Base cation deposition in europe-part I. Model description, results and uncertainties

Deposition of base cations (Na⁺, Mg²⁺, Ca²⁺, K⁺) in Europe was mapped for 1989 with a spatial resolution of 10 x 20 km using the so-called inferential modeling technique. Deposition fields resembled the geographic variability of sources, land-use and climate. Dry deposition constituted on average 45% of the total base cation deposition in Europe. Modeled deposition estimates compared reasonably well with deposition estimates derived from throughfall and bulk-precipitation measurements made at 174 sites scattered over Europe. Using error propagation, the random and systematic error in total deposition for an average grid cell of 10 x 20 km was estimated to equal 35–50% and 25–40%, respectively. Within individual grids a relatively large variability in deposition is expected.     

Trends in summer sulphate in Europe

A trend analysis of the sulphate concentration in Europe in the summer half-year was performed. Data from various measuring networks were analysed, but only stations with quality assured sampling methods and a record of more than 10 years were included in the study. 1978 served as the reference year for the trend, because in that year most stations started operation. The relatively dense network in Belgium provided the most valuable data, as evidenced by the fact that two sites at a distance of only 10 km apart correlated better than 95% over a month. The two sites also show a correlation of better than 90% over a season with two other stations at distances of 45 and 95 km. The relative decrease in summer-sulphate at the four stations in Belgium, as analysed by linear regression, was 3.3% per year which corresponds to an absolute decrease of 0.42 μgm⁻³ per year. In the Netherlands the average yearly decrease in summer-sulphate at two stations was 3.5% (−0.34 μgm⁻³). In other countries stations were further apart or only a single site wits in use, which limits the representativeness of the data. In northwestern Germany, a region with several monitoring stations, a yearly averaged decrease of 3.0% occurred. The lower absolute decrease (0.25 μgm⁻³) per year compared to that in the two neighbouring countries reflects the lower summer-time sulphate concentrations. In the remainder of Germany the average decrease was 1.6%. In South-Scandinavia the yearly relative decrease at two sites was 2.6% (0.13 μgm⁻³ absolute). There was no significant trend in the U.K. Al the Polish station the levels increased, it decreased at the Hungarian and Austrian station and remained constant at the Czechoslovakian site. Reasons for omission of the data from France from the trend analysis are discussed.     

Discrimination of factors influencing biota of a stream receiving multiple-source perturbations

Blaine Creek is a fifth-order stream located in eastern Kentucky that has been subject to contamination by oil brines, surface mining, and a coal fly ash settling pond discharge. Toxicity tests, effluent and receiving water chemical monitoring, and Blaine Creek benthic sampling were used to evaluate the effect of the ash pond effluent on the creek. Reproductive impairment of Ceriodaphnia was demonstrated at effluent concentrations ranging from 30 to 100%, but no instream impact on benthic invertebrates could be found at effluent flows that provided up to 65% of the creek's discharge. Correlation and regression analysis of physicochemical versus benthic monitoring data indicated that upstream oil brine contamination and scouring of the creek's predominately shifting sand substrate during rainfall events were the primary factors affecting the benthic fauna, and appeared to override potential effects from other sources. These results demonstrated the value of integrated field/laboratory investigations for effluent impact assessments.     

Humic acid enhanced remediation of an emplaced diesel source in groundwater. 1. Laboratory-based pilot scale test

The enhanced solubility of petroleum-derived compounds in humic acid solutions is the basis for a new groundwater remediation technology. In this unique pilot-scale test, a stationary contaminant source consisting of diesel fuel was placed below the water table in a model sand aquifer (1.2 x 5.5 x 1.8-m deep) and flushed with water at a flow rate of 2 cm/h over 5 years. At 51 days, laboratory grade humic acid was added to the water and maintained at a level of approximately 0.8 g/l. The addition of humic acid had only a small impact on the aqueous transport of the BTEX components, which were rapidly dissolved from the diesel, but had a large effect on the flushing of PAHs, including methylated naphthalenes (MNs). Binding to aqueous humic acid enhanced the solubilization of MNs two- to tenfold. During aqueous transport, biodegradation of the BTEX and PAHs occurred, limiting the lateral and longitudinal extent of the diesel contaminant plume in the model aquifer. It appears that through enhanced solubilization, the overall biodegradation rate of the MNs was increased. As the various MNs were depleted from the diesel source, the MN plume shrank and then disappeared.     

