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Over the last decades, the effects of climate change have become increasingly evident across natural environments. Apart from other areas, climate change poses a serious threat on water quality. More specifically, it is expected that the effects of global warming around the world will severely limit our ability to control the spread and occurrence of Harmful Algal Blooms (HABs) in the future. A HAB episode is characterised by rapid proliferation of algal biomass which can cause major implications on the environment, the ecosystems, on human health, the economy, and societies overall. One way of detecting the presence of algae is to determine the chlorophyll-a concentration levels in water. This project proposes an embedded system for early algae detection in water samples by means of chl-a fluorometry. The system makes use of a constructed sensor to detect chl-a fluorescence emission. Two versions of the sensor were designed and implemented, both of which were calibrated and then tested. Afterwards, the results were presented, and the system’s performance was evaluated and discussed. Lastly, it was concluded that the performance of the system was adequate for detecting a 50 μg/L limit of chl-a concentration, however, careful testing of the site is required for field applications in samples of natural water. / ­Under de senaste decennierna har effekterna av klimatförändringar blivit allt tydligare i naturliga miljöer. Förutom andra områden utgör klimatförändringarna ett allvarligt hot mot vattenkvaliteten.  I synnerhet förväntas effekterna av global uppvärmning över hela världen begränsa vår förmåga att kontrollera spridningen och förekomsten av skadliga algblomningar (HAB) i framtiden. En HAB-episod kännetecknas av snabb spridning av algbiomassa som kan orsaka stora konsekvenser för miljön, ekosystemen, människors hälsa, ekonomin och samhället i stort. Ett sätt att upptäcka förekomsten av alger är att bestämma klorofyll-a-koncentrationsnivåerna i vatten.  Detta projekt föreslår ett inbyggt system för tidig algedetektering i vattenprover med hjälp av chl-a fluorometri. Systemet använder en konstruerad sensor för att detektera chl-a-fluorescensemission. Två versioner av sensorn designades och implementerades, båda kalibrerades och testades sedan. Därefter presenterades resultaten och systemets prestanda utvärderades och diskuterades.  Slutligen drogs slutsatsen att systemets prestanda var tillräcklig för att detektera 50 μg/L-gräns för chl-a-koncentration, men noggrann testning av platsen krävs för fältapplikationer i prover av naturligt vatten.

yes / New non-lethal technologies (weapons and delivery systems) continue to make the news, both for their civil and military applications. Technologies which were considered to be in the realm of science fiction a few years ago, are now beginning to undergo field trials or, in some cases, are being deployed with police and soldiers on active service. As this, and our previous reports have highlighted, the development of acoustic weapons (Long Range Acoustic Device) and microwave weapons (Active Denial System) have proceeded rapidly as have advances in robotic, unmanned vehicles for the delivery of both lethal and non-lethal weapons. We repeat our concern that there is a danger of these new non-lethal technologies being `rushed¿ into service (1) without thorough testing for harmful health effects, (2) without a deeper consideration of civil and human rights, (3) without full discussion of their impact on arms control treaties and conventions, and (4) without further study of their social and cultural impact. Since many such weapons will have a rheostatic capacity along the non-lethal to lethal continuum, it is important that weapons developers and manufacturers, and those charged with the responsibility of using them, are held clearly accountable and have transparent rules of engagement. Of particular concern are a new generation of biological and chemical weapons. With respect to the health impact, NATO has a panel working on NLW human effects, the Human Factors and Medicine (HFM) Panel 073, which is due to report later this year (2004) on the Human Effects of Non-Lethal Technologies.1

<p dir="ltr">This study analyzes one subset of twelve lakes within Kosciusko County, Indiana between 2015 and 2021 to provide a quantitative understanding of the mechanisms which influence onset and occurrence of HABs. Analysis of water samples, balanced by imagery from satellite remote sensing platforms, are used to quantify the biogeochemical state of these water systems and better understand the mechanisms involved in formation of HABs. Parameters studied include in-situ measurements (e.g., water temperature), laboratory measurements (e.g., microcystin, nitrogen, and phosphorous concentrations), and satellite derived responses (chlorophyll-a). Results indicate no single parameter is correlated with cyanotoxin concentrations, but instead multiple parameters have a synergistic effect on algal bloom growth and toxicity.</p>

Alexandrium tamarense is a harmful algal species that can produce saxitoxins, a suite of powerful neurotoxins that bioaccumulate up the food chain and can have severe economic and health impacts. With harmful algal blooms increasing temporally and spatially, it is important for us to understand the relationship between harmful algal blooms and nutrients, particularly nitrogen from anthropogenic sources. To this end, the stable nitrogen isotopic composition (δ¹⁵N) of medium nitrate, algal cells and toxin in both nitrogen-replete and nitrogen-limited batch cultures of A. tamarense were measured in order to assess the potential for using the δ¹⁵N of the toxin as a tracer of the nitrogen source used for growth. A. tamarense cells grown under nitrate-replete conditions were depleted by 1.5‰ relative to the growth medium, and saxitoxin was depleted by 1.5‰ relative to the whole cells. Under nitrate-limiting conditions, the isotopic difference between cells and saxitoxin changed as nitrate in the growth medium was depleted, indicating uncoupling of toxin synthesis and cell growth rates under changing external nutrient conditions. Determination of the absolute magnitude of the isotopic differences between the medium nitrate and either the cells or the saxitoxin was confounded by 1) using two different nitrate sources – one nitrate source was used to grow the inoculum and a different nitrate source was used for the experimental medium - with different ‰ values and 2) the presence of an unidentified, isotopically-light, nitrogen blank in the low-nitrate medium samples. I conclude that STX nitrogen isotope values have the potential to be used as nitrogen source indicators. However, overall fractionation between whole cells and STX is unknown due to the uncoupling between cell growth and STX synthesis observed during my nitrogen-limited experiment. Based on previous research on cell growth and toxin production dynamics under different nutrient regimes, it is also reasonable to assume that the observed results here may differ if a different nitrogen source was utilized by the cells for STX production. Further research could include isotope analysis of cultures grown on different nitrogen sources, such as ammonium and urea; isotopic analysis of additional compounds, such as amino acids; or use of additional stable isotopes, such as C or O. / text