The Chronic Toxicity of Titanium Dioxide Nanoparticles to the Freshwater Amphipod Hyalella azteca

There has been an increased use of metal-oxide nanoparticles in both commercial and consumer products. The use of these products and waste generated during manufacture may ultimately be released into the aquatic environment and the potential for these contaminants to cause impacts must be assessed. This study examines the effect of titanium dioxide (TiO2) nanoparticles (NPs) on Hyalella azteca. Chronic toxicity exposures were conducted in 400mL of spiked test solution and contained 20 neonates. Samples collected for characterization of Ti in TiO2 NP exposure solutions were digested using ammonium persulfate as an oxidizing agent and dissolved in 2% HNO3, organisms were digested using 70% HNO3 and 30% H202. Dissolved Ti LC50 was 1404 µg Ti/L, all NP exposure’s had LC50 values above 100 mg TiO2/L. The IC50 value of dissolved Ti on growth was 914 µg Ti /L, while uncoated TiO2 NPs P25, PC105, NM101, and NM105 yield IC50 values of 23.4, 31.2, 16 and 14.5 mg TiO2/L respectively. NM103 (hydrophobic) and NM104 (hydrophilic) yielded IC50 values of 36.4 and 6.5 mg TiO2/L respectively. Testing was done to assess the impact dispersion methods of NPs would have on the toxicity to H.azteca. Organisms were exposed to NP solutions that had been dispersed by a 24h spin or were dispersed by a 24h spin and 5 minute sonication step. Organisms exposed to sonicated solutions showed lower dry weight than those exposed to stirred solutions. H.azteca were exposed to a ‘low’ and ‘high’ cadmium concentration in the presence and absence of P25 TiO2 NPs to determine the potential for NPs to acts a ligand to Cd. There was significantly lower bioaccumulation of Cd in organisms exposed in the presence of P25 TiO2 NPs in both concentrations. These results show dissolved Ti has greater impact on H.azteca than TiO2 NPs and it is difficult to relate physical particle characteristics to biological effect. TiO2 NPs with hydrophilic surface modification are more toxic than those with hydrophobic surface modifications. NP solutions dispersed by sonication are more toxic than those that are stirred. TiO2 NPs acted as a negative vector for cadmium, limiting Cd bioavailability

Allometry and growth of eight tree taxa in United Kingdom woodlands.

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0As part of a project to develop predictive ecosystem models of United Kingdom woodlands we have collated data from two United Kingdom woodlands - Wytham Woods and Alice Holt. Here we present data from 582 individual trees of eight taxa in the form of summary variables relating to the allometric relationships between trunk diameter, height, crown height, crown radius and trunk radial growth rate to the tree's light environment and diameter at breast height. In addition the raw data files containing the variables from which the summary data were obtained. Large sample sizes with longitudinal data spanning 22 years make these datasets useful for future studies concerned with the way trees change in size and shape over their life-span

Tropical forests in the deep human past

Since Darwin, studies of human evolution have tended to give primacy to open ‘savannah’ environments as the ecological cradle of our lineage, with dense tropical forests cast as hostile, unfavourable frontiers. These perceptions continue to shape both the geographical context of fieldwork as well as dominant narratives concerning hominin evolution. This paradigm persists despite new, ground-breaking research highlighting the role of tropical forests in the human story. For example, novel research in Africa's rainforests has uncovered archaeological sites dating back into the Pleistocene; genetic studies have revealed very deep human roots in Central and West Africa and in the tropics of Asia and the Pacific; an unprecedented number of coexistent hominin species have now been documented, including Homo erectus, the ‘Hobbit’ (Homo floresiensis), Homo luzonensis, Denisovans, and Homo sapiens. Some of the earliest members of our own species to reach South Asia, Southeast Asia, Oceania and the tropical Americas have shown an unexpected rapidity in their adaptation to even some of the more ‘extreme’ tropical settings. This includes the early human manipulation of species and even habitats. This volume builds on these currently disparate threads and, for the first time, draws together a group of interdisciplinary, agenda-setting papers that firmly places a broader spectrum of tropical environments at the heart of the deep human past1. The tropics: a frontier for the deep human past 2. African tropical forests 3. Southeast Asian and pacific forests 4. Neotropical forests 5. Synthesi

Long-term fertilization effects on crop yield and nitrate-N accumulation in soil in northwestern China

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Digital technology: coming of age?

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Flourishing, mental health professionals and the role of normative dialogue

This paper explores the dilemma faced by mental healthcare professionals in balancing treatment of mental disorders with promoting patient well-being and flourishing. With growing calls for a more explicit focus on patient flourishing in mental healthcare, we address two inter-related challenges: the lack of consensus on defining positive mental health and flourishing, and how professionals should respond to patients with controversial views on what is good for them. We discuss the relationship dynamics between healthcare providers and patients, proposing that ‘liberal’ approaches can provide a pragmatic framework to address disagreements about well-being in the context of flourishing-oriented mental healthcare. We acknowledge the criticisms of these approaches, including the potential for unintended paternalism and distrust. To mitigate these risks, we conclude by suggesting a mechanism to minimize the likelihood of unintended paternalism and foster patient trust

Changes in the carbon balance of tropical forest: evidence from long-term plots

The role of the world’s forests as a “sink” for atmospheric carbon dioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America revealed that biomass gain by tree growth exceeded losses from tree death in 38 out of 50 neotropical sites. These forest plots have accumulated 0.71 + 0.34 tons of carbon per hectare per year in recent decades. The data suggest that neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric CO2