Seeing the forest not for the carbon: why concentrating on land-use-induced carbon stock changes of soils in Brazil can be climate-unfriendly

Regional Environmental Change - Soil carbon stocks of 29 plots along a transect through tropical Brazil showed only minor soil carbon losses after land use shift, although replacement of...     

Hydromorphological and socio-cultural assessment of urban rivers to promote nature-based solutions in Jarabacoa,Dominican Republic

In Latin America and the Caribbean, river restoration projects are increasing, but many lack strategic planning and monitoring. We tested the applicability of a rapid visual social–ecological stream assessment method for restoration planning, complemented by a citizen survey on perceptions and uses of blue and green infrastructure. We applied the method at three urban streams in Jarabacoa (Dominican Republic) to identify and prioritize preferred areas for nature-based solutions. The method provides spatially explicit information for strategic river restoration planning, and its efficiency makes it suitable for use in data-poor contexts. It identifies well-preserved, moderately altered, and critically impaired areas regarding their hydromorphological and socio-cultural conditions, as well as demands on green and blue infrastructure. The transferability of the method can be improved by defining reference states for assessing the hydromorphology of tropical rivers, refining socio-cultural parameters to better address river services and widespread urban challenges, and balancing trade-offs between ecological and social restoration goals.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01565-3.     

Comparison of two methods for the determination of total organic halogen (TOX) in receiving waters

Two methods for the determination of total organic halogen (TOX), orginating from bleaching of pulp, in receiving waters have been compared. One of the methods (AC/MC) is based on adsorption of the halogenated matter onto an activated carbon sorbent. The halogen is determined by a microcoulometric technique after combustion of the carbon. The other method (XAD/PT) uses an XAD resin as sorbent and the determination of the halogen is carried out by potentiometric titration after a schöniger combustion of the resin eluate.Both methods showed good performance for samples consisting of spent bleach liquors diluted with distilled, fresh and brackish water. The repeatability was very good with a relative standard deviation less than a few per cent. The detection limit of the AC/MC method is about 0.1 μmol/1 and for the XAD/PT method about ten times higher. The AC/MC method gave in most cases 10–20% higher TOX concentrations compared to the XAD/PT method.     

Decomposition of heavy metal contaminated nettles (Urtica dioica L.) in soils subjected to heavy metal pollution by river sediments

Two incubation experiments were conducted to evaluate differences in the microbial use of non-contaminated and heavy metal contaminated nettle (Urtica dioica L.) shoot residues in three soils subjected to heavy metal pollution (Zn, Pb, Cu, and Cd) by river sediments. The microbial use of shoot residues was monitored by changes in microbial biomass C, biomass N, biomass P, ergosterol, N mineralisation, CO(2) production and O(2) consumption rates. Microbial biomass C, N, and P were estimated by fumigation extraction. In the non-amended soils, the mean microbial biomass C to soil organic C ratio decreased from 2.3% in the low metal soil to 1.1% in the high metal soils. In the 42-d incubation experiment, the addition of 2% nettle residues resulted in markedly increased contents of microbial biomass P (+240%), biomass C (+270%), biomass N (+310%), and ergosterol (+360%). The relative increase in the four microbial properties was similar for the three soils and did not show any clear heavy metal effect. The contents of microbial biomass C, N and P and ergosterol contents declined approximately by 30% during the incubation as in the non-amended soils. The ratios microbial biomass C to N, microbial biomass C to P, and ergosterol to microbial biomass C remained constant at 5.2, 26, and 0.5%, respectively. In the 6-d incubation experiment, the respiratory quotient CO(2)/O(2) increased from 0.74 in the low metal soil to 1.58 in the high metal soil in the non-amended soils. In the treatments amended with 4% nettle residues, the respiratory quotient was constant at 1.13, without any effects of the three soils or the two nettle treatments. Contaminated nettle residues led generally to significantly lower N mineralisation, CO(2) production and O(2) consumption rates than non-contaminated nettle residues. However, the absolute differences were small.     

Xenoestrogens in the River Elbe and its tributaries

4-Alkylphenols, 4-alkylphenol ethoxylates, 4-alkylphenoxy carboxylates, bisphenol A, bisphenol F, 4-hydroxyacetophenon, 4-hydroxybenzoic acid and steroid hormones were analyzed in water samples of the River Elbe and its tributaries Schwarze Elster, Mulde, Saale, Havel and Schwinge. Additionally, freshly deposited sediments (FDS, composite samples) of the River Elbe and its tributaries were analyzed. The concentrations in water samples ranged from (in ng/l): bisphenol A 4 to 92, branched nonylphenol 13 to 87, branched nonylphenol ethoxylates <0.5 to 120, 4-tert. nonylphenoxy carboxylates <10 to 940 and 4-hydroxybenzoic acid 4 to 12. Steroid hormones were only detected in the Czech tributaries Jizera and Vltava in concentrations near the limit of quantification. In FDS samples the concentrations amounted to (in g/kg d.w.): bisphenol A 10-380, branched nonylphenol 27-430, branched nonylphenol ethoxylates 24-3700, nonylphenoxy carboxylates <50 and 4-hydroxybenzoic acid 23-4400. Increased bisphenol A concentrations were found in water and FDS samples taken from the Czech-German border at Schmilka and the mouth of the Schwinge (only water sample). According to studies conducted in the Elbe Estuary and the German Bight, the River Elbe must be considered as a major source of pollution for the North Sea in respect of the compounds analyzed. A comparison of bisphenol A concentrations, 4-alkylphenols and the corresponding ethoxylates analyzed in the River Elbe and its tributaries with those found in other German surface waters indicated a low level of contamination. The evaluation of the data based on LOEC-values indicated that the concentrations were well below the effectivity threshold for some 4-alkylphenols. According to recent ecotoxicological investigations, for example, with prosobranch snails, bisphenol A concentrations found in water samples of the River Elbe and its tributaries may well be detrimental to aquatic organisms. On the basis of the monitoring data and its implications for estrogenic potency the inclusion of bisphenol A in the list of priority substances (European Union Directive 2000/60/EC, Annex X) should be considered.     

The stereochemistry of 1,2,5,6,9,10-hexabromocyclododecane and its graphic representation

1,2,5,6,9,10-Hexabromocyclododecane, a widely used additive flame retardant, is produced by bromination of cis,trans,trans-cyclododeca-1,5,9-triene, resulting in a mixture of three enantiomeric pairs of diastereomers. We present here the correct configuration and graphic representation of the six isomers. Recently, the complete separation of all six isomers has been achieved using chiral liquid chromatography.