Uncovering causes and effects of desertification using a Leopold matrix in Binh Thuan Province,Vietnam

Vietnam is a coastal country projected to be heavily affected by climate change.Binh Thuan Province is part of the driest region of Vietnam and is prone to desertification.An expert panel participated in developing a Leopold matrix which allowed for identification of desertification impact factors on the province's socioeconomic activities and assessment of the strength of cause-effect relationships in terms of magnitude and importance.Land use planning,surface water,and the length of the dry season are considered the most important causes,with the overall highest scores for both magnitude and importance in the cause-effect relationship.The largest effects of the different factors are perceived on water supply for agriculture and household use.Water availability and land use planning are important remedial action domains,while drought and land cover require monitoring to assess impacts.The indicators of cause and effect can be used in a longer-term general monitoring and assessment framework to combat desertification in the area.     

Identification of soil contamination hotspots with veterinary antibiotics using heavy metal concentrations and leaching data—a field study in China

In regions with high livestock densities, the usage of antibiotics and metals for veterinary purposes or as growth promoters poses a risk in manured soils. We investigated to which degree the concentrations and depth distributions of Cu, Zn, Cr and As could be used as a tracer to discover contaminations with sulfonamides, tetracyclines and fluoroquinolones. Besides, we estimated the potential vertical translocation of antibiotics and compared the results to measured data. In the peri-urban region of Beijing, China, soil was sampled from agricultural fields and a dry riverbed contaminated by organic waste disposal. The antibiotic concentrations reached 110 μg kg^?1 sulfamethazine, 111 μg kg^?1 chlortetracycline and 62 μg kg^?1 enrofloxacin in the topsoil of agricultural fields. Intriguingly, total concentrations of Cu, Zn, Cr and As were smaller than 65, 130, 36 and 10 mg kg^?1 in surface soil, respectively, therewith fulfilling Chinese quality standards. Correlations between sulfamethazine concentrations and Cu or Zn suggest that in regions with high manure applications, one might use the frequently existing monitoring data for metals to identify potential pollution hotspots for antibiotics in topsoils. In the subsoils, we found sulfamethazine down to ≥2 m depth on agricultural sites and down to ≥4 m depth in the riverbed. As no translocation of metals was observed, subsoil antibiotic contamination could not be predicted from metal data. Nevertheless, sulfonamide stocks in the subsoil could be estimated with an accuracy of 35–200 % from fertilisation data and potential leaching rates. While this may not be sufficient for precise prediction of antibiotic exposure, it may very well be useful for the pre-identification of risk hotspots for subsequent in-depth assessment studies.     

Evidence of enhanced atmospheric ammoniacal nitrogen in Hells Canyon national recreation area: implications for natural and cultural resources

Agriculture releases copious fertilizing pollutants to air sheds and waterways of the northwestern United States. To evaluate threats to natural resources and historic rock paintings in remote Hells Canyon, Oregon and Idaho, deposition of ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2), and hydrogen sulfide (H2S) at five stations along 60 km of the Snake River valley floor were passively sampled from July 2002 through June 2003, and ozone data and particulate chemistry were obtained from the Interagency Monitoring of Protected Visual Environments (IMPROVE) station at Hells Canyon. NH3 concentrations were high; biweekly averages peaked at 5-19 ppb in spring and summer and the nutrient-laden Snake River is a likely source. Fine particulate ammonium nitrate (NH4NO3) averaged 2.6 microg/m3 during the 20% of worst visibility days with winter drainage of air masses from the Snake River Basin and possibly long distance transport from southern California. Other pollutants were within background ranges. NH3 is corrosive to clay-based pictographs; nitrogen deposition can alter natural biotic communities and terrestrial ecosystem processes at levels reported here.     

Occurrence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Lake Maggiore (Italy and Switzerland)

Samples of air (gas and particulate phases), bulk deposition, aquatic settling material and sediments were collected in Lake Maggiore (LM) in order to determine their content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Air (gas and particulate phases) concentrations were 0.5 pg m(-3), 80 pg m(-3), 13 pg m(-3) and 106 pg m(-3) for SigmaPCDD/Fs, SigmaPCBs, Sigma dioxin-like PCBs (DL-PCBs) and SigmaPBDEs, respectively. Deposition fluxes ranged from 0.7 ng m(-2) d(-1) for SigmaPCDD/Fs to 32 ng m(-2) d(-1) for SigmaPCBs. Aquatic settling material presented concentrations of 0.4 ng g(-1) dry weight (dw) for SigmaPCDD/Fs, 13 ng g(-1) dw for SigmaPCB, 3.4 ng g(-1) dw for SigmaDL-PCBs and 5.7 ng g(-1) dw for SigmaPBDEs. Mean sediment concentrations were 0.4 ng g(-1) dw for SigmaPCDD/Fs, 11 ng g(-1) dw for SigmaPCB, 3 ng g(-1) dw for SigmaDL-PCBs and 5.1 ng g(-1) dw for SigmaPBDEs. Similar PCDD/F and DL-PCB congener patterns in all the environmental compartments of LM point to an important, if not dominant, contribution of atmospheric deposition as source of these pollutants into LM. In contrast, PBDE congener distribution was not similar in the different environmental compartments. BDE 47 dominated air and settling material, while BDE 209 was the predominant congener in the bulk atmospheric deposition. Moreover, sediments showed two distinct PBDE congener profiles. Lower PBDE concentrated sediments were dominated by congeners 47 and 99, while BDE 209 dominated in higher PBDE concentrated samples. This suggests the influence of local sources as well as atmospheric input of PBDEs into LM.     

