Impact of kelp forest on seawater chemistry - A review.

Kelp forests, globally distributed in cool temperate and polar waters, are renowned for their pivotal role in supporting species diversity and fostering macroalgae productivity. These high-canopy algal ecosystems dynamically influence their surroundings, particularly by altering the physicochemical properties of seawater. This review article aims to underscore the significance of kelp forests in modifying water masses. By serving as effective carbon sinks through the absorption of bicarbonate (HCO3-) and carbon dioxide (CO2) for photosynthesis, kelp forests mitigate nearby acidity levels while enhancing dissolved oxygen concentrations, essential for sustaining diverse marine communities. Additionally, kelp beds have exhibited the need to use inorganic ions (NO3-, NO2-, PO43-) from seawater in order to grow, albeit with associated increases in NH4+ concentrations. Specific examples and findings from relevant studies will be presented to illustrate the profound impact of kelp forests on seawater chemistry, emphasizing their vital role in marine ecosystems.

Local variability in snow concentrations of chlorinated persistent organic pollutants as a source of large uncertainty in interpreting spatial patterns at all scales.

Single point sampling, a widespread practice in snow studies in remote areas, due to logistical constraints, can present an unquantified error to the final study results. The low concentrations of studied chemicals, such as chlorinated persistent organic pollutants, contribute to the uncertainty. We conducted a field experiment in the Arctic to estimate the error stemming from differences in the composition of snow at short distances (1-3 m), including 13 single organochlorine pesticides and 6 polychlorinated biphenyls, thus providing the most detailed published dataset on the subject. We contrasted this variability with the uncertainty at larger spatial scales, both within one valley (regional scale, this study) and as described in the worldwide literature. The range of values for the coefficient of variation for local samples was 20-58% for single organochlorine pesticides (OCPs) and 33-54% for polychlorinated biphenyls (PCBs), and for regional samples it was 21-69% for OCPs and 65-93% for PCBs. We suggest that, to observe the actual changes in the concentration of selected compounds in snow, they should vary at the level of 40-60%, depending on the compound in question. The uncertainty margin remains much smaller than the current discrepancy between observation data and atmospheric deposition models considering snow, deeming field data on snow concentrations a useful ground-truthing dataset. However, field observations on spatial differences at all scales need to be interpreted with caution, and the dataset provided here on the local sampling uncertainty helps define the margins of such interpretations.

Development of cluster analysis methodology for identification of model rainfall hyetographs and its application at an urban precipitation field scale.

Despite growing access to precipitation time series records at a high temporal scale, in hydrology, and particularly urban hydrology, engineers still design and model drainage systems using scenarios of rainfall temporal distributions predefined by means of model hyetographs. This creates the need for the availability of credible statistical methods for the development and verification of already locally applied model hyetographs. The methodology development for identification of similar rainfall models is also important from the point of view of systems controlling stormwater runoff structure in real time, particularly those based on artificial intelligence. This paper presents a complete methodology of division of storm rainfalls sets into rainfalls clusters with similar temporal distributions, allowing for the final identification of local model hyetographs clusters. The methodology is based on cluster analysis, including the hierarchical agglomeration method and k-means clustering. The innovativeness of the postulated methodology involves: the objectivization of clusters determination number based on the analysis of total within sum of squares (wss) and the Calinski and Harabasz Index (CHIndex), verification of the internal coherence and external isolation of clusters based on the bootmean parameter, and the designated clusters profiling. The methodology is demonstrated at a scale of a large urban precipitation field of Kraków city on a total set of 1806 storm rainfalls from 25 rain gauges. The obtained results confirm the usefulness and repeatability of the developed methodology regarding storm rainfall clusters division, and identification of model hyetographs in particular clusters, at a scale of an entire city. The applied methodology can be successfully transferred on a global scale and applied in large urban agglomerations around the world.

No Correlation between Positive Fructose Hydrogen Breath Test and Clinical Symptoms in Children with Functional Gastrointestinal Disorders: A Retrospective Single-Centre Study.

