Transport and degradation of pesticides in a biopurification system under variable flux Part II: A macrocosm study

Transport of bentazone, isoproturon, linuron, metamitron and metalaxyl were studied under three different flows in macrocosms. The aim was to verify the observations from Part I of the accompanying paper, with an increase in column volume and decrease in chemical and hydraulic load. Very limited breakthrough occurred in the macrocosms for all pesticides, except bentazone, at all flows.From batch degradation experiments, it was observed that the lag time of metamitron and linuron decreased drastically in time for all flows, indicating a growth in the pesticide degrading population. This in contrast to isoproturon and metalaxyl, where an increase in lag time could be observed in time for all flows. From the batch degradation experiments, it could be concluded that the influence of flow on the lag time was minimal and that the inoculation of the pesticide-primed soil had a little surplus value on degradation.     

An attempt to electrically enhance phytoremediation of arsenic contaminated water

Water polluted with arsenic presents a challenge for remediation. A combination of phyto- and electro-remediation was attempted in this study. Four tanks were setup in order to assess the arsenic removal ability of the two methods separately and in combination. Lemna minor was chosen for As remediation and collected from a ditch in Utrecht, The Netherlands. The tanks were filled with surface water without any pre-cleaning, therefore containing various elements including metals as Mn (2.9 mg L(-1)), Cu (0.05 mg L(-1)), Fe (1.39 mg L(-1)), and Ba (0.13 mg L(-1)). This water was then spiked with As and allocated to a feed container, guaranteeing a continuous flow of 0.12 mL s(-1) to each tank. Two experiments were performed: Exp. 1 with 3 consecutive stages with rising applied voltage and Exp. 2, with a constant voltage over a period of 6 d. Measurements of pH and temperature were taken every working day, as well as water samples from outlets of all tanks including feed container for control. From the present study, there was no evidence that As had been taken up by the plants, but a strong depletion of As was observed in the tanks where current was applied. Preliminary results clearly showed that applying voltage to the electrodes caused 90% removal of As from the spiked surface water.     

Sorption kinetics and its effects on retention and leaching.

Sorption of pesticides to substrates used in biopurification systems is important as it controls the system's efficiency. Ideally, pesticide sorption should occur fast so that leaching of the pesticide in the biopurification system is minimized. Although modeling of pesticide transport commonly assumes equilibrium, this may not always be true in practice. Sorption kinetics have to be taken into account. This study investigated the batch sorption kinetics of linuron, isoproturon, metalaxyl, isoxaben and lenacil on substrates commonly used in a biopurification system, i.e. cow manure, straw, willow chopping, sandy loam soil, coconut chips, garden waste compost and peat mix. The first-order sorption kinetics model was fitted to the observed pesticide concentrations versus time resulting in an estimated kinetic rate constant alpha. Sorption appeared to be fast for the pesticides linuron and isoxaben, pesticides which were classified as immobile, while less mobile pesticides displayed an overall slower sorption. However, the substrate does not seem to be the main parameter influencing the sorption kinetics. Coconut chips, which is a substrate with a high organic matter content showed slow sorption for most of the pesticides. The effect of different estimated alpha values on the breakthrough of pesticides through a biopurification system was evaluated using the HYDRUS 1D model. Significant differences in leaching behavior were observed as a result of the obtained differences in sorption kinetics.     

Characterizing pesticide sorption and degradation in macro scale biopurification systems using column displacement experiments

The efficiency of biopurification systems to treat pesticide-contaminated water was previously studied in microcosms. To validate the obtained results, macrocosm systems were set-up. Four pesticides (linuron, isoproturon, bentazone, and metalaxyl) were continuously applied to ten different organic substrate mixes. Retention of the pesticides was similar and in some cases slightly lower in the macrocosms compared to the microcosms. Differences in retention between the different mixes were however minimal. Moreover, the classification of the retention strength of the pesticides was identical to that observed in microcosms: linuron > isoproturon > metalaxyl > bentazone. Monod kinetics were used to describe delayed degradation, which occurred for isoproturon, metalaxyl and bentazone. No breakthrough of linuron was observed, thus, this pesticide was appointed as the most retained and/or degraded pesticide, followed by isoproturon, metalaxyl and bentazone. Finally, most of the matrix mixes efficient in degrading or retaining pesticides were mixes containing dried cow manure.     

