Geostatistics as a validation tool for setting ozone standards for durum wheat

Which is the best standard for protecting plants from ozone? To answer this question, we must validate the standards by testing biological responses vs. ambient data in the field. A validation is missing for European and USA standards, because the networks for ozone, meteorology and plant responses are spatially independent. We proposed geostatistics as validation tool, and used durum wheat in central Italy as a test. The standards summarized ozone impact on yield better than hourly averages. Although USA criteria explained ozone-induced yield losses better than European criteria, USA legal level (75 ppb) protected only 39% of sites. European exposure-based standards protected ≥90%. Reducing the USA level to the Canadian 65 ppb or using W126 protected 91% and 97%, respectively. For a no-threshold accumulated stomatal flux, 22 mmol m⁻² was suggested to protect 97% of sites. In a multiple regression, precipitation explained 22% and ozone explained <0.9% of yield variability.     

干法腈纶废水混凝处理研究

针对干法腈纶废水的特点及目前混凝剂产品使用现状,采用无机混凝剂单一与无机/有机混凝剂复配进行混凝实验,确定最佳混凝剂和最佳混凝条件.结果表明:(1)单一无机混凝剂处理干法腈纶废水时,聚合硫酸铁(PFS)的混凝效果要好于其他无机混凝剂.当废水pH为11.03、PFS用量为700 mg/L时,COD去除率达到20.89%,较现有干法腈纶生产厂家普遍采用的混凝处理方法提高了7.89%～10.89%.(2)PFS与聚丙烯酰胺(PAM)复配的混凝效果明显比单一PFS好;PFS与阳离子型PAM复配的混凝效果最好,其最佳用量分别为400、7 mg/L,COD由1 700.00 mg/L降到1 331.44 mg/L,去除率达到21.68%,较现有干法腈纶生产厂家普遍采用的混凝处理方法提高了8.68%～11.68%.     

Long-term perspectives on world metal use—a system-dynamics model

In this paper, a system dynamics model is described, which simulates long-term trends in the production and consumption of metals (i.e. iron/steel and an aggregate of metals of medium abundance) in relation to impacts such as ore-grade decline, capital and energy requirements and waste flows. This metal model can be of assistance in exploring the issue of sustainability of metal resource use. Application of the model to historical trends shows it to be fairly capable of reproducing the long-term trends in the 1900–1990 period, among others on the basis of two intensity of use curves applied to 13 world regions. For future trends, a set of perspective-based long-term scenarios has been constructed that represent the major paradigms in resource use. These scenarios highlight some of the uncertain factors in the relation between economic growth, metal resource exploitation and use, and energy and environmental consequences. They also indicate that apparently similar metal flows in society may be the result of quite different and sometimes contrary assumptions on metal demand, production patterns and resource base characteristics. Such analyses contribute to a more open and transparent discussion on the issue at hand by adding quantitative explications to qualitative views.     

The assessment of electromigration as a new technique to study diffusion of radionuclides in clayey soils

For the performance assessment study of a geological disposal of High Level Waste (HLW) in clayey formations, migration studies are essential. For low permeability soils (clays), classical diffusion studies take a very long time. In order to reduce the experimental time, we propose an electrical field as driving force to accelerate the migration of ionic species. This paper reports the assessment of the electromigration technique as a powerful new and fast technique for migration studies. The apparent molecular diffusion coefficient can be derived by two independent methods using the migration parameters obtained from an electromigration experiment, namely the apparent dispersion coefficient and the apparent convection velocity. First, it can be calculated from the velocity of the migrating species by the Einstein relation. But, corrections are necessary for electroosmotic flow. The apparent electroosmotic mobility is experimentally determined as 2.2·10⁻⁹ m²/Vs. Second, it can be calculated from the relation between the apparent dispersion coefficient and the total apparent convection velocity. But it is necessary to know the dispersion length of the medium. The dispersion length for Boom Clay is experimentally determined as 8·10⁻⁵ m. Because of the serious reduction in time, it becomes possible to run series of experiments at different electrical fields to obtain averaged values for the apparent molecular diffusion coefficient according to the two methods. Experiments at different electrical fields have another advantage: the intercept of the linear relationship between the total apparent convection velocity and the apparent dispersion coefficient gives the apparent molecular diffusion coefficient. The apparent molecular diffusion coefficients obtained for ⁸⁵Sr, ¹³¹I and HTO are respectively 0.8·10⁻¹¹, 15·10⁻¹¹, and 24·10⁻¹¹ m²/s. These values are confirmed by pure diffusion experiments. The excellent agreement with the apparent molecular diffusion coefficients obtained by classical diffusion tests clearly demonstrates the feasibility of the electromigration technique for the determination of diffusion coefficients.     