Molecular approaches to microbiological monitoring: fecal source detection

Molecular methods are useful both to monitor natural communities of bacteria, and to track specific bacterial markers in complex environments. Length-heterogeneity polymerase chain reaction (LH-PCR) and terminal restriction fragment length polymorphism (T-RFLP) of 16S rDNAs discriminate among 16S rRNA genes based on length polymorphisms of their PCR products. With these methods, we developed an alternative indicator that distinguishes the source of fecal pollution in water. We amplify 16S rRNA gene fragments from the fecal anaerobic genus Bacteroides with specific primers. Because Bacteroides normally resides in gut habitats, its presence in water indicates fecal pollution. Molecular detection circumvents the complexities of growing anaerobic bacteria. We identified Bacteroides LH-PCR and T-RFLP ribosomal DNA markers unique to either ruminant or human feces. The same unique fecal markers were recovered from polluted natural waters. We cloned and sequenced the unique markers; marker sequences were used to design specific PCR primers that reliably distinguish human from ruminant sources of fecal contamination. Primers for more species are under development. This approach is more sensitive than fecal coliform assays, is comparable in complexity to standard food safety and public health diagnostic tests, and lends itself to automation and high-throughput. Thus molecular genetic markers for fecal anaerobic bacteria hold promise for monitoring bacterial pollution and water quality.     

An assessment of chemical contaminants in sediments from the St. Thomas East End Reserves,St. Thomas,USVI

The St. Thomas East End Reserves or STEER is located on the southeastern end of the island of St. Thomas, USVI. The STEER contains extensive mangroves and seagrass beds, along with coral reefs, lagoons, and cays. Within the watershed, however, are a large active landfill, numerous marinas, resorts, various commercial activities, an EPA Superfund Site, and residential areas, all of which have the potential to contribute pollutants to the STEER. As part of a project to develop an integrated assessment for the STEER, 185 chemical contaminants were analyzed in sediments from 24 sites. Higher levels of chemical contaminants were found in Mangrove Lagoon and Benner Bay in the western portion of the study area. The concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), zinc, copper, lead, and mercury were above a NOAA Effects Range-Low (ERL) sediment quality guideline at one or more sites, indicating impacts may be present in more sensitive species or life stages. Copper at one site in Benner Bay was above a NOAA Effects Range-Median (ERM) guideline indicating effects on benthic organisms were likely. The antifoulant boat hull ingredient tributyltin (TBT) was found at the third highest concentration in the history of NOAA’s National Status and Trends (NS&T) Program, which monitors the nation’s coastal and estuarine waters for chemical contaminants and bioeffects. The results from this project will provide resource managers with key information needed to make effective decisions affecting coral reef ecosystem health and gauge the efficacy of restoration activities.     

Organizational and population level learning as engines for career transitions

Building inductively on twenty-four in depth interviews, the authors argue that boundaryless organizations will alter both career theories and actual career mobility patterns. The paper illustrates how both organizational and population level learning can affect individual job transitions within and cross organizations. The three evolutionary learning steps of variation, selection and retention all remain important, but the impact of variation processes may increase. Boundaryless organizations will thus generate career patterns reflecting an underlying logic of organizational learning rather than producing simple atomistic exchange between unfettered actors.     

Dwarf mongoose and hornbill mutualism in the Taru desert,Kenya

Summary Dwarf mongooses in the Taru desert region of Kenya form foraging communities with a variety of endemic bird species, especially hornbills. The prey spectra of the mongooses and hornbills overlap almost completely. For the other bird species forming the foraging community only partial overlap exists. The association between the birds and mongooses is actively sought by both parties. The birds wait in tress around the termite mound where the monogooses are sleeping for them to emerge and the mongooses delay their foraging departure if no birds are present. There is a positive relationship between the number of mongooses in the group and the number of birds accompanying them. A true mutualism only exists between the mongooses and the two hornbill species Tockus deckeni and T. flavirostris since their presence or arrival affects the subsequent start of foraging. These two hornbill species have also been observed to influence the start of foraging actively by means of two behaviour patterns termed chivvying and waking. Both the mongooses and birds are exposed to a high predator pressure from raptors with an overlap in the birds of prey predating the various species. This predator pressure is counteracted behaviourally by the mongooses by means of an altruistic behaviour pattern, guarding. Both mongooses and birds warn vocally and flee when a raptor is sighted. The mongooses modify their guarding behaviour to compensate for the warning behaviour of the birds in two ways: (a) fewer mongooses guard when large numbers of birds are present and vice versa, (b) the frequency of the mongooses' intraspecific warning calls is significantly reduced in cases where birds are present in comparison with those where they are absent. The birds also sight and respond to the raptor first on significantly more occasions than the mongooses. In addition, the birds also warn for raptor species which do not predate them but which are mongoose predators, not, however, for raptors which are not mongoose predators. This mutualistic association with its high degree of compensatory behaviour by both parties appears to be unique for free-living vertebrates and has its closest parallel in the trophobiosis described for ants and aphids.