Nitrogen export from an agriculture watershed in the Taihu Lake area, China

Temporal changes in nitrogen concentrations and stream discharge, as well as sediment and nitrogen losses from erosion plots with different land uses, were studied in an agricultural watershed in the Taihu Lake area in eastern China. The highest overland runoff loads and nitrogen losses were measured under the upland at a convergent footslope. Much higher runoff, sediment and nitrogen losses were observed under upland cropping and vegetable fields than that under chestnut orchard and bamboo forest. Sediment associated nitrogen losses accounted for 8-43.5% of total nitrogen export via overland runoff. N lost in dissolved inorganic nitrogen forms (NO(3-)-N + NH4+-N) accounted for less than 50% of total water associated nitrogen export. Agricultural practices and weather-driven fluctuation in discharge were main reasons for the temporal variations in nutrient losses via stream discharge. Significant correlation between the total nitrogen concentration and stream discharge load was observed. Simple regression models could give satisfactory results for prediction of the total nitrogen concentrations in stream water and can be used for better quantifying nitrogen losses from arable land. Nitrogen losses from the studied watershed via stream discharge during rice season in the year 2002 were estimated to be 10.5 kg N/ha using these simple models.     

Inhibition of attachment of larval barnacles,Balanus amphitrite,by bacterial surface films

Films of bacteria on solid substrata can positively or negatively influence the attachment of marine invertebrate larvae. Effects of marine bacteria on the attachment of cypris larvae of the barnacle Balanus amphitrite Darwin were examined in the laboratory. Bacteria, grown to mid-exponential phase and allowed to adsorb irreversibly to polystyrene petri dishes, attached in densities of 10⁷ cells cm^-2. Assays (22h) were used to compare the effects of adsorbed cells of 18 different bacterial species on larval barnacle attachment. Most of the adsorbed bacteria either inhibited or had no effect on larval attachment compared to clean surfaces. Experiments testing the effect of larval age on barnacle attachment were conducted with six species of bacteria and showed that older larvae attached in higher percentages to clean surfaces and that bacterial films generally inhibited larval attaschment. Both the species of bacteria and the in situ age of the adsorbed bacteria affected barnacle attachment response: older films of Deleya (Pseudomonas) marina were more inhibitory. Bacterial extracellular materials may be involved in the inhibitory process.     

An evaluation of two diffusion culture techniques for estimating phytoplankton growth rates In situ

In comparative tests, acrylic diffusion chambers (voltume=42 ml) with polycarbonate filter membranes (1 m pore diameter) consistently supported higher cell yields and faster growth rates of summer phytoplankton populations and species from Narragansett Bay than did dialysis bags (volume=50 ml, 0.24–0.48 nm pore diameter) or bottle cultures (with or without added nutrients). Stirring of diffusion chambers or dialysis bags had less effect on growth responses than did the choice of the containment membrane. Exchange measurements showed the polycarbonate filters (0.49 ml cm^-2 h^-1) to be five times more permeable than dialysis membranes (0.09 ml cm^-2 h^-1) per unit area. The mean of measured half-life times for water in diffusion chambers was less than one hour while comparable half-life times for dialysis bags were approximately 3 h. Diatoms from the <10 m size fraction had higher growth rates than assemblages of microflagellates and non-motile ultraplankton. Stirring of diffusion chambers did not adversly effect the growth of microflagellates or non-motile ultraplankton. Growth responses in diffusion chambers moored in situ were generally similar to those measured in diffusion chambers incubated in outdoor tanks connected to a running seawater system.     

Developing an empirical model of phytoplankton primary production: a neural network case study

We describe the development of a neural network model for estimating primary production of phytoplankton. Data from an enriched estuary in the eastern United States, Chesapeake Bay, were used to train, validate and test the model. Two error backpropagation multilayer perceptrons were trained: a simpler one (3-5-1) and a more complex one (12-5-1). Both neural networks outperformed conventional empirical models, even though only the latter, which exploits a larger suite of predictive variables, provided truly accurate outputs. The application of this neural network model is thoroughly discussed and the results of a sensitivity analysis are also presented.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

Translating the 10 golden rules of reforestation for coral reef restoration

Efforts are accelerating to protect and restore ecosystems globally. With trillions of dollars in ecosystem services at stake, no clear framework exists for developing or prioritizing approaches to restore coral reefs even as efforts and investment opportunities to do so grow worldwide. Restoration may buy time for climate change mitigation, but it lacks rigorous guidance to meet objectives of scalability and effectiveness. Lessons from restoration of terrestrial ecosystems can and should be rapidly adopted for coral reef restoration. We propose how the 10 golden rules of effective forest restoration can be translated to accelerate efforts to restore coral reefs based on established principles of resilience, management, and local stewardship. We summarize steps to undertake reef restoration as a management strategy in the context of the diverse ecosystem service values that coral reefs provide. Outlining a clear blueprint is timely as more stakeholders seek to undertake restoration as the UN Decade on Ecosystem Restoration begins.     

Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysis

•Addition of hindered amine increased thermal stability and viscosity of TTTM. •Addition of hindered amine improved the CO₂ absorption performance of TTTM. •Good the CO₂ absorption of recycled solvents after two regenerations. •Important role of amine group in CO₂ absorption of TTTM confirmed by DFT analysis. Is it possible to improve CO₂ solubility in potassium carbonate (K₂CO₃)-based transition temperature mixtures (TTMs)? To assess this possibility, a ternary transition-temperature mixture (TTTM) was prepared by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform infrared spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliphatic functional groups in the prepared solvents. From thermogravimetric analysis (TGA), it was found that the addition of AMPD to the binary mixture can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temperature. In addition, Eyring’s absolute rate theory was used to compute the activation parameters (ΔG*, ΔH*, and ΔS*). The CO₂ solubility in liquids was measured at a temperature of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO₂ solubility of TTTM was improved by the addition of AMPD. At the pressure of about 1.8 MPa, the CO₂ mole fractions of TTM and TTTM were 0.1697 and 0.2022, respectively. To confirm the experimental data, density functional theory (DFT) was employed. From the DFT analysis, it was found that the TTTM+ CO₂ system has higher interaction energy (|ΔE |) than the TTM+ CO₂ system indicating the higher CO₂ affinity of the former system. This study might help scientists to better understand and to improve CO₂ solubility in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD.     

Ammonia emission from grassland and livestock production systems in the UK

Emissions of ammonia were measured from livestock excreta and fertilisers applied to grass swards, from grazed paddocks, from decomposing grass herbage and from an animal house containing dairy cows. Emissions from urine, dung, slurry and fertilisers were determined using a system of wind tunnels with each tunnel covering an area of 1 m(2). Emissions from grazed swards were determined using a micrometeorological mass balance method. From the results of these measurements, together with other published information, an inventory for ammonia emissions has been calculated for grassland and livestock production systems over the UK as a whole. It is estimated that emissions from grassland and cattle and sheep production amount to about 230 kt NH(3)-N annually, while emissions from pig and poultry production amount to about 40 kt and 80 kt NH(3)-N, respectively.     

Trace metals in the hair of habitants of the Ok Tedi region, Papua New Guinea

It has long been known that mining activity can markedly change the level and distribution of certain heavy metals in the adjacent environment. This pollution can be quite widespread and long lasting and often has deleterious effects on the health of local populations. In the present study scalp hair was used as the biopsy material because of its ease of collection and long history of use in this connection. Hair was collected from all the local villages in the vicinity of the mine site, as well as from Papua New Guinean nationals from other provinces, and European expatriates who were employed by the mining company and who were resident in the area. Hair from local people showed a remarkably high iron content by comparison with previously studied populations. The extreme variations in hair iron levels were reflected in the differential distribution of levels according to location, age and sex. Hair cadmium was also high in the population studied. Hair copper, lead, zinc and mercury all appeared to be within 'normal' limits by comparison with other general populations. These results are discussed in the context of the environmental and social impact of the mining operations on the local people.     

Chemical fractionation of copper, lead and zinc in ombrotrophic peat

Measurement of operationally defined chemical fractions in ombrotrophic peat samples provides information not obtained by total metal extractions. Examination of such sequential data permits interpretation of process dynamics. Results for copper, lead and zinc chemical fractionation of peat profiles from Ringinglow Bog, near Sheffield, Great Britain, are reported and discussed. Lead and zinc share similar patterns of partitioning. A considerable proportion of these records is in a form predisposed to transformation and mobilisation. In contrast, much of the copper is comparatively immobile, it being associated with the more chemically intractable fractions. The results suggest that peat copper deposition records may be used for reconstruction of pollution history. The use of lead and zinc records for these purposes is problematic.