Effect of biosolids amendment on the fate and mobility of non-steroidal anti-inflammatory drugs (NSAIDs) in a field-based lysimeter cell study.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used globally to treat and prevent illness. Biosolids change physico-chemical characteristics of soil and can affect the mobility of NSAIDs. A field-based lysimeter study evaluated the effect of three rates (0, 7, and 28 Mg ha-1) of alkaline treated biosolids (ATB) on the leaching potential of naproxen (NPX), ibuprofen (IBF), and ketoprofen (KTF) over 34 days in a sandy loam textured soil. Although all three NSAIDs in the lysimeter cells vertically migrated to deeper soil depths after spiking, the sum of all NPX, IBF, and KTF detected in the leachate samples from all treatments were only 0.03%, 0.02%, and 0.04% of the initial spiking mass to the surface soil, respectively. A mass balance analysis indicated a low accumulation of these compounds in the soil at the end of the study (Day 34) from all treatments with only 4.8%, 0.5%, and 0.7% of initial spiked NPX, IBF, and KTF, respectively. Application of ATB significantly increased soil pH and organic matter (OM) content of the soils but did not impact retention of the compounds in the soil profile. Overall, all three NSAIDs in the present study presented low mobility in the loamy sand textured agricultural soil.

Application of phosphorus loading models to understand drivers of eutrophication in a complex rural lake-watershed system.

Several lakes in southwestern Nova Scotia, Canada have experienced reoccurring algal blooms and possess concentrations of phosphorus (P) that are in the eutrophic to hypereutrophic range (>35 µg/L). In this study a mass balance modeling approach was used to evaluate the relative contribution of P sources within these watersheds and lakes. Primary sources of P included land runoff, septic systems, agricultural activities including mink fur farming, aquaculture, as well as internal loading. These sources were assessed for three different study years (1983, 2008, and 2017), based on availability of water quality data, and to quantify the relative impact of the mink farming industry as it rapidly expanded during this time period. A novel method to estimate P loads from intensive fur farming operations was developed, using agricultural census, remote sensing, and publicly available spatial data. A suite of simulations were generated, using a steady state mass balance model, to examine lake P concentrations and sources for baseline conditions (no anthropogenic sources), no mink farming, and varying levels of P retention on mink farms (25%, 50%, 75%) scenarios. An additional scenario was also constructed which involved calibrating mink farm P retention coefficients using available water quality data. In the baseline scenario it was predicted that all study lakes would be oligotrophic, indicating that cultural eutrophication of these lakes has occurred. In the no mink farming scenario, it was predicted that all study lakes would be oligotrophic except for Hourglass Lake, which was predicted to be mesotrophic due to inputs from an aquaculture facility. Internal loading of P from lake sediments was also identified as an important potential P loading mechanism, which will likely be exacerbated by climate change. These findings indicate that the P from mink farms is the primary driver of cultural eutrophication in the study lakes, and highlights the need to consider these nutrient sources within watershed management plans. It is recommended that lake remediation efforts continue to focus on reducing P inputs from mink farms, and on controlling P loading from any new anthropogenic development in these watersheds.

Fate and transport in environmental quality.

Changes in pollutant concentrations in environmental media occur both from pollutant transport in water or air and from local processes, such as adsorption, degradation, precipitation, straining, and so on. The terms "fate and transport" and "transport and fate" reflect the coupling of moving with the carrier media and biogeochemical processes describing local transformations or interactions. The Journal of Environmental Quality (JEQ) was one of the first to publish papers on fate and transport (F&T). This paper is a minireview written to commemorate the 50th anniversary of JEQ and show how the research interests, methodology, and public attention have been reflected in fate and transport publications in JEQ during the last 40 years. We report the statistics showing how the representation of different pollutant groups in papers changed with time. Major focus areas have included the effect of solution composition on F&T and concurrent F&T, the role of organic matter, and the relative role of different F&T pathways. The role of temporal and spatial heterogeneity has been studied at different scales. The value of long-term F&T studies and developments in modeling as the F&T research approach was amply demonstrated. Fate and transport studies have been an essential part of conservation measure evaluation and comparison and ecological risk assessment. For 50 years, JEQ has delivered new insights, methods, and applications related to F&T science. The importance of its service to society is recognized, and we look forward to new generations of F&T researchers presenting their contributions in JEQ.