Fructose malabsorption is regarded as one of the most common types of sugar intolerance. However, the correlation between gastrointestinal symptoms and positive results in fructose hydrogen breath tests (HBTs) remains unclear. The aim of this study was to assess the clinical importance of positive fructose HBT by correlating the HBT results with clinical features in children with various gastrointestinal symptoms. Clinical features and fructose HBT results were obtained from 323 consecutive children (2-18 years old, mean 10.7 ± 4.3 years) that were referred to the Tertiary Paediatric Gastroenterology Centre and diagnosed as having functional gastrointestinal disorders. A total of 114 out of 323 children (35.3%) had positive HBT results, of which 61 patients were females (53.5%) and 53 were males (46.5%). Children with positive HBT were significantly younger than children with negative HBT (9.0 vs. 11.6 years old; p < 0.001). The most frequent symptom among children with fructose malabsorption was recurrent abdominal pain (89.5%). Other important symptoms were diarrhoea, nausea, vomiting, and flatulence. However, no correlation between positive fructose HBT results and any of the reported symptoms or general clinical features was found. In conclusion, positive fructose HBT in children with functional gastrointestinal disorders can be attributed to their younger age but not to some peculiar clinical feature of the disease.

A High-Arctic flow-through lake system hydrochemical changes: Revvatnet, southwestern Svalbard (years 2010-2018).

Lake ecosystems are strongly coupled to features of their surrounding landscapes such as geomorphology, lithology, vegetation and hydrological characteristics. In the 2010-2018 summer seasons, we investigated an Arctic flow-through lake system Revvatnet, located in the vicinity of the coastal zone of Hornsund fjord in Svalbard, characterising its hydrological properties and the chemical composition of its waters. The lake system comprises of a small upper lake and a large lower one, the latter cone-shaped, with -29.1 m maximum depth. With near-neutral pH (full range 6.5-8.4) and low EC (7-147 µS cm-1), the lake has rather similar characteristics to many Arctic lakes. Metal and metalloid concentrations were either similar across the lake system or increased downstream (except Zn, which has important ore-bearing veins in the upper part of the catchment), which is consistent with the likely slow dissolution of suspended particles within the lakes. The ∑PAHs concentrations ranged from

Environmental characteristics of a tundra river system in Svalbard. Part 2: Chemical stress factors.

Bacterial communities in the Arctic environment are subject to multiple stress factors, including contaminants, although typically their concentrations are small. The Arctic contamination research has focused on persistent organic pollutants (POPs) because they are bioaccumulative, resistant to degradation and toxic for all organisms. Pollutants have entered the Arctic predominantly by atmospheric and oceanic long-range transport, and this was facilitated by their volatile or semi-volatile properties, while their chemical stability extended their lifetimes following emission. Chemicals present in the Arctic at detectable and quantifiable concentrations testify to their global impact. Chemical contamination may induce serious disorders in the integrity of polar ecosystems influencing the growth of bacterial communities. In this study, the abundance and the types of bacteria in the Arctic freshwater were examined and the microbial characteristics were compared to the amount of potentially harmful chemical compounds in particular elements of the Arctic catchment. The highest concentrations of all determined PAHs were observed in two samples in the vicinity of the estuary both in June and September 2016 and were 1964 ng L-1 (R12) and 3901 ng L-1 (R13) in June, and 2179 ng L-1 (R12) and 1349 ng L-1 (R13) in September. Remarkable concentrations of the sum of phenols and formaldehyde were detected also at the outflow of the Revelva river into the sea (R12) and were 0.24 mg L-1 in June and 0.35 mg L-1 in September 2016. The elevated concentrations of chemical compounds near the estuary suggest a potential impact of the water from the lower tributaries (including the glacier-fed stream measured at R13) or the sea currents and the sea aerosol as pollutant sources. The POPs' degradation at low temperature is not well understood but bacteria capable to degrading such compounds were noted in each sampling point.

Environmental characteristics of a tundra river system in Svalbard. Part 1: Bacterial abundance, community structure and nutrient levels.

The Arctic hosts a set of unique ecosystems, characterised by extreme environmental conditions and undergoing a rapid change resulting from the average temperature rising. We present a study on an aquatic ecosystem of the Revelva catchment (Spitsbergen), based on samples collected from the lake, river and their tributaries, in the summer of 2016. The landscape variety of the study site and the seasonal change in the hydrological regime modify the availability of nutrients. In general, the upper part of the catchment consists of the mountain rocky slopes which are especially abundant in iron minerals, sulphides and phosphorus minerals. The lower part of the catchment is covered by plants - lichens, saxifrages and bryophytes, which are a different source of nutrients. In the analysed water samples, the maximum concentrations of nutrients such as iron, boron and phosphorus were 0.28 µg L-1, 4.52 µg L-1 and 1.91 µg L-1, respectively, in June, while in September, Fe and B reached the concentrations of 1.32 µg L-1 and 2.71 µg L-1, respectively. The concentration of P in September was below the detection limit of 1.00 µg L-1, which may be explained by the necessity of bacteria to consume it immediately on current needs. We noted also an increase in TOC concentration between the June and September samples, which could originate both from the biomass accumulation in the catchment and the permafrost melting contributing to the hydrological regime of the river. The bacterial community developed in this environment consisted mainly of Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes phylum, while the presence of Acidobacteria was less pronounced than in other tundra-related environments. The described catchment shows that despite the relatively small amount of bioavailable nutrients, the Revelva system is biodiverse and one of the most significant biogeochemical changes occurs there in response to seasonally switching water sources.

