Contaminant Retention Potential of Forested Filter Strips Established as SMZs in the Piedmont of Georgia1

Abstract: It is common practice in the United States and elsewhere to maintain vegetated filter strips adjacent to streams to retain contaminants in surface runoff. Most research has evaluated contaminant retention in managed agricultural field strips, while relatively few studies have quantified retention in forested filter strips, particularly for dissolved contaminants. Plot‐scale overland flow experiments were conducted to evaluate the efficiency of natural forested filter strips established as streamside management zones (SMZs) for retaining phosphorus (P), atrazine, and picloram transported in runoff. Retention was evaluated for five different slope classes: 1‐2, 5‐7, 10‐12, 15‐17, and 20‐22%; two cover conditions: undisturbed forest floor (O horizon intact) and forest floor removed by raking; and two periods with contrasting soil moisture conditions: summer‐dry and winter‐wet season. Surface flow was collected at 0, 2, 4, 6, and 10 m within the filter strip to evaluate changes in solution concentration as it moved through the O horizon and the surface soil horizon mixing zone. On average, a 10 m length of forested SMZ with an undisturbed forest floor reduced initial solution concentration of total dissolved P by 51%, orthophosphate P by 49%, atrazine by 28%, and picloram by 5%. Percentages of mass retention through infiltration of water plus concentration reductions in runoff were 64% for total dissolved P, 62% for orthophosphate P, 47% for atrazine, and 28% for picloram for undisturbed forest floor conditions. Lower retention occurred following forest floor removal, particularly for P. Average dissolved P retention was 16% lower following forest floor removal. For undisturbed sites, differences in retention were more closely related to forest floor depth than to slope or antecedent soil moisture. These results indicate that forested SMZ filter strips provide a significant measure of surface water protection from dissolved P and herbicide delivery to surface water.     

Effects of copper deficiency and copper toxicity on organogenesis and some physiological and biochemical responses of Scots pine (Pinus sylvestris L.) seedlings grown in hydroculture

The morphological, physiological, and biochemical parameters of 6-week-old seedlings of Scots pine (Pinus sylvestris L.) were studied under deficiency (1.2 nM) and chronic exposure to copper (0.32, 1, 2.5, 5, and 10 μM CuSO₄) in hydroculture. The deposit of copper in the seed allowed the seedlings to develop under copper deficiency without visible disruption of growth. The high sensitivity of Scots pine to the toxic effects of copper was shown, which manifested as a significant inhibition of growth and development. The loss of dominance of the main root and a strong inhibition of lateral root development pointed to a lack of adaptive reorganization of the root system architecture under copper excess. A preferential accumulation of copper in the root and a minor translocation in aerial organs confirmed that Scots pine belongs to a group of plants that exclude copper. Selective impairment in the absorption of manganese was discovered, under both deficiency and excess of copper in the nutrient solution, which was independent of the degree of development of the root system. Following 10 μM CuSO₄ exposure, the absorption of manganese and iron from the nutrient solution was completely suppressed, and the development of seedlings was secured by the stock of these micronutrients in the seed. The absence of signs of oxidative stress in the seedling organs was shown under deficiency and excess of copper, as evidenced by the steady content of malondialdehyde and 4-hydroxyalkenals. Against this background, no changes in total superoxide dismutase activity in the organs of seedlings were revealed, and the increased content of low-molecular-weight antioxidants was observed in the roots under 1 μM and in the needles under 5 μM CuSO₄ exposures.

     

Wildfire,climate, and perceptions in Northeast Oregon

Regional Environmental Change - Wildfire poses a rising threat in the western USA, fueled by synergies between historical fire suppression, changing land use, insects and disease, and shifts toward...     

Managing water services in tropical regions: From land cover proxies to hydrologic fluxes

Watershed investment programs frequently use land cover as a proxy for water-based ecosystem services, an approach based on assumed relationships between land cover and hydrologic outcomes. Water flows are rarely quantified, and unanticipated results are common, suggesting land cover alone is not a reliable proxy for water services. We argue that managing key hydrologic fluxes at the site of intervention is more effective than promoting particular land-cover types. Moving beyond land cover proxies to a focus on hydrologic fluxes requires that programs (1) identify the specific water service of interest and associated hydrologic flux; (2) account for structural and ecological characteristics of the relevant land cover; and, (3) determine key mediators of the target hydrologic flux. Using examples from the tropics, we illustrate how this conceptual framework can clarify interventions with a higher probability of delivering desired water services than with land cover as a proxy.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0578-8) contains supplementary material, which is available to authorized users.     

