Influence of decomposition on chemical properties of plant- and manure-derived dissolved organic matter and sorption to goethite

Sorption of dissolved organic matter (DOM) plays an important role in maintaining the fertility and quality of soils in agricultural ecosystems. Few studies have examined the effects of decomposition on DOM sorption and chemical characteristics. This study investigated the sorption to goethite (alpha-FeOOH) of fresh and decomposed hydrophilic (HPL) and hydrophobic (HPB) DOM fractions extracted from the shoots and roots of crimson clover (Trifolium incarnatum L.), corn (Zea mays L.), soybean [Glycine max (L.) Merr.], hairy vetch (Vicia villosa L.), and dairy and poultry manures. Sorption was positively related to apparent molecular weight (MWAP), aromaticity as measured by absorptivity at 280 nm, and phenolic acid content. A 10-d laboratory microbial decomposition of the source organic matter generally increased the sorption of the extracted DOM onto goethite. The decomposition effect on sorption was greater for the HPL fractions than for the HPB fractions. There was a decrease in the MWAP values of the DOM samples following sorption to goethite. In many cases the reduction in MWAP was large, indicating a strong preference by goethite for the higher MWAP DOM fractions. The results of this laboratory-based research demonstrate that microbial processes affect the chemical characteristics of DOM which may affect the distribution of soil organic C pools.     

The influence of body size, condition index and tidal exposure on the variability in metal bioaccumulation in Mytilus edulis

Mussels are commonly used to monitor metal pollution despite high inter-individual variability in tissue concentrations. In this study, influences of body size, condition index and tidal height on concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were investigated. Body weight was inversely related to metal concentrations and for Cd, Mn, Pb and Zn the regression was affected by tidal height. Except for As, Fe and Mn metal concentrations were inversely related to physiological status though no differences between essential and non-essential metals were obvious. After correcting for body size, tidal height was related positively to As, Cd and Zn, negatively related to Cu, Fe and Mn while Co, Cr, Ni and Pb were independent of tidal height. The study recommends stringent measures during sampling for biomonitoring or metal concentrations at each location must be normalized to a common body size, CI and tidal height.     

WETLAND DESIGN METHODS FOR RESIDENTIAL WASTEWATER TREATMENT1

ABSTRACT: Constructed wetlands have recently gained popularity as an alternative method for wastewater treatment. This paper compares two design methodologies currently used for constructed wetlands; Tennessee Valley Authority (TVA) and the Environmental Protection Agency (EPA) methods. A discussion of parameters for both methods is given and a wetland treatment system is designed for an individual residence with typical BOD5 loads and flow rates. Calculation results revealed significant discrepancies in the required constructed wetlands volume, and thus detention time, stemming from inherent differences in the design methodologies. The EPA method relies heavily on plug flow kinetics, and is therefore sensitive to changes in the reaction rate constant and media porosity. Conversely, TVA determines the surface area by sizing in accordance with a recommended hydraulic loading criterion and is affected only by the hydraulic flow rates. This study concluded that a constructed wetland is a viable option under design considerations that are not favorable for traditional on-site wastewater treatment methods. However, it is recommended that conservative values for flow and loading rates be assumed to assure complete treatment for either of the design methods.     

MTBE and aromatic hydrocarbons in North Carolina stormwater runoff

A total of 249 stormwater samples were collected from 46 different sampling locations in North Carolina over an approximate 1-year period and analyzed to identify land use types where fuel oxygenates and aromatic hydrocarbons may be present in higher concentrations and at greater frequency. Samples were analyzed by gas chromatography-mass spectrometry in ion selective mode to achieve a quantitation limit of 0.05 microg/l. m-,p-Xylene and toluene were detected in over half of all samples analyzed, followed by MTBE: o-xylene: 1,3,5-trimethylbenzene: ethylbenzene; and 1,2,4-trimethylbenzene. Benzene, DIPE, TAME and 1,2,3-trimethylbenzene were detected in < 10% of the samples analyzed. Median contaminant concentrations (when detected) varied from 0.07 microg/l for ethylbenzene to 0.11 microg/l for toluene. All of the locations with significantly higher contaminant concentrations were associated with direct runoff from a gas station or discharge of contaminated groundwater from a former leaking underground storage tank. For all of the aromatic hydrocarbons, the maximum observed contaminant concentrations were over an order of magnitude lower than current drinking water standards.     

Removal of selected natural and synthetic estrogenic compounds in a Canadian full-scale municipal wastewater treatment plant.

The effect of a full-scale municipal wastewater treatment plant (WWTP) and each of the treatment units within the stream on the removal of endocrine-disrupting compounds was evaluated by tracking 17-beta-estradiol (E2), estrone (E1), and 17-alpha-ethinylestradiol (EE2). The overall performance of the WWTP compared well with other plants, as 90.5% removal of E1+E2 and 74.9% removal of EE2 were observed. A larger fraction of EE2 entered the plant in particulate form than E1 and E2, while a lower fraction of EE2 left the plant in particulate form than soluble form. The activated sludge units reduced the concentration of E1+E2 and EE2 in the liquid phase by 88.2% and 44.6%, respectively. The UV treatment process did not reduce the amount of estrogens. The aqueous phase of the tertiary lagoon solids contained higher levels of estrogens compared with the lagoon influent.     