Adaptive ecological niche migration does not negate extinction susceptibility.

Extinction rates in the modern world are currently at their highest in 66 million years and are likely to increase with projections of future climate change. Our knowledge of modern-day extinction risk is largely limited to decadal-centennial terrestrial records, while data from the marine realm is typically applied to high-order (> 1 million year) timescales. At present, it is unclear whether fossil organisms with common ancestry and ecological niche exhibit consistent indicators of ecological stress prior to extinction. The marine microfossil record, specifically that of the planktonic foraminifera, allows for high-resolution analyses of large numbers of fossil individuals with incredibly well-established ecological and phylogenetic history. Here, analysis of the isochronous extinction of two members of the planktonic foraminiferal genus Dentoglobigerina shows disruptive selection differentially compounded by permanent ecological niche migration, "pre-extinction gigantism", and photosymbiont bleaching prior to extinction. Despite shared ecological and phylogenetic affinity, and timing of extinction, the marked discrepancies observed within the pre-extinction phenotypic responses are species-specific. These behaviours may provide insights into the nature of evolution and extinction in the open ocean and can potentially assist in the recognition and understanding of marine extinction risk in response to global climate change.

Biodegradation kinetics of individual and mixture non-steroidal anti-inflammatory drugs in an agricultural soil receiving alkaline treated biosolids.

Land application of biosolids is one potential source of pharmaceuticals and personal care products (PPCPs) into agricultural soils. Degradation is an important natural attenuation pathway that affects the fate and transport of PPCPs in the soil system and biosolids application could alter the process. The present study assessed the effect of individual and mixture compound environments on the biodegradation rate and half-life of three non-steroidal anti-inflammatory drugs (NSAIDs), naproxen (NPX), ibuprofen (IBF), and ketoprofen (KTF), in a loamy sand textured agricultural soil receiving an alkaline treated biosolid (ATB) amendment. A prolonged half-life of the target NSAIDs was determined for sterile soils and shorter half-lives in unsterile soils, indicating the loss of target compounds in all treatments was mainly attributed to biodegradation and followed first-order kinetics. IBF and NPX showed low to moderate persistence in soil and ATB amended soil, with half-lives ranging from 4.9 to 14.8 days, while KTF appeared to be highly persistent with an average half-life of 33 days. The order in which the target NSAIDs disappeared in both soil and ATB amended soil was: IBF > NPX > KTF, for both individual and mixture compound treatments. Soils that received the ATB amendment demonstrated inhibited degradation of NPX in all treatments, as well as IBF and KTF in individual compound treatment over the 14-day incubation study. We also observed an inhibition effect from the ATB amendment in sterile soil treatments. In mixture compound treatments, IBF degradation was inhibited in both soil and ATB amended soil. The degradation rate of KTF in mixture compound environment in soil was lower, while the opposite effects were observed in ATB amended soils. For NPX, the degradation was enhanced in mixture compound environment in ATB amended soil, while the same degradation rate of NPX was calculated in soil.

Intercellular communication controls agonist-induced calcium oscillations independently of gap junctions in smooth muscle cells.

In this study, we report the existence of a communication system among human smooth muscle cells that uses mechanical forces to frequency modulate long-range calcium waves. An important consequence of this mechanical signaling is that changes in stiffness of the underlying extracellular matrix can interfere with the frequency modulation of Ca2+ waves, causing smooth muscle cells from healthy human donors to falsely perceive a much higher agonist dose than they actually received. This aberrant sensing of contractile agonist dose on stiffer matrices is completely absent in isolated smooth muscle cells, although the isolated cells can sense matrix rigidity. We show that the intercellular communication that enables this collective Ca2+ response in smooth muscle cells does not involve transport across gap junctions or extracellular diffusion of signaling molecules. Instead, our data support a collective model in which mechanical signaling among smooth muscle cells regulates their response to contractile agonists.

