In biology, the winter season is less studied than other seasons partly due to technical and logistical difficulties. The Arctic region is undergoing rapid changes with shorter and warmer winters, shorter snow duration and considerable changes in snow and ice cover as a result. Climate change also has other consequences such as added influx of DOC to aquatic systems which may have repercussions for aquatic food webs. This study investigates the effect of ice melt on benthic oxygen production and also investigates the pelagic counterpart. This study also investigates levels of light, CO2 and DOC and their impact on benthic and pelagic oxygen production in a simulated climate change scenario. Sampling for the study took place at the Umeå University Experimental Ecosystem Facility which exhibits artificial ponds, some of which had been treated to simulate changes caused by climate change such as added DOC or having been artificially heated during summers. Measurements for O2, CO2 and light (photosynthetic active radiation) were collected from these artificial ponds at three different occasions around the time of ice release: Iced over conditions, after ice melt and later in spring. Ice melt was not proven to result in a difference in benthic oxygen production, as no significance could be found between O2-production during ice-covered conditions and later during the spring. Ice release did however seem to be the cause of a significant effect in the pelagic habitat which exhibited higher O2-production during the period of ice release. A significant difference in O2-production was also found in the pelagic habitat between ponds treated with added DOC and ponds that were not, but no such difference could be found for the benthic habitat. This highlights important differences between the habitats. The study proposes that earlier times of ice release, higher levels of DOC and higher summer temperatures may perhaps influence the oxygen production in the benthic habitat to a lesser extent than the pelagic habitat in northern aquatic systems, but this requires further studies.

Minimizing adhesion of ice has been the subject of extensive studies for applications such aircraft wings, wind turbine blades spacecraft, power transmission wires, while a growing interest concerns coatings for aerospace applications. The work described here describes progress for coatings and ice release test method development over the last few years. Major achievements include: (1) New Rigid Adherent-Resistant Elastomers (RARE), (2) A new Epoxied Cylinder (EC) adhesion test, (3) Validation of an ice release test, and (4) Study of ice adhesion strength on coating thickness for a PDMS elastomer. Rigid Adhesion-Resistance Elastomers (RARE) are comprised of 3F 1 terminated with triethoxysilane moieties and linear 3F polyurethane (U-3F). Hybrid compositions U-3F-x are designated by polyurethane weight percent “x”. Interestingly, RARE coatings spontaneously “self-stratify” during coating deposition and cure. Cured RARE coatings are comprised of (1) a nanoscale surface layer with low work of adhesion, (2) a low modulus mesoscale and (3) a tough U-3F bulk, where “Mesoscale” is defined as a near surface region with a depth ~ 1000 nm. An EC adhesion test was developed to evaluate the fouling release characteristics of RARE. EC adhesion testing was devised by using the commercially available instrument, TA RSA-3. The TA RSA-3 is well suited for these tests as the 3.5 kg load cell facilitates accurate measurements. This test gives peak force (Ps) for EC removal. A striking compositional dependence was found for EC adhesion. A U-3F-50 hybrid coating had the lowest adhesion (Ps = 0.078 MPa) with good toughness (6.2 MPa). Bulk and surface characterization together with adhesion measurements established U-3F-x hybrid coatings, and U-3F-50 in particular, as new fluorous rigid adherent-resistant elastomers (RARE) that are tough, oil resistant, and optically transparent. Inspired by the Epoxied Cylinder (EC) adhesion test, a laboratory method for ice adhesion measurement with a commercially available instrument was established in the Wynne Laboratory. This is the first laboratory ice adhesion test that does not require a custom built apparatus. The temperature controlled chamber on TA RSA-3 is an enabling feature that is essential for the test. The method involves removal of an ice cylinder from a polymer coating with a probe and the determination of peak removal force (Ps). To validate the test method, the strength of ice adhesion was determined for a prototypical glassy polymer, poly(methyl methacrylate). The distance of the probe from the PMMA surface has been identified as a critical variable for Ps. The new test provides a readily available platform for investigating fundamental surface characteristics affecting ice adhesion. In addition to the ice release test, PMMA coatings were characterized using DSC, DCA and TM-AFM. This new laboratory ice release test was then employed to obtain the thickness dependence of ice adhesion for Sylgard 184, a filled polydimethylsiloxane elastomer. A correlation between ice adhesion and coating thickness (t) was found, that follows a relationship developed by Kendall over 40 years ago for removal of a rigid object from an elastomer. In particular, a nearly linear relationship between peak removal stress (Ps) and 1/t1/2 was found, with Ps decreasing from 550 kPa to 100 kPa with coating thickness increasing from 12 μm to 800 μm. While work of adhesion, which is related to surface free energy, is recognized as an important factor that can affect ice release, the results reported herein show that coating thickness can override this single parameter for elastomeric substrates. Base on the result, a general model is proposed for the removal of ice from low modulus elastomers (~10 MPa).