Changes in the nature of sewage sludge organic matter during a twenty-one-month incubation

Six sewage sludges from five sewage treatment plants in Australia were incubated for up to 21 months. Carbon losses at the end of the 21-mo incubation varied substantially. The remaining organic matter was isolated by treatment with hydrofluoric acid (HF) and characterized using a range of solid-state (13)C nuclear magnetic resonance (NMR) spectroscopic techniques. By every measure (signal distribution in cross polarization [CP] and Bloch decay [BD] spectra, carbon NMR observability determined by spin counting, and the appearance of proton spin relaxation editing subspectra), the chemical composition of the residual organic matter appeared to be little different from that of the original sludges, even for those sludges that experienced the greatest carbon losses. Importantly, these NMR properties distinguish sewage sludge organic matter from soil organic matter. Thus, it should be possible to follow the decomposition of sewage sludge organic matter applied to soils in the field using solid-state (13)C NMR spectroscopy.     

USING INFILTRATION ENHANCEMENT AND SOIL WATER MANAGEMENT TO REDUCE DIAZINON IN RUNOFF1

ABSTRACT: Pesticide runoff from dormant sprayed orchards is a major water quality problem in California's Central Valley. During the past several years, diazinon levels in the Sacramento and San Joaquin Rivers have exceeded water quality criteria for aquatic organisms. Orchard water management, via post‐application irrigation, and infiltration enhancement, through the use of a vegetative ground cover, are management practices that are believed to reduce pesticide loading to surface waters. Field experiments were conducted in Davis, California, to measure the effectiveness of these management practices in reducing the toxicity of storm water runoff. Treatments using a vegetative ground cover significantly reduced peak concentrations and cumulative pesticide mass in runoff for first flush experiments compared with bare soil treatments. Post‐application irrigation was found to be an effective means of reducing peak concentrations and cumulative mass in runoff from bare soil treatments, but showed no significant effect on vegetated treatments.     

Characterization of sewage sludge organic matter using solid-state carbon-13 nuclear magnetic resonance spectroscopy

Six sewage sludges from five sewage treatment plants in Australia were characterized using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Spectra were acquired both before and after removal of mineral components through treatment with hydrofluoric acid (HF). Carbon mass balance indicated that little organic matter was lost on HF treatment, which significantly improved NMR sensitivity and spectral resolution, and decreased acquisition time and hence cost of NMR analysis. Two NMR techniques were used, the standard cross polarization (CP) technique and Bloch decay (BD). The BD technique had not been applied previously to the analysis of sewage sludge. For each sludge sample, both before and after HF treatment, the BD spectrum contained significantly more alkyl carbon. Spin counting, another technique applied to sewage sludge here for the first time, showed that the BD spectra of the HF-treated sludges were quantitative, while approximately 30% of the CP NMR signal went undetected. The discrepancy between CP and BD spectra was attributed to the presence of alkyl carbon with such high molecular mobility that the efficiency of cross polarization is affected. This study shows that sewage sludge organic matter is significantly different in chemistry to soil organic matter and has implications for the application of sewage sludge to agricultural land.     

Microbial reduction of hexavalent chromium under vadose zone conditions

Hexavalent chromium [Cr(VI)] is a common contaminant associated with nuclear reactors and fuel processing. Improper disposal at facilities in and and semiarid regions has contaminated underlying vadose zones and aquifers. The objectives of this study were to assess the potential for immobilizing Cr(VI) using a native microbial community to reduce soluble Cr(VI) to insoluble Cr(III) under conditions similar to those in the vadose zone, and to evaluate the potential for enhancing biological Cr(VI) reduction through nutrient addition. Batch microcosm and unsaturated flow column experiments were performed. Native microbial communities in subsurface sediments with no prior Cr(VI) exposure were shown to be capable of Cr(VI) reduction. In both the batch and column experiments, Cr(VI) reduction and loss from the aqueous phase were enhanced by adding high levels of both nitrate (NO3-) and organic C (molasses). Nutrient amendments resulted in up to 87% reduction of the initial 67 mg L(-1) Cr(VI) in an unsaturated batch experiment. Molasses and nitrate additions to 15 cm long unsaturated flow columns receiving 65 mg L(-1) Cr(VI) resulted in microbially mediated reduction and immobilization of 10% of the Cr during a 45-d experiment. All of the immobilized Cr was in the form of Cr(III), as shown by XANES analysis. This suggests that biostimulation of microbial Cr(VI) reduction in vadose zones by nutrient amendment is a promising strategy, and that immobilization of close to 100% of Cr contamination could be achieved in a thick vadose zone with longer flow paths and longer contact times than in this experiment.     