Preimplantation genetic diagnosis for retinoblastoma survivors: a cost-effectiveness study.

This study aimed to investigate the cost-effectiveness of preimplantation genetic diagnosis (PGD) for the reproductive choices of patients with heritable retinoblastoma. The study modelled the costs of three cycles of in-vitro fertilization (IVF) and PGD across all uptake rates of PGD, number of children affected with retinoblastoma at each uptake rate and the estimated quality-adjusted life years (QALYs) gained. Cost-effectiveness analysis was conducted from the Australian public healthcare perspective. The intervention was the use of three cycles (one fresh and two frozen) of IVF and PGD with the aim of live births unaffected by the retinoblastoma phenotype. Compared with the standard care pathway (i.e. natural pregnancy), IVF and PGD resulted in a cost-saving to 18 years of age of AUD$2,747,294 for a base case of 100 couples with an uptake rate of 50%. IVF and PGD resulted in fewer affected (n = 56) and unaffected (n = 78) live births compared with standard care (71 affected and 83 unaffected live births), and an additional 0.03 QALYs per live birth. This modelling suggests that the use of IVF and PGD to achieve an unaffected child for patients with heritable retinoblastoma resulted in an overall cost-saving. There was an increase in QALYs per baby across all uptake rates. However, in total, fewer babies were born following the IVF and PGD pathway.

Long-term evaluation of the impact of urbanization on chloride levels in lakes in a temperate region.

The application of road salts for winter de-icing of roadways in cold regions has been demonstrated to increase chloride (Cl) concentrations in nearby surface waters and have a negative impact on aquatic organisms and processes. In addition to toxicity to aquatic organisms, high concentrations of Cl in lakes can alter mixing processes, resulting in prolonged anoxic conditions and associated water quality degradation. Elevated concentrations of Cl in freshwater environments in cold regions is a well-documented phenomenon, but few studies have undertaken a long-term evaluation of the impact of urbanization on lakes. In this paper, nine lakes in the Halifax region of Nova Scotia, Canada, were monitored over 35 years to observe Cl concentrations prior to, during, and after urbanizing development. Cl concentrations were observed to increase in most study lakes over the monitoring period and all nine exhibited seasonal trending in response to winter de-icing activities. Six of the lakes achieved a steady-state Cl level after an initial increase in response to development activities, two are potentially still in transition, and one was unaffected by development activities. Watershed land use was found to be a good predictor of the springtime concentration of Cl and can help to inform decision-making surrounding development activities. When the percent of developed land was 25% or more, the Cl concentrations tended to exceed Canadian freshwater quality guidelines for the protection of aquatic life.

Phenotype-genotype correlations and emerging pathways in ocular anterior segment dysgenesis.

Disorders of the anterior segment of the eye encompass a variety of clinical presentations including aniridia, Axenfeld and Rieger anomalies, primary congenital glaucoma, Peters anomaly, as well as syndromal associations. These conditions have a significant impact on vision due to disruption of the visual axis, and also secondary glaucoma which occurs in over 50% of patients. Ocular anterior segment disorders occur due to a complex interplay of developmental, embryological and genetic factors, and often have phenotypic overlaps and genetic heterogeneity. Here we present a review of the clinical features and genes associated with aniridia, Axenfeld and Rieger anomalies, primary congenital glaucoma, Peters anomaly, and syndromic forms of these conditions. We also highlight phenotype-genotype correlations, recent discoveries with next-generation sequencing which broaden known phenotypes, and new anterior segment genes and pathways. We provide a guide towards genetic diagnosis for clinicians investigating patients with anterior segment dysgenesis.

Microbial Water Quality: Monitoring and Modeling.

