Scaling up the electrokinetic-assisted phytoremediation of atrazine-polluted soils using reversal of electrode polarity: A mesocosm study.

Electrokinetic-assisted phytoremediation (EKPR) has been recently proposed for the removal of pesticides from polluted soils. In this work, we report the results from an EKPR experiment that was carried out in a mesocosm mock-up of 0.386 m3 using ryegrass (Lolium perenne L.) and a low permeability soil spiked with atrazine. Plants were initially grown for 35 days; then, the soil was spiked with atrazine at a dose of 2 mg kg-1 soil. A DC electrical field of 0.6 V cm-1 was applied 24 h every day, switching polarity daily. Another identical mock-up with the same experimental conditions but without plants was used for comparison purposes. The duration of the EKPR test was 19 days during which some operational parameters were registered (electric current intensity, soil pH and temperature) and soil porewater samples were taken and analysed. Plant tissues and soil samples from the different sections in which the mock-ups were divided, were also collected and analysed at the end of the experiment. 3-D profiles of soil pH, water content and atrazine residues concentration in plants and soil were obtained and discussed. The results of this experiment were compared with others previously reported by us from a similar EKPR pot test. In spite of the difficulties to get an adequate geometric and operational similarity between setups of different scale, the main output parameters of the EKPR process (electric current, specific current charge, overall atrazine removal, specific atrazine removal efficiency, root biomass:soil weight ratio) were discussed. It was shown that, although the processes carried out are essentially the same in both scales, their extent may be quite different; it highlights the limitations of small-scale experiments to predict the results at field conditions.

Enhancing the removal of atrazine from soils by electrokinetic-assisted phytoremediation using ryegrass (Lolium perenne L.).

Atrazine (ATR) continues being one of the most frequently detected pesticides in natural waters and soils. In this work, an electrokinetic-assisted phytoremediation pot test (EKPR) was performed for the remediation of an atrazine-spiked soil; a low electric voltage gradient (1 V cm-1) with two different electric field operation times (6 and 24 h per day) was used in combination with ryegrass (Lolium perenne L.). EKPR increased up to 27% and 7% the overall ATR removal from soil as compared to natural attenuation and phytoremediation treatments, respectively. ATR soil concentration vs time curves were fitted to a pseudofirst-order kinetic equation, obtaining ATR half-life values of 8.2, 7.1 and 5.4 days for the treatments corresponding, respectively, to 0, 6 and 24 h day-1 of electric current application. It clearly showed that the ATR removal from soils was enhanced by the electric field. ATR plant accumulation was significantly improved with respect to phytoremediation when the electric current was continuously applied throughout the experiment (24 h day-1); most of the ATR residues were accumulated in the shoot biomass of the ryegrass plants.

Can electrochemistry enhance the removal of organic pollutants by phytoremediation?

An electrokinetic-assisted phytoremediation test using maize (Zea mays L.) was conducted in order to assess the role of the electric field on the enhancement of plant uptake and degradation of the moderate polar pesticide atrazine in spiked soils. Twelve different treatments, including two different initial atrazine soil doses (5 and 10 mg kg-1) and two different values of the electric field applied (2 and 4 V cm-1), together with the corresponding control treatments without plants and/or without electric current, were tested. The application of an electric field during a period of 4 h a day and with periodical polarity inversion (each 2 h) did not caused significant changes in soil pH; moreover, maize plants increased the buffering capacity of the soil. The application of an electric field of 2 V cm-1 led to a slight decrease on maize biomass while the accumulation of atrazine and its main metabolites in plant tissues was significantly enhanced. On the overall, the yield of atrazine removal by electrokinetic-assisted phytoremediation with maize was increased up to 36.5% with respect to the phytoremediation process without electricity. On our knowledge, this work is the first one specifically focused on the removal of organic pollutants from soils by using the combination of phytoremediation and electrokinetic remediation.

Performance of waste-based amendments to reduce metal release from mine tailings: One-year leaching behaviour.

