Assessing environmental impacts of treated wastewater through monitoring of fecal indicator bacteria and salinity in irrigated soils

To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL⁻¹) than in summer (17 CFU 100 mL⁻¹); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL⁻¹) to winter (4 CFU 100 mL⁻¹), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g⁻¹ soil) were measured in deeper (20–25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m⁻¹ occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.     

Spatial and temporal occurrence of N-nitrosamines in seven drinking water supply systems

The spatiotemporal presence of eight N-nitrosamines in the water of seven supply systems in Quebec considered to be susceptible to these emerging disinfection by-products was evaluated. This is the first study on the presence of N-nitrosamines in drinking water utilities in Quebec. Seven sampling campaigns were carried out at several sampling points in each of the systems over a period of 1 year. The results show that N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), were not commonly detected in the water of the facilities under study (10 % of samples). The concentrations measured were lower than those reported in recent North American studies. None of the 195 samples taken exceeded the Ontario standard of 9 ng/L for NDMA (maximum value observed of 3.3 ng/L). N-nitrosomethylethylamine and N-nitrosopiperidine were detected once, with concentrations of 3.7 and 6.0 ng/L, respectively. Chloramination was identified as being the main risk factor regarding the presence of N-nitrosamines, but water quality and some operating parameters, in particular disinfectant residual, also seem to be related to their presence. NDMA concentrations at the end of the distribution systems were generally higher than water leaving the plant. No seasonal trends were observed for the formation of N-nitrosamines in the investigated supply systems. Finally, an association between the presence of N-nitrosamines and the levels of trihalomethanes and haloacetic acids was observed in some facilities.     

Utilizing the great blue heron (Ardea herodias) in ecological risk assessments of bioaccumulative contaminants

Selection of an appropriate species is a key element of effective ecological risk assessments (ERA), especially when site-specific field studies are to be employed. Great blue herons (GBH) possess several ideal characteristics of a receptor species for the assessment of bioaccumulative compounds in the environment, such as ease of study, high potential for exposure, widespread distribution, and territorial foraging behavior. Methodologies for assessing exposure and population health are described herein. As outlined, the collection of GBH eggs, GBH nestling blood, and adult GBH blood allows for the determination of contaminant concentrations in various GBH tissues, a top-down assessment, which can be done in conjunction with predicted dietary exposure, a bottom-up assessment, to support a multiple lines of evidence approach. Additionally, population parameters, such as productivity and survival, can also be measured to elucidate if the contaminant exposure may be causing population level effects. Over the course of two years, three GBH rookeries were monitored for productivity and nestling exposure. Nests were monitored from blinds and individually accessed at multiple time points to obtain measures of nestling health, band nestlings, and collect eggs and nestling plasma. Multiple nests could frequently be accessed by climbing one tree, resulting in minimal effort to obtain the necessary sample size. Additionally, 51 adult GBH, captured in their foraging areas, were banded, and provided a blood sample. With these samples, a statistical difference in tissue based exposure was identified between the reference and target area. Statistically significant differences were also identified between the upper and lower reaches of the target area, thereby identifying a range of doses geographically which could be correlated to specific measurement endpoints. The ability to identify a dose response greatly increases the ability of the dataset to determine causation, a key goal of such studies. Overall, the use of the described methods allowed for the collection of a statistically sufficient and ecologically relevant dataset with reasonable effort and minimal impact on GBH.     

A patch use model to separate effects of foraging costs on giving-up densities: an experiment with white-tailed deer (<Emphasis Type="Italic">Odocoileus virginianus</Emphasis>)

The giving-up density of food (GUD), the amount of food remaining in a patch when a forager ceases foraging there, can be used to compare the costs of foraging in different food patches. But, to draw inferences from GUDs, specific effects of foraging costs (predation risk, metabolic and missed opportunities costs) on GUDs have to be identified. As high predation risk, high metabolic costs and abundant food all should produce high GUDs, this does not allow us to infer directly the quality of a habitat. In order to separate the effect of each foraging cost, we developed an optimal foraging model based on food supplementation. We illustrate the use of our model in a study where we assessed the impact of a power line right-of-way in a white-tailed deer (Odocoileus virginianus) winter yard by determining whether the negative effects of cover loss outweigh the positive effects of browse regeneration.     

