Plant-Microbe Interactions Drive Denitrification Rates, Dissolved Nitrogen Removal, and the Abundance of Denitrification Genes in Stormwater Control Measures.

The microbial community and function along with nitrate/nitrite (NOx) removal rates, and nitrogen (N) partitioning into "uptake", "denitrification", and "remaining" via isotope tracers, were studied in soil bioretention mesocolumns (8 unique plant species). Total denitrification gene reads per million (rpm) were positively correlated with % denitrified ( r = 0.69) but negatively correlated with total NOx removal following simulated rain events ( r = -0.79). This is likely due to plant-microbe interactions. Plant species with greater root volume, plant and microbial assimilation %, and NOx removal % had lower denitrification genes and rates. This implies that although microorganisms have access to N, advantageous functions, like denitrification, may not increase. At the conclusion of the 1.5-year experiment, the microbial community was strongly influenced by plant species within the Top zone dominated by plant roots, and the presence or absence of a saturated zone influenced the microbial community within the Bottom zone. Leptospermum continentale was an outlier from the other plants and had much lower denitrification gene rpm (average 228) compared to the other species (range: 277 to 413). The antimicrobial properties and large root volume of Leptospermum continentale likely caused this denitrification gene depression.

Is bigger better? Driving factors of POTW performance in New York.

Like many regions around the world, New York State, USA, faces challenges in meeting wastewater treatment quality standards because of aging infrastructure, limited funding, shifting demographics and increasingly stringent environmental regulations. In recent decades construction of new wastewater treatment and distribution infrastructure in NY has most often occurred in exurban communities and suburban developments that are less dense than traditional urban cores. Here, we examine the role of size and capacity utilization on wastewater treatment effectiveness with respect to critical effluent parameters, and additionally explore which common facility engineering controls influence water quality treatment using a unique dataset of descriptive information. Our results challenge conventional wisdom, suggesting that the largest facilities (>30,000 m3/d), not the smallest (<300 m3/d), discharge TSS, BOD, and coliform at significantly higher relative effluent concentrations (i.e., the ratio of discharged concentrations to allowable limits). Capacity utilization was also positively correlated to higher concentrations of TSS, BOD, and coliform effluent concentrations in larger facilities, though those concentrations were often within regulated limits. This implies that smaller-sized facilities may perform better in terms of environmental quality, but that the largest facilities demonstrate efficiency in the sense that they are not "over-treating" wastewater while avoiding violations. Results from NY suggest that medium sized facilities (300-30,000 m3/d) are sophisticated enough to incorporate appropriate unit processes, and employ operators with sufficient training and oversight, to reach treatment outcomes that are both reliable and of high quality.

The Role of Denitrification in Stormwater Detention Basin Treatment of Nitrogen.

The nitrogen (N) cycling dynamics of four stormwater basins, two often saturated sites ("Wet Basins") and two quick draining sites ("Dry Basins"), were monitored over a ∼ 1-year period. This study paired stormwater and greenhouse gas monitoring with microbial analyses to elucidate the mechanisms controlling N treatment. Annual dissolved inorganic N (DIN) mass reductions (inflow minus outflow) were greater in the Dry Basin than in the Wet Basin, 2.16 vs 0.75 g N m-2 yr-1, respectively. The Dry Basin infiltrated a much larger volume of water and thus had greater DIN mass reductions, even though incoming and outgoing DIN concentrations were statistically the same for both sites. Wet Basins had higher proportions of denitrification genes and potential denitrification rates. The Wet Basin was capable of denitrifying 58% of incoming DIN, whereas the Dry Basin only denitrified 1%. These results emphasize the need for more mechanistic attention to basin design because the reductions calculated by comparing inflow and outflow loads may not be relevant at watershed scales. Denitrification is the only way to fully remove DIN from the terrestrial environment and receiving waterbodies. Consequently, at the watershed scale the Wet Basin may have better overall DIN treatment.

Roadside soils show low plant available zinc and copper concentrations.

Vehicle combustion and component wear are a major source of metal contamination in the environment, which could be especially concerning where road ditches are actively farmed. The objective of this study was to assess how site variables, namely age, traffic (vehicles day(-1)), and percent carbon (%C) affect metal accumulation in roadside soils. A soil chronosequence was established with sites ranging from 3 to 37 years old and bioavailable, or mobile, concentrations of Zinc (Zn) and Copper (Cu) were measured along major highways in North Carolina using a Mehlich III extraction. Mobile Zn and Cu concentrations were low overall, and when results were scaled via literature values to "total metal", the results were still generally lower than previous roadside studies. This could indicate farming on lands near roads would pose a low plant toxicity risk. Zinc and Cu were not correlated with annual average traffic count, but were positively correlated with lifetime traffic load (the product of site age and traffic count). This study shows an often overlooked variable, site age, should be included when considering roadside pollution accumulation. Zinc and Cu were more strongly associated with %C, than traffic load. Because vehicle combustion is also a carbon source, it is not obvious whether the metals and carbon are simply co-accumulating or whether the soil carbon in roadside soils may facilitate previously overlooked roles in sequestering metals on-site.

Move More Diabetes: using Lay Health Educators to support physical activity in a community-based chronic disease self-management program.

PURPOSE: The purpose of this article is to describe Move More Diabetes (MMD), which is used by Lay Health Educators (LHEs) to promote physical activity and improve diabetes self-management among individuals with type 2 diabetes. METHODS: Move More Diabetes used social marketing strategies to choose and segment the target audience, develop messages, and determine message delivery. Based on market research results, MMD chose natural peer support from LHEs as the main intervention strategy. RESULTS: Move More Diabetes built a sustainable volunteer network of 35 LHEs who recorded 1500 contacts with enrollees from 2004 to 2006. Participation improved when the program was not specific for diabetes. CONCLUSION: The MMD program demonstrated benefits of partnership and natural peer support and the utility of social marketing in planning and implementing a community-based chronic disease self-management and physical activity promotion program. This low-cost program can serve as a model for other rural communities interested in increasing physical activity to address chronic disease.