Final polishing

acronyms.tex

@@ -112,6 +112,10 @@
 	short = PLA,
 	long = polylactic acid
 }
+\DeclareAcronym{phb}{
+	short = PHB,
+	long = polyhydroxybutyrate
+}
 \DeclareAcronym{eva}{
 	short = EVA,
 	long = ethylene vinyl acetate,

appendices/solubility-tests.tex

@@ -5,7 +5,7 @@ \chapter{Solubility Tests}
 
 \begin{table}
 	\centering\footnotesize
-	\caption[\Ac{pe} solubility tests in \ac{tcb} and \textit{p}-xylene/\ac{tcb}.]{Testing the visual solubility of an ultra high-density \ac{pe}\textsuperscript{\textdagger} in \ac{tcb} at \SI{120}{\degreeCelsius} and in a 1:1-mixture (v+v) of \textit{p}-xylene and \ac{tcb} at \SI{150}{\degreeCelsius} after cooling down to room temperature.}
+	\caption[\Ac{pe} solubility tests in \ac{tcb} and \textit{p}-xylene/\ac{tcb}.]{Testing the visual solubility of an ultra high-density \ac{pe}\textsuperscript{\textdagger} in \ac{tcb} at \SI{120}{\degreeCelsius} and in a 1:1-mixture (v+v) of \textit{p}-xylene and \ac{tcb} at \SI{150}{\degreeCelsius} after cooling down to room temperature. The used ultra high-density \ac{pe} was found to be particularly difficult to dissolve in comparison to low-density \ac{pe}, \ac{pp}, and \ac{ps}.}
 	\label{tab:solubility-tests}
 	\begin{tabular}{S[table-format = 4]ll}
 		\toprule

chapters/plastic-mulching.tex

@@ -30,7 +30,7 @@ \section{Use and Properties of Plastic Mulches}
 
 The largest benefits plastic mulches are used for on immense scales worldwide stem from their distinct optical and material properties that allow transmission or reflectance of specific wavelengths of incoming solar radiation \citep{BrownBlack2001,Chalker-ScottImpact2007,CsizinszkyColor1995,GordonPlastic2008,HaynesUse1987}. In order to produce highly customizable materials with high flexibility, durability, easy processing, and freedom from odor and toxicity \citep{WrightIns2019}, \ac{pe} has become by far the most frequently used base material in agricultural mulch production \citep{Diaz-PerezBell2010,KaraEffects2013,LocascioRed2005,SivanNew2011}. Its properties are usually modified by additives such as plasticizers, colored pigments, \ac{uv} stabilizers, or other polymers. The main types of \ac{pe} used in agriculture are low- and high-density \ac{pe} and linear low-density \ac{pe}.
 High-density \ac{pe} is used to reduce weight and cost, contributes to the tear strength of the material, and provides a reliable moisture barrier \citep{LamontPlastics2005}. Linear low-density \ac{pe} is used for its elasticity and high puncture resistance \citep{AnthonyMultilayer1983}. Numerous other \ac{pe} mulching variations have already been patented, for instance composite mulches such as paper covered in styrene butadiene latex \citep{DalebrouxMulching1997}.
-\citet{SabbaghAgricultural2010} patented a non\-/degradable and mechanically stable mulch barrier consisting of low-density \ac{pe}, linear low-density \ac{pe}, and \ac{pa}\slash nylon impermeable to soil fumigants. However, the degradability of such materials, the tendency to create microplastic debris, and their practical application are unknown. Mulches containing \ac{pvc} were prohibited for mulching in the US for their toxicity and carcinogenic potential \citep{USEPAGuidelines2012} and have been restricted to greenhouse covering and irrigation pipes \citep{Scarascia-MugnozzaPlastic2011}. In order to achieve longer life cycles of three years or more \citep{BrucknerSpargelanbau2008} as specifically needed for strawberries and asparagus growth, \ac{eva} and \ac{eba} are added to \ac{pe} mulches as co-polymers \citep{EspiPlastic2006}.
+\citet{SabbaghAgricultural2010} patented a non\-/degradable and mechanically stable mulch barrier consisting of low-density \ac{pe}, linear low-density \ac{pe}, and \ac{pa}\slash nylon impermeable to soil fumigants. However, the degradability of such materials, the tendency to create microplastic debris, and their practical application are unknown. Mulches containing \ac{pvc} were prohibited for mulching in the US for their toxicity and carcinogenic potential \citep{USEPAGuidelines2012} and have been restricted to greenhouse covering and irrigation pipes \citep{Scarascia-MugnozzaPlastic2011}. In order to achieve longer life cycles of three years or more \citep{BrucknerSpargelanbau2008} as specifically needed for strawberries and asparagus growth, \ac{eva} and \ac{eba} are added to \ac{pe} mulches as copolymers \citep{EspiPlastic2006}.
 
