Human wastewater tracking in tropical Hawaiian island streams using qualitative and quantitative assessments of combined fecal indicating bacteria and sucralose, an organic micropollutant of emerging concern.

Prevalence of cesspools on tropical islands suggests that high concentrations of enteric bacteria in streams and coastal waters are an indicator of groundwater contamination by human wastewater. But enterococci bacteria may also be from homeothermic animals common to these watersheds or bacteria living in sediments. Sucralose, a manufactured chemical not destroyed in passage through the human gut, cesspools, septic systems, or wastewater treatment facilities, was used to test for the presence of human wastewater in streams on the island of Kauai, Hawaii. Effluent from six municipal wastewater treatment plants showed an average concentration of 39,167 ng/L of sucralose, roughly back-calculated to 9 ng/L per person, enough to present itself in cesspool effluent contaminated waters. Of 24 streams tested, 79% were positive for sucralose at least once in four sets of sampling. All streams tested positive for enterococci bacteria above established standards. Serial testing of the pair of indicators in the same location over time and applying the Multiplication Rule to the independent samples provide a probabilistic certainty level that the water is chronically polluted by human waste. When repeatedly paired with tests for enterococci, sucralose testing is a cost-effective means for assessing human health risk and for developing proper waste management programs that has been underutilized in under-developed tropical and island settings.

Regional and global perspectives of honey as a record of lead in the environment.

Honey from Apis mellifera is a useful and inexpensive biomonitor for mapping metal distributions in urban centers. The sampling resolution of a biomonitoring survey (e.g., city versus global scale) determines which geochemical processes are reflected in the results. This study presents Pb isotopic compositions and metal concentrations in honey from around the world, sampled at varying resolutions: honey from Canada (n = 21), the United States (n = 111), Belgium (n = 25), and New Zealand (n = 10), with additional samples from Afghanistan, Brazil, Cuba, Germany, Liberia, Taiwan, and Turkey. Honey was sampled at high resolution in two uniquely different land-use settings (New York Metro Area and the Hawaiian island of Kaua'i), at regional-scale resolution in eastern North America (including the Great Lakes region), and Pb isotopic compositions of all samples were compared on a global scale. At high sampling resolution, metal concentrations in honey reveal spatially significant concentration gradients: in New York City, metals associated with human activity and city infrastructure (e.g., Pb, Sb, Ti, V) are more concentrated in honey collected within the city compared to honey from upstate New York, and metal concentrations in honey from Kaua'i suggest polluting effects of nearby agricultural operations. At lower resolution (regional and global scales), lead isotopic compositions of honey are more useful than metal concentrations in revealing large-scale Pb processes (e.g., the enduring legacy of global leaded gasoline use throughout the twentieth century) and the continental origin of the honey. Lead isotopic compositions of honey collected from N. America (especially from the eastern USA) are more radiogenic (206Pb/207Pb: 1.132-1.253, 208Pb/206Pb: 2.001-2.129) compared to European honey, and honey from New Zealand, which has the least radiogenic isotopic compositions measured in this study (206Pb/207Pb: 1.077-1.160, 208Pb/206Pb: 2.090-2.187). Thus, biomonitoring using honey at different resolutions reflects differing processes and, to some extent, a honey terroir defined by the Pb isotopic composition. The data presented here provide important (and current) global context for future studies that utilize Pb isotopes in honey. Moreover, this study exhibits community science in action, as most of the honey was collected by collaborators around the world, working directly with local apiarists and hobby beekeepers.

Interannual variability in marine debris accumulation on Hawaiian shores: The role of North Pacific Ocean basin-scale dynamics.

Community-based marine debris removal efforts on the Hawaiian Islands of Kaua'i and Hawai'i, spanning 2013-2022, provided large datasets and documented remarkable variations in annual amounts of debris, mainly from abandoned, lost and derelict fishing gear. To test the hypothesis that the influx of marine debris on Hawaiian shores is determined by the proximity of the North Pacific garbage patch, whose pattern changes under the control of large-scale ocean dynamics, we compared these observational data with the output of an oceanographic drift model. The high correlations between the total mass of debris collected and the model, ranging between r = 0.81 and r = 0.84, validate the attribution of the strong interannual signal to significant migrations of the garbage patch reproduced in the model experiments. Synchronous variations in marine debris fluxes on the two islands, separated by >500 km, confirm the large scale of the interannual changes in the North Pacific marine debris system.

