Swabs are used as a collecting device for many biological samples and its complete elution is a desired step for clinical and forensic diagnostics. Swabs are made of cotton, rayon, polyurethane, foam or polyester and come in a spun or flocked-tipped format. They are used to extract biological samples from a patient, which includes saliva, mucous, blood, semen or other body fluids. These body fluids then undergo the process of elution where the collected samples are extracted from the swabs into an elution fluid. Apart from biological samples, the importance of swabbing and elution also becomes more evident in forensics, where the concentration of available cells is very low. One such example is rape kit analysis. Another field of application is the capture and release of bacterial spores from environmental contact surfaces and food surfaces, which also indicate the use of swabs in non-biological areas. The recovery of the biological material from the fibre matrix of the swab has a significant influence on diagnostic sensitivity of any assay. The recovery of micro-organisms from a matrix of swab fibres depends on the nature of the body fluid, the type of the swab fibres and the process of elution. Various methods are used to elute samples from swab, including the use of chemicals to digest the cotton fibres to remove intact cells (~20% recovery), centrifugation (~58% recovery), piezoelectric vibration or pressurized fluid-flow (~60% recovery). These methods are either passive (chemical elution) or provides a gentle tangential shear force through associated flow (centrifugation, piezoelectric and pressurized flow), resulting in a low recovery. The success of all the downstream processes of elution, like lysis, DNA amplification and detection, depends on the number of cells eluted from the swab fibre matrix. Hence, the recovery efficiency is an important parameter for determining the performance of elution, and higher value of the same is desired for most diagnostic assays. This thesis reports a magnetically-actuated physical impingement method for elution and recovery of artificial sputum samples from cotton fibres. A device has been fabricated to induce a rotating magnetic field on smaller magnetic particles in a vial for striking the swab within a confined gap. Elution of samples from the swab using this device was demonstrated using artificial sputum prepared by mixing 2% methyl cellulose in deionised water, loaded with fluorescent-tagged polystyrene beads and Escherichia coli bacteria at various concentrations. The recovery efficiency was found to increase with both rotational speed and elution time, but plateaus after 400 RPM and 120s respectively. At higher concentration of polystyrene beads, a maximum recovery of ~85% was achieved at 5x108 particles/ml sample. With lower concentration (106 particles/ml), the maximum efficiency (~93%) was found to be almost twice of the static condition (46.7%), while using only 620µL of elution volume. Similar trends were found in experiments with artificial sputum loaded with E. coli cells, and the maximum recovery was found to be ~90% at 105 CFU/ml concentration. The robust design and smaller size allows the device to be used in different clinical, forensic and laboratory settings. Also, due to cheaper means of manufacturing and assembly, the vials and smaller magnets can be discarded after every experiment, thereby preventing contamination. The device is most suitable for recovering cells from different body fluids like saliva, mucous, semen or blood, absorbed by the swab fibres. Apart from body fluids samples, swabs holding biological agents from environmental surfaces can also be eluted. A higher recovery at lower concentration facilitates the use of this device where the available analyte concentration is low. / Thesis / Master of Applied Science (MASc)

Aquifer Storage Recovery (ASR) is a recently developed (circa 1970) method (in the U.S.A.) to reduce groundwater-pumping stresses by injecting treated wastewater or surface water during periods of low demand into an aquifer followed by its recovery during periods of high demand. This method has been successfully implemented in numerous locations across the U.S.A. and worldwide, mainly due to the cost savings provided by the use of an unlimited reservoir (aquifer) in which to store water compared to the costs to construct surface impoundments and the inherent problems with storing such water for extended periods of time under evaporative atmospheric conditions. "This study describes the use of a highly discretized, three-dimensional, variable-density, numerical model (SEAWAT 2000) that incorporates the vertical variation of hydraulic conductivities, measured foot by foot, from a continuous core collected from the upper Floridan aquifer in southwest Florida, to evaluate the effects of small-scale heterogeneities on a hypothetical ASR system well. In order to compare these effects to the more general case in which average hydraulic parameters are used to characterize flow zones, a model is constructed with average parameters taken from the heterogeneous case. This study attempts to determine whether aquifer heterogeneities influence the performance of ASR systems, compared to assumed homogeneous conditions, by quantifying differences in recovery efficiency, horizontal and vertical flow due to advection and dispersion, plume dimensions, and storage periods. The results of this study indicate that 1) the geometry of the injectate plume under homogeneous and heterogeneous conditions differ significantly; 2) background formation total dissolved solids (TDS) concentrations significantly control the quantity of potable water available for recovery; 3) dispersion exhibits a strong control on vertical mixing; 4) multiple injection cycles are required to generate a plume of potable water for long term storage; and 5) the percent recoveries under homogeneous and heterogeneous conditions are generally similar only in low-salinity background concentrations, due to the absence of the effects of buoyancy. Although the percent recoveries of the systems modeled are similar, the success of an ASR well is strongly controlled by the existence of heterogeneities, which essentially determine the degree of horizontal and vertical mixing of the injectate with formation waters. Heterogeneities result in varying groundwater and mass transport paths during injection and recovery periods. Presumably these variations would need to be considered when evaluating potential variations in groundwater quality due to mixing between formation and injected water. Understanding potential variations in groundwater quality and treatment alternatives due to the presence of ASR-associated geochemical conditions, e.g., elevated arsenic concentrations, may also be improved with a detailed heterogeneous numerical model.