The interaction between bacterial abundance and selected pollutants concentration levels in an arctic catchment (southwest Spitsbergen, Svalbard).

Persistent organic pollutants (POPs) have been a topic of interest in environmental sciences for >60years. POPs in the Arctic have been investigated since the 1970s, when first atmospheric measurements revealed the presence of these pollutants in the polar regions. Major contaminant transport routes to the Arctic include atmospheric and oceanic transport, as well as inflow from rivers and sea ice. The sources of pollutants, such as industry, power generators, vehicle and ship exhausts, introduce the PAHs, phenols, formaldehyde or metals into the Arctic. Transport via sea currents, however, can take several years. The highest concentration levels of total PAHs were observed in two samples from the tributaries in July 2015 and were 1069ngL-1 and 3141ngL-1 and in September 2015, the highest concentrations were observed in samples collected from Revvatnet lake and were 978ngL-1 and 1823ngL-1. The highest concentrations of trace elements in both months were 41µgL-1 in the sample from the highest tributary (July 2015) and 79µgL-1 in the same sample (September 2015). The purpose of this study was also to determine abundance of bacteria in the Arctic freshwater of different types. Microbes are omnipresent and represent diverse biological communities. In the freshwater ecosystems, microorganisms form the base of the food chain supporting higher trophic levels. Although microbes are generally thought to live in the warm regions of Earth, many of them develop in cold climates. In the Revelva catchment, the biggest number of bacteria were detected at the river estuary in July 2015 and at the sampling point located in the Revvatnet lake in September 2015. Generally, the bacterial abundance indices depended on nutrient levels to a small extent, showing the environment of the Revelva catchment not to be nutrient limited, which is in accordance with its rich biological life also in macroscale.

Determination of selected chemical parameters in surface water samples collected from the Revelva catchment (Hornsund fjord, Svalbard).

ABSTRACT: Surface water samples (river and lake) were collected from the Revelva catchment every summer from 2010 to 2013. This study concerns importance of the use of some analytical techniques for pollutants and parameters determination in Arctic environmental samples based on the example of total organic carbon, phenols, and formaldehyde determination and measurement of pH and electrical conductivity parameters. Significant average concentration levels of formaldehyde were observed in 2012 and reached 0.26 mg/dm3. Furthermore, the highest determined levels of total organic carbon and electrical conductivity were observed in samples collected in summer 2013. The average value of total organic carbon in that year was 9.54 mg/dm3, and electrical conductivity increased to 63.0 µS/cm. The results of surface water samples analyses show an increasing trend in pollutants concentration levels over the years what may suggest that each year the emission of contaminants from lower latitudes is bigger and, consequently, more of them are deposited in the Arctic.

Phytoplankton communities of polar regions--Diversity depending on environmental conditions and chemical anthropopressure.

The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders in the integrity of polar ecosystems. However, for a long time these areas were believed to be free of chemical contamination, and relatively protected from widespread anthropogenic pressure, due their remoteness and extreme climate conditions. Nowadays, there is a growing amount of data that prove that xenobiotics are transported thousands of kilometers by the air and ocean currents and then they are deposed in colder regions and accumulate in many environments, including the habitats of marine and freshwater cyanobacteria. Cyanobacteria (blue green algae), as a natural part of phytoplankton assemblages, are globally distributed, but in high polar ecosystems they represent the dominant primary producers. These microorganisms are continuously exposed to various concentration levels of the compounds that are present in their habitats and act as nourishment or the factors influencing the growth and development of cyanobacteria in other way. The most common group of contaminants in Arctic and Antarctic are persistent organic pollutants (POPs), characterized by durability and resistance to degradation. It is important to determine their concentrations in all phytoplankton species cells and in their environment to get to know the possibility of contaminants to transfer to higher trophic levels, considering however that some strains of microalgae are capable of metabolizing xenobiotics, make them less toxic or even remove them from the environment.