Hawaiian Residents’ Preferences for Miconia Control Program Attributes Using Conjoint Choice Experiment and Latent Class Analysis

Invasive species control or eradication is an important issue. On the islands of Hawaii, this problem is exceedingly evident when it comes to Miconia calvescens (Miconia). Adequate funding is needed to control or eradicate this invasive plant, but with the limited amount of funding available for the fight against Miconia, it is important to make sure that the fund is being spent in a way that addresses the needs or preferences of the Hawaiian residents. Using the conjoint choice experiment method, we designed a survey that would measure the Hawaiian residents’ willingness to support Miconia control program attributes. The attributes focused on were cost, biodiversity loss, extent of spread and soil erosion. Latent class approach was used to assess the surveyed population to see the different preferences by individual classes. The results show three different classes or groups of individuals with varying preferences for a control program of which cost and erosion were the top preferred attributes among the classes. These groups were defined by their socio-demographics of income, the length of residency and exposure to farming/gardening activities. Even with a preference for lower cost, a group showed willingness to pay more ($2.40) for a program that reduces erosion from high to low. Finally, the biodiversity attribute had very low consideration from a majority of the respondents showing the need for educating the public regarding its importance in preserving the unique environment in Hawaii.     

The influence of socioeconomic, environmental, and demographic factors on municipality-scale land-cover change in Mexico

Land-cover change is the result of complex multi-scale interactions between socioeconomic, demographic, and environmental factors. Demographic change, in particular, is thought to be a major driver of forest change. Most studies have evaluated these interactions at the regional or the national level, but few studies have evaluated these dynamics across multiple spatial scales within a country. In this study, we evaluated the effect of demographic, environmental, and socioeconomic variables on land-cover change between 2001 and 2010 for all Mexican municipalities (n?=?2,443) as well as by biome (n?=?4). We used a land-cover classification based on 250-m MODIS data to examine the change in cover classes (i.e., woody, mixed woody, and agriculture/herbaceous vegetation). We evaluated the trends of land-cover change and identified the major factors correlated with woody vegetation change in Mexico. At the national scale, the variation in woody vegetation was best explained by environmental variables, particularly precipitation; municipalities where woody cover increased tended to be in areas with low average annual precipitation (i.e., desert and dry forest biomes). Demographic variables did not contribute much to the model at the national scale. Elevation, temperature, and population density explained the change in woody cover when municipalities were grouped by biome (i.e., moist forest, dry forest, coniferous forest, and deserts). Land-cover change at the biome level showed two main trends: (1) the tropical moist biome lost woody vegetation to agriculture and herbaceous vegetation, and (2) the desert biome increased in woody vegetation within more open-canopy shrublands.     

Relationship of Destruction Parameters to the Destruction/Removal Efficiency of PCBs

The destruction/removal efficiency (DRE), and the ability to accurately measure it, is a function of the concentration of the chemical compound in the input waste, the incinerator design and operation, sampling methods, and the analytical procedures. All of these are interrelated. This paper discusses the basic DRE equation [DRE = W_In W_out)/W_in × 100] and how it relates to some of the other destruction parameters. Some example data from the literature are presented. While PCBs have been used as the example, the equations and graphs are equally valid for some other hazardous compounds (POHCs), with the substitution of the 99.99% DRE requirement in lieu of the 99.9999% DRE for PCBs. The use of the relationships discussed in this paper should allow incinerator operators to more efficiently plan demonstration test burns which will adequately demonstrate the DRE.     

Numerical Simulation of the Thermal Destruction of Some Chlorinated C1 and C2 Hydrocarbons

We have numerically modeled the breakdown of small quantities of several chlorinated hydrocarbons (CH₃CI, CH₂CI₂, CHCI₃, CCI₄, C₂H₃CI, and C₂H₅CI) in a lean mixture of combustion products between 800 and 1480 K. This simulates the fate of poorly atomized waste in a liquid-Injection Incinerator. Kinetics calculations were performed using the CHEMKIN and SENKIN programs, with a reaction mechanism that was developed at Louisiana State University to model flat-flame burner experiments.

A 99.99-percent destruction efficiency was attained In one second at temperatures ranging from 1280 to 960 K, with CCI4 requiring the highest temperature for destruction and C₂H₅CI the lowest. For all compounds except C₂H₅CI, there was a range of temperatures at which byproducts accounted for several percent of the elemental chlorine at the outlet. The more heavily chlorinated compounds formed more byproducts even though the amount of elemental chlorine was the same in all cases. The sensitivity of results to residence time, equivalence ratio, temperature profile, and the presence of additional chlorine, was examined for the case of CHCI₃.     

Developmental toxicity of two common corn pesticides to the endangered southern bell frog (Litoria raniformis)

To examine the link between corn agriculture and the observed decline of the endangered southern bell frog (SBF), the effects of two corn crop pesticides on larval growth and development were investigated. Tadpoles were exposed to terbufos sulfone (10 μg/L), a major breakdown product of the insecticide terbufos, and the herbicide atrazine (25 μg/L) individually and as a mixture until the completion of metamorphosis. Atrazine did not interact synergistically with terbufos sulfone or result in significant effects on growth and development alone, although there was some indication of accelerated metamorphosis in the pilot study. Terbufos sulfone alone and as a mixture (terbufos/atrazine) significantly slowed larval development and ultimately delayed metamorphosis. The observed developmental effects from an environmentally relevant concentration of terbufos sulfone indicates a risk posed by this persistent degradation product to the endangered SBF, which breeds and develops in the rice bays adjacent to corn fields treated with pesticides.     

Is the reproduction of Donax trunculus affected by their sites of origin contrasted by their level of contamination?

The reproductive cycle of bivalves is regulated by several natural environmental factors but exposure to chemical pollutants can also interfere and may result in advanced or delayed spawning season. To our knowledge, the gametogenic cycle of the suspension-feeder bivalve Donax trunculus has not yet been used as biomonitoring tool in ecotoxicological surveys. The aim of this study was to examine over a year physiological reproductive endpoints (sex-ratio, gametogenic and energy reserve cycles) and biological indices (condition index, allometry) in D. trunculus originating from two sites differing by their level of contamination. Specimens were collected bimonthly from November 2008 to October 2009 from a polluted site (Radès Méliane) and a comparatively reference site (Sidi Jehmi) in the Gulf of Tunis (Tunisia). Five stages were depicted by histological examination of gonads: undifferentiated, developing, mature, spawn and spent. Differences in the gametogenic cycle according to the site of origin of bivalves were observed. The spawning period began in March and was maximum in May in bivalves from both sites, but the percentage of spawning animals was higher in the polluted site vs the reference site. The spawning period was shorter in animals from the polluted site comparatively to the reference site. Energy reserves (glycogen, lipids) were higher in March and May comparatively to the other studied periods in bivalves from both sites. Lower energy reserves levels were usually observed in animals from the polluted site compared to the reference site. Seasonal variations of the condition index were associated to the reproductive and nutritive status of bivalves. Differences in allometry were depicted between bivalves from both studied sites. If we try to link allometry, energy reserves and reproduction, it can be hypothesized that for bivalves from the reference site, energy reserves are allocated to gametogenesis and length growth. For bivalves from the polluted site, energy reserves could be devoted to tolerance to chemical stress and to reproductive processes. Therefore, D. trunculus appears as a suitable sentinel species for the assessment of the ecotoxicological risk of contaminants such as endocrine disruptors.