Phragmites sp. physiological changes in a constructed wetland treating an effluent contaminated with a diazo dye (DR81)

The role of Phragmites sp. in phytoremediation of wastewaters containing azo dyes is still, in many ways, at its initial stage of investigation. This plant response to the long-term exposure to a highly conjugated di-azo dye (Direct Red 81, DR81) was assessed using a vertical flow constructed wetland, at pilot scale. A reed bed fed with water was used as control. Changes in photosynthetic pigment content in response to the plant contact with synthetic DR81 effluent highlight Phragmites plasticity. Phragmites leaf enzymatic system responded rapidly to the stress imposed; in general, within 1 day, the up-regulation of foliar reactive oxygen species-scavenging enzymes (especially superoxide dismutase, ascorbate peroxidase (APX), glutathione peroxidase (GPX) and peroxidase) was noticed as plants entered in contact with synthetic DR81 effluent. This prompt activation decreased the endogenous levels of H₂O₂ and the malonyldialdehyde content beyond reference values. Glutathione S-transferase (GST) activity intensification was not enough to cope with stress imposed by DR81. GPX activity was pivotal for the detoxification pathways after a 24-h exposure. Carotenoid pool was depleted during this shock. After the imposed DR81 stress, plants were harvested. In the next vegetative cycle, Phragmites had already recovered from the chemical stress. Principal component analysis (PCA) highlights the role of GPX, GST, APX, and carotenoids along catalase (CAT) in the detoxification process.     

A national reconnaissance for selected organic micropollutants in sediments on French territory

To collect a large data set regarding the occurrence of organic substances in sediment, this study presents the examination of 20 micropollutants, as a national survey. The list of target compounds contains two alkylphenols, three polycyclic aromatic hydrocarbons (PAHs) not commonly included in monitoring programmes, six pesticides or metabolites, five pharmaceutical compounds, two hormones, one UV filter and bisphenol A. The selective and sensitive analytical methods, based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) or gas chromatography-time-of-flight mass spectrometry (GC-ToF-MS), allow the quantification at limits comprised between 0.5 and 23 ng/g, depending on the compound. The paper summarizes the analytical results from 154 sampling points. Of the 20 target compounds, 9 were determined at least once, and the sediments contained a maximum of 7 substances. The most frequently detected were PAHs (frequency, 77 %; max., 1,400 ng/g). The pharmaceutical compounds, hormones and pesticides were rarely detected in the samples; the most frequently detected was carbamazepine (frequency, 6 %; max., 31 ng/g). In some cases, the levels of PAHs and bisphenol A exceed the predicted no-effect concentration (PNEC) values.     

Silver behaviour along the salinity gradient of the Gironde Estuary

Dissolved and particulate Ag concentrations (Ag_D and Ag_P, respectively) were measured in surface water and suspended particulate matter (SPM) along the salinity gradient of the Gironde Estuary, South West France, during three cruises (2008–2009) covering contrasting hydrological conditions, i.e. two cruises during intermediate and one during high freshwater discharge (~740 and ~2,300 m³/s). Silver distribution reflected non-conservative behaviour with 60–70 % of Ag_P in freshwater particles being desorbed by chlorocomplexation. The amount of Ag_P desorbed was similar to the so-called reactive, potentially bioavailable Ag_P fraction (60?±?4 %) extracted from river SPM by 1 M HCl. Both Ag_P (0.22?±?0.05 mg/kg) and Ag_P/Th_P (0.025–0.028) in the residual fraction of fluvial and estuarine SPM were similar to those in SPM from the estuary mouth and in coastal sediments from the shelf off the Gironde Estuary, indicating that chlorocomplexation desorbs the reactive Ag_P. The data show that desorption of reactive Ag_P mainly occurs inside the estuary during low and intermediate discharge, whereas expulsion of partially Ag_P-depleted SPM (Ag_P/Th_P ~0.040) during the flood implies ongoing desorption in the coastal ocean, e.g. in the nearby oyster production areas (Marennes-Oléron Bay). The highest Ag_D levels (6–8 ng/L) occurred in the mid-salinity range (15–20) of the Gironde Estuary and were decoupled from freshwater discharge. In the maximum turbidity zone, Ag_D were at minimum, showing that high SPM concentrations (a) induce Ag_D adsorption in estuarine freshwater and (b) counterbalance Ag_P desorption in the low salinity range (1–3). Accordingly, Ag behaviour in turbid estuaries appears to be controlled by the balance between salinity and SPM levels. The first estimates of daily Ag_D net fluxes for the Gironde Estuary (Boyle’s method) showed relatively stable theoretical Ag_D at zero salinity (Ag _D ⁰ = 25–30 ng/L) for the contrasting hydrological situations. Accordingly, Ag_D net fluxes were very similar for the situations with intermediate discharge (1.7 and 1.6 g/day) and clearly higher during the flood (5.0 g/day) despite incomplete desorption. Applying Ag _D ⁰ to the annual freshwater inputs provided an annual net Ag_D flux (0.64–0.89 t/year in 2008 and 0.56–0.77 t/year in 2009) that was 12–50 times greater than the Ag_D gross flux. This estimate was consistent with net Ag_D flux estimates obtained from gross Ag_P flux considering 60 % desorption in the estuarine salinity gradient.     

