Operational and environmental factors affecting disinfection byproducts formation in ballast water treatment systems

To prevent the worldwide spread of invasive aquatic species, the ballast water of ships may be disinfected with either physical or chemical treatment systems. Excess chemicals, such as chlorine, are neutralized before the ballast water can be discharged. Unfortunately, disinfection byproducts (DBPs) formed during treatment are not neutralized and remain potentially toxic. In this study, DBPs obtained from land-based tests of seven different ballast water treatment systems (BWTSs) have been statistically analyzed. Effect of operational factors (treatment type, holding time, source of carbon and active substance dosages) and environmental variables (salinity, pH, temperature, organic matter) were related to the formation of DBPs, such as trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs) and aldehydes. THMs and HAAs were the groups with major occurrences and concentrations detected in all BWTSs. Treatment type and source of carbon were the operational factors with major significance on DBP production, especially in chlorination systems. Salinity is the main variable determining DBP composition, as it differs between brominated-DBPs and chlorinated-DBPs. Concentration and type of organic matter (dissolved and particulate) have also a significant influence on the formation of total DBPs. According to the specific group of DBPs, some factors get significance. For instance, THMs are significantly affected by pH, and the production of aldehydes correlates positively with oxidant dos

Global marine plankton functional type biomass distributions: Phaeocystis spp.

Vogt, M. ... et. al.-- 14 pages, 9 figures, 4 tables, 1 appendix, The original and gridded data can be downloaded from PANGAEA: https://doi.org/10.1594/PANGAEA.779101The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to carbon biomass using species-specific carbon conversion factors. Microscopic counts of single-celled and colonial Phaeocystis were obtained both through the mining of online databases and by accepting direct submissions (both published and unpublished) from Phaeocystis specialists. We recorded abundance data from a total of 1595 depth-resolved stations sampled between 1955–2009. The quality-controlled dataset includes 5057 counts of individual Phaeocystis cells resolved to species level and information regarding life-stages from 3526 samples. 83% of stations were located in the Northern Hemisphere while 17% were located in the Southern Hemisphere. Most data were located in the latitude range of 50–70º N. While the seasonal distribution of Northern Hemisphere data was well-balanced, Southern Hemisphere data was biased towards summer months. Mean species- and form-specific cell diameters were determined from previously published studies. Cell diameters were used to calculate the cellular biovolume of Phaeocystis cells, assuming spherical geometry. Cell biomass was calculated using a carbon conversion factor for prymnesiophytes. For colonies, the number of cells per colony was derived from the colony volume. Cell numbers were then converted to carbon concentrations. An estimation of colonial mucus carbon was included a posteriori, assuming a mean colony size for each species. Carbon content per cell ranged from 9 pg C cell−1 (single-celled Phaeocystis antarctica) to 29 pgC cell−1 (colonial Phaeocystis globosa). Non-zero Phaeocystis cell biomasses (without mucus carbon) range from 2.9 × 10−5 to 5.4 × 103 μg Cl−1, with a mean of 45.7 μg Cl−1 and a median of 3.0 μg Cl−1. The highest biomasses occur in the Southern Ocean below 70º S (up to 783.9 μg Cl−1) and in the North Atlantic around 50º N (up to 5.4 × 103 μg Cl−1). The original and gridded data can be downloaded from PANGAEA, doi:10.1594/PANGAEA.779101Peer Reviewe

Disparities between in situ and optically derived carbon biomassand growth rates of the prymnesiophyte <i>Phaeocystis globosa</i>

The oceans play a pivotal role in the global carbon cycle. It is not practical to measure the global daily production of organic carbon, the product of phytoplankton standing stock and its growth rate using discrete oceanographic methods. Instead, optical proxies from Earth-orbiting satellites must be used. To test the accuracy of optically derived proxies of phytoplankton physiology and growth rate, hyperspectral reflectance data from the wax and wane of a Phaeocystis bloom in laboratory mesocosms were compared with standard ex situ data. Chlorophyll biomass could be estimated accurately from reflectance using specific chlorophyll absorption algorithms. However, the conversion of chlorophyll (Chl) to carbon (C) was obscured by the non-linear increase in C : Chl under nutrient-limited growth. Although C : Chl was inversely correlated (r2 = 0.88) with the in situ fluorometric growth rate indicator Fv / Fm (Photosystem II quantum efficiency), none of them was linearly correlated to growth rate, constraining the accurate calculation of Phaeocystis growth or production rates. Unfortunately, the optical proxy ?ph (quantum efficiency of fluorescence: the ratio of the number of fluoresced photons to the number of photons absorbed by the phytoplankton) did not show any correlation with Phaeocystis growth rate, and therefore it is concluded that ?ph cannot be applied in the remotely sensed measurement of this species' carbon production rate