the pickling steps such as quinoline, isoquinoline, 8-methylquinoline or polyether phosphoric acid. Low levels PCDD/Fs were achieved in air emissions when air control devices are used. On the contrary, filter dusts are highly contaminated; indicating that the absence of air control devices would increase the risk of fugitive emissions. Homologue profiles and Principal Component Analysis demonstrate there are differences in the formation mechanisms in the bath zone (ashes) compared to the stack location (filter dusts and air emissions), related to the de novo synthesis and reaction time. The annual PCDD/F emission to the atmosphere for this sector during 2002 has been estimated in 0.023g I-TEQ. The emission factor of plants with air control devices has been calculated at 0.030microg I-TEQ/ton of galvanised steel.     

Ten years measuring PCDDs/PCDFs in ambient air in Catalonia (Spain)

This work summarizes the results of a ten year surveillance programme on PCDD/F in ambient air carried out in Catalonia (Spain). The study has been conducted by the Dioxin Laboratory of Spanish Council for Scientific Research (CSIC) in collaboration with the Environment Department of the Catalonian Government. 175 samples have been collected throughout Catalonia from 1994 to 2004. Different sampling locations classified as industrial, traffic, urban, suburban and rural sites have been monitored in order to find the most contaminated zones as well as the ones with expected background concentrations. The highest concentrations found in this study were determined at the industrial locations. Concentrations ranging from 5 to 1196 fg I-TEQ/m3, with a mean value of 140 fg I-TEQ/m3 and from 10 to 357 fg I-TEQ/m3, with a mean value of 72 fg I-TEQ/m3 were determined in industrial and traffic sampling points, respectively. In contrast, the lowest concentrations were found in rural stations, ranging from 5 to 45 fg I-TEQ/m3, with a mean value of 28 fg I-TEQ/m3. The PCDD/F concentration trend in Catalonian ambient air shown a clear drop of the median values occurred during the study sampling period. A decline of about 70% was observed from 1997-1998 to 2003-2004.