Exogenous factors in collective policy learning: the case of municipal flood risk governance in the Netherlands

ABSTRACT

Conceptualizing and analyzing collective policy learning processes is a major ongoing theoretical and empirical challenge. A key gap concerns the role of exogenous factors, which remains under-theorized in the policy learning literature. In this paper, we aim to advance the understanding of the role that exogenous factors play in collective learning processes. We propose a typology of exogenous factors (i.e. material, socioeconomic, institutional, discursive), and subsequently apply this in a comparative study of flood risk policymaking in two municipalities in the Netherlands. We find that exogenous factors are indeed essential for understanding collective learning in these cases, as the combined influence with endogenous factors can steer similar learning processes towards different learning products. We conclude our contribution by identifying two opportunities for further developing the collective learning framework, namely regarding the distinction of varying learning products, and the dynamics of exogenous factors over time.     

Loblolly pine response to wet-weather harvesting on wet flats after 5 years

The timing of forestry operations relative to weather conditions is a consideration in applying Forestry Best Management Practices (BMPs). Harvesting during different seasons can result in degrees of soil disturbance, the distribution of logging debris, and potentially future stand productivity. The purpose of this study is to examine the response of loblolly pine (Pinus taeda L.) stands after wet- and dry-weather harvesting combined with three site preparation treatments. A 20 × 20 meter grid was established in fifteen 20-year-old, 3.3-ha loblolly pine plantations in South Carolina. A census of soil physical disturbance and slash distribution was made after harvesting. Growth was measured on 1/125th-ha plots at ages two and five. Dry-weather harvested (DWH) sites were 91% undisturbed, and 9% compressed. Wet-weather harvested (WWH) sites were 41% undisturbed, and 59% disturbed. WWH sites averaged 9% bare soil, while DWH sites averaged 16% with 1 kg m^-2 less logging residue; primarily in the form of heavy and light slash. At age five, the green-weight biomass of flat-planted DWH and WWH sites were 13.3 and 12.6 kg tree^-1 respectively, and on the bedded DWH and WWH sites were 18.6 and 22.8 kg tree^-1. Wet weather harvesting did not seem to adversely affect stand growth, and may have improved it. Due to a prolonged drought, bedding had a larger effect on WWH sites than DWH harvested sites. The effects of droughty conditions may be influencing treatment response on these highly productive sites; however, the long-term effects of harvesting on stand growth remain to be seen.     

Evaluation of a novel passive sampling technique for monitoring volcanogenic hydrogen sulfide

A novel, low-cost passive sampling procedure for monitoring of volcanogenic hydrogen sulfide is reported. The technique is based on absorption of H2S onto treated sections of photographic paper, which are housed in plastic film canisters during exposure. The H2S reacts with silver halide in the photographic paper, causing a colour-change reaction from white, through brown, to black, depending on concentration of atmospheric H2S. The sampler is sensitive to < 30 ppb to approximately 1000 ppb of H2S. Here we present results from a series of optimization and quantification experiments. An active sampling procedure for rapid H2S measurement is also reported, based on absorption of H2S onto Whatman No. 41 cellulose filters treated with silver nitrate, and was shown to be quantitative using a single filter at flow rates <1.0 L min(-1) for collection of <200 microg of sulfide (as H2S). Determination of sulfide collected on the substrates was performed using a rapid flow-injection technique based on the fluorescence quenching of fluorescein mercuric acetate (FMA) by sulfide. This was optimized at a FMA concentration of 8 mg L(-1), at which 100% quenching was obtained at a solution sulfide concentration of 3 mg L(-1).     

Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Key attributes of the source zone and the expanding dissolved plume at a trichloroethene (TCE) site in Australia were evaluated using trends in groundwater monitoring data along with data from on-line volatile organic compound (VOC) samplers and passive flux meters (PFMs) deployed in selected wells. These data indicate that: (1) residual TCE source mass in the saturated zone, estimated using two innovative techniques, is small ( 10 kg), which is also reflected in small source mass discharge ( 3 g/day); (2) the plume is disconnecting, based on TCE concentration contours and TCE fluxes in wells along a longitudinal transect; (3) there is minimal biodegradation, based on TCE mass discharge of  6 g/day at a plume control plane  175 m from source, which is also consistent with aerobic geochemical conditions observed in the plume; and (4) residual TCE in the vadose zone provides episodic inputs of TCE mass to the plume during infiltration/recharge events. TCE flux data also suggest that the small residual TCE source mass is present in the low-permeability zones, thus making source treatment difficult. Our analysis, based on a synthesis of the archived data and new data, suggests that source treatment is unwarranted, and that containment of the large TCE plume ( 1.2 km long,  0.3 km wide; 17 m deep;  2000–2500 kg TCE mass) or institutional controls, along with a long-term flux monitoring program, might be necessary. The flux-based site management approach outlined in this paper provides a novel way of looking beyond the complexities of groundwater contamination in heterogeneous domains, to make intelligent and informed site decisions based on strategic measurement of the appropriate metrics.     

A review on human exposure to brominated flame retardants--particularly polybrominated diphenyl ethers

Brominated flame retardants (BFRs) have been and are still heavily used as additive or reactive chemicals in polymers and textiles. Only a few of the BFRs have been assessed in human subjects with a major data set on internal exposures to polybrominated diphenyl ethers (PBDEs). Increasing PBDE levels have been observed in mothers' milk from Sweden as well as in blood from Germany and Norway. The levels are in general lower than PCB levels. However, the PBDE concentrations found in the North Americans are considerably higher compared to European subjects. The PBDEs are dominated by 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Decabromodiphenyl ether (BDE-209) is reported both in the general population and in occupationally exposed persons showing the bioavailability of this high molecular weight compound. While the lower and medium brominated diphenyl ethers are persistent, BDE-209 has a fairly short half-life of approximately 2 weeks. Tetrabromobisphenol A (TBBPA) is readily eliminated in humans showing a half-life of about 2 days. Still, TBBPA is accumulated in humans but a continuous exposure to this BFR is required to maintain a certain level in the human subject. TBBPA has not been detected in the general population but in people exposed at work. The current review addresses human exposure routes and levels of BFRs.     

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in the serum of US Air Force veterans in 2002

We measured levels of PCDDs, PCDFs, non-ortho, and mono-ortho substituted PCBs in 106 US Air Force Vietnam veterans, participants of the Air Force Health Study (AFHS) who attended the final medical examination in 2002. Twelve veterans were Ranch Hands involved in aerial spraying of herbicides in Vietnam (1962-1971), and 94 were Comparisons who flew transport missions in Southeast Asia (SEA) during the same time period. These veterans had no previous 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) measurement because they had not attended any of the previous AFHS examinations, or their previous measurements were missing or not valid. The mean TCDD levels in 2002 were 1.7 pg/g lipid in Comparisons and 5.5 pg/g lipid in Ranch Hands. The mean PCDD toxic equivalent - TEQ (1997) in Comparisons was 12.6 pg/g lipid, 5.4 pg/g lipid for PCDFs, 5.2 pg/g lipid for non-ortho PCBs, and 9.4 pg/g lipid for mono-ortho PCBs, with a total mean TEQ (1997) of 32.6 pg/g lipid. Corresponding mean TEQs in Ranch Hands were 15.5 pg/g lipid for PCDDs, 4.6 pg/g lipid for PCDFs, 2.2 pg/g lipid for non-ortho PCBs, and 9.3 pg/g lipid for mono-ortho PCBs, yielding the total mean TEQ (1997) of 31.6pg/g lipid. Using the re-evaluated 2005 WHO TEFs, the total mean TEQs (2005) decreased by about 28% in both Comparisons and Ranch Hands, to 23.6 pg/g lipid and 22.8 pg/g lipid, respectively. This was mainly due to changes of TEFs for the group of mono-ortho PCBs, which decreased the mono-ortho PCBs TEQs by almost 90% in both Ranch Hands and Comparisons.     

