Predictive abilities of numerical sediment quality guidelines in Sydney Harbour, Australia, and vicinity

Matching chemical and toxicological data of surficial sediments from Sydney Harbour, Australia, and vicinity, were collected to evaluate predictive abilities of Effects Range-Low (ERL), Effects Range-Median (ERM) and other sediment quality guidelines (SQGs). Samples (n=103) containing a wide range of chemicals and concentrations were subjected to a battery of 4-6 toxicity tests. ERLs and functionally equivalent low-range SQGs were highly predictive of non-toxicity when not exceeded, as incidences of toxicity were 0-8%. ERMs and other mid-range SQGs were predictive of toxicity in combined test data with > or = 80% of toxic samples with one or more SQG exceeded. Predictive abilities of mid-range SQGs were low for amphipod survival tests (generally < 20% toxic samples), but the incidence of toxicity increased with increasing numbers of SQGs exceeded and increasing mean SQG quotients. Predictive abilities of SQGs generally matched their narrative intent when outcomes of multiple toxicity tests were considered, and were consistent with North American data. Functionally equivalent SQGs gave comparable results (except where developed for single chemical classes), indicating that predictive abilities were primarily influenced by sensitivities of test species and/or the bioavailability of contaminants.     

Variations in stream water and sediment phosphorus among select Ozark catchments

Stream sediments play a large role in the transport and fate of soluble reactive phosphorus (SRP) in stream ecosystems, and equilibrium P concentrations (EPC 0) of benthic sediments at which P is neither adsorbed nor desorbed are often related to stream water SRP concentrations. This study evaluated (i) the variation among water chemistry and sediment-P interactions among streams draining catchments that varied in the land use; (ii) the relations between SRP concentration, sediment EPC 0, and other measured abiotic factors (e.g., particle size distribution, slope of linear sorption isotherms, etc.) in the stream sediments; and (iii) the use of the traditional Mehlich-3 (M3) soil extraction on stream sediments to elucidate other abiotic factors (e.g, M3P, P saturation ratio, etc.) related to SRP concentration in stream sediments. Stream water and sediments were sampled at 22 selected Ozark streams in northwest Arkansas during fall 2003 and spring 2004. Nitrate-N concentrations in the water column (r = 0.69) and modified P saturation ratios (PSR mod) ) of the benthic sediments (r = 0.79) at the selected streams increased with an increase in percent pasture in the catchments, whereas SRP concentration (r = -0.56) and Mehlich-3-extractable P (M3P) content (r = -0.47) decreased with an increase in the percent forested area. Soluble reactive P concentrations in the stream water were positively correlated to sediment EPC 0 (r = 0.51), although sediment EPC(0) was generally greater than SRP. The M3 soil extraction was useful in identifying abiotic factors related to SRP concentrations in the selected streams, in particular SRP concentrations were positively correlated to M3P contents (r = 0.50) and PSR mod (r = 0.71) of the benthic sediments. Thus, M3P and EPC 0 estimates from stream sediments may be valuable yet simple indicators of whether benthic sediments act as sinks or sources of P in fluvial systems, as well as estimating changes in stream SRP concentrations.     

Factors influencing the concentration of volatile fatty acids, ammonia, and other nutrients in stored liquid pig manure

In order to minimize odor and manage nutrients in liquid pig manure we need to be able to predict what operational practices most influence the concentrations of volatile fatty acids (VFAs), ammonium nitrogen (NH(4)(+)-N), and other nutrients present in the manure. To determine this, we collected manure from 15 pig operations in southwestern Ontario in the fall of 2001 and 2002 and spring of 2002 and 2003. The manure was stored in concrete tanks at all operations. Manure from finishing pigs had the highest concentration of VFAs, NH(4)(+)-N, and other nutrients, followed by manure from mixed operations, and then manure from sow operations. The average concentration of total VFAs and NH(4)(+)-N in finishing pig manure was 166 mM compared with 36 and 99 mM, respectively, in sow manure. Total N, P, and K were 2.3, 2.5, and 1.7 times greater, respectively, in finishing pig compared with sow manure. There was no seasonal or year to year variation in amount. The diet of the pigs, use of feed additives or antibiotics, location of tanks, and whether the tanks were covered or mixed were not significant factors contributing to the difference in manure chemistry. The main reason for the differences between the three types of manure was manure dilution. The average dry matter content of finishing pig manure was 4.5 times that of sow manure. This was due to larger density of pigs in finishing compared with sow operations, less manure storage capacity per pig for finishing compared with sow operations, and more wash water being used for sow operations.     

