Increase In Carbon Dioxide Concentration Research Articles

Atmospheric change causes declines in woodland arthropods and impacts specific trophic groups

Abstract Arthropod assemblages form a fundamental part of terrestrial ecosystems, underpinning ecosystem processes and services. Yet, little is known about how invertebrate communities, as a whole, respond to climatic and atmospheric changes, including predicted increases in carbon dioxide concentrations (CO2). To date, woodland Free Air CO2 Enrichment (FACE) studies have focused entirely on northern hemisphere managed plantations. We manipulated atmospheric CO2 in a mature, native Eucalyptus woodland (0.15 ha, >32 000 m3) in Australia, using the Eucalyptus FACE (‘EucFACE’) facility. We used three complementary sampling methods (vacuum sampling, pitfall and sticky trapping) to record invertebrate abundances under ambient and elevated levels of CO2 (400 versus 550 ppm). Based on the collection of over 83 000 invertebrates, we found significant declines in the overall abundance of ground‐dwelling (14.7%) and aerial (12.9%) arthropods under elevated CO2, with significant decreases in herbivore, omnivore, scavenger and parasitoid functional groups. Even though several groups showed varying declines in abundance, elevated CO2 did not measurably affect community composition. The results of the present study indicate that atmospheric CO2 levels predicted within the next 35 years may cause declines in arthropod abundances in Eucalyptus woodland. Declines found in several functional groups suggest that elevated atmospheric CO2 has the potential to affect ecosystem processes, possibly including nutrient cycling by herbivores and omnivores, as well as biocontrol by parasitoids.

Non-invasive multiwavelength photoplethysmography under low partial pressure of oxygen

A reduction in partial pressure of oxygen in the environment may be caused by a gain in altitude, which reduces the atmospheric pressure; it may also be caused by the carbon dioxide generated from breathing in an enclosed space. Does inhaling oxygen of lower partial pressure affect the oxygen-carrying function of haemoglobin in vivo? This study uses non-invasive multiwavelength photoplethysmography to measure the effects that inhaling this type of oxygen can have on the plethysmography of the appendages of the body (fingertips). The results indicate that under low partial pressure of oxygen, be it the result of a gain in carbon dioxide concentration or altitude, the change in visible light absorption is the biggest for short wavelengths (approximately 620 or 640 nm) near deoxyhaemoglobin, which has higher absorption coefficient. Moreover, increasing carbon dioxide concentration from 5000 to 10,000 ppm doubly reduces the absorption rate of these short wavelengths.

Comparative analysis of separation technologies for processing carbon dioxide rich natural gas in ultra-deepwater oil fields

Offshore oil production in ultra-deepwater, with associated natural gas showing high carbon dioxide content and high gas to oil ratio, poses stringent constraints to upstream gas processing technologies. Under such circumstances, oil and gas are processed in Floating Production Storage and Offloading rigs, whose topside facilities are limited in terms of weight and footprint of equipment. Energy demands, supplied by on-site generation, also reduce the availability of space and weight to oil and gas processing. This work evaluates carbon dioxide separation alternatives applicable to this challenging scenario in terms of technical, economic and environmental aspects, considering early enhanced oil recovery as the destination of carbon dioxide. The Brazilian Pre-Salt fields are used as case study due to their unusual high capacity gas processing on the production topside, a consequence of the high gas to oil ratio and carbon dioxide content. The set of studied carbon dioxide separation technologies encompasses membrane permeation, chemical absorption by aqueous methyl diethanolamine with piperazine, physical absorption with propylene carbonate and hybrid variants physical absorption and membranes, membranes and chemical absorption, and two stages membrane, technically assessed by process simulation. Due to the continuous injection of carbon dioxide to enhanced oil recovery, the reservoir content of carbon dioxide increases along production life-cycle, which means that the performances of technologies have to be compared under short-term, mid-term and long-term carbon dioxide content in the associated gas, respectively, of 10%, 30% and 50% (mol), for gas production of 6 million sm3/d. Chemical absorption exhibits the lowest hydrocarbon losses and the lowest specific electric power consumption at the expense of the highest footprint, for all investigated scenarios. The lowest life-cycle costs are for chemical absorption and two stages membrane, respectively $0.57 and $0.46 million/GJ of exported gas, while the largest cost belongs to the hybrid membrane and chemical absorption ($1.78 million/GJ of exported gas). Chemical absorption holds the lowest carbon dioxide emission per ton of injected carbon dioxide (0.15 t/t), seconded by membrane permeation (0.19 t/t). Hybrid membrane and chemical absorption inherits the small footprint of membrane permeation and, despite its highest life-cycle cost, is recommended for flexibility reasons due to increasing carbon dioxide content in the reservoir life-time in cases of ultra-deepwater fields with high gas to oil ratio, high carbon dioxide content and early carbon dioxide enhanced oil recovery. Contrarily to the widely acceptance of membrane permeation as a leading small footprint solution, the overall performance analysis, under the adopted premises, remarkably favors chemical absorption.