Comparative distributions of alkalies,alkaline earths and lead among major tissues of the tuna thunnus alalunga

The occurrences of K, Rb, Cs, Ca, Sr, Ba and Pb have been determined in various tissues of the tuna fish Thunnus alalunga. K, Rb, and Cs are distributed uniformly throughout the organs of the fish; 95% of the ca and Sr, and 70% of the Ba and Pb are contained in the skeleton. It is found that there are smaller amouts of Cs, Ba and Pb associated with the nutrient metals K and Ca in a marine animal compared to a terrestrial animal. This difference is a result of the purity of K and Ca in sea-water and the smaller amounts of trace metals associated with them compared to the impurity of K and Ca in terrestrial rocks. Food-chain enhancement and depletion of metals can be evaluated by comparing rations of trace metals to abundant nutrient metals in seawater and tuna. Cs is enriched relative to K in going from seawater to tuna by a factor of 13. Sr and Ba are both depleted by factors of 5 relative to Ca in going from seawater to tuna, while Pb is enriched relative to Ca by a factor of 14. Special clean laboratory procedures were used to prepare samples for accurate analysis by stable isotope dilution mass spectrometric techniques.Contribution No. 2640. Publications of the Division of Geological and Planetary Sciences, Californai Institute of Technology, Pasadena, California 91125, USA.     

Job satisfaction and teamwork: the role of supervisor support

The link between teamwork and job satisfaction was investigated in a sample of 48 manufacturing companies comprising 4708 employees. Two separate research questions were addressed. First, it was proposed that supervisor support would be a weaker source of job satisfaction in companies with higher levels of teamworking. Multilevel analysis indicated that the extent of teamwork at the company level of analysis moderated the relationship between individual perceptions of supervisor support and job satisfaction. Second, it was proposed that the extent of teamwork would be positively related to perceptions of job autonomy but negatively related to perceptions of supervisor support. Further, it was proposed that the link between teamwork and job autonomy would be explained by job enrichment practices associated with teamwork. Analyses of aggregated company data supported these propositions and provided evidence for a complex mediational path between teamwork and job satisfaction. Implications for implementing teamwork in organizations are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Valuation of National Park System Visitation: The Efficient Use of Count Data Models, Meta-Analysis, and Secondary Visitor Survey Data

The National Park Service (NPS) currently manages a large and diverse system of park units nationwide which received an estimated 279 million recreational visits in 2011. This article uses park visitor data collected by the NPS Visitor Services Project to estimate a consistent set of count data travel cost models of park visitor willingness to pay (WTP). Models were estimated using 58 different park unit survey datasets. WTP estimates for these 58 park surveys were used within a meta-regression analysis model to predict average and total WTP for NPS recreational visitation system-wide. Estimated WTP per NPS visit in 2011 averaged $102 system-wide, and ranged across park units from $67 to $288. Total 2011 visitor WTP for the NPS system is estimated at $28.5 billion with a 95% confidence interval of $19.7–$43.1 billion. The estimation of a meta-regression model using consistently collected data and identical specification of visitor WTP models greatly reduces problems common to meta-regression models, including sample selection bias, primary data heterogeneity, and heteroskedasticity, as well as some aspects of panel effects. The article provides the first estimate of total annual NPS visitor WTP within the literature directly based on NPS visitor survey data.     

Detection and occurrence of pentachlorophenol residues in chicken liver and fat

A method for the detection of pentachlorophenol (PCP) residues in chicken liver and fat is presented. A detection limit of 0.002 mg/kg was achieved. Recoveries from liver and fat were in the range 82-88% and 95-97%, respectively. Low level residues of PCP were found in all 1072 liver and 723 fat samples. These levels were less than 0.010 mg/kg in 92.7% of the fat and 75.6% of the livers. Only 0.75% of the liver samples had PCP levels greater than 0.1 mg/kg. None of the more toxic impurities of PCP were detected in the chicken tissues.