From traditional to modern fee systems

This paper deals with the environmentally important issue regarding how best to motivate citizens to reduce their individual waste production. The paper discusses the pros and cons of the various financial incentives incorporated into the waste charging mechanism, pay-as-you-throw (PAYT). Pay-as-you-throw breaks with the tradition of paying for waste services through general blanket taxes or levies in the form of flat rates in that households are required to pay individually adjusted fees in the same way as water and electricity bills are calculated on an individual consumption basis. This difference is achieved through the interplay of three principal components which mark the technical implementation of PAYT: identification as a vehicle to attain accountability, measurement of the generated waste and/or corresponding services, and unit pricing as the basis for individual charges proportional to the extent of the obtained services. However, any motivating factor for inducing citizens to dispose of their recyclable discards and residual waste must be supported by a well developed collection infrastructure, good media information and an appropriate, transparent charging policy. Of particular importance is the use of a multi-tiered charge model, i.e., the charging of a fixed minimum fee plus certain variable components payable in respect of the service structure. The introduction of a basic charge, albeit reducing the intensity of the incentives created by the PAYT system, ensures that certain fixed costs for the provision of waste services will be covered independently from the actual waste developments and, at the same time, minimises the temptation to attempt to bypass the system. Such an arrangement for the waste charges neither contradicts the principle of pay-as-you-throw nor does it impair the waste diversion for which it is implemented. Waste statistics and figures representing the waste charging situation in Germany indicate that there is a relatively good correlation between the level of recycling and the amount of perceived financial motivation provided by PAYT. Waste stream developments in areas using such charging schemes generally suggest that the reduction goals are being achieved. Single figures on decreasing quantities of collected residual waste, however, say little about the actual efficiency of differentiated waste charging models and deliver little in the way of reasoned explanation as to why the diffusion of variable rate pricing is progressing painstakingly slowly. To evaluate the success, feasibility and problems of PAYT schemes, one needs to consider the various ways for technically implementing this approach in practice, and must take a broader look into the wide spectrum of available waste services and into more factors that influence their efficiency and acceptance. Urban structure settings assume a particular importance here as do the specific goals of social policy which, among others, are reflected in the charging mechanisms applied. Practical experience, however, shows that solutions can be found which allow most of the concerns and area specifics to be accommodated and waste streams to be influenced in the desired way. Aside from this, positive effects as to waste collection efficiency can also be achieved, which contribute towards long-term environmental improvements and countervail the incremental costs of implementing PAYT.     

Carbon source in the future chemical industries

Rising crude oil prices favour the exploitation of hitherto unutilised energy carriers and the realisation of new technologies in all sectors where carbon is used. These changed economic constraints necessitate both savings in conventional petrochemistry and a change to oil-independent carbon sources in the chemical industry. While, in coal chemistry, the synthesis and process principles of petrochemistry — fragmentation of the raw material and subsequent buildup of molecular structures — can be maintained, the raw material structure largely remains unchanged in the chemistry of renewable raw materials. This lecture is to demonstrate the structural as well as the technological and energy criteria of the chemistry of alternative carbon sources, to forecast the chances of commercial realization and to discuss some promising fields of research and development.     

The influence of EDDS on the uptake of heavy metals in hydroponically grown sunflowers

Phytoextraction is an environmentally friendly in situ technique for cleaning up metal contaminated land. Unfortunately, efficient metal uptake by remediation plants is often limited by low phytoavailability of the targeted metals. Chelant assisted phytoextraction has been proposed to improve the efficiency of phytoextraction. Phytoremediation involves several subsequent steps: transfer of metals from the bulk soil to the root surfaces, uptake into the roots and translocation to the shoots. Nutrient solution experiments address the latter two steps. In this context we investigated the influence of the biodegradable chelating agent SS-EDDS on uptake of essential (Cu and Zn) and non-essential (Pb) metals by sunflowers from nutrient solution. EDDS was detected in shoots and xylem sap for the first time, proving that it is taken up into the above ground biomass of plants. The essential metals Cu and Zn were decreased in shoots in the presence of EDDS whereas uptake of the non-essential Pb was enhanced. We suggest that in the presence of EDDS all three metals were taken up by the non-selective apoplastic pathway as the EDDS complexes, whereas in the absence of EDDS essential metal uptake was primarily selective along the symplastic pathway. This shows that synthetic chelating agents do not necessarily increase uptake of heavy metals, when soluble concentrations are equal in the presence and absence of chelates.     

The tox is in the detail: technical fundamentals for designing,performing, and interpreting experiments on toxicity of microplastics and associated substances

Over the last 10 years, there has been a plethora of experimental studies estimating the potential of microplastic particles (MPs) to exert toxic effects in the environment, many specifically focusing on their postulated capacity to enhance the transfer of environmental pollutants into organisms after ingestion. Obviously, there is little to no consensus on appropriate experimental design, which is mainly owing to the novelty, the interdisciplinarity of the subject, and the complexity of parameters involved. This results in fundamental discrepancies regarding the materials applied, the approach for spiking MPs with pollutants, and the exact exposure scenario. Aiming for a non-chemist audience and providing illustrative, representative, and comparative examples, this review first outlines the theoretical essentials of processes involved in sorption. Also, it discusses the implications for designing experimental approaches using MPs and interpreting the results obtained under consideration of their relevance for environmental conditions. It may help to improve the interpretation of studies on MP toxicity already published, while also calling experimenters’ attention to various aspects important to consider when designing and performing environmentally relevant experiments with MPs.

     

Handling the phosphorus paradox in agriculture and natural ecosystems: Scarcity,necessity, and burden of P

This special issue of Ambio compiles a series of contributions made at the 8th International Phosphorus Workshop (IPW8), held in September 2016 in Rostock, Germany. The introducing overview article summarizes major published scientific findings in the time period from IPW7 (2015) until recently, including presentations from IPW8. The P issue was subdivided into four themes along the logical sequence of P utilization in production, environmental, and societal systems: (1) Sufficiency and efficiency of P utilization, especially in animal husbandry and crop production; (2) P recycling: technologies and product applications; (3) P fluxes and cycling in the environment; and (4) P governance. The latter two themes had separate sessions for the first time in the International Phosphorus Workshops series; thus, this overview presents a scene-setting rather than an overview of the latest research for these themes. In summary, this paper details new findings in agricultural and environmental P research, which indicate reduced P inputs, improved management options, and provide translations into governance options for a more sustainable P use.