Microbial water quality lies in the nexus of human, animal, and environmental health. Multidisciplinary efforts are under way to understand how microbial water quality can be monitored, predicted, and managed. This special collection of papers in the was inspired by the idea of creating a special section containing the panoramic view of advances and challenges in the arena of microbial water quality research. It addresses various facets of health-related microorganism release, transport, and survival in the environment. The papers analyze the spatiotemporal variability of microbial water quality, selection of predictors of the spatiotemporal variations, the role of bottom sediments and biofilms, correlations between concentrations of indicator and pathogenic organisms and the role for risk assessment techniques, use of molecular markers, subsurface microbial transport as related to microbial water quality, antibiotic resistance, real-time monitoring and nowcasting, watershed scale modeling, and monitoring design. Both authors and editors represent international experience in the field. The findings underscore the challenges of observing and understanding microbial water quality; they also suggest promising research directions for improving the knowledge base needed to protect and improve our water sources.

New mutations in GJA8 expand the phenotype to include total sclerocornea.

This project expands the disease spectrum for mutations in GJA8 to include total sclerocornea, rudimentary lenses and microphthalmia, in addition to this gene's previously known role in isolated congenital cataracts. Ophthalmic findings revealed bilateral total sclerocornea in 3 probands, with small abnormal lenses in 2 of the cases, and cataracts and microphthalmia in 1 case. Next-generation sequencing revealed de novo heterozygous mutations affecting the same codon of GJA8 : (c.281G>A; p.(Gly94Glu) and c.280G>C; p.(Gly94Arg)) in 2 of the probands, in addition to the c.151G>A; p.(Asp51Asn) mutation we had previously identified in the third case. In silico analysis predicted all of the mutations to be pathogenic. These cases show that deleterious, heterozygous mutations in GJA8 can lead to a severe ocular phenotype of total sclerocornea, abnormal lenses, and/or cataracts with or without microphthalmia, broadening the phenotype associated with this gene. GJA8 should be included when investigating patients with the severe anterior segment abnormality of total sclerocornea.

Sorption and desorption of selected non-steroidal anti-inflammatory drugs in an agricultural loam-textured soil.

Non-steroidal, anti-inflammatory drugs (NSAIDs) are widely used pharmaceutical products with analgesic and anti-inflammatory effects that are consistently detected in municipal wastewater systems and in municipal biosolids. Land application of biosolids and irrigation with reclaimed wastewater introduces these compounds into agricultural environments, which is an emerging issue of concern for ecosystem health. In this study, the sorption-desorption behaviour of four commonly consumed NSAIDs, including naproxen (NPX), ibuprofen (IBU), ketoprofen (KTF), and diclofenac (DCF), was examined in a loam textured soil exposed to either an individual-compound or a mixture of the four NSAIDs. The proportion of NSAIDs adsorbed to the soil in the mixture-compound system was 72%, 55%, 50% and 45%, for diclofenac, naproxen, ketoprofen, and ibuprofen, respectively, and differed slightly from the individual compound adsorption. Diclofenac displayed strong sorption and low desorption in both the individual-compound and mixture-compound systems. Naproxen and ibuprofen exhibited significant differences between the adsorption isotherms of the individual-compound and mixture-compound systems. Results of this study highlight differences in the sorption behaviour of NSAIDs, when present as mixtures, possibly through multilayer bonding effects or complexation with cationic metals or organo-clays from the soil. Soil organic matter (SOM) may have played a role in determining some of the interactions between the compounds but other factors associated with the mixture-compound system, such as cation bridging or multilayer cooperative adsorption. Desorption data suggests that the mechanisms involved in binding NSAIDs to the soil surface are also influence by the presence of other compounds in a mixture. A reduction in desorption was observed for all four NSAIDs in the mixture-compound system relative to the individual-compound system, but were greatest for naproxen and ibuprofen. The sorption-desorption hysteresis increased for naproxen and ibuprofen in the mixture-compound system. This study suggests that cooperative adsorption plays a role in the interaction of NSAIDs when present as mixtures rather than as individual compounds.

Evidence for Ethylene-Vinyl-Alcohol-Copolymer Liquid Embolic Agent as a Monotherapy in Treatment of Endoleaks.