Glyphosate residue concentrations in honey attributed through geospatial analysis to proximity of large-scale agriculture and transfer off-site by bees.

Honey taken directly from 59 bee hives on the Hawaiian island of Kaua'i was analyzed for glyphosate residue using ELISA techniques. Glyphosate residue was detected (> LOQ) in 27% of honey samples, at concentrations up to 342 ppb, with a mean = 118 ppb, S.E.M. 24 ppb. Of 15 honey samples store-purchased on Kaua'i, glyphosate was detected in 33%, with a mean concentration of 41 ppb, S.E.M. 14. Glyphosate residue was not detected in two samples from the island of Molokai but was in one of four samples from the island of Hawai'i. Presence and concentration of glyphosate residues were geospatially mapped with respect to Hawaiian land divisions. Mapping showed higher occurrence of glyphosate that was over LOQ (48%) and concentrations of glyphosate (mean = 125 ppb, S.E.M. 25 ppb; N = 15) in honey from the western, predominantly agricultural, half of Kaua'i versus the eastern half (4%, mean = 15 ppb; N = 1). Geographic Information System analysis of land use percentage was performed within a circular zone of 1 Km radius around each hive. Various land use types within each circular zone were transcribed into polygons and percent land use calculated. Only agriculture land use showed a strong positive correlation with glyphosate concentration. High glyphosate concentrations were also detected when extensive golf courses and/or highways were nearby. This suggests herbicide migration from the site of use into other areas by bees. Best management practices in use for curtailing pesticide migration are not effective and must be carefully re-assessed.

Plastic ingestion by Newell's (Puffinus newelli) and wedge-tailed shearwaters (Ardenna pacifica) in Hawaii.

The ingestion of plastic by seabirds has been used as an indicator of pollution in the marine environment. On Kaua'i, HI, USA, 50.0 % of Newell's (Puffinus newelli) and 76.9 % of wedge-tailed shearwater (Ardenna pacifica) fledglings necropsied during 2007-2014 contained plastic items in their digestive tract, while 42.1 % of adult wedge-tailed shearwaters had ingested plastic. For both species, the frequency of plastic ingestion has increased since the 1980s with some evidence that the mass and the number of items ingested per bird have also increased. The color of plastic ingested by the shearwaters was assessed relative to beach-washed plastics by using Jaccard's index (where J = 1 complete similarity). The color (J = 0.65-0.68) of items ingested by both species, and the type ingested by wedge-tailed shearwaters (J = 0.85-0.87), overlapped with plastic available in the local environment indicating moderate selection for plastic color and type. This study has shown that the Hawaiian populations of shearwaters, like many seabird species, provide useful but worrying insights into plastic pollution and the health of our oceans.

Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae.

Sewage effluent, storm runoff, discharge from polluted rivers, and inputs of groundwater have all been suggested as potential sources of land derived nutrients into Hanalei Bay, Kauai. We determined the nitrogen isotopic signatures (delta(15)N) of different nitrate sources to Hanalei Bay along with the isotopic signature recorded by 11 species of macroalgal collected in the Bay. The macroalgae integrate the isotopic signatures of the nitrate sources over time, thus these data along with the nitrate to dissolved inorganic phosphate molar ratios (N:P) of the macroalgae were used to determine the major nitrate source to the bay ecosystem and which of the macro-nutrients is limiting algae growth, respectively. Relatively low delta(15)N values (average -0.5% per hundred) were observed in all algae collected throughout the Bay; implicating fertilizer, rather than domestic sewage, as an important external source of nitrogen to the coastal water around Hanalei. The N:P ratio in the algae compared to the ratio in the Bay waters imply that the Hanalei Bay coastal ecosystem is nitrogen limited and thus, increased nitrogen input may potentially impact this coastal ecosystem and specifically the coral reefs in the Bay. Identifying the major source of nutrient loading to the Bay is important for risk assessment and potential remediation plans.