Persulfate activation with biochar supported nanoscale zero- valent iron: Engineering application for effective degradation of NCB in soil.

Nitrochlorobenzene (NCB) is very common in pesticide and chemical industries, which has become a major problem in soil environment. However, the remediation of NCB contaminated soil is received finite concern. Using biochar as a substrate for nanoscale-zero valent iron (nZVI/p-BC) to activate peroxodisulfate (PDS), a novel heterogeneous oxidative system had been applied in the current study to remediate NCB contaminants in soil. The degradation efficiencies and kinetics of m-NCB, p-NCB, and o-NCB by various systems were contrasted in soil slurry. Key factors including the dosage of nZVI/p-BC, the molar ratio of nZVI/PDS, initial pH and temperature on degradation of NCB were further examined. The results confirmed that the nZVI/p-BC/PDS displayed the remarkable performance for removing NCB compared with other systems. Higher temperature with nZVI/PDS molar ratio of 2:1 under the acidic condition favored the reduction of NCB. The treatment for NCB with optimal conditions were evaluated for the engineering application. The mechanism of nZVI/p-BC/PDS indicated that electron transfer between p-BC and nZVI was responsible for activation of PDS, generating active species (SO4•-, •OH and 1O2) via both the free and non-free radical pathways. Experimental results revealed prominent availability of nZVI/p-BC/PDS system in remediation of actual contaminated field by NCB.

Tracking the transformation of persistent organic pollutants in food webs using multi element isotope and enantiomer fractionation.

In order to track the transformation of persistent organic pollutants (POPs) in food webs, field experiments were conducted at two sites using stable isotope and enantiomer fractionation concepts. The enantiomers of α-hexachlorocyclohexane (α-HCH) were selected as representative compounds for POPs. Isotope and enantiomer fractionation allowed the characterization of α-HCH enantiomer biotransformation processes along trophic levels of the food web - from soil and plants to animal livers, fat tissues and milk. The enrichment of heavy isotopes in soils, plants and sediments as well as the changes of enantiomer fractionation indicate that the biotransformation of α-HCH occurred in these compartments. Moreover, the increase of carbon and chlorine isotopic compositions as well as the changes of enantiomer fractionation of liver, fat tissues and milk demonstrated that the overall HCH exposure was much higher than estimates based on concentration levels, while the isotope and enantiomer fractionation revealed the enantiomer specific enantiomer uptake across the blood-brain barriers. Dual element isotope analysis suggested that complex transformation processes have occurred along the potential food web from the HCH sources over different environmental compartments to animal livers, fat tissues and milk. The results imply that the analyses of stable isotope compositions and concentrations has potential to reconstruct the exposure of higher organisms to POPs.

Uptake and Metabolization of HCH Isomers in Trees Examined over an Annual Growth Period by Compound-Specific Isotope Analysis and Enantiomer Fractionation.

To understand the role of plants for natural attenuation, a field study was conducted to characterize the fate of HCH in trees over an annual growth period using compound-specific isotope analysis and enantiomer fractionation. Stable and slightly higher δ13C and δ37Cl values of HCH of host soil samples compared to the muck (consisting nearly exclusively of HCH) revealed that masking isotope effects caused by the limited bioavailability may underestimate the real extent of HCH transformation in soil. In contrast, an increase of δ13C and δ37Cl values in trees indicated the transformation of HCH. A large variability of δ13C and δ37Cl values in trees over the growth period was observed, representing different transformation extents among different growth times, which is further supported by the shift of the enantiomer fraction (EF), indicating the preferential transformation of enantiomers also varied over the different growth periods. Based on dual-element isotope analysis, different predominant transformation mechanisms were observed during the growing seasons. Our observation implies that plants are acting as biological pumps driving a cycle of uptake and metabolization of HCH and refeed during littering to soil catalyzing their transformation. The changes of the transformation mechanism in different seasons have implications for phytoscreening and shed new light on phytoremediation of HCH at field sites.

Synthetic Mesh in Contaminated Abdominal Wall Surgery: Friend or Foe? A Literature Review.