Impaction collection and slurry sampling for the determination of arsenic, cadmium, and lead in sidestream cigarette smoke by inductively coupled plasma-mass spectrometry

The slurry sampling technique has been applied for the determination of arsenic, cadmium and lead in sidestream cigarette smoke condensate (SS CSC) by inductively coupled plasma mass spectrometry (ICP-MS). The smoke collection system consists of a "fishtail" chimney in conjunction with an impaction trap and a mixed cellulose ester (MCE) backup filter for the SS CSC collection. The smoke condensates, collected at three different regions of the system (i.e. the inner wall of the chimney, the impaction trap and the MCE filter), were individually prepared and analyzed and showed that about 70 and 20% of Cd and Pb, respectively, were trapped by the impaction trap and the MCE filter with less than 5% trapped by the chimney. In contrast, about 60% of As was trapped by the impactor and a relatively high percentage of As, about 30%, was deposited onto the inner wall of the chimney. The uneven distribution of trace metals at each collection stage strongly suggested that the composition of smoke aerosol and the associated physical form of the analytes may be different. The yields of As, Cd and Pb for the sidestream cigarette smoke of the 1R4F reference cigarette were 29.5 +/- 2.4, 421 +/- 6.6 and 46.4 +/- 0.9 ng cigarette(-1)(n= 3) respectively, when the cigarette was smoked according to the smoking regime: 45 mL puff volume of 2-s puff duration at an interval of 30 s with 50% ventilation holes covered. The analytical results for the slurry sampling technique were also compared with other sample preparation techniques and show good agreement.     

Evaluating an Air Quality Health Index (AQHI) amendment for communities impacted by residential woodsmoke in British Columbia,Canada

ABSTRACT

Smoke from burning biomass is an important source of fine particulate matter (PM_2.5), but the health risks may not be fully captured by the Canadian Air Quality Health Index (AQHI). In May 2018, the province of British Columbia launched an evidence-based amendment (AQHI-Plus) to improve AQHI performance for wildfire smoke, but the AQHI-Plus was not developed or tested on data from the residential woodsmoke season. This study assesses how the AQHI and AQHI-Plus are associated with acute health outcomes during the cooler seasons of 2010–2017 in British Columbia, Canada. Monthly and daily patterns of temperature and PM_2.5 concentrations were used to identify Local Health Areas (LHAs) that were impacted by residential woodsmoke. The effects of the AQHI and AQHI-Plus on five acute health outcomes (including non-accidental mortality, outpatient physician visits, and medical dispensations for cardiopulmonary conditions) were estimated using generalized linear mixed effect models with Poisson distributions adjusted for long- and short-term temperature trends. Values of the Akaike information criterion (AIC) were compared to evaluate whether the AQHI or AQHI-Plus was better fitted to each health outcome. Eleven LHAs were categorized as woodsmoke-impacted. In these LHAs, the AQHI and AQHI-Plus associations with acute health outcomes were sensitive to temperature adjustments. After temperature adjustments, the most consistent associations were observed for the two asthma-specific outcomes where the AQHI-Plus was better fitted than the AQHI. The improved performance of the AQHI-Plus for susceptible populations with asthma is consistent between communities impacted by residential woodsmoke and wildfire smoke.

Implications: Canada’s Air Quality Health Index (AQHI) is a three pollutant index used to communicate the short term health impact of degraded air quality. As fine particulate matter (PM_2.5) is the lowest weighted pollutant in the AQHI, the index is poorly reflective of woodsmoke impacts. The present analysis found that an AQHI amendment developed for improved sensitivity to PM_2.5 during wildfire seasons (AQHI-Plus) is also more predictive of acute asthma-related health outcomes in communities impacted by residential woodsmoke. The BC Ministry of Environment and Climate Change Strategy has piloted the AQHI-Plus year-round. Other jurisdictions should consider whether their air quality indices are reflective of the risks posed by woodsmoke.     

Integrated assessment of the impacts of agricultural drainwater in the Salinas River (California,USA)

The Salinas River is the largest of the three rivers that drain into the Monterey Bay National Marine Sanctuary in central California. Large areas of this watershed are cultivated year-round in row crops and previous laboratory studies have demonstrated that acute toxicity of agricultural drainwater to Ceriodaphnia dubia is caused by the organophosphate (OP) pesticides chlorpyrifos and diazinon. In the current study, we used a combination of ecotoxicologic tools to investigate incidence of chemical contamination and toxicity in waters and sediments in the river downstream of a previously uncharacterized agricultural drainage creek system. Water column toxicity was investigated using a cladoceran C. dubia while sediment toxicity was investigated using an amphipod Hyalella azteca. Ecological impacts of drainwater were investigated using bioassessments of macroinvertebrate community structure. The results indicated that Salinas River water downstream of the agricultural drain is acutely toxic to Ceriodaphnia, and toxicity to this species was highly correlated with combined toxic units (TUs) of chlorpyrifos and diazinon. Laboratory tests were used to demonstrate that sediments in this system were acutely toxic to H. azteca, which is a resident genus. Macroinvertebrate community structure was moderately impacted downstream of the agricultural drain input. While the lowest macroinvertebrate abundances were measured at the station demonstrating the greatest water column and sediment toxicity and the highest concentrations of pesticides, macroinvertebrate metrics were more significantly correlated with bank vegetation cover than any other variable. Results of this study suggest that pesticide pollution is the likely cause of laboratory-measured toxicity in the Salinas River samples and that this factor may interact with other factors to impact the macroinvertebrate community in the system.