Changes in nutrient availability from calcareous to acid wetland habitats with closely related brown moss species: increase instead of decrease in N and P

To test whether shifts in nutrient availability from calcareous to mineral-poor habitats could be a driving force in the evolution of seven closely related wetland brown mosses, we measured soil and vascular plant nutrients and conducted a laboratory incubation experiment with Swedish and some Dutch samples, in which net N and P-mineralization, respiration and microbial characteristics were measured. In spite of high respiration and microbial N, net N-mineralization appeared to be low for the calcareous Palustriella falcata and Scorpidium spp. Net N-mineralization significantly increased (and respiration and microbial N decreased) for the mineral-poor Sarmentypnum exannulatum, Straminergon stramineum and Warnstorfia fluitans, probably due to a decrease in microbial N-demand. Even though values were mainly negative, net P-mineralization showed a similar increase from calcareous to mineral-poor fens, probably due to lower precipitation of calcium phosphate. The calcareous habitat of the early wetland mosses may thus have been nutrient-poor instead of nutrient-rich. Adaptation to mineral-poor habitats, probably driven by expansion of mineral-poor wetlands when the boreal zone became colder and wetter, may have been associated with higher availability of ammonium and phosphate. However, this may have stimulated Sphagnum more than brown mosses, which may have been restricted to particular niches with perhaps some nitrification.     

Intoxicating paricá seeds of the brazilian maué indians

Paricà seeds were reportedly used as a snuff and enema ingredient by the Brazilian Mauù Indians. We analyzed, by gas chromatography/mass spectrometry, paricà seeds from the first half of the 19th century. Despite their considerable age, the seeds yielded as much as 15 mg/g of theAnadenanthera alkaloid bufotenin, as identified by retention time on a capillary column and the mass spectrum. This analytical finding supports the view that the seeds originated from anAnadenanthera species.     

LCI data and data quality

Life cycle inventory (LCI) is becoming an established environmental management tool that quantifies all resource usage and waste generation associated with providing specific goods or services to society. LCIs are increasingly used by industry as well as policy makers to provide a holistic ‘macro’ overview of the environmental profile of a good or service. This information, effectively combined with relevant information obtained from other environmental management tools, is very useful in guiding strategic environmental decision making. LCIs are very data intensive. There is a risk that they imply a level of accuracy that does not exist. This is especially true today, because the availability of accurate LCI data is limited. Also, it is not easy for LCI users, decision-makers and other interested parties to differentiate between ‘good quality’ and ‘poor quality’ LCI data. Several data quality requirements for ‘good’ LCI data can be defined only in relation to the specific study in which they are used. In this paper we show how and why the use of a common LCI database for some of the more commonly used LCI data, together with increased documentation and harmonisation of the data quality features of all LCI data, is key to the further development of LCI as a useful and pragmatic environmental management tool. Initiatives already underway to make this happen are also described.     

Hypotonicity activates a lanthanide-sensitive pathway for K+ release in A6 epithelia

The nature of the pathway forK⁺ release activated duringregulatory volume decrease (RVD) in A6 epithelia was investigated bymeasuring cell thickness (T_c) asan index of cell volume and by probingK⁺ efflux with⁸⁶Rb as tracer forK⁺(R_Rb). Cell swelling was inducedby sudden reduction of basolateral osmolality (from 260 to 140 mosmol/kgH₂O). Experiments wereperformed in the absence of Na⁺transport. Apical R_Rb wasnegligible in iso- and hyposmotic conditions. On the other hand,osmotic shock increased basolateralR_Rb(R^bl_Rb) rapidly, reaching a maximum 7 minafter the peak in T_c. Quinine (0.5 mM) completely inhibited RVD and R^bl_Rb.Also verapamil (0.2 mM) impeded volume recovery considerably; lidocaine(0.2 mM) did not exert a noticeable effect. TheK⁺ channel blockerBa²⁺ (30 mM) delayed RVD but couldnot prevent complete volume recovery. Cs⁺ inhibited RVD noticeably atconcentrations <40 mM. With large Cs⁺ concentrations (>40 mM), theinitial osmometric swelling was followed by a gradual increase ofT_c, suggesting activation of Cs⁺ influx. Chronic exposure ofthe basolateral surface to 0.5 mM La³⁺ orGd³⁺ completely abolished RVD andR^bl_Rb. Acute administration oflanthanides at the time of osmolality decrease did not affect theinitial phase of RVD and reduced R^bl_Rbonly slightly. Apical Gd³⁺ exertedan inhibitory effect on RVD and R^bl_Rb.The effect of Gd³⁺ shouldtherefore be localized at an intracellular site. The role ofCa²⁺ entry could be excluded byfailure of extracellular Ca²⁺removal to inhibit volume recovery. In contrast to lanthanides, chronically and acutely administeredMg²⁺ (0.5 mM) inhibited RVD andR^bl_Rb by ~50%. These data suggest thatK⁺ excretion during RVD occursthrough a rather poorly selective pathway that does not seem to bedirectly activated by membrane stretch.

     

The effect of inoculation and the type of carrier material used on the biofiltration of methyl sulphides

 Low elimination capacities (less than 10 g m^-3 day^-1) were observed for the odorant dimethyl sulphide (Me₂S) when either wood bark or compost was used as the carrier material in a laboratory-scale biofilter. Enrichment experiments were set up by incubation of garden soil samples during 4 weeks with 100 ppm (v/v) headspace concentrations of both Me₂S and dimethyl disulphide (Me₂S₂). After transfer to a mineral medium, Me₂S- and Me₂S₂-degrading enrichment cultures were obtained for all five soil samples tested, both compounds being converted stoichiometrically to sulphuric acid. Upon inoculation of the laboratory-scale biofilter with one of these enrichment cultures (±120 g cell dry weight m^-3 reactor), the elimination capacity for Me₂S increased in a 3-week period to 35 g m^-3 day^-1 and 680 g m^-3 day^-1 when wood bark and compost were used as the respective carrier materials. Both inoculated biofilters were able to degrade Me₂S₂, however the elimination capacities obtained for Me₂S₂ were lower (e.g. 24 g m^-3 day^-1 for the wood bark filter) compared to those for Me₂S. For both inoculated biofilters, a gradual decrease of the elimination capacity for the methyl sulphides was observed as a result of acidification of the carrier material, suggesting that pH regulation is necessary if long-term biofiltration experiments are to be performed. Received: 6 June 1995/Received revision: 10 August 1995/Accepted: 22 August 1995