Spiders in mofette fields—Survival of the toughest in natural carbon dioxide springs?

In mofette fields, natural carbon dioxide springs, organisms have to stand extreme CO2 concentrations up to 100%. These hostile conditions are spatially small-scaled and further influenced by earth tides, wind and temperature. The present project investigated the influence of increased atmospheric CO2 concentration on spiders as representatives of above-ground organisms by means of pitfall traps in three mofette fields, differing in habitat conditions in the Plesná valley, eastern Cheb Basin, Czech Republic.Among the 71 recorded spider species four were rarely found in the Czech Republic. A canonical correspondence analysis revealed significant influences of environmental parameters on the spider assemblages. Two groups of spiders are clearly distinguishable, one being positively influenced by humidity and the second by temperature. A cluster analysis showed distinct and congruent results: spider assemblages of pitfall traps at spots with a mean CO2 concentration above 7.6% grouped close together and this grouping was independent of site. At >7.6% CO2 significantly fewer individuals and species were found in comparison to areas with lower CO2 concentration. Between 2.5 and 10% CO2, spiders indicated increased CO2 concentrations much more sensitively than endogeic organisms (Nematoda, Collembola) in a nearby mofette field. Unlike in nematodes, collembolans and plants, no mofettovageous or mofettophilous spiders were detected. In contrast to humidity, CO2 concentration and temperature, the vegetation cover was not among the factors, which significantly influenced spiders. This is explained by the fact that mofettophilous plants occurred at spots where almost no spiders could live. In a field experiment, most Pardosa pullata males tested passed a 30cm long corridor with increased carbon dioxide concentration. These results and that of pitfall traps showed that relatively large and wandering specimens respectively were able to transit moderately hostile spots. Further experiments are necessary to find out if there is any active avoidance of high-CO2 areas by spiders.

Investigation of a combined gas-steam system with flue gas recirculation

Abstract This article presents changes in the operating parameters of a combined gas-steam cycle with a CO2 capture installation and flue gas recirculation. Parametric equations are solved in a purpose-built mathematical model of the system using the Ebsilon Professional code. Recirculated flue gases from the heat recovery boiler outlet, after being cooled and dried, are fed together with primary air into the mixer and then into the gas turbine compressor. This leads to an increase in carbon dioxide concentration in the flue gases fed into the CO2 capture installation from 7.12 to 15.7%. As a consequence, there is a reduction in the demand for heat in the form of steam extracted from the turbine for the amine solution regeneration in the CO2 capture reactor. In addition, the flue gas recirculation involves a rise in the flue gas temperature (by 18 K) at the heat recovery boiler inlet and makes it possible to produce more steam. These changes contribute to an increase in net electricity generation efficiency by 1%. The proposed model and the obtained results of numerical simulations are useful in the analysis of combined gas-steam cycles integrated with carbon dioxide separation from flue gases.

Climate changes and photosynthesis

Abstract This paper is a review. According to the latest data issued by the UN, global warming causes danger to human health and well-being, as well as to animals and plants. As global warming is mainly caused by anthropogenic activities, it was considered that emission of the so-called greenhouse gases should be reduced and in some cases even prohibited. Plants are more easily exposed to biological damage than any other living organisms. The paper deals with the biochemical measures that will increase plants' biological potential, in particular, their photosynthetic and energy opportunities and, therefore, will contribute to drought resistance and will prevent increase of carbon dioxide concentrations in the atmosphere. Solar energy is environmentally friendly and its conversion to energy of chemical substances is carried out only by photosynthesis – effective mechanism characteristic of plants. However, microorganism photosynthesis occurs more frequently than higher plant photosynthesis. More than half of photosynthesis taking place on the earth surface occurs in single-celled organisms, especially algae, in particular, diatomic organisms.

The effects of elevated carbon dioxide and temperature levels on tilapia (Oreochromis mossambicus): Respiratory enzymes, blood pH and hematological parameters.

