Assessment of Bioenergy Cropping Scenarios for the Boone River Watershed in North Central Iowa,United States

Several biofuel cropping scenarios were evaluated with an improved version of Soil and Water Assessment Tool (SWAT) as part of the CenUSA Bioenergy consortium for the Boone River Watershed (BRW), which drains about 2,370 km² in north central Iowa. The adoption of corn stover removal, switchgrass, and/or Miscanthus biofuel cropping systems was simulated to assess the impact of cellulosic biofuel production on pollutant losses. The stover removal results indicate removal of 20 or 50% of corn stover in the BRW would have negligible effects on streamflow and relatively minor or negligible effects on sediment and nutrient losses, even on higher sloped cropland. Complete cropland conversion into switchgrass or Miscanthus, resulted in reductions of streamflow, sediment, nitrate, and other pollutants ranging between 23‐99%. The predicted nitrate reductions due to Miscanthus adoption were over two times greater compared to switchgrass, with the largest impacts occurring for tile‐drained cropland. Targeting of switchgrass or Miscanthus on cropland ≥2% slope or ≥7% slope revealed a disproportionate amount of sediment and sediment‐bound nutrient reductions could be obtained by protecting these relatively small areas of higher sloped cropland. Overall, the results indicate that all biofuel cropping systems could be effectively implemented in the BRW, with the most robust approach being corn stover removal adopted on tile‐drained cropland in combination with a perennial biofuel crop on higher sloped landscapes. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Effect of water harvesting on growth of young olive trees in degraded Syrian dryland

Olive (Olea europaea L.) is a drought-tolerant tree which is usually grown in areas with a Mediterranean climate that receive >350 mm of annual rainfall. However, olive growing in Syria has recently expanded into drier areas (200–300 mm annual rainfall) where irrigation resources are limited. This study, carried out between November 2002 and October 2005, aimed to investigate the response of a little known Syrian drought-tolerant olive variety (Qaisi) to water harvesting and limited summer irrigation (200 l per tree) in an arid area (average annual rainfall of 210 mm) with Mediterranean climate in Syria. Soil moisture and growth of four-year-old trees were monitored regularly. Olive leaves were sampled at different stages to determine water content, specific mass, and N content. Stomatal conductance was also measured in 2005. Our results showed that water harvesting and summer irrigation improved soil moisture content, leaf water content (up to 36% higher in Sep. 2003), leaf N content (up to 45% higher in Aug. 2003), leaf stomatal conductance (up to 55% higher in Apr. 2005), and relative trunk growth rate. Water harvesting was most successful in wet years, although the water storage capacity was not enough to retain all harvested water. This study indicated that it is possible to grow drought-tolerant olive varieties in arid areas under little or no irrigation, but proper water and nutrient management should be considered for sustainable growth.     

Relative influence of the dissolved humic material on the solid-phase extraction efficiency of pesticides from environmental water

The effect of organic matter on the solid-phase extraction (SPE) efficiency for pesticides belonging to different chemical groups (urea-derivatives, carbamates and triazines) and having different polarities, was simultaneously studied for the first time in pure and simulated water samples. SPE was carried out in precolumns packed with C18 silica or styrene-divinylbenzene copolymer PLRP-S phases on-line coupled to high performance liquid chromatography (HPLC) analysis. Retention factors in water (k'_W) were estimated for 25 compounds and used for the calculation of the theoretical breakthrough volume (Vb_T) in pure water. Experimental breakthrough volumes (Vb_E) were first determined using purified and deionized water as the matrix for selected compounds having Vb_T < 500 mL; then, the same water with an added humic acid sodium salt (HA) at 0.4–5.6 mg/L of dissolved organic carbon (DOC) content, was used as the matrix for compounds having VbE < 500 mL in pure water. Several polar pesticides showed negative linear or logarithmic Vb_E curves depending on HA content; their recoveries were also determined in environmental samples having low dissolved organic carbon values, between 0.5–6.4 mg/L. A similar behavior was observed for these compounds in simulated and natural water samples, where DOC concentration and the percolated volume (Vp) mainly determine the solute recoveries values. However, the variation of recoveries as a function of DOC content could be negative or null depending on the two examined conditions (Vp lower or larger than Vb_E in pure water). Results demonstrated that breakthrough volume must always be considered to correctly interpret the participation of dissolved humic material on the SPE efficiency of organic micropollutants in water.     