Geotechnical properties of municipal solid waste at different phases of biodegradation

This paper presents the results of laboratory investigation conducted to determine the variation of geotechnical properties of synthetic municipal solid waste (MSW) at different phases of degradation. Synthetic MSW samples were prepared based on the composition of MSW generated in the United States and were degraded in bioreactors with leachate recirculation. Degradation of the synthetic MSW was quantified based on the gas composition and organic content, and the samples exhumed from the bioreactor cells at different phases of degradation were tested for the geotechnical properties. Hydraulic conductivity, compressibility and shear strength of initial and degraded synthetic MSW were all determined at constant initial moisture content of 50% on wet weight basis. Hydraulic conductivity of synthetic MSW was reduced by two orders of magnitude due to degradation. Compression ratio was reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. Direct shear tests showed that the fresh and degraded synthetic MSW exhibited continuous strength gain with increase in horizontal deformation, with the cohesion increased from 1 kPa for fresh MSW to 16–40 kPa for degraded MSW and the friction angle decreased from 35° for fresh MSW to 28° for degraded MSW. During the triaxial tests under CU condition, the total strength parameters, cohesion and friction angle, were found to vary from 21 to 57 kPa and 1° to 9°, respectively, while the effective strength parameters, cohesion and friction angle varied from 18 to 56 kPa and from 1° to 11°, respectively. Similar to direct shear test results, as the waste degrades an increase in cohesion and slight decrease in friction angle was observed. Decreased friction angle and increased cohesion with increased degradation is believed to be due to the highly cohesive nature of the synthetic MSW. Variation of synthetic MSW properties from this study also suggests that significant changes in geotechnical properties of MSW can occur due to enhanced degradation induced by leachate recirculation.     

Pesticide pressure and fish farming in barrage pond in Northeastern France Part I: site characterization and water quality

Purpose

Fish farming in barrage pond is a rearing system commonly used worldwide. Obtaining good water quality is essential to improve sustainability of these ecosystems, both for health of fish consumers and environmental considerations. However, ponds are often located in agricultural landscape, but few study reports impact of pesticide pressure on these ecosystems. This study characterizes five sites in Northeastern France. This work establishes an initial framework for pesticide monitoring with the aim to improve understanding of the fate of pesticides in ponds.

Methods

This framework is based on surveys indicating managements and Geographical Information System (GIS) for five ponds and their watersheds (sites: C-0, C-25, C-45, C-75 and C-85) and completes with some analysis of a large spectrum of pesticide residues in surface waters.

Results

Watersheds show a gradient of crop proportion ranging from 0% to 82% of the watershed area, mainly rapeseed, wheat, barley and maize. Ponds were representative of local Northeastern France management. Many pesticides, and also nutrients, were measured in water with concentrations varying between sites and seasons. The sum of quantified molecules ranged from 0.17 ??g/l for site C-0 (March) to 8.81 ??g/l for site C-25 (October). Concentrations of metaldehyde, quinmerac, isoproturon and bentazon were sometimes above 1 ??g/l.

Conclusions

There is a strong connection between pond and watershed, due to water supply throughout the fish production cycle. Sites with small pond/big watershed are the most exposed to acute contamination a few days after spraying because water discharges are not diluted.     

Source apportionment of urban fine and ultra-fine particle number concentration in a Western Mediterranean city

