Der Weg in die Nachhaltigkeit

Ohne Zusammenfassung     

Matrix-immobilized organoclay for the sorption of polycyclic aromatic hydrocarbons and pentachlorophenol from groundwater

Sorbent materials consisting of organoclay immobilized onto the surface of a solid support were evaluated for use in pentachlorophenol (PCP) and polycyclic aromatic hydrocarbon (PAH) remediation of groundwater at a creosote-contaminated Superfund site. Cetylpyridinium-exchanged low pH montmorillonite clay (CP-LPHM) was bonded to either sand (CP-LPHM/sand) or granular activated carbon (GAC) (CP-LPHM/GAC) using the free acid form of carboxymethylcellulose as an adhesive. Effluent from an oil-water separator was eluted through equal bed volumes of composite (4 g 3:2 CP-LPHM/GAC or 13 g CP-LPHM/sand), affinity-extracted, and quantitatively analyzed by GC/MS. PCP, naphthalene, fluorene, phenanthrene, pyrene, and total PAHs were initially reduced by both CP-LPHM/GAC (> or =99%, 61%, 99%, > or =99%, 97%, and 94%, respectively) and CP-LPHM/sand (90%, 70%, 94%, 95%, 93%, and 86%, respectively). Complete breakthrough of naphthalene occurred after approximately 15 h of elution through 3:2 CP-LPHM/GAC and 22 h through CP-LPHM/sand. PCP showed complete breakthrough following 18 h of elution through 3:2 CP-LPHM/GAC and 26 h through CP-LPHM/sand. However, 50% breakthrough was not attained for higher molecular weight PAHs, as fluoranthene, pyrene, benzo[a]anthracene, and chrysene continued to be greatly reduced with both 3:2 CP-LPHM/GAC (98%, 95%, 94%, and 95%, respectively) and CP-LPHM/sand (75%, 73%, 76%, and 78%, respectively) after 48 h of continuous elution. Results confirm prior studies, indicating that these organoclay-containing composites have a high capacity for contaminants found in wood preserving waste. Further, results suggest that the inclusion of CP-LPHM may be useful as part of an effective strategy for groundwater remediation of high concentrations of PCP and PAHs, in particular high molecular weight and carcinogenic PAHs.     

Knowledge and utilization of edible mushrooms by local populations of the rain forest of south Cameroon

Indigenous knowledge of edible fungi and their utilization by local populations were investigated in southern Cameroon from 1996 to 1999. Some 100 participants from the major ethnic groups, comprising Bantu farmers and Bagyeli (Pygmy) hunter-gatherers, were interviewed. Mushroom usage by 30 families, (319 persons), was monitored daily for over a year. Mushroom knowledge among both groups was extensive. Over 50 vernacular names were provided by respondents. In Bantu households, women and children, and to some extent hunters, harvest mushrooms. In contrast, the whole Bagyeli household participates. Bantu harvest mushrooms preferentially in secondary forests while Bagyeli collect them predominantly in primary forests. Mushroom consumption is low for both groups, 1.1 and 1.4 kg of fresh mushrooms per person per year, respectively, a rate that is much lower than in central and eastern Africa. The apparent discrepancy between extensive mushroom knowledge and rather infrequent mushroom consumption probably relates to the social valuation of mushrooms.     

Tracking the anthropogenic drivers of ecological impacts

Despite the pivotal role human factors (anthropogenic drivers) are presumed to play in global environmental change, substantial uncertainties and contradictory conclusions about them continue. We attempt to further discipline the human factors issue by estimating the effects of two anthropogenic drivers, population and affluence, on a wide variety of global environmental impacts, including greenhouse gas emissions, emissions of ozone depleting substances, and the ecological footprint. Population proportionately increases all types of impacts examined. Affluence typically increases impacts, but the specific effect depends on the type of impact. These findings refocus attention on population and material affluence as principal threats to sustainability and challenge predictions of an ameliorating effect of rising affluence on impacts.     

Bioaccumulation of 14C-17alpha-ethinylestradiol by the aquatic oligochaete Lumbriculus variegatus in spiked artificial sediment

A bioaccumulation study was performed with the endobenthic freshwater oligochaete Lumbriculus variegatus MULLER exposed to the radiolabelled synthetic steroid 17alpha-ethinylestradiol (14C-EE2) in a spiked artificial sediment. Concentration of total radioactivity increased constantly and almost linearly during 35 days of exposure. The accumulation factor normalised to worm lipid content and sediment TOC (AFlipid/OC) was 75 at the end of the uptake period, but a steady state was not reached. Uptake kinetics were calculated fitting the measured AFs to a kinetic rate equation for constant uptake from sediment using iterative non-linear regression analysis. After 10 days of elimination in contaminant-free sediment 50% of the accumulated total radioactivity was excreted by the worms. Extracts from L. variegatus sampled at the end of the uptake phase were analysed by thin layer chromatography (TLC). The results showed that 6% of the total radioactivity incorporated by the worms was 14C-EE2. After treatment of extracts with beta-glucuronidase the amount of 14C-EE2 increased to 84%. These results suggest that L. variegatus has the potency to accumulate high amounts of conjugated EE2. Hence, a transfer of EE2 to benthivores and subsequent secondary poisoning of predators might be possible.     

Assessment of the importance of sorption for steroid estrogens removal during activated sludge treatment

Distribution coefficients (K(d)) between water and activated sludge particles (f(oc)=27.7+/-0.1%) were measured for the steroid estrogens (SE), estrone (E1), 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) in batch experiments. Experimental concentration levels ranged from environmentally realistic low ng/l to the high microg/l. In this range K(d)s were independent of their water concentration. The experimentally obtained K(d)s (with 95% confidence intervals) were 402+/-126 l/kg, 476+/-192 l/kg and 584+/-136 l/kg for E1, E2 and EE2, respectively. K(d)s were used to estimate the fraction of the total SE concentration that is expected to be sorbed in the activated sludge treatment tanks of a typical STP assuming equilibrium conditions. Assuming a suspended solids concentration of 4 g/l dissolved solids (ds), it was estimated that 61+/-9%, 66+/-13% and 70+/-6% of the total concentration of E1, E2 and EE2, respectively, would be sorbed during activated sludge treatment. The fraction of the SEs that was expected to be sorbed to suspended sludge particles in the effluents from a typical Danish STP was estimated to be only 0.20+/-0.06%, 0.24+/-0.10% and 0.29+/-0.07% of the total concentration of E1, E2 and EE2, respectively, at a suspended solids concentration of 5 mg/lds. For a typical STP the removal of steroid estrogens with excess sludge was estimated to be only 1.5-1.8% of the total loading if equilibrium conditions exists. Sorption is therefore not important for the fate of SEs in STPs compared to biodegradation.