Aquifer storage and recovery (ASR) is a particular scheme of artificial recharge of groundwater by injecting fresh water into aquifers and subsequently recovering the stored water during times of peak demand or extended drought. In the era of combating climate change, ASR, as an effective means for water reuse and sustainable management of water resources in concert with the natural environment, represents a huge opportunity for climate change adaptation to mitigate water availability stress.The success of an ASR scheme is quantified by the recovery efficiency (RE), defined as the volume of stored water that can be recovered for supply purposes divided by the total volume injected. It is not uncommon that RE may be significantly lower than 100% because of the water quality changes as a consequence of the mixing between the injected water and native groundwater and the interaction between injected water and soil. Thus, the key of a successful ASR scheme is (1) to select appropriate aquifers and (2) to design optimal operational processes to build up a bubble of injected water with minimized negative impact from such mixing and interaction. To achieve this, this thesis develops an integrated knowledge base with sound interdisciplinary science and understanding of the mixing processes under operational ASR management in aquifers with various hydrogeological conditions. Analytical and numerical modeling are conducted to improve the scientific understanding of mixing processes involved in ASR schemes and to provide specific technical guidance for improving ASR efficiency under complex hydrogeological conditions. (1) An efficient approach is developed to analytically evaluate solute transport in a horizontal radial flow field with a multistep pumping and examine the ASR performance in homogeneous, isotropic aquifer with advective and dispersive transport processes. (2) Numerical and analytical studies are conducted to investigate the efficiency of an ASR system in dual-domain aquifers with mass transfer limitations under various hydrogeological and operational conditions. Simple and effective relationships between transport parameters and ASR operational parameters are derived to quantify the effectiveness and ascertain the potential of ASR systems with mass transfer limitations.(3) Effects of hydrogeological and operational parameters on ASR efficiency are assessed in homogeneous/stratified, isotropic/anisotropic coastal aquifers. Effects of transverse dispersion are particularly investigated in such aquifers.(4) Finally, we test and study an innovative ASR scheme for improving the RE in brackish aquifers: injection through a fully-penetrated well and recovery through a partially-penetrated well.