Report: Combustion Byproducts and Their Health Effects: Summary of the 10th International Congress

The 10th International Congress on Combustion Byproducts and their Health Effects was held in Ischia, Italy, from June 17-20, 2007. It is sponsored by the US NIEHS, NSF, Coalition for Responsible Waste Incineration (CRWI), and Electric Power Research Institute (EPRI). The congress focused on: the origin, characterization, and health impacts of combustion-generated fine and ultrafine particles; emissions of mercury and dioxins, and the development/application of novel analytical/diagnostic tools. The consensus of the discussion was that particle-associated organics, metals, and persistent free radicals (PFRs) produced by combustion sources are the likely source of the observed health impacts of airborne PM rather than simple physical irritation of the particles. Ultrafine particle-induced oxidative stress is a likely progenitor of the observed health impacts, but important biological and chemical details and possible catalytic cycles remain unresolved. Other key conclusions were: (1) In urban settings, 70% of airborne fine particles are a result of combustion emissions and 50% are due to primary emissions from combustion sources, (2) In addition to soot, combustion produces one, possibly two, classes of nanoparticles with mean diameters of?~10?nm and?~1?nm. (3) The most common metrics used to describe particle toxicity, viz. surface area, sulfate concentration, total carbon, and organic carbon, cannot fully explain observed health impacts, (4) Metals contained in combustion-generated ultrafine and fine particles mediate formation of toxic air pollutants such as PCDD/F and PFRs. (5) The combination of metal-containing nanoparticles, organic carbon compounds, and PFRs can lead to a cycle generating oxidative stress in exposed organisms.     

The treatment of contaminated water at remedial wood preserving sites

Contaminated groundwater and surface water have posed a great challenge in restoring wood preserving sites to beneficial use. Often contaminated groundwater plumes extend far beyond the legal property limits, adversely impacting drinking water supplies and crop lands. To contain, treat, and/or remediate these valuable resources is an important part of restoring these impacted sites. Various options are available for remediating the groundwater and other affected media at these sites. Frequently, pump and treat technologies have been used that can provide well‐head treatment at installed extraction wells. This approach has shown to be costly and excessively time consuming. Some of the technologies used for pump and treat are granular activated carbon (GAC), biotreatment, and chemical oxidation. Other approaches use in‐situ treatment applications that include enhanced bioremediation, monitored natural attenuation (biotic and abiotic), and chemical reduction/fixation. Ultimately, it may only be feasible, economically or practicably, to use hydraulic containment systems. Depending upon site‐specific conditions, these treatment approaches can be used in various combinations to offer the best remedial action. A comparison of water treatment system costs extrapolated from the treatability studies performed on contaminated groundwater from the McCormick/Baxter Superfund site in Stockton, California, yielded operation and maintenance costs of $1.19/1,000 gal. for carbon treatment and $7.53/1,000 gal. for ultraviolet (UV) peroxidation, respectively.     

The Impact of a Change in Collection Frequency on Kerbside Recycling Behaviours

The research monitors the changes in recycling performance indicators arising from halving the collection frequency of a kerbside newspaper collection scheme. The changes in the performance parameters are explained in terms of the underlying behavioural changes that could have occurred within the community. This interpretation is aided by a computer simulation of the kerbside recycling activity of the community. Moving from a 2-week collection to a 4-week collection did not substantially affect the number of households recycling, nor the overall weights collected. A small weight loss, however, may have occurred, from a small minority of households, unable to accommodate the extra storage demand of the new regime. Model predictions were consistent with the observed performance data. It is postulated that the scheme could withstand considerable intervention before significant behavioural changes are induced. It demonstrates that cost-cutting interventions can be undertaken without significantly compromising individual participations. The case-study also highlights the caution needed in the interpretation of the recycling performance indicators themselves.