48 research outputs found
A review of the pesticide MCPA in the land-water environment and emerging research needs
peer-reviewedDue to its high solubility and poor adsorption to the soil matrix, the postemergence
herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) is susceptible
to transport into surface and groundwater bodies, where it can result in
compromised water quality and breaches of legislative standards. However,
there is still poor understanding of catchment scale dynamics and transport,
particularly across heterogeneous hydrogeological settings. While it is known
that MCPA degrades under aerobic conditions, negligible breakdown can
occur in anaerobic environments, potentially creating a legacy in saturated
soils. Fast runoff pathways post application are likely transport routes, but the
relative contribution from the mobilization of legacy MCPA from anaerobic
zones has yet to be quantified, making the delineation of MCPA sources
encountered during monitoring programs challenging. While ecotoxicological
effects have been examined, little is known about the interaction of MCPA
(and its degradation products) with other pesticides, with nutrients or with colloids,
and how this combines with environmental conditions to contribute to
multiple stressor effects. We examine the state of MCPA knowledge, using case
study examples from Ireland, and consider the implications of its widespread
detection in waterbodies and drinking water supplies. Research themes
required to ensure the sustainable and safe use of MCPA in an evolving agricultural,
social and political landscape are identified here. These include the
need to identify mitigation measures and/or alternative treatments, to gain
insights into the conditions governing mobilization and attenuation, to map
pathways of migration and to identify direct, synergistic and antagonistic ecotoxicological
effects
Economic Crisis and Investor Behaviour
This study investigates the effects of crises on domestic and foreign investors’ behaviours by utilizing a nonlinear approach. Considering the nonlinearity inherent in many financial variables, this study proposes an appropriate econometric modelling for analysing the investors’ behaviour, particularly during turbulent times. Specifically, STAR-STGARCH family models and generalized impulse response function analysis (GIRF) are employed to understand the different reactions of foreign and domestic investors at the Malaysian Stock Exchange market during the 1997 Asian crisis. The results of the model and the GIRF analysis have shown that foreign investors exhibited a herding behavior during the crisis and responded the shock more quickly than the domestic investors. When the same analysis is applied to understand the effects of the 2008 Subprime Mortgage Crisis in the Malaysian market, the behaviors of foreign and domestic investors are found to be very similar
Estimation Bias and Inference in Overlapping Autoregressions: Implications for the Target-Zone Literature
Samples with overlapping observations are used for the study of uncovered interest rate parity, the predictability of long-run stock returns and the credibility of exchange rate target zones. This paper quantifies the biases in parameter estimation and size distortions of hypothesis tests of overlapping linear and polynomial autoregressions, which have been used in target-zone applications. We show that both estimation bias and size distortions of hypothesis tests are generally larger, if the amount of overlap is larger, the sample size is smaller, and autoregressive root of the data-generating process is closer to unity. In particular, the estimates are biased in a way that makes it more likely that the predictions of the Bertola-Svensson model will be supported. Size distortions of various tests also turn out to be substantial even when using a heteroskedasticity and autocorrelation-consistent covariance matrix. Copyright 2008 Blackwell Publishing Ltd and the Department of Economics, University of Oxford.