Motivation: The health effects of platinum on the human body are a great concern. It affects the respiratory system as well as the skin. The demands for platinum have seemingly increased over the last few years due to its use in automobile exhaust gas catalysts. Thus there will be an increase in the production and processing of platinum and therefore a greater possibility of exposure to platinum compounds. This is why it is of great importance to evaluate the surface sampling methods, to ensure that they are effective for platinum use. Objectives: 1) To evaluate and compare a few different surface sampling methods for removal of platinum salts from contaminated surfaces in order to determine which one of these methods has the best retention and recovery efficiency. 2) To use the most effective method to monitor surface contamination on porous and non–porous surfaces in a platinum refinery. Methods: Two types of filters (mixed cellulose ester and polyvinyl chloride) and GhostwipesTM were evaluated and compared in this study. Platinum solution (hexachloroplatinic acid) concentrations of 50, 150 and 300 ug Pt/ml solution were used. The retention efficiency of the different sampling mediums was tested by releasing 1 ml of each concentration directly onto the sampling medium. Efficiencies were tested on a non–porous (glass) and porous surface (semi–face bricks). This was done to see how the collection efficiency of the medium will differ on these two surfaces. A total of three wipes were used per surface, however were analyzed individually. All the samples were analyzed using the Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP–AES) analytical method by an accredited laboratory. Results: The results obtained indicated the retention and recovery efficiencies of the three sampling mediums at the three platinum concentrations of 50, 150 and 300 ug Pt/ml solutions. The retention efficiency of the GhostwipesTM was 93.2% at 50 ug Pt/ml solution, 95.3% at 150 ug Pt/ml solution and 93.6% at 300 ug Pt/ml solution, whilst the mixed cellulose ester (MCE) filters and polyvinyl chloride (PVC) filters were lower than 30% at all three concentrations. The overall recovery efficiencies of all three concentrations of the GhostwipesTM and MCE filter were the highest: the GhostwipesTM with levels of 73.9 %, 84.4% and 63.5% and the MCE filters with levels of 71.4%, 84.4% and 80.2%, whilst the PVC filters did not achieve levels above 60%. The wipe materials were also evaluated in terms of the ASTM E1792 standard requirements for wipe materials. Conclusion: GhostwipesTM were found to be the most suitable sampling medium based on retention and recovery efficiencies. The GhostwipesTM also complies with all the requirements listed in the ASTM E1792 standard for wipe materials, which makes it the most suitable wipe sampling material. The MCE and PVC filters however do not comply with all the ASTM E1792 requirements. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.

Motivation: The health effects of platinum on the human body are a great concern. It affects the respiratory system as well as the skin. The demands for platinum have seemingly increased over the last few years due to its use in automobile exhaust gas catalysts. Thus there will be an increase in the production and processing of platinum and therefore a greater possibility of exposure to platinum compounds. This is why it is of great importance to evaluate the surface sampling methods, to ensure that they are effective for platinum use. Objectives: 1) To evaluate and compare a few different surface sampling methods for removal of platinum salts from contaminated surfaces in order to determine which one of these methods has the best retention and recovery efficiency. 2) To use the most effective method to monitor surface contamination on porous and non–porous surfaces in a platinum refinery. Methods: Two types of filters (mixed cellulose ester and polyvinyl chloride) and GhostwipesTM were evaluated and compared in this study. Platinum solution (hexachloroplatinic acid) concentrations of 50, 150 and 300 ug Pt/ml solution were used. The retention efficiency of the different sampling mediums was tested by releasing 1 ml of each concentration directly onto the sampling medium. Efficiencies were tested on a non–porous (glass) and porous surface (semi–face bricks). This was done to see how the collection efficiency of the medium will differ on these two surfaces. A total of three wipes were used per surface, however were analyzed individually. All the samples were analyzed using the Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP–AES) analytical method by an accredited laboratory. Results: The results obtained indicated the retention and recovery efficiencies of the three sampling mediums at the three platinum concentrations of 50, 150 and 300 ug Pt/ml solutions. The retention efficiency of the GhostwipesTM was 93.2% at 50 ug Pt/ml solution, 95.3% at 150 ug Pt/ml solution and 93.6% at 300 ug Pt/ml solution, whilst the mixed cellulose ester (MCE) filters and polyvinyl chloride (PVC) filters were lower than 30% at all three concentrations. The overall recovery efficiencies of all three concentrations of the GhostwipesTM and MCE filter were the highest: the GhostwipesTM with levels of 73.9 %, 84.4% and 63.5% and the MCE filters with levels of 71.4%, 84.4% and 80.2%, whilst the PVC filters did not achieve levels above 60%. The wipe materials were also evaluated in terms of the ASTM E1792 standard requirements for wipe materials. Conclusion: GhostwipesTM were found to be the most suitable sampling medium based on retention and recovery efficiencies. The GhostwipesTM also complies with all the requirements listed in the ASTM E1792 standard for wipe materials, which makes it the most suitable wipe sampling material. The MCE and PVC filters however do not comply with all the ASTM E1792 requirements. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.