A cross-scale impact assessment of European nature protection policies under contrasting future socio-economic pathways

Regional Environmental Change - Protection of natural or semi-natural ecosystems is an important part of societal strategies for maintaining biodiversity, ecosystem services, and achieving overall...     

Bioassay responses and effects on benthos after pilot remediations in the delta of the rivers Rhine and Meuse

Chemical and biological monitoring was carried out for 5 years following pilot remediations at two locations in the Rhine-Meuse delta. The remediations consisted of partial excavation of the contaminated sediments, followed by applying a clean layer of sandy material on top. After the remediation, a new silty sediment top layer was formed exhibiting a lower toxicity in five sediment/sediment pore water bioassays. Compared to the unremediated sites, lower metal and PAH concentrations were found at the remediated sites, but in one location at the same time elevated HCH, PCB and HCB levels were recorded. One year after the remediation, the differences became smaller, although effects-based classification showed that the remediated site showed a higher quality up to the last year. In both remediated sites a rapid recolonization of nematodes, oligochaetes and chironomids was observed, while the recolonization by bivalves was slower. A few years after the remediation the differences decrease.     

Sustainable Business Sites in the Netherlands: A Survey of Policies and Experiences

The concept of eco-industrial sites or sustainable business sites is a noteworthy newcomer in the family of location types. The origin of this type may be considered as a consequence of two development trends, namely the segmentation of the location market on the one hand (an outcome of changing locational tendencies) and the aim of government policy to integrate economic and environmental objectives on the other. In this paper, both trends are analysed. The central aim is to establish the progress of implementing the newly developed location concept in practice and to identify factors of success and failure. The situation in the Netherlands is used as a frame of reference. After the outline of the background, the concept of sustainable business sites, including its definition, is considered and criticized. Then a tentative inventory is presented of the approximately 60 eco-parks which have developed in the past 10 years in the Netherlands, including the results of a questionnaire survey of these 60 parks. To get a better insight into the factors which determine success or failure, short case-studies of a number of the parks are presented. Finally, a number of conclusions are presented, including a discussion of an alternative view of the concept of eco-industrial sites which applies to the continuity of both firm and environment.     

Effectiveness of unit-based pricing of waste in the Netherlands: Applying a general equilibrium model

Differential and variable rates (DVR) in waste collection charging give a price incentive to households to reduce their waste and increase recycling. International empirical evidence confirms the effectiveness of DVR schemes, with limited unwanted side effects. In the Netherlands, currently some 20% of the population is charged at DVR. This is less than in several other countries. Taking into account differences between types of households and dwellings, this study analyses various scenarios for extended use of DVR in the Netherlands. The analysis shows that further penetration of DVR is a cost-effective instrument for waste reduction and more recycling. Moreover, DVR can itself be seen as a necessary condition for the successful implementation of other economic instruments, such as waste taxes. It is therefore recommended to stimulate municipalities to adopt DVR schemes in the Netherlands, accompanied by the provision of adequate facilities for waste separation by households. Before introducing DVR in ‘very strongly urbanized’ municipalities (i.e. the 12 largest cities in the Netherlands) a pilot experiment in one of them might be useful to test the behavioral response in this category.     

A new look at atmospheric carbon dioxide

Carbon dioxide is increasing in the atmosphere and is of considerable concern in global climate change because of its greenhouse gas warming potential. The rate of increase has accelerated since measurements began at Mauna Loa Observatory in 1958 where carbon dioxide increased from less than 1 part per million per year (ppm yr^?1) prior to 1970 to more than 2 ppm yr^?1 in recent years. Here we show that the anthropogenic component (atmospheric value reduced by the pre-industrial value of 280 ppm) of atmospheric carbon dioxide has been increasing exponentially with a doubling time of about 30 years since the beginning of the industrial revolution (～1800). Even during the 1970s, when fossil fuel emissions dropped sharply in response to the “oil crisis” of 1973, the anthropogenic atmospheric carbon dioxide level continued increasing exponentially at Mauna Loa Observatory. Since the growth rate (time derivative) of an exponential has the same characteristic lifetime as the function itself, the carbon dioxide growth rate is also doubling at the same rate. This explains the observation that the linear growth rate of carbon dioxide has more than doubled in the past 40 years. The accelerating growth rate is simply the outcome of exponential growth in carbon dioxide with a nearly constant doubling time of about 30 years (about 2%/yr) and appears to have tracked human population since the pre-industrial era.