Electrokinetic remediation of organochlorines in soil: enhancement techniques and integration with other remediation technologies

Electrokinetic remediation has been increasingly used in soils and other matrices for numerous contaminants such as inorganic, organic, radionuclides, explosives and their mixtures. Several strategies were tested to improve this technology effectiveness, namely techniques to solubilize contaminants, control soil pH and also couple electrokinetics with other remediation technologies. This review focus in the experimental work carried out in organochlorines soil electroremediation, aiming to systemize useful information to researchers in this field. It is not possible to clearly state what technique is the best, since experimental approaches and targeted contaminants are different. Further research is needed in the application of some of the reviewed techniques. Also a number of technical and environmental issues will require evaluation for full-scale application. Removal efficiencies reported in real contaminated soils are much lower than the ones obtained with spiked kaolinite, showing the influence of other factors like aging of the contamination and adsorption to soil particles, resulting in important challenges when transferring technologies into the field.     

Savviness of prey to introduced predators

The prey naivety hypothesis posits that prey are vulnerable to introduced predators because many generations in slow gradual coevolution are needed for appropriate avoidance responses to develop. It predicts that prey will be more responsive to native than introduced predators and less responsive to introduced predators that differ substantially from native predators and from those newly established. To test these predictions, we conducted a global meta-analysis of studies that measured the wariness responses of small mammals to the scent of sympatric mammalian mesopredators. We identified 26 studies that met our selection criteria. These studies comprised 134 experiments reporting on the responses of 36 small mammal species to the scent of six introduced mesopredators and 12 native mesopredators. For each introduced mesopredator, we measured their phylogenetic and functional distance to local native mesopredators and the number of years sympatric with their prey. We used predator and prey body mass as a measure of predation risk. Globally, small mammals were similarly wary of the scent of native and introduced mesopredators; phylogenetic and functional distance between introduced mesopredators and closest native mesopredators had no effect on wariness; and wariness was unrelated to the number of prey generations, or years, since first contact with introduced mesopredators. Small mammal wariness was associated with predator-prey body mass ratio, regardless of the nativity. The one thing animals do not seem to recognize is whether their predators are native.     

EMAP Design and River Reach File 3 (RF3) as a Sample Frame in the Central Valley, California

The Central Valley, California, R-EMAP project assessed the effects of highly modified, agriculturally dominated landuse on the aquatic resources of the lower portion of the Central Valley watersheds. The focus of this paper is to assess the utility of the EMAP design and the River Reach File version 3 (RF3) 1:100,000 scale Digital Line Graph (DLG) as a sampling frame. The study area is 34,099 mi²(88,316 km²) and comprises the lower reaches of the Sacramento River and San Joaquin River watersheds to the 1000 ft. (305 m) elevation. Sampling sites are selected using a tessellation stratified design to represent the two main populations of interest: natural streams and man-made waterways. Sites are selected to represent 13,226 miles of streams and sloughs, and 14,648 miles of irrigation canals, ditches and drains. To achieve an approximately equal sample size across stream orders and basins, the sample design was weighted by Strahler order categories to ensure sampling occurred in the higher order streams. Based on office and field reconnaissance, the study provided information on the quality of RF3 as a sampling frame. Site selection using RF3 had a success rate of approximately 44%. The RF3 database has an error rate of approximately 7%. When human influence factors were included, the error rate increased to 16%. There was an 11% error rate when selecting sites for natural streams, and approximately a 14% error rate for man-made waterways. The reconnaissance information indicated that presence or absence of irrigation ditches and return drains depends on changing agricultural uses. Some of the error in the RF3 for natural streams and man-made waterways can be attributed to rapid urban expansion, especially in the San Joaquin basin.