 Although this depends on regional climatic conditions and land use practices, maximum yields are mainly achieved by optimizing the amount of solar radiation absorbed by the crop. Further microclimatic parameters to be modified include the root zone and leaf temperature, humidity, and therewith soil moisture and plant transpiration rates, for example to manage soil temperatures at night or in colder regions by preventing evaporative cooling and emission of long\-/wave radiation from the soil \citep{HamOptical1993}. This is achieved by controlling the gas and heat exchange between the soil and the environment \citep{LamontPlastic1993,TararaMicroclimate2000}. For such purposes, black, transparent, and white mulches are the colors used most commonly. However, the color selection strongly depends on the crop type and the crop's environment, as well as the temperature that can be tolerated by plants and seedlings \citep{LamontPlastic1993,TararaMicroclimate2000}.
 
@@ -78,7 +78,7 @@ \subsection{Disposal and Recycling of Used Plastic Mulches}
 In Europe, regulations concerning landfilling vary considerably between countries. While in Central Europe and Scandinavia (excepting Finland) less than \SI{10}{\percent} of both agricultural and non-agricultural plastic waste is disposed of in landfills or landfill bans are implemented, in Spain and most eastern and southeastern countries more than \SI{50}{\percent} of plastic waste are estimated to be landfilled \citep{PlasticsEuropePlastics2015}. However, contaminated mulches are mostly unsuitable for landfilling due to the risk of pesticide leaching \citep{GartheManaging2004,WangSoil2013}. \ac{pe} sheets may even function as a vector and facilitate transfer of pesticides into the soil by absorbing the pesticide in the non\-/crystalline areas of the film \citep{HuckinsLipidcontaining1993,NerinAbsorption1996} and further migration of the pesticide to the soil matrix \citep{RamosPolyethylene2015}. The decreasing space available for landfills and concerns over the disposal of contaminated plastic render incineration of plastics a viable alternative, especially for power production \citep{GartheManaging2004}. High\-/temperature combustion (\SI{>1000}{\degreeCelsius}) of \ac{pe} and \ac{pvc} produces as emission products mainly the ozone\-/damaging greenhouse gas \ch{CO2}, \ch{CO}, and polycyclic aromatic hydrocarbons \citep{WangComparative2003}. Illegal on\-/site burning of halide\-/containing plastics may even release carcinogenic dioxins at levels 20 times that of controlled high temperature incineration and 40 times that of atmospheric particulate matter \citep{LevitanRecycling2003}.
 
 A desired alternative to landfill disposal and incineration is the recycling of used mulching films. In 1991, a patent application was filed that proposed the use of a recycling machine designed for cleaning and shredding agricultural plastic waste \citep{VacchelliAnlage1992}. However, no information is available whether such machinery was or is being used at some point. This may imply that the cost and effort exceed the benefits of small\-/scale recycling machines. Recycling used mulch is only possible if contaminants make up less than \SI{5}{\percent} of the total weight of the mulch \citep{ClarkeRecycling1996}. Studies have shown that this \SI{5}{\percent} threshold is exceeded dramatically with the actual contaminant weight being up to \SIrange{40}{50}{\percent} \citep{HussainPlastics2003, LevitanRecycling2003,NerinAssessing1999}. This leaves large amounts of mulching films not being recycled at all---a problem scarcely stressed in the scientific literature but in a US newspaper for agricultural operators \citep{KotrbaWhat2008}.
-Also, the Waste Framework Directive by the \citet{EuropeanParliamentDirective2008} does not specify disposal or recycling procedures concerning agricultural plastic waste. Since plastic disposal in an environmentally safe manner is more recommendatory than effectively implemented in terms of regulations both in the US and the EU, the fate of used plastic mulches is largely unknown.
+Also, the \citet{EUWasteFrameworkDirectiveDirective2008} does not specify disposal or recycling procedures concerning agricultural plastic waste. Since plastic disposal in an environmentally safe manner is more recommendatory than effectively implemented in terms of regulations both in the US and the EU, the fate of used plastic mulches is largely unknown.
 For want of alternatives, farmers may dispose of the waste through illegal on-site burning or unsuitable pits \citep{HemphillAgricultural1993, Scarascia-MugnozzaPlastic2011}. In the UK, for example, only two
 plants are known to reprocess agricultural plastic waste, which makes the collection of the mulch and transport to the plant excessively costly for remote and small\-/scale operators \citep{ScottishExecutiveEnvironmentGroupCode2006}. In Germany, the environmental agencies of the federal states list the temporary storage and disposal of used mulch in the statement of costs for vegetable farmers \citep{BayerischeLandesanstaltfurLandwirtschaftFeldgemuseanbau2005}. Although no precise instructions have been established for mulch disposal in Germany, transport to reprocessing plants appears to be common practice \citep{StraeterAlles2011}.