Enhancement of amniocyte growth on a precoated surface

This study investigates whether cell-free amniotic fluid facilitates cell attachment to the surface of culture plates and thereby promotes rapid amniocyte growth. Isolated or pooled cell-free amniotic fluid samples at different volumes were added to culture plates. Trypsinized subcultures, grown in Eagle's minimum essential alpha medium supplemented with fetal bovine serum (4–20 per cent), were monitored by cell counts. The results demonstrated growth stimulation on culture plates precoated with amniotic fluid. The minimal time for coating the culture plates was 6h. Maximal coating was observed after an overnight incubation with 2–3 ml of the fluid per culture vessel. No synergistic effect from addition of fetal bovine serum to amniotic fluid was observed. A freshly coated surface provided the best amniocyte growth. When primary cultures are grown on a precoated surface, there is an increase in colony counts in 80 per cent of the samples tested. This method may be used to improve amniocyte growth, especially in samples with relatively small numbers of cells.     

20th-century urban landslides in the Basilicata region of Italy

The geology, relief, neotectonics, climate, and vegetation of Basilicata make the region vulnerable to landslides, but the number of reported landslides in the region has increased over recent centuries, and this has been interpreted as a result of changes in land use. This interpretation is confirmed by documentary evidence presented in this article (concentrating on the example of the town of Grassano, where urban landslides are an almost exclusively 20th-century phenomenon), which shows the increase in landslides to have been real, rapid, and caused by humankind.     

Size and composition distribution of airborne particulate matter in northern California: I--particulate mass, carbon, and water-soluble ions

The San Joaquin Valley (SJV) in California has one of the most severe particulate air quality problems in the United States during the winter season. In the current study, measurements of particulate matter (PM) smaller than 10 microm in aerodynamic diameter (PM10), fine particles (PM18), and ultrafine particles (PM0.1) made during the period December 16, 2000-February 3, 2001, at six locations near or within the SJV are discussed: Bodega Bay, Davis, Sacramento, Modesto, Bakersfield, and Sequoia National Park. Airborne PM1.8 concentrations at the most heavily polluted site (Bakersfield) increased from 20 to 172 microg/m3 during the period December 16, 2000-January 7, 2001. The majority of the fine particle mass was ammonium nitrate driven by an excess of gas-phase ammonia. Peak PM0.1 concentrations (8-12 hr average) were approximately 2.4 microg/m3 measured at night in Sacramento and Bakersfield. Ultrafine particle concentrations were distinctly diurnal, with daytime concentrations approximately 50% lower than nighttime concentrations. PMO.1 concentrations did not accumulate during the multiweek stagnation period; rather, PMO.1 mass decreased at Bakersfield as PM1.8 mass was increasing. The majority of the ultrafine particle mass was associated with carbonaceous material. The high concentrations of ultrafine particles in the SJV pose a potential serious public health threat that should be addressed.     

Ambient air analysis round robin

A laboratory intercomparison study was carried out to determine the current capability of Canadian laboratories for the analysis of dioxins and furans in ambient air. Seven laboratories (government and private) participated in the analysis of exposed foam/filter samples, ambient air extracts and standard mixtures. The results indicated that a number of laboratories were capable of the aforementioned analyses; however, further analytical methodology development is also required.     

Detection and attribution of lake-level dynamics in north-eastern central Europe in recent decades

The lake-rich glacial landscapes of north-eastern central Europe play an important role in the preservation and use of water resources, including protection of biodiversity, carbon storage and promotion of tourism. With a view to the last c. 20 years and the future, a regional ‘syndrome of water shortage’ has been frequently stated, which impairs particularly peatlands, flowing waters and lakes. Accordingly, the overall question addressed in this study is: What can regional and local gauging records tell us about decadal hydrological changes of lakes and their catchments? In the study area, most of the gauging records of lakes begin only in the late 1990s. Forty-five lake-level records were analysed by hierarchical agglomerative clustering, looking for the trend in the 1999–2008 time window. The analyses show that lake levels had varying dynamics, namely a negative, unclear or even a positive trend. The proportional shares of these three groups are 23 (51 %) to 15 (34 %) to 7 lakes (15 %), respectively. In group 1, largely groundwater-fed lakes, lake-level changes depend on groundwater-level changes. These are controlled by decreasing groundwater recharge in the catchments, which are caused by specific seasonal weather conditions in the observation period, and the impact of the dominating pine forests, which consume high quantities of water. In group 2, mainly stream lakes, direct human impact drives the lake levels through the management of weirs and ground sills. Nearly all lakes in group 3, consisting of river, stream and spring lakes, were subject to impoundment measures initiated by local rewetting projects. Thus, an important finding with respect to the impact of climate and land use is the fact that the (‘natural’) lakes of the region, primarily fed by groundwater and precipitation, show a predominantly negative lake-level trend in the period studied. Beyond the 10-year-time window analysed, further regional data show that periodic lake-level fluctuations with amplitudes of c. 1–2(–3) m are characteristic for regional groundwater-fed lakes.