Changes in aquatic vegetation and floodplain land cover in the Upper Mississippi and Illinois rivers (1989–2000–2010)

Quantifying changes in the cover of river-floodplain systems can provide important insights into the processes that structure these landscapes as well as the potential consequences to the ecosystem services they provide. We examined net changes in 13 different aquatic and floodplain land cover classes using photo interpreted maps of the navigable portions of the Upper Mississippi River (UMR, above the confluence with the Ohio River) and Illinois River from 1989 to 2000 and from 2000 to 2010. We detected net decreases in vegetated aquatic area in nearly all river reaches from 1989 to 2000. The only river reaches that experienced a subsequent recovery of vegetated aquatic area from 2000 to 2010 were located in the northern portion of the UMR (above navigation pool 14) and two reaches in the Illinois River. Changes on the floodplain were dominated by urban development, which increased in nearly every river reach studied from 1989 to 2000. Agricultural lands declined in most river reaches from 2000 to 2010. The loss of agricultural land cover in the northern UMR was accompanied by increases in forest cover, whereas in the lower UMR and Illinois River, declines in agriculture were accompanied by increases in forest and shallow marsh communities. The changes in aquatic vegetation occupied between 5 and 20% of the total aquatic area and are likely associated with previously reported regional improvements in water clarity, while smaller (1–15% of the total floodplain area) changes in anthropogenic land cover types on the floodplain are likely driven by broad-scale socio-economic conditions.     

Studies on degradation of glyphosate by several oxidative chemical processes: Ozonation,photolysis and heterogeneous photocatalysis

Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO₂ as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O₃/pH 10 process was 1.8 minutes.     

Toxicity assessment of 2,4-D and MCPA herbicides in primary culture of fish hepatic cells

In this study, we used primary cultures of fish hepatic cells as a tool for evaluating the effects of environmental contamination. Primary hepatic cell cultures derived from the subtropical fish Metynnis roosevelti were exposed to different concentrations (0.275, 2.75 and 27.5 μg L^?1) of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA). Cellular respiratory activity was evaluated by polarography using three substrates: 0.5 M glucose, 0.5 M succinate and 0.5 M α-ketoglutarate. Significant changes were observed in cellular oxygen consumption with 0.5 M α-ketoglutarate. Even at low concentrations, 2,4-D and MCPA were potent uncouplers of oxidative phosphorylation. Primary cultures of M. roosevelti liver cells may provide a useful tool for the evaluation of environmental contaminant effects. A review of regulations regarding permitted concentrations of these herbicides is needed.     

Polybrominated diphenyl ethers and their methoxylated and hydroxylated analogs in Brown Bullhead (Ameiurus nebulosus) plasma from Lake Ontario

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) were detected and quantified in Brown Bullhead (Ameiurus nebulosus) from Lake Ontario. Samples were collected in 2006 from three different locations near the city of Toronto: Frenchman’s Bay, Toronto Island, and Tommy Thompson Park. A total of 117 plasma samples were pooled into 19 samples, separating males and females by site of capture. Pooled samples were analyzed for 36 PBDEs, 20 MeO-PBDEs and 20 OH-PBDEs, but only six PBDEs, five MeO- and eight OH-compounds were confirmed against standards currently available. These peaks were quantified as “identified” peaks, while peaks matching ion ratios but not matching the retention time of the available standards were quantified as “unidentified” peaks. Both “identified” and “unidentified” concentrations were combined to obtain a total concentration. No significant variations were obtained for total PBDE concentrations, ranging from 3.33 to 9.02 ng g^?1 wet weight. However, OH- and MeO-PBDE totals ranged over 1 order of magnitude among the samples (not detected – 3.57 ng g^?1 wet weight for OH-PBDEs and not detected ?0.10 ng/g wet weight for MeO-PBDE). The results of this study suggested that these compounds are ubiquitous in biota. Source estimation of MeO- and OH-PBDEs in freshwater fish were discussed. Considering that up to date no freshwater sources for MeO- or OH-PBDEs have been reported, concentrations found should be mainly related to bioaccumulation from anthropogenic sources, although other sources could not be dismissed.     

Factor-Augmenting Technical Change: An Empirical Assessment

This paper estimates factor-specific technical change and input substitution using a structural approach. It contributes to the existing literature by introducing various technology drivers for factor productivities and by assessing the impact of endogenous technical change on the elasticity of substitution. The empirical results suggest that factor productivities are indeed endogenous. In addition, technology drivers are factor-specific. Whereas the R&D stock and machinery imports are important determinants of energy and capital productivity, the education stock is statistically related to labour productivity. The rate of energy-augmenting technical change is larger than that of either labour or capital. By contrast, the productivity of these two factors grows at similar rates. Estimates of the elasticity of substitution are within the range identified by previous literature. In addition, we show that endogenous technical change reduces substitution. Because the elasticity of substitution is lower than one, knowledge and human capital can ultimately have an energy-using effect. The estimated structure of endogenous technical change suggests that Integrated Assessment models focusing on energy-saving technical change might underestimate climate policy costs.