Oreochromis mossambicus were exposed to two different temperature and carbon dioxide partial pressure levels for about two weeks, as the ambient (Control; 25°C, 3.3mg/L CO2), high CO2 (25°C, 14mg/L CO2), high temperature (30°C, 3mg/L CO2) and combined (30°C, 14.1mg/L CO2) groups. No mortality was observed during the experiments. As a result of the study, elevated CO2 concentrations cause negative effects on the hematological parameters. At the end of the study, while the blood Carbonic Anhydrase (CA) activity, in the high CO2 group (25°C, 14mg/L CO2), statistically increased at the 7th day compared to the control group, it decreased at the 14th day (p<0.05). In addition, the blood CA activity, in the combined (30°C, 14.1mg/L CO2) group, showed a decrease at the 14th day compared to the control group (p<0.05). At the end of study, unlike the blood CA activity, gill, liver and kidney CA activity showed an increase in the tissues compared to the control groups (p<0.05). Furthermore, the Na(+), K(+)-ATPase activities were stimulated significantly in the gills in both high CO2 and temperature groups at day 7, but it showed a significant amount of inhibition at the 14th day compared to the control groups. Overall, increasing carbon dioxide concentration in different temperatures has negative effects on the hematological parameters and respiratory enzyme of the tilapia fish. In addition, it is observed that the fish survive at negative conditions with adaptation mechanisms.

Transient tracer distributions in the Fram Strait in 2012 and inferred anthropogenic carbon content and transport

Abstract. The storage of anthropogenic carbon in the ocean's interior is an important process which modulates the increasing carbon dioxide concentrations in the atmosphere. The polar regions are expected to be net sinks for anthropogenic carbon. Transport estimates of dissolved inorganic carbon and the anthropogenic offset can thus provide information about the magnitude of the corresponding storage processes. Here we present a transient tracer, dissolved inorganic carbon (DIC) and total alkalinity (TA) data set along 78°50′ N sampled in the Fram Strait in 2012. A theory on tracer relationships is introduced, which allows for an application of the inverse-Gaussian–transit-time distribution (IG-TTD) at high latitudes and the estimation of anthropogenic carbon concentrations. Mean current velocity measurements along the same section from 2002–2010 were used to estimate the net flux of DIC and anthropogenic carbon by the boundary currents above 840 m through the Fram Strait. The new theory explains the differences between the theoretical (IG-TTD-based) tracer age relationship and the specific tracer age relationship of the field data, by saturation effects during water mass formation and/or the deliberate release experiment of SF6 in the Greenland Sea in 1996, rather than by different mixing or ventilation processes. Based on this assumption, a maximum SF6 excess of 0.5–0.8 fmol kg−1 was determined in the Fram Strait at intermediate depths (500–1600 m). The anthropogenic carbon concentrations are 50–55 µmol kg−1 in the Atlantic Water/Recirculating Atlantic Water, 40–45 µmol kg−1 in the Polar Surface Water/warm Polar Surface Water and between 10 and 35 µmol kg−1 in the deeper water layers, with lowest concentrations in the bottom layer. The net fluxes through the Fram Strait indicate a net outflow of ∼ 0.4 DIC and ∼ 0.01 PgC yr−1 anthropogenic carbon from the Arctic Ocean into the North Atlantic, albeit with high uncertainties.

Harnessing facilitation: Why successful re-introduction of Stratiotes aloides requires high densities under high nitrogen loading

Dense mats of floating vegetation form complex structures that support high biodiversity in wetlands. Since the 1960s, however, high-density stands of Stratiotes aloides have shown strong declines throughout Europe and restoration efforts have often failed, both of which have been linked to high nitrogen (N) input rates. The low success rate of reintroduction is striking, since seemingly healthy, high-density stands are observed to grow under similar environmental conditions. We therefore hypothesise that N tolerance of S. aloides increases with density due to joint N uptake and detoxification. To test our hypothesis, we set up a controlled full factorial mesocosm experiment in which we manipulated N loading and S. aloides density, and investigated interacting effects on habitat biogeochemistry and plant performance. High-density S. aloides stands strongly lowered ammonium availability through shared uptake, even at extremely high N loads. Furthermore, dense stands strongly reduced water layer oxygen concentrations, which stimulated sediment phosphorus mobilisation, and increased carbon dioxide concentrations, which enhanced underwater photosynthesis. High-density stands thus not only detoxify ammonium, but also facilitate population growth through habitat manipulation. Combined, these mechanisms enabled S. aloides to remain viable at high loads of 800kgNha−1y−1, whereas low-density stands already collapsed at 200kgNha−1y−1. Overall, our results show that under similar environmental conditions, high-density stands can thrive, while restoration or natural recruitment by a low number of individuals may be impossible. We therefore conclude that acknowledging and harnessing intraspecific facilitation can be vital for successful conservation and restoration.

