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The population growth, the expansion of the city and the increase of the automotive park of the canton Cuenca has caused a deterioration in air quality, which puts at risk the agricultural production in the nearby rural areas, the objective of the present study was to determine the concentration of Pb in the foliage of cabbage lettuces in the San Joaquín parish. Twelve lettuces of cabbage were planted in two beds that were located in open-pit and greenhouse conditions with a common substrate soil for the development of the plants, the substrate was characterized, the results showed that the content of lead in the foliage of the Lettuce came mostly from the air. At the time of harvest, foliage samples were sent for the analysis of the Pb content by the atomic absorption method, the lowest value corresponded to the greenhouse crop with an average of 0,066 mg / kg, while the open crop obtained value of 0,087 mg / kg, according to the independent T-test, there is no significant statistical difference, these values of lead concentration are below the limits established by the World Health Organization, which is considered that lettuces they are not contaminated with Pb associated with vehicles and fuels. [ABSTRACT FROM AUTHOR]

We studied a rodent community in the San Joaquin Desert of California, United States, from 1993 to 2016. Using biannual trapping on a 144-trap plot, we found that mice of various species were rarely caught in appreciable numbers in contrast to many other studies of rodent communities in arid North America. Most captures were made of 3 species of kangaroo rats: giant kangaroo rat (Dipodomys ingens), Heermann's kangaroo rat (D. heermanni), and San Joaquin kangaroo rat (D. nitratoides). The site was dominated by D. ingens, which, in many years, was the only kangaroo rat captured. Precipitation varied extremely across the study period with 2 periods of high rainfall and 2 periods of well-below-average rainfall. The rodent community seems to have been responding to both bottom-up control and the competitive dominance of D. ingens. In particular, our trapping showed 2 complete cycles of abundance of D. ingens, from very high numbers to crashes with either no or only 2 individuals caught during a session. In both cases, the species recovered after these crashes in abundance. Although we found some D. ingens living to 4-5 years, and D. heermanni and D. nitratoides living up to 3 years, annual survivorship estimates were low compared with other studies of kangaroo rats. Other studies, however, were of much shorter duration and therefore may have missed eventual downturns in population abundances. Dipodomys ingens is a protected species, and from a conservation standpoint, our data indicate that populations can be highly resilient even in the face of high environmental variability. [ABSTRACT FROM AUTHOR]

Abstract: Prognostic meteorological models such as Mesoscale Model (MM5) and Weather Research and Forecasting (WRF) are often used to supply inputs for retrospective air quality modeling done to support ozone and PM2.5 emission control demonstrations. In this study, multiple configurations of the WRF model are applied at 4 km grid resolution and compared to routine meteorological measurements and special study measurements taken in California during May–June 2010. One configuration is routinely used by US EPA to generate meteorological inputs for regulatory air quality modeling and another that is used by research scientists for evaluating meteorology and air quality. Mixing layer heights estimated from airborne High Spectral Resolution Lidar (HSRL) measurements of aerosol backscatter are compared with WRF modeled planetary boundary layer (PBL) height estimates. Both WRF configurations generally capture the variability in HSRL mixing height between days, hour-to-hour, and between surface features such as terrain and land–water interfaces. Fractional bias over all flights and both model configurations range from −38% to 32% and fractional error ranges from 22% to 58%. Surface and upper level measurements of temperature, water mixing ratio, and winds are generally well characterized by both WRF model configurations, often more closely matching surface observations than the input analysis data (12-NAM). The WRF model generally captures orographic and mesoscale meteorological features in the central Valley (bifurcation of wind flow from the San Francisco bay into the Sacramento and San Joaquin valleys) and Los Angeles air basin (ocean-land flows) during this summer period. [Copyright &y& Elsevier]

Chinook salmon, Oncorhynchus tshawytscha (Walbaum), populations have declined rapidly along the western coast of North America since the year 2000, possibly because of factors such as habitat loss, altered hydrology and barriers to migration. However, few analyses have rigorously examined which of these factors actually explain historical patterns of extirpation. Data were compiled on flow regimes, habitat loss and migration barriers for 27 streams that historically supported autumn run salmon and 22 streams that supported spring runs. The probability of extirpation in streams supporting autumn run was predicted solely by migration barriers. All other factors were >10 times less likely to explain existing variation. By contrast, models for spring run salmon suggest that habitat loss and altered flow regimes were also predictors of extirpation. These results suggest that regional extirpation of Chinook salmon has been driven by multiple forms of environmental change, and restoration efforts must address a multitude of bottlenecks that now impact spring and autumn run populations. [ABSTRACT FROM AUTHOR]

Climate variability and changing cropping patterns are two main factors directly influencing catchment hydrological processes and agricultural productivity. Assessing the response of hydrological processes and agricultural production to the combined impacts is of great importance for enhancing water resources management, water productivity and agriculture sustainability. SWAT (Soil and Water Assessment Tools) models embedded with 2007 and 2018 land use were built for the San Joaquin watershed (SJWS) in California's Central Valley. Global sensitivity analysis were conducted to select parameters that have the largest influence on evapotranspiration (ET) processes. The model was calibrated and validated produced good agreement for monthly ET from remote sensing and yield of 8 major crops using county level reported yields during the periods of 2001–2009 and 2010–2018. Based on the outputs of the calibrated SJWS SWAT model, regional ET showed a significant increase, which was caused by rises in temperature and changing cropping patterns associated with increase in area under nut crop production. Seven major crop yields increased excluding alfalfa, implying that the impacts of increasing temperature and small decreases in precipitation were not dominant factors in explaining observed changes in yield. From periods 2001–2009–2010–2018, total water productivity (WP) increased slightly from 2.11 to 2.15 kg/m3, associated with more water-intensive permanent crop production systems. Total economic water productivity (EWP) increased significantly by 111% from 0.55 to 1.16 US$/m3, which also indicated the substantial economic benefit brought to the SJWS by expanding the land area under high-EWP crops such as nut crops and vegetables. Nutritional water productivity (NWP) for energy, protein and fat were reduced from 1211 kcal/m3, 183 g/m3 and 105 g/m3 to 1141 kcal/m3, 111 g/m3 and 88 g/m3 during the period 2010–2018 mostly due to high water use. Total NWP for calcium was increased from 114 to 145 mg/m3, respectively. This study provides initial insights into the response of WP, EWP and NWP to the changing cropping patterns and climate variability for major crops in the SJWS, which could be used by a wide range of stakeholders including farmers, commodity boards, irrigation districts, groundwater sustainability basins, environmental justice groups and policy makers to optimize water resources planning and management. We recommend creating a comprehensive index that incorporates WP, EWP and NWP for making sustainable water resources planning and management decisions. • Climate variability and cropping patterns change were analyzed from 1999 to 2018. • Regional evapotranspiration significantly increased over the past twenty years. • Total WP only increased slightly for the low WP of nut trees and its extended area. • Total EWP increased significantly by 111% from 0.55 to 1.16 US$/m3. • The paper also explores changes in NWP for various crops grown in the watershed. [ABSTRACT FROM AUTHOR]