As the climate in California warms and wildfires become larger and more severe, satellite-based observational tools are frequently used for studying impact of those fires on air quality. However little objective work has been done to quantify the skill these satellite observations of smoke plumes have in predicting impacts to PM2.5 concentrations at ground level monitors, especially those monitors used to determine attainment values for air quality under the Clean Air Act. Using PM2.5 monitoring data from a suite of monitors throughout the Central California area, we found a significant, but weak relationship between satellite-observed smoke plumes and PM2.5 concentrations measured at the surface. However, when combined with an autoregressive statistical model that uses weather and seasonal factors to identify thresholds for flagging unusual events at these sites, we found that the presence of smoke plumes could reliably identify periods of wildfire influence with 95% accuracy.

California's Stream Pollution Trends program (SPoT) assesses long-term water quality trends, using 100 base-of-the-watershed sampling sites. Annual statewide sediment surveys from 2008 to 2012 identified consistent levels of statewide toxicity (19%), using the freshwater amphipod Hyalella azteca. Significant contaminant trends included a decrease in PCBs, stable concentrations of metals and PAHs, and a statewide increase in detections and concentrations of pyrethroid pesticides. The pyrethroid pesticide bifenthrin was detected in 69% of samples (n = 410). Detection of toxicity increased in a subset of samples tested at a more environmentally relevant test temperature (15 °C), and the magnitude of toxicity was much greater, indicating pyrethroid pesticides as a probable cause. Pyrethroid toxicity thresholds (LC50) were exceeded in 83% of samples with high toxicity. Principal components analysis related pyrethroids, metals and total organic carbon to urban land use.

Heavy metals in urban soils can compromise human health, especially in urban gardens, where gardeners may ingest contaminated dust or crops. To identify patterns of urban garden metal contamination, we measured concentrations and bioavailability of Pb, As, and Cd in soils associated with twelve community gardens in Los Angeles County, CA. This included sequential extractions to partition metals among exchangeable, reducible, organic, or residual fractions. Proximity to road increased all metal concentrations, suggesting vehicle emissions sources. Reducible Pb increased with neighborhood age, suggesting leaded paint as a likely pollutant source. Exchangeable Cd and As both increased with road proximity. Only cultivated soils showed an increase in exchangeable As with road proximity, potentially due to reducing humic acid interactions while Cd bioavailability was mitigated by organic matter. Understanding the geochemical phases and metal bioavailability allows incorporation of contamination patterns into urban planning.

Pacific angel sharks (Squatina californica) are a benthic elasmobranch that occupy intermediate trophic level positions in coastal food webs. Angel sharks’ life history characteristics make them susceptible to accumulating high amounts of contaminants. Four angel sharks were opportunistically captured in southern California and their liver and uterine contents were analyzed for PCBs, DDTs and other pesticides. High DDT:PCB ratios were found in the sharks indicating direct or indirect foraging near a local EPA Superfund Site. Organic contaminants were measured in ovulated eggs, indicating that females are able to maternally offload contaminants. Despite the potential mismatch between ovarian and uterine fecundity, we estimated females to offload approximately 13±5% of their total body load, which represents the upper limit of this capability. Although low in sample size, the initial findings from this study suggest that habitat use might play an important role in contaminant accumulation in this species.

Effects of Cu-loading on macrofaunal recolonization were examined in Shelter Island Yacht Basin (San Diego Bay, California). Sediments with high and low Cu levels were defaunated and Cu-spiked, translocated, and then placed back into the environment. These demonstrated that the alteration observed in benthic communities associated with Cu contamination occurs during initial recolonization. After a 3-month exposure to sediments with varying Cu levels, two primary colonizing communities were identified: (1) a “mouth assemblage” resembling adjacent background fauna associated with low-Cu levels that was more diverse and predominantly dominated by surface- and subsurface-deposit feeders, burrowers, and tube builders, and (2) a “head assemblage” resembling adjacent background fauna associated with high-Cu concentrations, with few dominant species and an increasing importance of carnivores and mobile epifauna. Cu loading can cause reduced biodiversity and lower structural complexity that may last several months if high concentrations persist, with a direct effect on community functioning.

Fine particulate matter samples (PM2.5) were collected from three locations around the Denver–Metropolitan area to study the impacts of the ground–level light rail on airborne metal concentrations. Size–segregated PM was collected on board the trains, at the side of the tracks, and at a background location in downtown Denver. Results from this study showed highest crustal enrichment factors of metals in samples collected on board the train, despite lower concentrations of total PM2.5. Metals commonly found in steel such as Fe, Cr, Mn, and Ni, all exhibited elevated concentrations relating to train activity over the background site. Iron in the PM2.5 at track–side and on board the trains was above the background by a factor of 1.89 and 1.54, respectively. For Mn, the ratios were 1.34 for the track–side and 0.94 for the on board samples. Cr and Ni exhibited higher ratios over the background only in samples collected on board the trains at 1.59 (Cr) and 1.26 (Ni). Soluble metals were measured with Ni (53–71%), Cu (52–81%), and Zn (30–81%) exhibiting the highest solubilities across the different sites. Soluble Fe ranged from 8–15% for the total measured Fe, indicating a non–crustal source of Fe. Soluble Fe was also characterized as Fe(II) and Fe(III) with 87–90% of the soluble Fe being Fe(II), similar to results from studies in Los Angeles, CA and East St. Louis, IL but higher than in Atlanta, GA and Waukesha, WI.