OBJECTIVE: Endoleak remains the Achilles heel of endovascular aneurysm repair and the exclusion of Type II endoleaks, in particular, remains challenging. This systematic review presents the evidence for ethylene-vinyl-alcohol-copolymer liquid embolic agent as a monotherapy in the treatment of endoleaks. METHODS: A systematic literature search was performed for all studies reporting the use of liquid embolic agent as a sole agent in the treatment of endoleaks. Patient numbers, clinical details (endoleak type, route of delivery) and outcome in terms of survival, technical and clinical success with freedom from endoleak together with follow-up period were examined. RESULTS: Only 12 articles reporting the use of liquid embolic as the sole treatment modality for endoleaks in 174 patients were identified. All but 21 patients had a Type II endoleak. Transarterial embolization was attempted in 73% of patients with 48 patients having direct sac puncture. Technical success was high at 96%, but in patients with adequate imaging, the clinical success rate dropped to 79%. Complications were sparsely reported and follow-up ranged from 0 to 75 months. CONCLUSIONS: This review highlights the lack of data regarding the use of liquid embolic agent as a monotherapy with only 4 studies including more than 10 patients. Data from the largest series suggests a learning curve exists and no study reports on cost effectiveness. Technical success does not always translate into clinical success and with the largest series only reporting median 4-month follow-up no claims regarding durability can be made. In problematic Type II endoleaks, however, liquid embolic agent is a welcome addition to the treatment armamentarium.

Vascular training in Scotland and Northern Ireland: The trainee perspective prior to introduction of the new vascular curriculum.

BACKGROUND: The last decade has seen the evolution of vascular surgery from a sub-specialty of general surgery to that of an independent, stand-alone specialty. The introduction of a vascular-only curriculum is anticipated to require significant change from the current provision for vascular surgical training to allow vascular trainees to acquire the specialist skills in elective, emergency, and endovascular surgery to provide endovascular services in the future. AIM: To provide an insight into current vascular training in Scotland and Northern Ireland. METHOD: Specialty trainees in general surgery, with a sub-specialty interest in vascular in Scotland and Northern Ireland were asked to carry out a voluntary online survey between May 2012 and July 2012. RESULTS: 22 specialty trainees/specialist registrars who have declared a sub-specialty interest in vascular surgery were identified and polled. 20 trainees completed the survey. 13 trainees still participated in general surgical on-call rotas. Formal teaching opportunities were readily available but only 10 trainees could attend regularly. All trainees worked in units offering endovascular treatment for aneurysm and occlusive disease, but few had dedicated training sessions in endovascular skills. All endovascular simulation-based training was industry sponsored. The majority of trainees report a good overall training experience and are keen to see the implementation of a vascular-specific curriculum. 15 trainees had undertaken a dedicated period of research towards a higher degree, with only 50% based on a vascular topic. CONCLUSION: The majority of trainees reported a positive training experience with Scotland and Northern Ireland having great potential as vascular training deaneries. The survey identifies specific areas that could be improved by the development of the new curriculum in vascular surgery to provide excellent vascular training in Scotland and Northern Ireland.

Baseline and storm event monitoring of Bacteroidales marker concentrations and enteric pathogen presence in a rural Canadian watershed.

Bacteroidales 16S rRNA gene markers were evaluated for their use as a microbial source tracking tool in a well characterized 750 ha agricultural watershed in Nova Scotia, Canada. Water quality monitoring was conducted following the validation of host-specific and universal Bacteroidales (AllBac) markers for their proficiency in this particular geographic region, which provided further evidence that these markers are geographically stable. Increasing Escherichia coli concentrations were positively correlated (p < 0.01) with concentrations of the AllBac marker in water samples, suggesting that this universal marker is more suited as a positive DNA control rather than as an indicator of recent fecal contamination. Ruminant (BacR) and bovine (CowM2) specific marker detection was associated with increased runoff due to precipitation in sub-watersheds putatively impacted by cattle farming, demonstrating that the BacR and CowM2 markers can be used to detect the recent introduction of fecal matter from cattle farming activities during rainfall events. However, the human associated marker (BacH) was only detected once in spite of numerous on-site residential wastewater treatment systems in the watershed, suggesting that this assay is not sensitive enough to detect this type of human sewage source. E. coli O157:H7 and Salmonella spp. DNA was not detected in any of the 149 watershed samples; however, 114 (76.5%) of those samples tested positive for Campylobacter spp. No significant correlation (p > 0.05) was found between Campylobacter spp. presence and either E. coli or AllBac marker levels. Further studies should be conducted to assess the origins of Campylobacter spp. in these types of watersheds, and to quantify pathogen cell numbers to allow for a human health risk assessment.

