Components and tidal modulation of the wave field in a semi-enclosed shallow bay

The wave fields of coastal bays are comprised of waves generated by far-off storms that enter the bay to combine with waves generated locally by winds inside the bay and regionally outside the bay. In any given location, the resultant wave field varies spatially and temporally, and affects coastal features, such as beaches in estuaries and bays (BEBs). However, wave fields in enclosed bays with tidal shoals are poorly studied, limiting the efficacy of coastal protection and restoration projects in these systems, a critical focus in light of ongoing sea level rise. Here we present observations of the wave field in Tomales Bay, a 20-km-long, narrow, semi-enclosed embayment on the wave-dominated coast of Northern California (USA) with a spring-tide range of 2.5 m. We deployed pressure sensors near several beaches along the linear axis of the bay. Low-frequency waves (4∗10−2−2.5∗10−1 Hz or 4–25-s period) were not observed further than 4 km of the mouth, delineating the “outer bay” region, where remotely generated swell and regionally generated wind waves could dominate. The wave spectrum of the landward “inner bay” was dominated by fetch-limited waves generated within the bay with frequency ≥2.5∗10−1Hz. The energy of both ocean waves and locally generated wind waves across all sites were controlled by the tide, but the former by changes in attenuation and the latter likely by modulation of wave generation. Wave energies were low at low tide and high at high tide, but high-frequency wind wave energy was increased during ebb tides while lower-frequency swell energy was reduced during ebb tides, suggesting different mechanisms of tidal influences. Thus, in addition to fluctuations in winds and the presence of ocean waves, tides exert a strong control on the wave energy spectra at coastal features in mesotidal regions. In general, events that may be impactful for BEB morphology are expected to occur when waves due to high winds or high-swell event arrive during high-tide periods. However, no such events were observed during our study and questions remain as to how rarely such events occur across the bay

A Behavioral Change Perspective of Maroon Soil Fertility Management in Traditional Shifting Cultivation in Suriname

In Suriname, the Maroons have practiced shifting cultivation for generations, but now the increasing influence of modern society is causing a trend of decreasing fallow periods with potentially adverse effects for the vulnerable tropical soils. Adoption of appropriate soil fertility management (SFM) practices is currently slow. Combining methods from cultural ecology and environmental psychology, this study identifies two groups with divergent behavioral intentions which we term semi-permanent cultivators and shifting cultivators. Semi-permanent cultivators intend to practice more permanent agriculture and experiment individually with plot-level SFM. Shifting cultivators rely on traditional knowledge that is not adequate for their reduced fallow periods, but perceive constraints that prevent them practicing more permanent agriculture. Semi-permanent cultivators act as a strong reference group setting a subjective norm, yet feel no need to exchange knowledge with shifting cultivators who are in danger of feeling marginalized. Drawing on a political ecology perspective, we conclude that cultural ecological knowledge declined due to negative perceptions of external actors setting a strong subjective norm. Semi-permanent cultivators who wish to enter the market economy are most likely to adopt SFM. We conclude that any future SFM intervention must be based on an in-depth understanding of each group’s behavior, in order to avoid exacerbating processes of marginalization

Atmospheric sources of trace element contamination in cultivated urban areas: A review

Producing food in cities has garnered increasing attention over the past decade. Although there are ecological and social benefits, cultivated urban areas (CUAs) also bear contamination hazards, including from trace elements (TEs). Trace element contamination has been studied extensively in CUAs, but atmospheric sources remain understudied and poorly understood. A brief discussion is offered on atmospheric particulate deposition processes in cities and their implications for urban food production. Available findings are discussed and contrasted. Existing research assesses atmospheric deposition indirectly or otherwise lacks controls for other TE contaminants. There is little to no engagement with methodological guidelines from the atmospheric sciences, which reduces confidence in the findings so far attained. Suggestions are delineated to combine techniques used in the atmospheric sciences with the robust methodologies already generated by studies on TE contamination in CUAs, such as isotope and TE ratios analyses