The energy used by building sector accounts for approximately 40% of the total energy usage. In residential buildings, 30-60% of this energy is used for space heating which is mainly wasted by transmission heat losses. A share of 20-30% is lost by the discarded residential wastewater and the rest is devoted to ventilation heat loss.   The main objective of this work was to evaluate the thermal potential of residential wastewater for improving the performance of mechanical ventilation with heat recovery (MVHR) systems during the coldest periods of year. The recovered heat from wastewater was used to preheat the incoming cold outdoor air to the MVHR in order to avoid frost formation on the heat exchanger surface.   Dynamic simulations using TRNSYS were used to evaluate the performance of the suggested air preheating systems as well as the impact of air preheating on the entire system. Temperature control systems were suggested based on the identified frost thresholds in order to optimally use the limited thermal capacity of wastewater and maintain high temperature efficiency of MVHR. Two configurations of air preheating systems with temperature stratified and unstratified tanks were designed and compared. A life cycle cost analysis further investigated the cost effectiveness of the studied systems.   The results obtained by this research work indicated that residential wastewater had the sufficient thermal potential to reduce the defrosting need of MVHR systems (equipped with a plate heat exchanger) in central Swedish cities to 25%. For colder regions in northern Sweden, the defrosting time was decreased by 50%. The temperature control systems could assure MVHR temperature efficiencies of more than 80% for most of the heating season while frosting period was minimized. LCC analysis revealed that wastewater air preheating systems equipped with temperature stratified and unstratified storage tanks could pay off their costs in 17 and 8 years, respectively. / <p>QC 20190830</p>

Le bois de tension est un tissu développé par les angiospermes afin de redresser ou de maintenir leur position verticale. Ce tissu génère de fortes contraintes de tension capables de courber un tronc vers le haut. Dans la littérature, l’anatomie du bois de tension est caractérisée par la présence d’une couche gélatineuse (couche G) non lignifiée dans la paroi des fibres. Cette thèse vise à étudier la diversité anatomique du bois de tension ainsi que les mécanismes de génération des contraintes de tension associés et les éventuelles variations de l’efficience du redressement, afin de comprendre comment les arbres se redressent. Elle s’appuie sur des observations anatomiques sur 291 espèces tropicales, sur des estimations de contraintes de maturation sur arbres adultes ainsi que sur une nouvelle méthode d’estimation des contraintes de maturation sur des individus juvéniles artificiellement inclinés et tuteurés en serre. Nos résultats montrent que la couche G est présente dans la majorité des espèces, bien qu’elle soit majoritairement masquée par de la lignine. Dans un faible nombre d’espèces, la couche G est absente du bois de tension. Dans ces espèces, le mécanisme de génération des contraintes de tension implique l’interaction du bois avec l’écorce. Bien que la contrainte de tension soit générée dans des compartiments distincts (le bois et/ou l’écorce), ces deux mécanismes de génération des contraintes de tension ont une efficience de redressement similaire dans le stade juvénile. Les résultats de cette étude ouvrent de nouvelles perspectives de recherche, notamment sur le rôle fonctionnel de la lignine dans la couche G. / Tension wood is a tissue developed by angiosperms to upright or maintain their vertical position. This tissue generates a strong tensile stress able to curve the stem upwards. In the literature, tension wood anatomy is characterized by the presence of an unlignified gelatinous layer (G-layer) in the fibre cell wall. The aims of this thesis are to study the anatomical diversity of tension wood as well as the associated mechanisms of tensile stress generation and eventual variations of uprighting efficiency in order to understand how trees upright. This thesis relies on anatomical observations of 291 tropical species, on estimations of maturation strain on adult trees and on estimations of maturation strain on artificially tilted young trees tied to a pole in a greenhouse. Our results show that the G-layer is present in the majority of the species, although it is mainly hidden by lignin. The G-layer is absent in tension wood of a few number of species. In these species, the mechanism of tensile stress generation involves the interaction of wood and bark. Although tensile stress is generated in separated tissues (wood and/or bark), these two mechanism of tensile stress generation show a similar efficiency of uprighting in juvenile trees. Results of this study open new prospects of research, including on functional role of lignin in the G-layer.