Community-based first aid: a program report on the intersection of community-based participatory research and first aid education in a remote Canadian Aboriginal community.

CONTEXT: Community-based first aid training is the collaborative development of locally relevant emergency response training. The Sachigo Lake Wilderness Emergency Response Education Initiative was developed, delivered, and evaluated through two intensive 5-day first aid courses. Sachigo Lake First Nation is a remote Aboriginal community of 450 people in northern Ontario, Canada, with no local paramedical services. These courses were developed in collaboration with the community, with a goal of building community capacity to respond to medical emergencies. ISSUE: Most first aid training programs rely on standardized curriculum developed for urban and rural contexts with established emergency response systems. Delivering effective community-based first aid training in a remote Aboriginal community required specific adaptations to conventional first aid educational content and pedagogy. LESSONS LEARNED: Three key lessons emerged during this program that used collaborative principles to adapt conventional first aid concepts and curriculum: (1) standardized approaches may not be relevant nor appropriate; (2) relationships between course participants and the people they help are relevant and important; (3) curriculum must be attentive to existing informal and formal emergency response systems. These lessons may be instructive for the development of other programs in similar settings.

A puzzle over several decades: eye anomalies with FRAS1 and STRA6 mutations in the same family.

Fraser syndrome (FS) and microphthalmia syndromic 9 (MCOPS9) are autosomal recessive conditions with distinct, and some overlapping features affecting the ocular, respiratory and cardiac systems. Mutations in FRAS1 and FREM2 occur in FS, and mutations in STRA6 occur in MCOPS9. We report two sibships, in the same family, where four deceased offspring had ocular, respiratory and cardiac abnormalities. Two sibs with microphthalmia had syndactyly and laryngeal stenosis, suggesting a clinical diagnosis of FS. Our results indicate that they were compound heterozygotes for novel FRAS1 mutations, p.Cys729Phe and p.Leu3813Pro. The other two sibs, first cousins to the first sib pair, had anophthalmia, lung hypoplasia and cardiac anomalies, suggesting a retrospective diagnosis of MCOPS9. Our results indicate compound heterozygous STRA6 mutations, a novel frameshift leading to p.Tyr18* and a p.Thr644Met mutation. The one surviving individual from these sibships is heterozygous for the p.Tyr18*STRA6 mutation and has bilateral ocular colobomata and microphthalmia. This work emphasises the need for careful phenotypic characterisation to determine genes for assessment in ocular syndromic conditions. It also indicates that heterozygous STRA6 mutations may rarely contribute to microphthalmia and coloboma.

Population dynamics of Escherichia coli inoculated by irrigation into the phyllosphere of spinach grown under commercial production conditions.

Recent outbreaks of food-borne illnesses associated with the consumption of fresh produce have increased attention on irrigation water as a potential source of pathogen contamination. A better understanding of the behaviour of enteric pathogens introduced into agricultural systems during irrigation will aid in risk assessments and support the development of appropriate farm-level water management practices. For this reason, the survival dynamics of two nalidixic acid resistant strains of Escherichia coli after their spray inoculation into the phyllosphere and soil of field spinach were examined over two growing seasons. E. coli strains NAR, an environmental isolate, and DM3n, a non-pathogenic serotype O157:H7, were applied at rates of 104 to 107 cfu/100ml to the fully developed spinach plants that arose subsequent to the harvesting of their upper leafy portions for commercial purposes (secondary-growth plants). After 72 h, E. coli on spinach were reduced by 3-5 logs. Culturable E. coli were recovered from plants up to 6 days post-inoculation. Survival in soil was greater than in the phyllosphere. Under ambient conditions, the mean 72 h first order decay constant computed by Chick's Law was 0.1 h⁻¹. Although light reduction studies indicated UV irradiation negatively influenced the persistence of E. coli, a simple relationship between UV exposure and phyllosphere E. coli densities could not be established. E. coli introduced to the leafy portions of spinach via spray irrigation displayed rapid declines in their culturability under the open environmental conditions experienced during this study. A 6 day period between the last irrigation and harvest would minimize the risks of E. coli survival in the spinach phyllosphere. E. coli NAR was identified as a possible surrogate for the O157:H7 strain, DM3n.

