Sodium thiosulfate (Na2S2O3) has been tested in a pilot plant as an oxidation inhibitor in flue gas desulfurization by lime and limestone slurry scrubbing with and without MgO and adiplc acid additives. The effectiveness of thiosulfate is proportional to the inhibitor product, defined as the product of thiosulfate concentration (M), calcium concentration (M), and the moles of SO2 absorbed per hour per liter of hold tank volume. Gypsum saturation was less than 100 percent and scaling was eliminated when the inhibitor product exceeded 0.3 × 10−6(gmol/L)3/h. Thiosulfate was relatively more effective in systems with chlorides and less effective in systems promoted by MgO. An inhibitor product greater than 10−6(gmol/L)3/h significantly enhanced dewatering of solids from limestone scrubbing. SO2 removal and/or limestone utilization were increased in systems that started with less than 10 mM dissolved calcium.
The nonnative brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), has become an abundant pest of mid-Atlantic soybean since its introduction in the mid-1990s. Currently, there is little information indicating how this new pest should be managed in soybean or if economic thresholds developed for native stink bugs should be adjusted. In 2010 and 2011, field cage studies were conducted in Beltsville, MD, and Suffolk, VA, to evaluate H. halys injury to three different soybean reproductive development stages. Cages were infested for 2 wk using densities of zero, one, two, four, or eight stink bugs (fifth instars and adults) per 0.3 row-m. Cage plots were harvested, and subsamples were taken to determine pod losses and seed quality. Feeding injury to soybean caused by H. halys was similar to that of native stink bugs, as evidenced by seed destruction, punctures, and destroyed pods. Densities of four stink bugs per 0.3 row-m resulted in significant seed damage in three of four experiments. The full flowering (R2) soybean development stage was least affected by H. halys feeding. The full pod (R4) and the full seed (R6) stage were similarly sensitive to injury. There was no significant yield loss was associated with stink bug densities at either location, although there were significant differences among stages in two of four experiments. The data do not indicate that threshold densities for H. halys should be different than for the native stink bugs.
Stink bugs (Hemiptera: Pentatomidae) are suspected to change their intraplant vertical distribution in response to changes in environmental conditions. As a result, this could influence sweep-net sampling efficiency in a soybean canopy. We examined the effects of both ambient and within-soybean canopy temperature and relative humidity on stink bug vertical distribution in 2 0.38m row spaced commercial soybean fields with full canopies in Virginia, one in 2010 and one in 2011. Temperature and relative humidity were monitored in the upper and lower plant canopy. The within-canopy vertical distribution of a minimum of 20 stink bugs was documented at each of 4 different observation times: observations were replicated on different days 14 times in the morning, 14 around noon, 15 during the midafternoon, and 5 observations were replicated in the early evening. Chinavia hilaris Say was the primary species observed with 88% of the total in 2010 and 59% in 2011; the remainder was primarily Euschistus servus Say. No significant relationship was observed between the environmental parameters measured or time of day on the vertical distribution of stink bugs in the canopy. Regardless of environmental conditions, an average of 15 - 20% of stink bugs was located below the typical 38cm zone of a sweep net sampling. Efficiency of sweep net sampling for stink bugs in soybean did not appear to be significantly affected by changes in temperature, relative humidity, or time of day, and sweep netting the upper canopy accessed approximately 80% of the total population.
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