Environmental impact of two successive chemical treatments in a small shallow eutrophied lake: Part I. Case of aluminium sulphate

This paper deals with the efficiency and effects of addition of aluminium sulphate on soft water quality of a shallow eutrophic lake. Almost all the controlled variables improved with treatment, especially nutrient concentrations such as soluble reactive phosphorus (SRP) and transparency. However, aluminium sulphate was not added in sufficient quantity to reduce the total phosphorus content. SRP concentration was significantly reduced in the short term. Moreover, external loading of phosphorus was high and not taken into account by the in-lake treatments. Finally, resuspension of sediment (polymictic lake) removed the alum hydroxide layer on the sediment surface, which reduced treatment effectiveness. No significant pH decrease was noted following alum addition. According to bibliographical toxicological data, monomeric aluminium content does not show any toxic effect on aquatic fauna and flora. In spite of low SRP in the water column, the treatment did not prevent appearance of Microcystis sp. colony (> 10 colony per ml) approximately 30 days after alum application.     

Forests in the time of peace

ABSTRACT

The signing of Colombia’s peace agreement in 2016 signaled the end of a decades-long war between the government and the FARC (Las Fuerzas Armadas Revolucionarias de Colombia), but also an emerging assault against the country’s forests. This article aims to understand the interactions between forests and peace. In doing so, it traces landscape transformations of deforestation and possibilities for making landscapes livable in the midst of disturbance. Drawing on field research, including interviews and participant observation carried out in Colombia from 2016 to 2018, it reveals how deforestation is driven by ongoing colonization and land grabbing, mostly dedicated to extensive cattle ranching, coca cultivation, and campesinos’ transition to ‘licit’ agricultural alternatives. The article also shows how emerging coordination among farmers and forests following forest disturbance contributes to an interpretation of peace in which forests are integral. The article concludes with a call to incorporate forests in the construction of peace.     

Contest behaviour in the speckled wood butterfly (Pararge aegeria): seasonal phenotypic plasticity and the functional significance of flight performance

Although contemporary animal contest theory emphasises the importance of physical asymmetries in resolving disputes, such asymmetries do not obviously settle fights in all groups. Territorial male butterflies, for example, compete via elaborate non-contact aerial interactions in which success is determined by relative persistence. Prior research suggests that the resolution of these contests is not clearly related to physical variables such as body size or energy reserves. However, given that the contests involve elaborate aerial manoeuvres, one long-standing suggestion is that asymmetries in flight performance, and thus flight morphology, may be important. We addressed this hypothesis via a manipulative investigation into the biophysical correlates of contest success in the speckled wood butterfly, Pararge aegeria. This species possesses the ability for significant adaptive phenotypic plasticity in relevant flight morphological parameters. We took advantage of this plasticity to rear 90 individuals of markedly varying flight morphologies, which we then pitted against each other in a semi-controlled experimental fashion. Multiple logistic and lognormal analyses provided little evidence for the relevance of morphological parameters, including relative flight musculature, wing loading and wing aspect ratio (wing length relative to area), to the outcome and/or duration of experimental contests. Instead, we found a positive effect of age upon contest success. Given that ability for high acceleration is strongly linked to variation in these morphological parameters, our findings suggest that flight performance is not a strong determinant of resource-holding potential in this notably territorial butterfly.     

Effect of oxygen and salt on haemolymph oxygen binding in the brine shrimp Artemia franciscana

The oxygen-binding properties of haemolymph from laboratory-reared Artemia franciscana were investigated in vitro. Adult female brine shrimp without eggs were acclimated to seven different combinations of salinity and oxygen. The oxygen affinity (P₅₀) of unprocessed haemolymph rises with acclimation oxygen partial pressure (PO₂) up to normoxic values, after which no influence of oxygen occurs. The increase in P₅₀ with acclimation PO₂ can be explained by the change in proportion of each of three different haemoglobins in the haemolymph. Salinity acclimation has no effect on haemolymph P₅₀. The effects of the different major salts [NaNO₃, NaCl, Ca(NO₃)₂, Mg(NO₃)₂], pH, and the metal-binding ligand EGTA on the oxygen-binding properties of buffered haemolymph (of shrimp acclimated to 10 salinity) were also studied. Little or no effect of these salts could be found. A small Bohr effect (pH 6.5 to 9.1, =-0.11) was noted. Addition of EGTA caused a significant decrease of the oxygen affinity at concentrations up to 50 mmoll^-1.     

Effect of environmental factors on byssal thread formation

The effects of various factors on byssal thread formation have been examined in the laboratory using Modiolus demissus and Mytilus edulis. With M. demissus thread formation (threads/mussel/h0 and proportion of mussels forming threads decreased with increasing size; prior exposure to air enhanced subsequent thread formation; mechanical agitation reduced thread formation. In addition, low salinity acclimated mussels adapted more rapidly to 32 ppt than high salinity acclimated mussels did to 16 ppt; threads were not formed in the absence of calcium and/or magnesium; and there was no reduction in thread formation at temperatures as high as 27° to 28°C. M. edulis died and thread formation approached zero at temperatures exceeding 26°C.