Influence of Sediments on Concentrations of Fluridone and Penoxsulam in the Water Column and Sediment Pore Water.

Control of invasive aquatic plants is crucial for the maintenance of chemical, biological and ecological balances in many fresh water systems. Exposure of invasive plants to herbicides used for their control may be reduced by sorption to organic matter in sediments. Since granular herbicide formulations have closer contact with sediments (compared to liquid formulations), concentrations in the water column may be much lower. To test this hypothesis, microcosms containing sediments with < 1%, 6.4%, 19.7%, and 44% organic matter were treated with liquid and granular formulations of fluridone and penoxsulam. Herbicide concentrations in the water column and sediment pore water were monitored over 40 days. The presence of sediments (regardless of organic carbon content) significantly reduced concentrations of fluridone in the water column from the granular formulations relative to the liquid formulation. A similar, though less extreme, pattern was observed for penoxsulam in most of the organic carbon treatments.

Class and ambition in the status attainment process: A Spanish replication.

There are two principal theoretical schools that seek to explain status outcomes in early adulthood: those focusing on intergenerational transmission of class privilege and those emphasizing individual characteristics, particularly ambition. The first may be called the structuralist school and the second the psycho-social school, following the Wisconsin Model of Status Attainment. A second structuralist perspective, Segmented Assimilation, highlights transmission of socio-economic status across immigrant generations, but emphasizes the positive role of co-ethnic resources for upward mobility and preventing downward assimilation. We examine these alternative predictions using a large longitudinal sample of youths in Spain that includes both children of native parentage and children of immigrants. Spain possesses characteristics that make it uniquely suitable to examine these predictions. Results show that both family socio-economic status and ambition, measured by adolescent educational aspirations and expectations, play important roles in educational and occupational attainment, but the influence of family status persists even after controlling for ambition. The influence of co-ethnic nationalities disappears after these controls, except among Chinese and Filipino youths, a result consistent with segmented assimilation. Predictive models of status attainment yield identical results for children of immigrants and children of natives, indicating that in Spain, they have become part of a common youth universe. Theoretical and practical implications of the analysis are discussed.

Neighborhood environments and self-rated health in Mainland China, Japan and South Korea.

Neighborhood environments are considered crucial determinants of self-rated health. Previous research has documented a positive association between the quality of neighborhood environments and health status. However, the relationship between neighborhood environments and health status in East Asian countries has received far less attention. This study examined the relationship between the three main types of neighborhood environments (built, natural, and social) and self-rated health in Mainland China, Japan, and South Korea. It also compared the neighborhood effects on self-rated health across the three countries. Our analytical sample included 3,675, 2,390, and 1,500 respondents in China, Japan, and South Korea respectively from the 2010 East Asian Social Survey. Ordinal Logistic Regression models were estimated for each country and the country differences were tested. This study found that neighborhood built, natural and social environments are positively associated with self-rated health in China, Japan and South Korea. These effects vary somewhat by country, and neighborhood social environment has the strongest association with self-rated health in Japan, followed by South Korea and then China. The similar relationship between perceived neighborhood environments and self-rated health across the three countries underscores the prevalent impact of perceived neighborhood environments on health. The greater association between social environment and self-rated health in Japan suggests the greater need of community based support system in an aging society not only for the older people, but also for the general population, especially those who are living in poor neighborhood social environment.

Dreaming in Spain: Parental Determinants of Immigrant Children's Ambition.

We examine determinants of educational and occupational aspirations and expectations among children of immigrants in Spain on the basis of a unique data set that includes statistically representative data for foreign-origin secondary students in Madrid and Barcelona plus a sample of one-fourth of their parents. Independently collected data for both generations allow us to establish effects of parental characteristics on children's orientations without the confounding potential inherent in children's reports about parents. We analyze first determinants of parental ambition and, through a series of step-wise regressions, the effects of these goals and other parental and family characteristics on children's aspirations and expectations. A structural equations model synthesizes results of the analysis. The model confirms predictions from the research literature, especially those based on the Wisconsin status attainment model, but rejects others, including the predicted significance of private vs. public school attendance. Parental ambition, knowledge of Spanish by parents and children, gender, and children's age are major determinants of youths' educational and occupational goals. These results have direct implications for policy; these are discussed in the conclusion.

Dreams Fulfilled and Shattered: Determinants of Segmented Assimilation in the Second Generation.

We summarize prior theories on the adaptation process of the contemporary immigrant second generation as a prelude to presenting additive and interactive models showing the impact of family variables, school contexts and academic outcomes on the process. For this purpose, we regress indicators of educational and occupational achievement in early adulthood on predictors measured three and six years earlier. The Children of Immigrants Longitudinal Study (CILS), used for the analysis, allows us to establish a clear temporal order among exogenous predictors and the two dependent variables. We also construct a Downward Assimilation Index (DAI), based on six indicators and regress it on the same set of predictors. Results confirm a pattern of segmented assimilation in the second generation, with a significant proportion of the sample experiencing downward assimilation. Predictors of the latter are the obverse of those of educational and occupational achievement. Significant interaction effects emerge between these predictors and early school contexts, defined by different class and racial compositions. Implications of these results for theory and policy are examined.

Moving Ahead in Madrid: Aspirations and Expectations in the Spanish Second Generation.