I dagens samhälle ligger stort fokus på energianvändningen för bostäder och kommersiella fastigheter. Energianvändningen beskriver inte bara en byggnads energibehov, utan också miljö- och ekonomiska aspekter. Flerbostadshus är en del av Sveriges bostad- och servicesektor, som utgör 40 % av Sveriges totala energianvändning (Henning, 2017). Ventilationssystem i flerbostadshus utgör således en betydande del av fastighetens energianvändning och måste därför ständigt effektiviseras för att tjäna ett hållbart samhälle. I nuläget är den verkliga energianvändningen för ett flertal av JM:s driftsatta FTX-aggregat (till- och frånluftssystem med värmeåtervinning) okänd. Detta på grund av att tillgängliga energiberäkningar och deklarationer redovisar byggnadens totala energianvändning uppdelat i fyra huvudkategorier; uppvärmning, komfortkyla, tappvatten och byggnadens fastighetsenergi. Energianvändningen för ventilationssystemet framgår inte specifikt från dessa beräkningar, utan delas in i kategorierna uppvärmning och byggnadens fastighetsenergi. Rapporten undersöker, under perioden mars – juni 2018, energianvändningen för totalt elva stycken FTX-aggregat i två av JM:s projekt i Stockholm, Kista Torn och Nya Kvarnen 2. Undersökningens syfte är att försöka beräkna den verkliga energianvändningen för dessa FTX-aggregat. Energiberäkningar har genomförts med värden hämtade från egna samt tidigare utförda mätningar, som jämförts med projekterade värden. Resultatet indikerar att den genomsnittliga energianvändningen för FTX-aggregaten i Kista Torn är ca 120 000 kWh/år. Den större delen av energianvändningen går åt till att värma tilluften. Undersökningen visar på att den genomsnittliga temperaturverkningsgraden är ca 7 % lägre än den projekterade verkningsgraden. De beräkningar som genomförts visar även att uppvärmningskostnaden har ökat med ca 150 000 kr/år, i jämförelse med de projekterade värdena. Det beror till stor del på den minskade temperaturverkningsgraden, men också på grund av förändrade luftflöden i aggregaten. Undersökningen i Nya Kvarnen 2 har inte kunnat göras lika omfattande. Beräkningarna som genomförts här tyder på att energianvändningen uppgår till ca 61 000 kWh/år och aggregat. Tillförlitligheten av beräkningarna störs dock av att inga egna mätningar kunde utföras, att dokumentationen var bristfällig, samt att övervakningssystemet SCADA redovisade orimliga värden. Slutsatsen för rapporten indikerar att den verkliga energianvändningen för FTX-aggregaten generellt är högre än vad som tidigare projekterats. Energianvändningen varierar markant beroende på luftflöden och temperaturverkningsgrad. Störst påverkan på energianvändningen har dock temperaturverkningsgraden. Det visade sig att temperaturverkningsgraden vara svår att bestämma, då många felkällor och faktorer påverkar framtagningen, samt att resultatet varierar beroende på vald mätmetod. För bättre kontroll på energianvändning rekommenderas fler och mer kontinuerligt genomförda mätningar. Alternativt skulle övervakningsprogrammet SCADA kunna användas i större utsträckning för beräkning av energianvändning, förutsatt att precisionen och placering av temperaturgivare förbättras. / In today's society the energy use within residential and commercial real estate is of great importance. Energy use does not only describe a building's energy needs, but also its environmental and economic aspects. Apartment buildings are a part the Swedish residential and service sector, which constitutes 40 % of Sweden's total energy use (Henning, 2017). The ventilation system in apartment buildings makes up a significant part of the property's energy use, it must therefore continuously be improved to work towards a more sustainable society. The actual energy use for several of JM's powered air assemblies is unknown today. Energy calculations and declarations show that the building's total energy use is divided into four main categories; heating, comfort cooling, tap water and property energy. The energy use of the ventilation system is not made apparent in these aforementioned calculations since it is distrubuted into two of the main categories, heating and property energy. The report examines the energy use for a total of eleven air assemblies within two of JM's projects in Stockholm, Kista Torn and Nya Kvarnen 2. The purpose of the study is to find the actual energy use of these air assemblies. Energy calculations will be carried out using values ​​taken from our own and previously performed measurements, which will be compared to expected projected data. The result indicate that the average energy use of the air assemblies in Kista Tower is approximately 120 000 kWh/year. The majority of the energy use goes to heating the supply air. The study shows that the average heat recovery efficiency is circa 7 % lower than the projected efficiency. The calculations show that the cost of heating has increased by approximately 150 000 SEK/year compared to projected data. This is largely due to the reduced heat recovery efficiency but partly due to changes in the airflow within the air assemblies. The study made in Nya Kvarnen 2 was not as extensive, although calculations of energy use have been carried out. These calculations show an energy use of approximately 61 000 kWh/year for each separate air assembly. The reliability of these numbers is considered low because no control measurements could be made. The documentation was inadequate along with the monitoring system, SCADA, which reported unrealistic values. The conclusion of the report shows that the actual energy use of the air assemblies is in general higher than expected. The energy use varies depending on the airflow and heat recovery efficiency, however the greatest impact comes from the heat recovery efficiency in the air assemblies. Heat recovery efficiency was proven difficult to determine because of the multiple sources and factors affecting the measurement. This made the results fluctuate greatly depending on the method chosen of calculating the heat recovery efficiency. To oversee the actual energy use in these air assemblies, more frequent measurements are recommended. Alternatively, the SCADA monitoring program could be used to calculate the energy use, but to do so the accuracy and placement of temperature sensors needs to be improved.