Linnebjer—A South Swedish Oak Forest and Meadow Area—Revisited after Half a Century

An oak forest and three wet meadows/fens were reinvestigated after 50 years concerning tree vitality, biomass and productivity, and soil chemistry. Sulphur and nitrogen deposition has changed dramatically during these years, and the aim was to analyse the differences in both the oak forest and the open field ecosystems. Trees were re-measured and soil profiles were resampled. Important visible changes in the oak forest were stated concerning the vitality of oaks. Aboveground there was a decrease in tree biomass, production and litter fall, but a huge increase in standing dead logs. During the years, the deposition of sulphur had decreased drastically, but nitrogen deposition was still high. Soil acidification in the forest had decreased, reflected in an increased base saturation in the forest, in spite of slightly lowered pH-values. Strongly increased amounts of exchangeable Ca and Mg now appeared in the forest soil, and a substantial transport of calcium and magnesium had obviously taken place from the forest soil to the meadow and fens during the years. However, the most important soil change was the accumulation of organic matter. The increased accumulation of organic matter in turn meant increased amounts of colloid particles and microsites for ion exchange in the soil. This favoured 2-valence base cations, and especially Ca and Mg that increased very much in all the studied ecosystems. Carbon as well as nitrogen had strongly increased in the forest, meadow and fen soils. This was interpreted as a natural result of increased vegetation growth due to high nitrogen deposition, increased global annual temperature and increased carbon dioxide concentration in air. It was concluded that the decreased deposition of sulphur had had a positive effect on soil chemistry, and that the deposition of nitrogen probably had stimulated vegetation growth in general, and contributed to increased amount of organic matter in the soils. However, in this studied oak forest, the decreased vitality and many killed trees were also suspected to be a result of high nitrogen deposition. Obviously increased tree growth was counteracted by decreased stress resistance, and increased appearance of pathogens in the oak trees.

Carbon Dioxide: The Good News

1. This paper addresses the question of whether, and how much, increased carbon dioxide concentrations have benefited the biosphere and humanity by stimulating plant growth, warming the planet and increasing rainfall.2. Empirical data confirms that the biosphere’s productivity has increased by about 14% since 1982, in large part as a result of rising carbon dioxide levels.3. Thousands of scientific experiments indicate that increasing carbon dioxide concentrations in the air have contributed to increases in crop yields.4. These increases in yield are very likely to have reduced the appropriation of land for farming by 11–17% compared with what it would otherwise be, resulting in more land being left wild.5. Satellite evidence confirms that increasing carbon dioxide concentrations have also resulted in greater productivity of wild terrestrial ecosystems in all vegetation types.6. Increasing carbon dioxide concentrations have also increased the productivity of many marine ecosystems.7. In recent decades, trends in climate-sensitive indicators of human and environmental wellbeing have improved and continue to do so despite claims that they would deteriorate because of global warming.8. Compared with the benefits from carbon dioxide on crop and biosphere productivity, the adverse impacts of carbon dioxide – on the frequency and intensity of extreme weather, on sea level, vector-borne disease prevalence and human health – have been too small to measure or have been swamped by other factors.9. Models used to influence policy on climate change have overestimated the rate of warming, underestimated direct benefits of carbon dioxide, overestimated the harms from climate change and underestimated human capacity to adapt so as to capture the benefits while reducing the harms.10. It is very likely that the impact of rising carbon dioxide concentrations is currently net beneficial for both humanity and the biosphere generally. These benefits are real, whereas the costs of warming are uncertain. Halting the increase in carbon dioxide concentrations abruptly would deprive people and the planet of the benefits of carbon dioxide much sooner than they would reduce any costs of warming.