Investigation of source apportioning for α-HCH using enantioselective analysis

Enantiomeric analysis can be used as a complementary tool for source apportionment of chiral compounds, particularly for α-HCH. In this study we used archived samples from studies related to the distribution of POPs in air–water and air–soil–grass systems. Such approach is based on the behaviour of chiral compounds released into the atmosphere from a primary source, when they are expected to show racemic or close to racemic composition. Contrarily, when chiral compounds have been reemitted from secondary sources (e.g. water or soil), their enantiomeric signatures are frequently non-racemic and are similar to the signature of the secondary source. To show such evidence, extracts from passive air samples deployed throughout Europe were analyzed for the enantiomers of α-HCH. The proximity to a large water body showed a high impact on the enantiomeric signatures: Baltic air had enantiomeric fractions (EFs) < 0.500, while Mediterranean air had predominantly EFs > 0.500. Similarly, Atlantic air showed a latitude influence: above 50°N most EFs < 0.500, whereas at latitudes below 50°N, EFs were > 0.500. A similar trend was also observed for EFs of α-HCH measured in air samples from a latitudinal transect during an Atlantic cruise. This transect shows that samples from higher latitudes (above 40°N) have EF < 0.500, whereas in the more southern samples (African coast and Southern Atlantic), there is no clear trend for EFs. Inland air samples showed a large range in EF values, with racemic signatures for samples with the highest α-HCH concentrations and an increasing spread in the EFs for lower α-HCH concentrations. As expected, the EF values of α-HCH in air, soils and grass were also impacted by latitude. Correlations between EFs and geographic characteristics of the sampling locations, as well as α-HCH concentrations, α-/γ-isomer ratios, or temperature suggest that enantioselective analysis can give additional information on the distribution and sources of α-HCH in the environment.     

Methane production potential from anaerobic digestion of plant biomass residues and food waste as substrates

Journal of Material Cycles and Waste Management - This research aimed to evaluate the production of biogas from anaerobic digestion (AD) using swine manure inoculum associated with different...     

Consumption of low-density polyethylene,polypropylene, and polystyrene materials by larvae of the greater wax moth,Galleria mellonella L. (Lepidoptera,Pyralidae), impacts on their ontogeny

Low-density polyethylene (LDPE), biaxially oriented polypropylene (BOPP), and expanded polystyrene (EXPS) are the most common plastics found in every home of the world, but only ~ 10% enter the recycling chains. Consequently, the study of plastic biodegradation by microorganisms and insects, such as the wax moths, has gained special interest. Galleria mellonella (L.) has been shown to consume single-layered polyethylene and polystyrene, though biological impacts of this consumption have been rarely reported. We evaluated the consumption of different plastics by G. mellonella larvae (L7, mean size: 25–30 mm) and its effect on larval duration, survival, and development. For this, we offered the larvae five diets: single-layered LDPE, EXPS, BOPP, triple-layered polyethylene (SB, for silo-bags), and a control with beeswax. We recorded the state and weight of the materials and the state of larvae until they reached the adult stage. Larvae consumed more PE (both LDPE and SB) and EXPS than BOPP; still, they were able to emerge as adults in all treatments. Larvae that consumed plastics turned into pupal stage faster than those that consumed beeswax, regardless of the type and amount of plastic consumed. This is the first report of wild G. mellonella larvae in Argentina consuming biaxially polypropylene and silo-bags.

     

Sulphur isotope mass balance of dissolved sulphate ion in a freshwater dam reservoir

We show that sulphur isotopic composition can be a useful tool to discriminate between various sources of sulphate and a tool for better understanding of the sulphur cycling and mass balance. Our investigations, carried out in a dam reservoir, demonstrate differences in sulphur biogeochemistry between different seasons, caused by recharge water supply in spring and intensive sulphate reduction in summer. In the riverine-affected part of the reservoir δ³⁴S(SO₄ ²⁻) varied from 4.7 to 5.9‰ in spring, and from 4.1 to 4.6‰ in summer. In the lacustrine-affected part δ³⁴S(SO₄²⁻) varied from 4.0 to 5.0‰ in spring, and from 4.5 to 5.4‰ in summer. Diurnal variations of δ³⁴S(SO₄ ²⁻) were negligible as compared to seasonal variations.     

A methodology to determine gaseous emissions in a composting plant

Environmental impacts associated to different waste treatments are of interest in the decision-making process at local, regional and international level. However, all the environmental burdens of an organic waste biological treatment are not always considered. Real data on gaseous emissions released from full-scale composting plants are difficult to obtain. These emissions are related to the composting technology and waste characteristics and therefore, an exhaustive sampling campaign is necessary to obtain representative and reliable data of a single plant. This work proposes a methodology to systematically determine gaseous emissions of a composting plant and presents the results obtained in the application of this methodology to a plant treating source-separated organic fraction of municipal solid waste (OFMSW) for the determination of ammonia and total volatile organic compounds (VOC). Emission factors from the biological treatment process obtained for ammonia and VOC were 3.9 kg Mg OFMSW⁻¹ and 0.206 kg Mg OFMSW⁻¹ respectively. Emissions associated to energy use and production were also quantified (60.5 kg CO₂ Mg OFMSW⁻¹ and 0.66 kg VOC Mg OFMSW⁻¹). Other relevant parameters such as energy and water consumption and amount of rejected waste were also determined. A new functional unit is presented to relate emission factors to the biodegradation efficiency of the composting process and consists in the reduction of the Respiration Index of the treated material. Using this new functional unit, the atmospheric emissions released from a composting plant are directly related to the plant specific efficiency.