The dominant source of coastal pollution adversely affecting the regional coastal water quality is the seasonally variable urban runoff discharged via southern California’s rivers. Here, we use a surface transport model of coastal circulation driven by current maps from high frequency radar to compute two-year hindcasts to assess the temporal and spatial statistics of 20 southern California stormwater discharges. These models provide a quantitative, statistical measure of the spatial extent of the discharge plumes in the coastal receiving waters, defined here as a discharge’s “exposure”. We use these exposure maps from this synthesis effort to (1) assess the probability of stormwater connectivity to nearby Marine Protected Areas, and (2) develop a methodology to estimate the mass transport of stormwater discharges. The results of the spatial and temporal analysis are found to be relevant to the hindcast assessment of coastal discharges and for use in forecasting transport of southern California discharges.

Salinization is a global problem, including in California, USA, where over two million hectares of irrigated lands have deteriorated due to salt loading. Because of freshwater shortage, some farmlands are also irrigated with agricultural drainage water, which further exacerbates the salinization process. With the objectives of rapidly quantifying spatial and temporal progression of salinization and identifying yield potential for a high-value crop, we conducted 2-year salinity surveys in a salt-affected farm in California by utilizing a dual dipole electromagnetic induction technology (EM38). The EM-predicted conductivity (ECₑ) was consistent with the ground-truth soil data ECₛ and increased with depth. About 50 and 25 % of the ECₑ data in moderately (A) and severely (B) affected salinity zones surpassed 500 and 1000 mS m⁻¹ levels, respectively. In the northern part of B, up to 70 % samples remained within 500–1000 mS m⁻¹ range. There was eastbound salt loading in the northern and southern parts of A. Rhizosphere salinity showed spatial dependence up to 500 m lateral distance. The shifts in salinity could be due to dispersion and leaching of solutes. High crop yield reduction was estimated in the southwestern and northeastern parts of the field that had typically elevated ECₑ. Around 43 % surveyed area was conducive to attaining 80 % of full yield potential, and the central part of the field was determined to be most suitable for crop growth. Coupling of EM results with production values indicated that under elevated saline condition, it would be feasible to grow a high-value tomato crop.

The levels and composition of particulate matter in Ash Meadows National Wildlife Refuge (NWR) that hosts the only population of the endangered Devil’s Hole pupfish (Cyprinodon diabolis) were examined to obtain baseline air quality information. PM₁₀ and PM₂.₅ mass concentrations were measured using continuous monitors over a period of 12 months. In addition, integrated PM₁₀ and PM₂.₅ filter samples were collected and a subset chemically analyzed for elements, ions, elemental carbon, and organic carbon. The average filter-based PM₁₀ (10.9 μg m⁻³) and PM₂.₅ (5.1 μg m⁻³) levels at Ash Meadows NWR are similar to those previously measured at rural and continental background sites in the southwestern USA. Mineral dust accounted for the largest percentage of aerosol mass, with the highest concentrations being measured during fall months of 2009. Elemental and organic carbon levels were generally low, except for August 29, 2009. During this event, transport of wildfire smoke was suggested, by the passage of air masses over wildfires in California, Utah, and Arizona. Ammonium sulfate varied with season, with the highest concentrations in spring and the lowest in fall and winter. Halite (NaCl) quantities were very low, except for the filter samples collected during a windy period on October 4, 2009 indicating the possible contribution of alkaline playa dust upwind of the site. Above average concentrations of crustal calcium compounds, including carbonates and gypsum, were measured in the PM₁₀ sample collected on November 9, 2009 as well as the two preceding months, ascribed to wind-driven dusty conditions prevailing throughout the late summer and fall of 2009.

To better understand the past and present impact of contaminants of emerging concern (CECs) in coastal and marine ecosystems, archived samples were analyzed for a broad suite of analytes, including pharmaceuticals and personal care products (PPCPs), flame retardants (including PBDEs), perfluorinated compounds (PFCs), and current-use pesticides. Surface sediment, mussels (Mytilus spp.) and sediment core samples collected from the California (USA) coast were obtained from environmental specimen banks. Selected CECs were detected in recent surface sediments, with nonylphenol (4-NP), its mono- and di-ethoxylates (NP1EO and NP2EO), triclocarban, and pyrethroid insecticides in the greatest abundance. Alkylphenols, triclocarban, and triclosan were present in sediment core segments from the 1970s, as well as in Mytilus tissue collected during the 1990s. Increasing concentrations of some CECs (e.g., miconazole, triclosan) were observed in the surface layers (ca. 2007) of a sediment core, in contrast to peak concentrations of 4-NP and triclocarban corresponding to input during the 1970s, and an apparent peak input for PBDEs during the 1990s. These results suggest that chemicals sometimes referred to as “emerging” (e.g., alkylphenols, triclocarban) have been present in the aquatic environment for several decades and are decreasing in concentration, whereas others (e.g., miconazole, triclosan) are increasing.