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Global warming has been considered to accelerate the expansion of cyanobacterial blooms, which are frequently composed of the bloom-forming genera, Microcystis and Pseudanabaena, in freshwater ecosystems worldwide. Nonetheless, the impact of changes due to toxin production or lack thereof on the growth of co-existing strains, both arising from increasing temperature, has remained unknown to date. We conducted competition experiments involving toxic Microcystis PCC7806, a non-toxic mcyB− mutant, and two strains of Pseudanabaena (TH-1 and DC-1) identified as P. mucicola. In mono-culture, the specific growth ratio of Pseudanabaena increased; nevertheless, the maximum cell density declined with increasing temperature. The maximum growth ratios of Pseudanabaena TH-1 and Pseudanabaena DC-1 were 0.512 day−1 in the 30 °C group and 0.440 day−1 in the 35 °C group, respectively. The optimum temperature for the growth of Pseudanabaena was 25 °C. Remarkably, there was no significant disparity in the maximum cell density of Microcystis PCC7806 and the mcyB− mutant across varied temperature groups, even though their maximum growth rates differed marginally, reaching 0.280 day−1 and 0.306 day−1 in the 30 °C group, respectively. In co-cultures, the growth of Pseudanabaena TH-1 was uniformly inhibited, whereas that of DC-1 was somewhat influenced by co-culturing with toxic and non-toxic Microcystis, except for the 35 °C group, where inhibition was absent amongst DC-1 and Microcystis. Moreover, the growth of Microcystis was promoted with a co-culture of TH-1 in the 20 °C groups. Conversely, the co-culture of Microcystis with Pseudanabaena DC-1 led to the inhibition of the former in the 30 °C and 35 °C groups. With a Lotka–Volterra competition model, the results showed that Microcystis dominated or co-existed with Pseudanabaena, conforming to expectations from the wild. [ABSTRACT FROM AUTHOR]

Aquatic products are important sources of animal proteins in human diet, especially in developing countries. As such, the safety of aquatic products is of primary concern. In this study, a standard method is used to detect malachite green (MG) and chloramphenicol (CAP) and to analyse the contents of these banned chemicals in turtle, mandarin fish and grass carp sampled from the region surrounding Dongting Lake area in Hunan, China. Results showed that 10.6% of the samples were MG-positive, most of them turtles. CAP was found in 8.3% of the samples, mostly in mandarin fish. These data indicated that these banned substances are still used in the surveyed area. Hence, adequate strategies must be implemented by the local government to control these banned substances. [ABSTRACT FROM PUBLISHER]

The purpose of the study was to determine plant availability of boron (B) and relaxation of soil acid to rape seedling exhibited by B-doped goethite in acidic soil. For this purpose, two kinds of B-doped goethite were synthesized: one was goethite with adsorbed B prepared by reacting goethite with borax solution, and the other was goethite with occluded B by synthesizing goethite in the presence of boric acid. The reaction process in soil-like natural minerals of the B-doped goethite was simulated in a rhizobox culture system. Results showed that the B-doped goethite can provide available B for rape growth. Its addition on acidic soil can alleviate soil acidification by increasing soil pH and decreasing soil exchangeable acid. The observation that nutrient uptake was improved supports the view that the B-doped goethite improved soil quality, as also proved by the increase of root morphology and dry weight. [ABSTRACT FROM AUTHOR]

The effectiveness of sediment dredging for the control of internal phosphorus (P) loading, was investigated seasonally in the eutrophic Lake Taihu. The high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) techniques were used to measure the concentrations of soluble Fe(II) and soluble reactive P (SRP) as well as DGT-labile Fe/P in the non-dredging and post-dredging sediments. The P resupply kinetics from sediment solids were interpreted using DGT Induced Fluxes in Sediments (DIFS) modeling. The results showed no obvious improvement in water and sediment quality after dredging for 6years, due to their geographical proximity (a line distance of approximately 9km). However, dredging significantly decreased the concentrations of soluble Fe(II)/SRP and DGT-labile Fe/P in sediments, with effects varying at different depths below the sediment-water interface; More pronounced effects appeared in January and April. The diffusive flux of pore water SRP from sediments decreased from 0.746, 4.08 and 0.353mg/m 2 /d to 0.174, 1.58 and 0.048mg/m 2 /d in April, July and January, respectively. DIFS modeling indicated that the P retention capability of sediment solids was improved in April in post-dredging site. Positive correlations between pore water soluble Fe(II) and SRP as well as between DGT-labile Fe and P, reflect the key role of Fe redox cycling in regulating dredging effectiveness. This effect is especially important in winter and spring, while in summer and autumn, the decomposition of algae promoted the release of P from sediments and suppressed dredging effectiveness. Overall, the high-resolution HR-Peeper and DGT measurements indicated a successful control of internal P loading by dredging, and the post-dredging effectiveness was suppressed by algal bloom., (Copyright © 2017 Elsevier B.V. All rights reserved.)