A better way to improve understanding and quantification of nitrous oxide (N₂O) emitted from intensive maize cropping systems is to develop an advanced emissions measurement method This study developed an open path (OP) method to measure N₂O emissions from four adjacent maize plots managed by tillage practices of no-till (NT) and chisel plow (ChP), and different nitrogen (N) treatments from 2014 to 2016. Anhydrous ammonia (220 kg NH₃-N ha^-1) was applied in once or equally split (full vs. split rate) and applied in different timing (Fall vs. Spring). The spring N application occurred either before planting (pre-plant) or in season (side-dress). Emissions measurements were conducted by using the OP method (the scanning OP Fourier transform infrared spectrometry (OP-FTIR) + the gas point-sampling system + a backward Lagrangian stochastic (bLS) dispersion model) and static closed chamber methods. The performance and feasibility of the OP measurements were assessed by a sensitivity analysis, starting with errors associated with the OP-FTIR for calculating N₂O concentrations, and then errors associated with the bLS model for estimating N₂O emissions. The quantification of N₂O concentrations using the OP-FTIR spectrum was influenced by ambient humidity, temperature, and the path length between a spectrometer and a retro-reflector. The optimal quantitative method mitigated these ambient interference effects on N₂O quantification. The averaged bias of the calculated N₂O concentrations from the spectra acquired from wide ranges of humidity (0.5 – 2.0 % water vapor content), temperature (10 – 35 °C), and path length (100 – 135 meters) was 1.4 %. The precision of the OP-FTIR N₂O concentrations was 5.4 part per billion(3σ) in a stationary flow condition for a 30-minute averaging period. The emissions measurement from multiple sources showed that the field of interest was likely interfered by adjacent fields. Fields with low emission rates were more sensitive to the adjacent fields with high emissions, resulting in substantial biases and uncertainties. The minimum detection limit of the N₂O emission rates was 1.2 µg m^-2 s^-1 (MDL; 3σ). The OP measurements showed that the NT practice potentially reduced N₂O emission compared with ChP. Under the long-term NT treatments, the split-N rate application (110 kg NH₃-N ha^-1 in the fall and spring) resulted in lower N₂O emissions than the full application (220 kg NH₃-N ha^-1 in the fall). The management of NT coupled with split-N rate application minimized N₂O emissions among treatments in this study, resulting in N₂O-N losses of 3.8, 13.2, and 6.6 N kg ha^-1 over 9-, 35-, and 20-days after the spring NH₃ application in 2014, 2015, and 2016, respectively. The spring pre-plant N application in 2015 also resulted in higher N₂O emissions than the spring side-dress application in 2016, and the increased N₂O-N loss was corresponding to lower N recovery efficiency in 2015 measurements. A comparison of chamber and OP measurements showed that soil N₂O emissions were likely underestimated by 10x without considering the wind-induced effect on gas transport at the ground-atmospheric interface. This study showed that the OP method provides a great opportunity to study agricultural N₂O emissions as well as management optimization for the sustainability of the agroecosystems.