INTRODUCTION: The use of synthetic mesh in contaminated fields is controversial. In the last decade, published data have grown in this matter suggesting favorable outcomes. However, multiple variables and scenarios that influence the results still make difficult to obtain convincing recommendations. METHODS: We performed a review of relevant available data in English regarding the use of synthetic meshes in contaminated abdominal wall surgery using the Medline database. Articles including patients undergoing ventral hernia in contaminated fields were included for analysis. RESULTS: Most studies support the use of synthetic meshes for ventral hernia repair in contaminated fields, as they have shown lower recurrence rate and similar wound morbidity. Although no mesh seems ideal in this setting, most surgeons advocate for the use of reduced-in-weight polypropylene mesh. Sublay location of the prosthesis associated with complete fascial closure appears to offer better results in these patients. In addition, current evidence suggests that the use of prophylactic synthetic mesh when performing a stoma or for stoma reversal incisional hernias might be beneficial. CONCLUSION: A better understanding of surgical site occurrences and its prevention, as well as the introduction of new reduced-in-weight meshes have allowed using synthetic meshes in a contaminated field. Although the use of mesh has indeed shown promising results in these patients, the surgical team should still balance pros and cons at the time of placing synthetics in contaminated fields.

Soil from a Hexachlorocyclohexane Contaminated Field Site Inoculates Wheat in a Pot Experiment to Facilitate the Microbial Transformation of ß-Hexachlorocyclohexane Examined by Compound-Specific Isotope Analysis.

ß-Hexachlorocyclohexane (ß-HCH) is a remnant from former HCH pesticide production. Its removal from the environment gained attention in the last few years since it is the most stable HCH isomer. However, knowledge about the transformation of ß-HCH in soil-plant systems is still limited. Therefore, experiments with a contaminated field soil were conducted to investigate the transformation of ß-HCH in soil-plant systems by compound specific isotope analysis (CSIA). The results showed that the δ13C and δ37Cl values of ß-HCH in the soil of the planted control remained stable, revealing no transformation due to a low bioavailability. Remarkably, an increase of the δ13C and δ37Cl values in soil and plant tissues of the spiked treatments were observed, indicating the transformation of ß-HCH in both the soil and the plant. This was surprising as previously it was shown that wheat is unable to transform ß-HCH when growing in hydroponic culture or garden soil. Thus, results of this work indicate for the first time that a microbial community of the soil inoculated the wheat and then facilitated the transformation of ß-HCH in the wheat, which may have implications for the development of phytoremediation concepts. A high abundance of HCH degraders belonging to Sphingomonas sp., Mycobacterium sp., and others was detected in the ß-HCH-treated bulk and rhizosphere soil, potentially supporting the biotransformation.

Effects of straw return with N fertilizer reduction on crop yield, plant diseases and pests and potential heavy metal risk in a Chinese rice paddy: A field study of 2 consecutive wheat-rice cycles.

Understanding the comprehensive effect on crop production and quality, soil acidification, and Cd accumulation and distribution for wheat-rice rotation under N fertilization and continuous straw return is important for proper contaminated agricultural soil management. A 2-year paddy field experiment was conducted to study the effects of above factors change in the Zhejiang province, China. Fertilization treatments included: conventional N fertilizer application (N3), 20% reduction of N application (N2), 40% reduction of N application (N1), combined with three portions of straw incorporation: all straws retention (N3), half of the straws into the fields (S2), 20% straws retention(S1). The N1 treatments significantly decreased crop yields compared to N2 and N3 treatments. Except for C2-wheat, soil pH generally decreased with increasing N fertilizer input in the order of N1>N2>N3, regardless of how many straws was amended. Moreover, we found that straw addition plus N fertilization had a intersystem impacts on Cd accumulation, distribution and availability. Although total Cd had different trends among 4 experimental seasons, when the N reduced 20% applied, the DTPA-Cd contents were lowest among 3 out of four experimental seasons, except for that of C2-wheat, where N2 treatments ranked the second lower contents. For most seasons, Cd contents in straws were higher than soils and lowest in grains, and S2N2 treatment performed an intermediate value among all treatments. Furthermore, our study demonstrated that S2 or N2 treatments or S2N2 reduced the potential risk of plant diseases and pests with lower disease index, disease cluster rate. Notably, the relative outbreak of pests was remarkably suppressed under S2 treatments, especially S2N2. Thus, these findings demonstrated that in wheat-rice rotation reducing 20% N fertilization with 50% straw returning may be a win-win practice in this region for the equilibrium between agricultural productivity, quality and low Cd polluted risk.