Extensive measurements on particle number concentration and size distribution (13–800 nm), together with detailed chemical composition of PM_2.5 have constituted the main inputs of the database used for a source apportionment analysis. Data were collected at an urban background site in Barcelona, Western Mediterranean.The source identification analysis helped us to distinguish five emission sources (vehicle exhausts, mineral dust, sea spray, industrial source and fuel-oil combustion) and two atmospheric processes (photochemical induced nucleation and regional/urban background particles derived from coagulation and condensation processes). After that, a multilinear regression analysis was applied in order to quantify the contribution of each factor.This study reveals that vehicle exhausts contribute dominantly to the number concentration in all the particle sizes (52–86%), but especially in the range 30–200 nm. This work also points out the importance of the regional and/or urban formed aerosols (secondary inorganic particles) on the total number concentration (around 25% of the total number), with a higher impact on the accumulation mode. The photo-chemically induced nucleation of aerosols only represents a small proportion of the total number as an annual mean (3%), but is very relevant when considering only the nucleation mode (13–20 nm) fraction (23%). The other sources recognized registered sporadic contributions to the total number, coinciding with specific meteorological scenarios.This study discloses the main sources and features affecting and controlling the fine and ultra-fine aerosols in a typical city in the Western Mediterranean coast. Whereas the road traffic appears to be the most important source of sub-micrometric aerosols, other sources may not be negligible under specific meteorological conditions.     

Climate change in Algeria and its impact on durum wheat

According to IPCC reports, the Mediterranean basin and particularly the North African area are amongst the most vulnerable regions to climate change. However, the information concerning the North African zone is very limited, and studies on climate change have never been conducted in Algeria up to now. This paper aims at bridging this information gap and initiates a first research on the impact of climate change on durum wheat cropping, the most strategic commodity in the food system and in the national economy of Algeria. Climate projections for the distant future (2071–2100), obtained from the ARPEGE-Climate model of Météo-France run under the medium A1B SRES scenario, are introduced into a simple agrometeorological crop model previously validated with field data. Two options for the sowing date are assessed: a dynamical date, chosen within the traditional sowing window by means of a rainfall criterion, or a prescribed date with supplemental irrigation on the same day. Crop development is modelled using thermal time, and maximum yield is determined from the accumulation of solar radiation. A water stress index is inferred from a daily water balance model, and actual yield is estimated from potential yield corrected by the water stress index. The model also takes into account the occurrence of dry periods during the growing season, which can induce partial or total failure of the crop cycle. Two stations, representative of two of the three agroclimatic areas where durum wheat is grown, were chosen: Algiers in the central northern region and Bordj Bou Arreridj in the eastern high plains. Climate change is not similar for both areas, but a tendency towards aridity is clear especially in spring. Future temperature and potential evapotranspiration increase in both regions with a maximum in spring and summer. In Algiers, rainfall will decrease throughout the year and mainly in spring and summer. Conversely, summer precipitation in Bordj Bou Arreridj will increase significantly. In both regions, the autumn rains will increase in the future climate, the possibilities of early sowing will be improved, crop cycle will be reduced, and harvest will take place earlier. In Algiers, yields tend to decrease in the future climate, whereas in Bordj Bou Arreridj, a dynamical (earlier) sowing will tend to keep yields at their current level.     

Analyzing the hydrologic effects of region-wide land and water development interventions: a case study of the Upper Blue Nile basin

In the drylands of the Upper Blue Nile basin, high climate variability and land degradation are rampant. To enhance adaptive capacity in the region, various soil and water conservation interventions have been implemented. Moreover, water resources development schemes such as the Grand Ethiopian Renaissance Dam should be implemented by 2025. We modeled the effects of these interventions on surface runoff in the basin for both current and future (2025) basin conditions, using the runoff coefficient method in a spatially explicit approach. Under current conditions, we observed high spatial variability of mean annual runoff. The northeastern Blue Nile-1 sub-basin produces the highest mean annual runoff (391 mm or 10 × 10⁹ m³), whereas the northwestern Blue Nile-2 sub-basin produces the lowest mean annual runoff (178 mm or 0.2 × 10⁹ m³). The basin generates a total annual runoff volume of 47.7 × 10⁹ m³, of which about 54 % comes from cultivated land. The strong association between land use and topography masked the direct effect of rainfall on runoff. By 2025, total annual runoff yield could decrease by up to 38 % if appropriate basin-wide soil and water conservation interventions and the Grand Ethiopian Renaissance Dam are implemented. However, the full effects of most physical structures will only last for 1 or 2 years without regular maintenance. The improved understanding of the dynamics of the Upper Blue Nile basin’s hydrology provided by the present study will help planners to design appropriate management scenarios. Developing the basin’s database remains important for a holistic understanding of the impacts of future development interventions.