Maize is the dominant crop in northwestern Germany and is mostly cultivated on sandy soils. Additionally, due to intensive livestock husbandry and biogas production, large amounts of liquid manures are produced. The current farm practice leads to high N and P surpluses at field level accompanied by environmental pollution, like nitrate leaching, eutrophication of non-agricultural ecosystems, and N2O emissions. The accruing liquid manures are often used for maize fertilization. Thereby, slurries are mainly broadcast applied using trailing hose applicators followed by incorporation into the topsoil. In addition, a mineral N P starter fertilizer (MSF) is band-applied below the seed-corn at planting to overcome the limited nutrient availability during the early growth stages. Using a slurry injection technique below the maize row before planting might serve a substitute for MSF. Addition of a nitrification inhibitor (NI) into the slurry before injection seems to be an option to further decrease N losses. The objectives of this thesis were to compare the current and novel fertilizing strategies with a special focus on soil mineral nitrogen (SMN) dynamics and plant P, zinc (Zn) and manganese (Mn) status. For both issues the effect of adding a NI into the slurry was investigated. To characterize the SMN dynamics after slurry injection an appropriate soil sampling strategy had to be developed. Therefore, three consecutive field trials were conducted. The first testing of the new soil sampling approach was implemented in an existing experiment where the slurry was injected at a depth of 12 cm (upper rim) below the soil surface. The soil profile (75 cm wide) centered below the maize row was sampled using a grid-like approach to a depth of 90 cm. Around the injection zone, soil monoliths (SM) were sampled using a purpose-built soil shovel. Below the SMs and in the interrow space (15 and 30 cm distance to the row) a standardized auger procedure was used. The second experiment aimed to improve the sampling strategy with focus on sample homogenization quality and necessary sample sizes per pooled sample. In the third experiment this improved sampling strategy was validated. Results from the first testing of the sampling procedure showed that the strategy is suitable, although some problems occurred. Especially the high spread in values among the replications caused high coefficients of variation (CV; mostly 40 – 60%). The improvement trial revealed that for the SM, which contains the slurry band, an intensive homogenization is required. In addition, suitable sample sizes (twelve auger samples and six soil monolith samples per pooled sample) have to be collected to obtain reliable SMN values. Following this enhanced sampling strategy in the final validation trial, the spread in values was considerably reduced and resulted in CV values of mostly < 20%. The method can be adapted to other fertilizer placement strategies and further row crops. To compare both fertilizing strategies with respect to the spatial and temporal SMN dynamics as well as to the plant nutrient status two field trials were conducted using pig slurry on sandy soils in 2014 and 2015. Four treatments were tested: unfertilized control, broadcast application + MSF, injection, and injection + NI. Soil samples were taken using the new sampling strategy at several dates during the growing season. Plant samples were simultaneously collected to evaluate the plant P, Zn, and Mn status at different growth stages. In 2014, all fertilized N was displaced from the top soil layer of the broadcast treatment until the 6-leaf stage due to heavy rainfall, while N displacement was significantly smaller after slurry injection. The lateral movement of injected slurry N was negligible. In 2015, almost no displacement of fertilized N out of the top soil layer occurred independently of treatments, due to distinctly lower rainfall. The release of slurry N was delayed following broadcast application and large SMN concentrations were detected in the injection zones until the 10-leaf stage. The addition of a NI resulted in significantly increased NH4-N shares in the injection zone throughout the early growth stages (+ 46% in 2014 and + 12% in 2015 at 6-leaf stage). Thus, in 2014 SMN displacement was delayed, and in 2015 increased SMN concentrations were found around the slurry band, most probably due to lower N losses via denitrification. Furthermore, NI addition significantly increased the nutrient uptake by maize during early growth in both years. With P deficiency due to cold weather conditions in 2015, broadcast application showed higher P uptake until the 6-leaf stage (36 – 58%), while it was lower at the 8- (32%) and 10- (19%) leaf stages compared to slurry injection (+ NI). Zn availability was enhanced during early growth after slurry injection (+ NI) and Zn as well as Mn uptake were higher at harvest. Furthermore, dry matter yields were higher (2014) or equal (2015) compared to broadcast application. The P balances were decreased by 10 – 14 kg P ha-1, while Zn and Mn balances were excessive independent of treatments. The field trials showed that after slurry injection, especially when combined with a NI, the applied nitrogen is located in a soil zone with better spatial availability for plant roots compared to broadcast application. Furthermore, the MSF can be substituted without affecting early growth of maize. In conclusion, slurry injection leads to equal (or even higher) yields and enables farmers in northwestern Germany to reduce the P and N surpluses. This would support several goals concerning sustainable land use: Lower pollution of ground and surface waters, reduced emission of NH3, more efficient use of the limited rock P reserves, and less need of transporting organic manures out of regions with intensive animal husbandry and/or biogas production. However, slurry injection enhances the risk of N2O emissions, which contributes to climate change. Thus, for a final evaluation of the environmental impact a life cycle assessment would be worthwhile.