Soil and plant biodegradation of chlorpyrifos in fields of cauliflower and brussels sprouts crops

For the protection of early and summer cauliflower and brussels sprouts crops against root fly, the insecticide chlorpyrifos was applied at planting onto soil around the stem of the plant, or in the planting line. In the soil, chlorpyrifos (1) was transformed into the insecticide metabolites oxon, 0,0‐diethyl‐0‐(3,5,6‐tri‐chloro‐2‐pyridinyl) phosphate (2), and 3,5,6‐trichloro‐2‐pyridinol (3). The soil half life time of chlorpyrifos could be 2.8 times greater (42 days relative to 15 days) when the field history as to cauliflower monoculture and insecticide treatments was short (1 year), than when it was long (8 years). Rains and season also had cumulative effects on the chlorpyrifos soil half life times. In the leaves of cabbage, chlorpyrifos and compound 3 were observed at concentrations which were higher, especially when their soil concentrations were high. Chlorpyrifos and compounds 2 and 3 however were not detected in the “flower” of cauliflower, nor in the brussels sprouts itself, the limit of sensitivity being 0.02 ppm of fresh weight.     

Effect of chlorophenolic pesticides on the photochemistry of riboflavin

The possibility of riboflavin sensitized photo‐oxidation of polychlorinated pesticides was investigated. The dye proved to be an inefficient sensitizer for that purpose, when irradiated with visible light, in aereated aqueous solutions. A quenching of singlet and triplet excited states of the chromophore (depending on the concentrations of the quencher) is responsible for this failure in the photo‐degradation of the pesticides, which resulted easily oxidizable, via singlet oxygen mechanism, when proflavine was employed as a sensitizer. Parallel, and as a direct consequence, the rate of aerobic riboflavin photobleaching decreased drastically in the presence of the chlorophenols.

The implication of our results on the inhibition of riboflavin degradation by the presence of chlorinated phenolic pesticides in the environment, is discussed, from the point of view of a kinetic and mechanistic study.     

Multi-scale sustainability evaluation of natural resource management systems: Quantifying indicators for different scales of analysis and their trade-offs using linear programming

The purposes of this paper are: (a) to describe a framework designed for multi-scale sustainability evaluation of Natural Resource Management Systems (NRMS), and (b) to illustrate its application for quantitative analysis using linear programming. The framework described here is intended to contribute to the operationalisation of the concept of sustainability by supporting the processes of design, evaluation and implementation of alternative NRMS at different scales. In this paper, Linear Programming is used for the quantitative analysis of indicators and their trade-offs; using a schematised example, the basic characteristics of the Multi-scale Multiple Goal Linear Programming (M-MGLP) method are described. In M-MGLP, indicators pertaining to different scales of analysis can be set as objectives or constraints for the optimisation. In this way, stakeholders interacting in a specific region can be made aware of the consequences of alternative NRMS in terms of the different indicators at the same scale and/or for indicators at other scales of analysis. The paper ends with a discussion of the main strengths and limitations of the framework and, specifically, of linear programming.     

Sex ratio of juvenile loggerhead turtles in the Mediterranean Sea: is it really 1:1?

Sex ratios are a crucial parameter for evaluating population viability. In species with complex life history patterns and temperature sex determination mechanisms, such as the loggerhead turtle (Caretta caretta), sex ratios may vary within a population and among populations. In the Mediterranean, juvenile sex ratios appear to not differ significantly from 1:1, although estimates for hatchling sex ratios are highly female biased. The immigration of males from the Atlantic has been suggested as a possible cause of such variation. Here, we present results of a multi-year investigation (2000–2011) on the sex ratios of loggerhead turtles foraging along the south Tyrrhenian coast, Western Mediterranean, with the aim of providing a better understanding of the potentially underlying forces that drive regional and age-dependent differences in sex ratios. Sex was determined through visual examination of the gonads in 271 dead turtles (curved carapace length range 29.5–89 cm). A fragment of the mitochondrial DNA control region was sequenced from 61 specimens to characterise the demographic composition of this foraging assemblage by applying a many-to-many mixed stock analysis approach. No significant association was found between sex ratios and years or size classes, although the largest size was male biased. Juvenile sex ratio was 1.56:1, which was different from an even sex ratio but still less female biased than hatchling sex ratios from Mediterranean beaches. Results of the mixed stock analysis indicate that juvenile sex ratios in the Mediterranean are largely unaffected by immigration of Atlantic individuals into the basin, as previously suggested. Continued long-term monitoring of juvenile sex ratios is necessary to detect biologically significant sex ratio shifts in the Mediterranean loggerhead turtle population.     

Above- and belowground biomass and nutrient pools of Spartina alterniflora (smooth cordgrass) in a South American salt marsh

In order to examine the role of position in the tidal range on biomass production and nutrient pools in Spartina alterniflora in an Argentinian estuary, we estimated productivity, the concentration of C, N and P in tissues and pools (concentration×biomass) of these elements in low (LM) and high (HM) zones. Aboveground biomass of S. alterniflora was higher in HM than in LM. Aboveground primary productivity was 106 and 439 g dry wt m^?2 year^?1 in LM and HM, respectively. Belowground biomass was similar in LM and HM. Belowground primary productivity was 526 and 744 g dry wt m^?2 year^?1 for LM and HM, respectively. Nutrient pools were higher in HM than in LM. Biomass and productivity values were low, which makes nutrient pools low. The lower values of the parameters analysed in LM than in HM indicate that position in the tidal range is an important factor in this system, possibly due to the effect of flooding. Moreover, this pattern is opposite to the general one observed in the northern hemisphere, meaning that studying marshes from different environments is worth doing. Because pools were higher in HM, this zone would be more important for nutrient input to the estuary.     