Greenhouse gas emissions from surface flow and subsurface flow constructed wetlands treating dairy wastewater.

Agricultural wastewater treatment is important for protecting water quality in rural ecosystems, and constructed wetlands are an effective treatment option. During treatment, however, some C and N are converted to CH(4), N(2)O, respectively, which are potent greenhouse gases (GHGs). The objective of this study was to assess CH(4), N(2)O, and CO(2) emissions from surface flow (SF) and subsurface flow (SSF) constructed wetlands. Six constructed wetlands (three SF and three SSF; 6.6 m(2) each) were loaded with dairy wastewater in Truro, Nova Scotia, Canada. From August 2005 through September 2006, GHG fluxes were measured continuously using transparent steady-state chambers that encompassed the entire wetlands. Flux densities of all gases were significantly (p < 0.01) different between SF and SSF wetlands changed significantly with time. Overall, SF wetlands had significantly (p < 0.01) higher emissions of CH(4) N(2)O than SSF wetlands and therefore had 180% higher total GHG emissions. The ratio of N(2)O to CH(4) emissions (CO(2)-equivalent) was nearly 1:1 in both wetland types. Emissions of CH(4)-C as a percentage of C removal varied seasonally from 0.2 to 27% were 2 to 3x higher in SF than SSF wetlands. The ratio of N(2)O-N emitted to N removed was between 0.1 and 1.6%, and the difference between wetland types was inconsistent. Thus, N(2)O emissions had a similar contribution to N removal in both wetland types, but SSF wetlands emitted less CH(4) while removing more C from the wastewater than SF wetlands.

Adsorption, sedimentation, and inactivation of E. coli within wastewater treatment wetlands.

Bacteria fate and transport within constructed wetlands must be understood if engineered wetlands are to become a reliable form of wastewater treatment. This study investigated the relative importance of microbial treatment mechanisms in constructed wetlands treating both domestic and agricultural wastewater. Escherichia coli (E. coli) inactivation, adsorption, and settling rates were measured in the lab within two types of wastewater (dairy wastewater lagoon effluent and domestic septic tank effluent). In situ E. coli inactivation was also measured within a domestic wastewater treatment wetland and the adsorption of E. coli was also measured within the wetland effluent. Inactivation of E. coli appears to be the most significant contributor to E. coli removal within the wastewaters and wetland environments examined in this study. E. coli survived longer within the dairy wastewater (DW) compared to the domestic wastewater treatment wetland water (WW). First order rate constants for E. coli inactivation within the WW in the lab ranged from 0.09 day(-1) (d(-1)) at 7.6 degrees C to 0.18d(-1) at 22.8 degrees C. The average in situ rate constant observed within the domestic wetland ranged from 0.02 d(-1) to 0.03 d(-1) at an average water temperature of 17 degrees C. First order rate constants for E. coli inactivation within the DW ranged from 0.01 d(-1) at 7.7 degrees C to 0.04 d(-1) at 24.6 degrees C. Calculated distribution coefficients (K(d)) were 19,000 mL g(-1), 324,000 mL g(-1), and 293 mL g(-1) for E. coli with domestic septic tank effluent (STE), treated wetland effluent (WLE), and DW, respectively. Approximately 50%, 20%, and 90% of E. coli were "free floating" or associated with particles <5 microm in size within the STE, WLE, and DW respectively. Although 10-50% of E. coli were found to associate with particles >5 microm within both the STE and DW, settling did not appear to contribute to E. coli removal within sedimentation experiments, indicating that the particles the bacteria were associated with had very small settling velocities. The results of this study highlight the importance of wastewater characterization when designing a treatment wetland system for bacterial removal. This study illustrated the level of variability in E. coli removal processes that can be observed within different wastewater, and wetland environments.