Surgical site infection in mesh repair for ventral hernia in contaminated field: A systematic review and meta-analysis.

BACKGROUND: Given the risk of surgical site infection (SSI), the use of mesh in contaminated ventral hernia repair (VHR) is not standardized and still a clinical dilemma. This meta-analysis aimed to assess whether mesh use increased the risk of SSI in patients following VHR in contaminated field. METHODS: We performed a systematic review of published literature. Studies comparing the mesh repair and anatomic repair, the use of mesh in different Center for Disease Control and Prevention (CDC) wound classes and mesh repair with synthetic mesh or other type of meshes to treat complicated and contaminated VHR were considered for analysis. The main outcome was SSI incidence. RESULTS: Six studies compared mesh and suture repairs. No significant difference in SSI incidence was observed between patients with complicated VHR in the mesh and suture repair groups.Five studies analyzed mesh repair in patients by field contamination level. There was no significant difference between the use of mesh in clean-contaminated, contaminated and dirty field versus clean wound class. Moreover, there was no significant difference between the use of mesh in clean-contaminated and contaminated cases.Four studies compared mesh repair technique with synthetic mesh or other type of meshes were included. The incidence of SSI was significantly lower in the synthetic mesh group. CONCLUSIONS: The use of mesh repair in the management of complicated VHR compared to suture repair is not associated with an increased incidence of SSI even in potentially contaminated fields.

White rot fungus Pleurotus pulmonarius enhanced bioremediation of highly PCDD/F-contaminated field soil via solid state fermentation.

This study was performed to evaluate the use of white rot fungus, Pleurotus pulmonarius, to treat polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in contaminated soil using solid state fermentation (SSF). The soil was collected from a long-closed pentachlorophenol plant in southern Taiwan. The non-sterilized soil with a total PCDD/F concentration of 14,000 ±â€¯2400 ng I-TEQ kg-1 was mixed directly with the solid fungal inocula at dry w/w ratio of 1:1.4 (ratio-adjusted test) and incubated at 26 ±â€¯2 °C in a controlled environment. The highest PCDD/F decomposition was observed during the mycelium colonization. Pearson correlation coefficient (r) studied during this period (35 days) indicated that laccase had no significant correlation (r = -0.53), while manganese peroxidase had a strong positive correlation (r = 0.88) with PCDD/F decomposition efficiency. After 72 days, the more toxic congeners, tetra- and penta-CDD/Fs were removed to non-detectable levels. Meanwhile, the removal efficiencies of hexa-, hepta-, and octa-CDD/Fs were >80%, >97%, and >90%, respectively. The simultaneous degradation of low and high chlorinated DD/Fs suggested that overall removal was nonspecific. The overall PCDD/F removal was 96%, and the residual concentration (276 ng I-TEQ kg-1) was below the regulatory control limit (1000 ng I-TEQ kg-1). In conclusion, this study shows that P. pulmonarius via SSF can successfully remediate the PCDD/F-contaminated field soil. Furthermore, this SSF technique overcame the well-known intractability of PCDD/F biodegradation in non-sterilized soil, making it promising for actual field application.

Aerobic co-composting degradation of highly PCDD/F-contaminated field soil. A study of bacterial community.

This study investigated bacterial communities during aerobic food waste co-composting degradation of highly PCDD/F-contaminated field soil. The total initial toxic equivalent quantity (TEQ) of the soil was 16,004 ng-TEQ kg-1 dry weight. After 42-day composting and bioactivity-enhanced monitored natural attenuation (MNA), the final compost product's TEQ reduced to 1916 ng-TEQ kg-1 dry weight (approximately 75% degradation) with a degradation rate of 136.33 ng-TEQ kg-1 day-1. Variations in bacterial communities and PCDD/F degraders were identified by next-generation sequencing (NGS). Thermophilic conditions of the co-composting process resulted in fewer observed bacteria and PCDD/F concentrations. Numerous organic compound degraders were identified by NGS, supporting the conclusion that PCDD/Fs were degraded during food waste co-composting. Bacterial communities of the composting process were defined by four phyla (Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes). At the genus level, Bacillus (Firmicutes) emerged as the most dominant phylotype. Further studies on specific roles of these bacterial strains are needed, especially for the thermophiles which contributed to the high degradation rate of the co-co-composting treatment's first 14 days.