Modelling the contributions to marine acidification from deposited SOx, NOx, and NHx in the Baltic Sea: Past and present situations

We have examined the effects of historical atmospheric depositions of sulphate, nitrate, and ammonium from land and shipping on the acid–base balance in the Baltic Sea. The modelling considers the 1750–2014 period, when land and ship emissions changed greatly, with increasing carbon dioxide concentrations, SOx, NOx, and NHx emissions, and nutrient loads.The present results indicate that Baltic Sea acidification due to the atmospheric deposition of acids peaked around 1980, with a pH cumulative decrease of approximately 10−2 in surface waters. This is one order of magnitude less than the cumulative acidification due to increased atmospheric CO2. The acidification contribution of shipping is one order of magnitude less than that of land emissions. However, the pH trend due to atmospheric acids has started to reverse due to reduced land emissions, though the effect of shipping is ongoing.The effect of strong atmospheric acids on Baltic Sea water depends on the region and period studied. The largest total alkalinity sink per surface area is in the south-western Baltic Sea where shipping is intense. Considering the entire Baltic Sea over the 2001–2010 period, the pH changes are approximately −3×10−3 to −11×10−3 and −4×10−4 to −16×10−4 pH units attributable to all emissions and ship emissions only, respectively. The corresponding changes in total alkalinity are approximately −10 to −30µmolkg−1 and −1 to −4µmolkg−1 attributable to all emissions and ship emissions only, respectively.

Laboratory seawater studies are justified

In our view, your report 'Seawater studies up short' ( Nature 524 , 18 – 19 ; 2015 ) fails to capture the nuances of the survey results you discuss (see C. E. Cornwall and C. L. Hurd ICES J. Mar. Sci. http://doi.org/68g ; 2015 ). Researchers aim to follow the 2010 'Guide to best practices for ocean acidification research and data reporting' ( go.nature.com/sp5kgn ) as they strive to understand how marine organisms are likely to respond to the falling pH of the world's oceans, caused by increased carbon dioxide concentrations. The logistical constraints of testing the effects of seawater acidification on marine life in the laboratory are considerable. However, experiments must be replicated while complying with the requirements for manipulating and monitoring seawater carbonate chemistry. The paper, co-authored by two of us, does not conclude from its meta-analysis of such manipulation experiments that all these studies come up short. Rather, it uses them to highlight the importance and challenges of proper experimental design for such testing. The examples of experimental pitfalls it cites are intended not as criticisms, but to guide future efforts. Together with palaeo-record investigations, modelling studies and natural and manipulated field experiments, we believe that laboratory experiments are crucial to the mechanistic understanding and prediction of ocean-acidification impacts.

Increasing carbon dioxide concentration in the upper atmosphere observed by SABER

AbstractCarbon dioxide measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument between 2002 and 2014 were analyzed to reveal the rate of increase of CO2 in the mesosphere and lower thermosphere. The CO2 data show a trend of ~5% per decade at ~80 km and below, in good agreement with the tropospheric trend observed at Mauna Loa. Above 80 km, the SABER CO2 trend is larger than in the lower atmosphere, reaching ~12% per decade at 110 km. The large relative trend in the upper atmosphere is consistent with results from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS). On the other hand, the CO2 trend deduced from the Whole Atmosphere Community Climate Model remains close to 5% everywhere. The spatial coverage of the SABER instrument allows us to analyze the CO2 trend as a function of latitude for the first time. The trend is larger in the Northern Hemisphere than in the Southern Hemisphere mesopause above 80 km. The agreement between SABER and ACE‐FTS suggests that the rate of increase of CO2 in the upper atmosphere over the past 13 years is considerably larger than can be explained by chemistry‐climate models.

Predicting the impact of increasing carbon dioxide concentration and temperature on seed germination and seedling establishment of African grasses in Brazilian Cerrado

Global climate changes and biological invasions are environmental disturbances that may interact synergistically, causing loss of biodiversity. As the early stages of development are the most sensitive and easily affected by these constraints, this study investigated the effects of increased carbon dioxide (CO2) and temperature, as forecasted for 2100, on seed germination and early development of three species of invasive African grasses that have gradually replaced landscapes of the Brazilian Cerrado biome. It was observed that these parameters affected percentage and rate of germination in Urochloa brizantha, rate of germination and mean germination time in Urochloa decumbens and accelerated autotrophy acquisition in U. brizantha, U. decumbens and Megathyrsus maximus. Regarding root elongation, all species showed changes in total length, absolute and relative growth rate, but at different stages of development or time intervals, with increased temperature being more significant than increased CO2, probably due to seed reserves still being the main carbon sources at this stage. Taken together, the results indicate that the effects of CO2 and increased temperature are species specific and highlight the greatest potential of U. brizantha to germinate, and of U. decumbens for seedling establishment under these environmental changes.