This paper examines determinants of aspirations and expectations among children of immigrants based on a statistically representative sample of 3,375 second generation youths interviewed in 101 public and private secondary schools in metropolitan Madrid. We review the past literature on status attainment in general and aspirations and expectations, in particular, and draw from it a set of six hypotheses to guide the analysis. Most theoretical statements in this field have been developed on the basis of U.S. data; studies in other immigrant-receiving countries, especially outside the Anglophone world, have been scarce. The study thus provides an opportunity to test and refine existing hypotheses in a different national context. We present breakdowns of educational and occupational aspirations and expectations by gender, parental education and type of school attended. This is followed by multivariate regressions of all four dependent variables on these three plus other predictors suggested by the research literature. This analysis ends with structural equation models - recursive and non-recursive - that provide an integrated theoretical statement of the causal structure of ambition in the Spanish context. Implications of our findings for theory and policy are examined. Suggestions for future research in this field are discussed.

The Adaptation of the Immigrant Second Generation in America: Theoretical Overview and Recent Evidence.

This paper summarises a research program on the new immigrant second generation initiated in the early 1990s and completed in 2006. The four field waves of the Children of Immigrants Longitudinal Study (CILS) are described and the main theoretical models emerging from it are presented and graphically summarised. After considering critical views of this theory, we present the most recent results from this longitudinal research program in the forum of quantitative models predicting downward assimilation in early adulthood and qualitative interviews identifying ways to escape it by disadvantaged children of immigrants. Quantitative results strongly support the predicted effects of exogenous variables identified by segmented assimilation theory and identify the intervening factors during adolescence that mediate their influence on adult outcomes. Qualitative evidence gathered during the last stage of the study points to three factors that can lead to exceptional educational achievement among disadvantaged youths. All three indicate the positive influence of selective acculturation. Implications of these findings for theory and policy are discussed.

Toxicity of 19 adjuvants to juvenile Lepomis macrochirus (bluegill sunfish).

Nineteen adjuvants, many used as surfactants for aquatic herbicide applications, were applied in static bioassay to bluegill sunfish (Lepomis macrochirus) for 96 h to determine median lethal concentrations (LC50). Surfactants are added to the tank mix as a percentage (v/v) of the total volume, in contrast to herbicide application rates, which are usually expressed in kilograms per hectare. Two ethoxylated tallow amine products were the most toxic, having LC50 values of 1.6 and 2.9 ppm (all values v/v). Seven alcohol/glycol-based surfactants had 96-h LC50 values of 4.0 to 11.6 ppm (mean = 7.9 ppm). The polysiloxane- or silicone-based surfactants had toxicities of 18.1 to 29.7 ppm (mean = 24.7). Two limonene-based products had LC50 values of 10.2 and 30.2 ppm. A methylated seed oil with emulsifier had a LC50 of 53.1 ppm. Two acid/buffer utility adjuvants had LC50 values of 60.8 and 221 ppm. To compare the relative safety of the tested surfactants, we assumed maximum label rate applications to 1 m deep water with uniform mixing. This comparison of relative safety is based on mortality to 50% of the test organisms and does not imply application rates that would not result in any mortality. The two ethoxylated tallow amines, neither used or recommended for aquatic applications, had a relative safety factor of 12.6 or less. Relative safety factor varied from 6.2 to 20.4 for the seven alcohol/glycol surfactants, 38.4 to 63.2 for silicone-based products, 5.5 to 16.1 for limonene products, 113 for methylated seed oil, and 132.2 to 315.7 for acid/buffer utility adjuvants. When used according to label recommendations under normal use conditions, these adjuvants should not be present in acutely toxic concentrations; however, the most toxic adjuvants in very shallow water (< 10 cm) would be toxic to bluegill sunfish that did not move to deeper water to avoid lethal concentrations.

Dissipation of triclopyr herbicide applied in Lake Minnetonka, MN concurrently with Rhodamine WT dye.

Fluorescent dye was applied concurrently with triclopyr in two 6.5-ha treatment plots in Lake Minnetonka, MN for data collection to support full aquatic registration of this herbicide. The herbicide and dye mixture was applied by airboat to Phelps Bay with weighted, trailing hoses to maximize uniform distribution of these materials in the water column. A surface application was made to the Carsons Bay plot to attain theoretical triclopyr and dye concentrations of 2500 and 10 micrograms litre-1, respectively. Water samples collected at various times following application showed very little movement of the herbicide and dye out of the Carsons Bay plot. Triclopyr residues moved to a greater extent out of the Phelps Bay plot. The dye was easily tracked in real-time using field fluorometers, which allowed new sampling stations to be established to monitor this movement. Dye concentrations were strongly correlated to herbicide concentrations (r2 = 0.97 in both plots) but were less predictive of the triclopyr metabolite 3,5,6-trichloropyridinol (TCP; r2 = 0.82 in Phelps and r2 = 0.73 in Carsons), probably due to its differential metabolism and degradation. The inert dye can be used to compare the dissipation of herbicide residues by dilution versus microbial or other breakdown processes. Vertical sampling of dye in the water column showed that surface applications of aquatic herbicides can delay uniform mixing in the water column by several days. Although the dye aided the tracking of residues outside the treatment areas, predetermined sampling times and stations were still needed if very low concentrations of herbicide were to be detected at times and stations where the dye had been diluted below its limit of detection.