Biological Meshes for Inguinal Hernia Repair - Review of the Literature.

INTRODUCTION: Biological meshes are a potential alternative to the synthetic meshes to avoid complications and are used in a contaminated field for incarcerated inguinal hernias. The clinical experiences gained with biological meshes for repair of inguinal hernias are presented in this review. MATERIALS AND METHODS: In a literature search of the Medline database using the key word "Biological mesh," 2,277 citations were found. There remained 14 studies in which biological meshes had been used to repair inguinal hernias. RESULTS: In prospective randomized trials, the use of polypropylene vs. biological meshes was compared in open inguinal hernia repair. There was no difference in the recurrence rate, but differences were observed in the postsurgical pain incidence in favor of the biological mesh. In the remaining retrospective studies, the recurrence rates were also acceptable. The biological mesh was used successfully in a potentially contaminated setting. CONCLUSION: Inguinal hernias can be repaired with biological meshes with reasonable recurrence rate, also as an alternative in a potentially contaminated field.

Practice patterns in complex ventral hernia repair and place of biological grafts: a national survey among French digestive academic surgeons.

BACKGROUND: Despite the prevalence of complex ventral hernias, there is little agreement on the most appropriate technique or prosthetic to repair these defects, especially in contaminated fields. Our objective was to determine French surgical practice patterns among academic surgeons in complex ventral hernia repair (CVHR) with regard to indications, most appropriate techniques, choice of prosthesis, and experience with complications. METHODS: A survey consisting of 21 questions and 6 case-scenarios was e-mailed to French practicing academic surgeons performing CVHR, representing all French University Hospitals. RESULTS: Forty over 54 surgeons (74%) responded to the survey, representing 29 French University Hospitals. Regarding the techniques used for CVHR, primary closure without reinforcement was provided in 31.6% of cases, primary closure using the component separation technique without mesh use in 43.7% of cases, mesh positioned as a bridge in 16.5% of cases, size reduction of the defect by using aponeurotomy incisions without mesh use in 8.2% of cases. Among the 40 respondents, 36 had experience with biologic mesh. There was a strong consensus among surveyed surgeons for not using synthetic mesh in contaminated or dirty fields (100%), but for using it in clean settings (100%). There was also a strong consensus between respondents for using biologic mesh in contaminated (82.5%) or infected (77.5%) fields and for not using it in clean setting (95%). In clean-contaminated surgery, there was no consensus for defining the optimal therapeutic strategy in CVHR. Infection was the most common complication reported after biologic mesh used (58%). The most commonly reported influences for the use of biologic grafts included literature, conferences and discussion with colleagues (85.0%), personal experience (45.0%) and cost (40.0%). CONCLUSIONS: Despite a lack of level I evidence, biologic meshes are being used by 90% of surveyed surgeons for CVHR. Importantly, there was a strong consensus for using them in contaminated or infected fields and for not using them in clean setting. To better guide surgeons, prospective, randomized trials should be undertaken to evaluate the short- and long-term outcomes associated with these materials in various surgical wound classifications.

Use of bovine pericardium graft for abdominal wall reconstruction in contaminated fields.

AIM: To employ, in such conditions, a biological graft such as bovine pericardium that offers resistance to infection. METHODS: In our surgical department, from January 2006 to June 2010, 48 patients underwent abdominal wall reconstruction using acellular bovine pericardium; of these 34 patients had a contaminated wound due to diffuse peritonitis (complicated diverticulitis, bowel perforation, intestinal infarction, strangled hernia, etc.) and 14 patients had hernia relapse on infected synthetic mesh. RESULTS: In our series, one patient died of multi-organ failure 3 d after surgery. After placement of the pericardium mesh four cases of hernia relapse occurred. CONCLUSION: Recurrence rate is similar to that of prosthetic mesh repair and the application of acellular bovine pericardium (Tutomesh(®), Tutogen Medical Gmbh Germany) is moreover a safe and feasible option that can be employed to manage complicated abdominal wall defects where prosthetic mesh is unsuitable.