A one-year leaching experiment has been conducted in order to assess the effectiveness of several amendments on metal immobilization in mine tailings from an old Pb/Zn mining area of Central Spain (San Quintín mine). Demineralized water was used as leaching solution, selecting doses equivalent to the annual rainfall conditions of the studied area. Columns with mine tailings without any amendment and others treated with 10% of sugar foam (SF), 15% of drinking water treatment sludge (DWS), 30% of paper mill sludge (PMS) and 15% of olive mill waste (OMW) were used. SF, DWS and PMS amendments increased the pH of leachates from values of approximately 4 to around neutrality. Additionally, the release of sulfate ions from the oxidation of pyritic residues was decreased in some extent by SF and DWS amendments. Metal leaching was effectively reduced by the amendments reaching overall decreases with respect to the unamended columns of 79-96% for Pb, 36-100% for Zn, 50-99% for Cu and 44-100% for Cd. The effect of the amendments in leachate pH, sulfate concentration and metal release from mine tailings was kept throughout the whole experimental period. Our results showed that the application of different organic and inorganic amendments based on by-products and waste materials may be a feasible alternative for the restoration of soils around abandoned metal mines.

Assessing the phytoremediation potential of crop and grass plants for atrazine-spiked soils.

Pollution of soil and groundwater by atrazine has become an increasing environmental concern in the last decade. A phytoremediation test using plastic pots was conducted in order to assess the ability of several crops and grasses to remove atrazine from a soil of low permeability spiked with this herbicide. Four plant species were assessed for their ability to degrade or accumulate atrazine from soils: two grasses, i.e., ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea), and two crops, i.e., barley (Hordeum vulgare) and maize (Zea mays). Three different doses of atrazine were used for the contamination of the pots: 2, 5 and 10 mg kg-1. 16 days after spiking, the initial amount of atrazine was reduced by 88.6-99.6% in planted pots, while a decrease of only 63.1-78.2% was found for the unplanted pots, thus showing the contribution of plants to soil decontamination. All the plant species were capable of accumulating atrazine and its N-dealkylated metabolites, i.e., deethylatrazine and deisopropylatrazine, in their tissues. Some toxic responses, such as biomass decreases and/or chlorosis, were observed in plants to a greater or lesser extent for initial soil doses of atrazine above 2 mg kg-1. Maize was the plant species with the highest ability to accumulate atrazine derivatives, reaching up to 38.4% of the initial atrazine added to the soil. Rhizosphere degradation/mineralization by microorganisms or plant enzymes, together with degradation inside the plants, have been proposed as the mechanisms that contributed to a higher extent than plant accumulation to explain the removal of atrazine from soils.

Chemical and plant tests to assess the viability of amendments to reduce metal availability in mine soils and tailings.

The goal of this research was to assess the potential of several industrial wastes to immobilise metals in two polluted soils deriving from an old Pb/Zn mine. Two different approaches were used to assess the performance of different amendments: a chemical one, using extraction by ethylenediaminetetraacetic acid (EDTA), and a biological one, using Lupinus albus as a bio-indicator. Four amendments were used: inorganic sugar production waste (named 'sugar foam', SF), sludge from a drinking water treatment sludge (DWS), organic waste from olive mill waste (OMW) and paper mill sludge (PMS). Amendment to soil ratios ranged from 0.1 to 0.3 (w/w). All the amendments were capable of significantly decreasing (p < 0.05) EDTA-extractable Pb, Zn and Cu concentrations in the two soils used, with decreases in ranges 21-100, 25-100 and 2-100 % for Pb, Zn and Cu, respectively. The amendments tested were also effective in reducing the bioavailability of Pb and Zn for L. albus, which gave rise to a decrease in shoot metal accumulation by the lupine plants compared to that found in the control soil. That decrease reached up to 5.6 and 2.8 times for Pb and Zn, respectively, being statistically significant in most cases. Moreover, application of the OMW, DWS and SF amendments led to higher average values of plant biomass (up to 71%) than those obtained in the control soil. The results obtained showed the technology put forward to be a viable means of remediating mine soils as it led to a decrease in the availability and toxicity of metals and, thus, facilitated the growth of a vegetation layer.