Late Pleistocene–Holocene ground surface heat flux changes reconstructed from borehole temperature data (the Urals, Russia)

Abstract. We use geothermal reconstruction of the ground surface temperature (GST) history early obtained in the Middle Urals to determine the surface heat flux (SHF) history over the past 35 kyr. A new algorithm of GST–SHF transformation was applied to solve this problem. The timescale of geothermal reconstructions has been corrected by comparing the estimated heat flux and annual insolation at the latitude of 60° N. The consistency of SHF and insolation changes on the interval 35–6 kyr BP with the linear correlation coefficient R = 0.99 points to orbital factors as the main cause of climatic changes during the Pleistocene–Holocene transition. The amplitude of SHF variations is about 1.3% of the insolation change amplitude. The increase of carbon dioxide concentrations lagged by 2–3 kyr from the SHF increase and occurred synchronously with GST changes.

Biological Sinks for Carbon Dioxide – An Option for Agroforestry Systems in the Tropics

One of the core questions, that need to be answered in the present discussion about climate change, is how the increase of carbon dioxide content in the atmosphere can be minimized if not stopped. This Greenhouse Gas (GHG) is the main reason for the increase of average temperature. Under business as usual (BAU) conditions an increase in temperature between 1.7-4.5֯C is expected during the next 100 years. One option to counter this trend is through reforestation and the conservation of forests functioning as carbon sinks. Estimates are giving an amount of 60 Petagram (Pg) or 60 Gigatons (Gt) as exchange of carbon between the terrestrial ecosystems and the atmosphere annually. Tropical forests and agroforestry systems show promising options in the process of binding atmospheric carbon dioxide. The use of agroforestry methods, like the Rainforestation Farming strategy, open very interesting options due to ecological and economical advantages, while contributing to the reduction of carbon dioxide concentrations.

Morality of a Carbon Tax: Transition to a Sustainable Economy

A carbon tax is needed to address the negative externalities caused by carbon emissions. Increased carbon dioxide concentrations in the atmosphere have a direct and negative impact on net social benefit to current and future generations. Our current human population has a moral obligation to future generations and, therefore, is responsible for excess burning of fossil fuels. This essential carbon tax is needed to help wean humans off their fossil fuel reliance. One should not be concerned with the economic losses this could cause because an economy based off unlimited growth is unsustainable and must be altered. A new, sustainable economic system must be developed in order to ensure continued human prosperity. This sustainable economic system will utilize a carbon tax and also includes features proposed by Jackson (2009) in Prosperity without Growth such as a reduced work week, a transition into a service economy, and increased public investment. This paper will include a defense of the morality of a mandatory carbon tax, a discussion of its potential socio-economic benefits, and the argument that a sustainable economy is possible if swift actions are taken.

Growth and physiological models for Atlantic salmon (Salmo salar L.) parr exposed to elevated carbon dioxide concentrations at high temperature

Atlantic salmon (Salmo salar L.) parr (33 g start weight) were exposed to five different mean levels of carbon dioxide partial pressure for about five weeks in an open flow system: 0.7 mmHg (1.9 mg L− 1; control group), 3.9 mmHg (10 mg L− 1; low group), 6.5 mmHg (17 mg L− 1; medium group), 9.5 mmHg (25 mg L− 1; high group) and 12.4 mmHg (33 mg L− 1; very high group). The water temperature was 15 °C. Plasma chloride concentration decreased linearly with increasing carbon dioxide concentration on days 9, 20 and 37 (p < 0.05). The mean reduction in plasma chloride was 0.65 mM/(mg L− 1 CO2). The specific growth rate (SGR) decreased with decreasing plasma chloride concentration (p < 0.05). The relationship between carbon dioxide concentration and SGR can be described using a second-order polynomial model (p < 0.01). Based on this second-order polynomial model, SGR is 100% until 15 mg L− 1 is exceeded and minor reductions occur between 15 and 20 mg L− 1. However, at higher concentrations the reductions in SGR increase very fast. That the relationship between CO2 and growth was curvilinear rather than linear seems an important overall advance in the state of knowledge. It should also be noted that some fish grew well even at high CO2 concentration (38 mg L− 1).

General Chemistry Students’ Understanding of Climate Change and the Chemistry Related to Climate Change

While much is known about secondary students’ perspectives of climate change, rather less is known about undergraduate students’ perspectives. The purpose of this study is to investigate general chemistry students’ understanding of the chemistry underlying climate change. Findings that emerged from the analysis of the 24 interviews indicate that students confuse the greenhouse effect, global warming, and the ozone layer. In terms of chemistry concepts, the students lack a particulate-level understanding of greenhouse gases, making it difficult for them to understand the mechanism of the greenhouse effect and corresponding links to the impact of increasing carbon dioxide concentrations and climate change.