Effects of a phycotoxin,okadaic acid,on oyster heart cell survival

Okadaic acid (OA) is a dinoflagellate toxin which accumulates in shellfish producing diarrhetic shellfish poisoning (DSP) in humans. It was found that OA is a highly selective inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A) which produces a marked increase in phosphorylation of several proteins, including p38 mitogen-activated protein (MAP) kinase. The cytotoxicity attributed to OA and the effects on p38 MAP kinase and calcium current were examined in the oyster Crassostrea gigas in this study. Data showed that p38 MAP kinase is strongly expressed in oyster heart and that OA bioaccumulated in cultured heart cells. Hence the effects of OA was tested in vitro and in vivo on oysters. OA was found to (i) exert a positive chronotropic effect on cultured atrial cardiomyocytes which is related to an increase in calcium current via PKC as shown by patch clamp measurements, (ii) produce an activation/phosphorylation of MAP kinase as shown by Westernblot while the non-phosphorylated p38 remained constant during treatment, (iii) did not induce a pro-apoptotic effect. Data suggest that OA may also stimulate the anti-apoptotic pathway by phosphatase inhibition.     

Is there really a green paradox?

In the absence of a CO₂ tax, the anticipation of a cheaper renewable backstop increases current emissions of CO₂. Since the date at which renewables are phased in is brought forward and more generally future emissions of CO₂ will decrease, the effect on global warming is unclear. Green welfare falls if the backstop is relatively expensive and full exhaustion of fossil fuels is optimal, but may increase if the backstop is sufficiently cheap relative to the cost of extracting the last drop of fossil fuels plus marginal global warming damages as then it is attractive to leave more fossil fuels unexploited and thus limit CO₂ emissions. We establish these results by analyzing depletion of non-renewable fossil fuels followed by a switch to a clean renewable backstop, paying attention to timing of the switch and the amount of fossil fuels remaining unexploited. We also discuss the potential for limit pricing when the non-renewable resource is owned by a monopolist. Finally, we show that if backstops are already used and more backstops become economically viable as the price of fossil fuels rises, a lower cost of the backstop will either postpone fossil fuel exhaustion or leave more fossil fuel in situ, thus boosting green welfare. However, if a market economy does not internalize global warming externalities and renewables have not kicked in yet, full exhaustion of fossil fuel will occur in finite time and a backstop subsidy always curbs green welfare.     

On the fine structure of the thermal bar front

The thermal bar—a hydrodynamic phenomenon, arising in natural basins due to successive changes of the water temperature across the temperature of maximum density (T_m, which is close to 4°C)—has been studied in laboratory experiments and by numerical simulations. The experiments were performed in a rectangular tank with an inclined bottom, filled with water with initial temperature T₀ < T_m and then heated at the surface. During the heating a basin-wide circulation develops, consisting of down-slope cascades in regions where T < T_m, a subsurface off-shore jet in the region where T > T_m, and a compensating flow at intermediate depths towards the shallow part of the tank, supplying both off-shore flows with waters from deeper regions. Analysis of the water temperature and density fields as well as the currents has revealed that the location of the convergence zone of the surface current (when formed) does not coincide with that of the Tm-isotherm. The thermal bar front is typically understood as a convergence zone near the 4°C-isotherm, formed due to the effect of cabbeling. Our experiments demonstrate, however, that the front is associated with the leading edge of the subsurface current. The increasing distance between the 4°C-isotherm and the subsurface jet has been recorded in the laboratory experiments. Numerical simulation results corroborate the laboratory experiments. A scaling analysis predicts the speed of propagation of this frontal zone to be U ~ [g × Δρ/ρ × H]^1/2, where H is the depth (increasing with time) of the upper thermo-active layer, ρ₀ a reference density, and Δρ is the characteristic horizontal density difference across the front. A combined analysis of laboratory, field and numerical data has corroborated this law.     

Isotopic fractionation between seawater and the shell of <Emphasis Type="Italic">Scrobicularia plana</Emphasis> (Bivalvia) and its application for age validation

This study analyzed the isotopic profiles of four aragonitic shells of Scrobicularia plana in conjunction with measured seawater temperatures and salinities. Comparison of δ¹⁸O_SHELL with expected values revealed fractionation of δ¹⁸O in near equilibrium with the ambient environment. Growth cessation occurred between November and March. Carbonate deposition stopped when temperatures were <12°C. Analysis of δ¹³C_SHELL values suggested that carbon in the shell does not reflect the DIC in ambient water, likely due to the incorporation of metabolic carbon. An ontogenetic trend of increasing δ¹³C values over time was observed, likely related to changes in metabolic activity. Annual growth patterns were inferred from δ¹⁸O_SHELL profiles and compared with internal and external growth lines. Estimations of age based on external lines were unreliable, resulting in overestimation of age and underestimation of growth rates, likely due to the disturbance lines being wrongly identified as annual. Analysis of internal lines may lead to over- or underestimation of age and was more reliable in recent portions of the shell.