Postoperative Discomfort After Abdominal Surgery: An Observational Study.

PURPOSE: Patients who have surgery may experience distress in the following days. Although postoperative distress is a common experience, few studies have analyzed these patient complaints in-depth. The purpose of the present study was to analyze the potential causes of patients' discomfort after abdominal surgery. DESIGN: This was a prospective and observational study. METHODS: Patients (N = 131) were asked to rate their discomfort twice using a list of nine items in the first 6 to 8 hours after surgery and at 24 hours after its completion. Participants were asked to score intensity from 0 (absent) to 10 (unbearable). FINDINGS: The main causes of discomfort at 24 hours were pain (82%), movement restriction (79%), and dry mouth (70%). These items also had the highest scores (by gender, women scored higher than did men in insomnia, dry mouth, and abdominal distension). No significant differences were observed between patients who had undergone open or laparoscopic surgery. CONCLUSION: It was concluded that pain, movement restriction, and dry mouth were the most disturbing causes of discomfort. Therefore, symptoms other than pain should be considered to improve the well-being of patients after abdominal surgery.

Effectiveness of problem-solving technique in caring for family caregivers: a clinical trial study in an urban area of Catalonia (Spain).

AIMS AND OBJECTIVES: To evaluate the effectiveness of the problem-solving technique in reducing symptoms of anxiety and depression among primary caregivers and to describe and evaluate the process carried out by nurses to find strengths and areas of improvement. BACKGROUND: In Spain, home care for the chronically ill patients and their family caregivers should be a priority in health and social policies due to the increase in ageing population and the progressive increase in dependent individuals. One of the areas involved is home-based nursing and counselling for family caregivers. DESIGN: This is a clinical trial study (during 2007-2011) with a mixed analysis methodology. METHODS: Quantitative analysis was used to evaluate the effectiveness of the problem-solving technique in reducing symptoms of anxiety and depression. The clinical trial involved a control and experimental group and pre-post intervention measurements, using the Goldberg Scale. The practical application of the technique was evaluated by qualitative analysis. RESULTS: There was a statistically significant improvement in symptoms of anxiety and depression in the intervention group after application of the technique. Positive aspects and resistance factors in its implementation were noted. CONCLUSIONS: The problem-solving technique is a cost-effective intervention for reducing symptoms of anxiety and depression in family caregivers of the chronically ill patients. Positive aspects of the technique were satisfaction of the caregiver and nurse, and work done together based on reflection. Resistance factors identified were difficulty in maintaining written records and subjective perception of a lack of time in everyday practice for its consistent application. RELEVANCE TO CLINICAL PRACTICE: The problem-solving technique is an important tool to reduce the suffering of family caregivers of chronically ill patients and a prevention element of family claudication.

[Care for a family carer in Primary Care using the uncertainty theory]. / Cuidar a una cuidadora familiar en Atención Primaria a partir de la teoría de la incertidumbre.

This case discussion starts from the Uncertainty Theory of illness of Merle Mishel, who raised the idea that even without a solution to the uncertainty, a person should accept it as a part of their life and reinterpret it as an opportunity to promote a new view of life governed by probability. The author proposes theoretical concepts that allow the phenomena experienced by family caregivers to be approached from the perspective of their experiences and stress. It establishes uncertainty and indecisiveness as contradictions that should not create anxiety permanently. This can be released gradually, if we create lines of flight though the care. Among these lines are located the Problem Solving Method as a strategy useful in primary health care to reduce the uncertainty of the caregivers. This article describes the outcome of Isabel, a 63- year-old female family caregiver of her dependent mother and her daughter with anorexia. The primary care nurse identifies the problem of weariness of the care-givers role and that of conflict of decisions during home visits. It describes the assessment made from the main concepts of the theory and the work with the care-givers by the problem solving method in order to reduce anxiety and help to mobilize internal resources and increase their welfare.