Movement of water infiltrated from a recharge basin to wells

Local surface water and stormflow were infiltrated intermittently from a 40-ha basin between September 2003 and September 2007 to determine the feasibility of recharging alluvial aquifers pumped for public supply, near Stockton, California. Infiltration of water produced a pressure response that propagated through unconsolidated alluvial-fan deposits to 125 m below land surface (bls) in 5 d and through deeper, more consolidated alluvial deposits to 194 m bls in 25 d, resulting in increased water levels in nearby monitoring wells. The top of the saturated zone near the basin fluctuates seasonally from depths of about 15 to 20 m. Since the start of recharge, water infiltrated from the basin has reached depths as great as 165 m bls. On the basis of sulfur hexafluoride tracer test data, basin water moved downward through the saturated alluvial deposits until reaching more permeable zones about 110 m bls. Once reaching these permeable zones, water moved rapidly to nearby pumping wells at rates as high as 13 m/d. Flow to wells through highly permeable material was confirmed on the basis of flowmeter logging, and simulated numerically using a two-dimensional radial groundwater flow model. Arsenic concentrations increased slightly as a result of recharge from 2 to 6 μg/L immediately below the basin. Although few water-quality issues were identified during sample collection, high groundwater velocities and short travel times to nearby wells may have implications for groundwater management at this and at other sites in heterogeneous alluvial aquifers.     

Inter-annual variability of wet season freshwater plume extent into the Great Barrier Reef lagoon based on satellite coastal ocean colour observations

Riverine freshwater plumes are the major transport mechanism for nutrients, sediments and pollutants into the Great Barrier Reef (GBR) lagoon and connect the land with the receiving coastal and marine waters. Knowledge of the variability of the freshwater extent into the GBR lagoon is relevant for marine park management to develop strategies for improving ecosystem health and risk assessments. In this study, freshwater extent has been estimated for the entire GBR lagoon area from daily satellite observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) between 2002 and 2010. To enable a reliable mapping of freshwater plumes we applied a physics-based coastal ocean colour algorithm, that simultaneously retrieves chlorophyll-a, non-algal particulate matter and coloured dissolved organic matter (CDOM), from which we used CDOM as a surrogate for salinity (S) for mapping the freshwater extent.     

Terrestrial pollutant runoff to the Great Barrier Reef: An update of issues, priorities and management responses

The Great Barrier Reef (GBR) is a World Heritage Area and contains extensive areas of coral reef, seagrass meadows and fisheries resources. From adjacent catchments, numerous rivers discharge pollutants from agricultural, urban, mining and industrial activity. Pollutant sources have been identified and include suspended sediment from erosion in cattle grazing areas; nitrate from fertiliser application on crop lands; and herbicides from various land uses. The fate and effects of these pollutants in the receiving marine environment are relatively well understood. The Australian and Queensland Governments responded to the concerns of pollution of the GBR from catchment runoff with a plan to address this issue in 2003 (Reef Plan; updated 2009), incentive-based voluntary management initiatives in 2007 (Reef Rescue) and a State regulatory approach in 2009, the Reef Protection Package. This paper reviews new research relevant to the catchment to GBR continuum and evaluates the appropriateness of current management responses.     

Survey of PAH in low density residential stormwater ponds in coastal South Carolina: false dark mussels (Mytilopsis leucophaeata) as potential biomonitors

The distribution of PAHs was studied in sediment and false dark mussels, Mytilopsis leucophaeata, of three brackish stormwater retention ponds on Kiawah Island, a gated residential community and golf resort. Impervious surface in pond watersheds ranged from 5 to 30%. Sediment concentrations were lower than those found in other studies of suburban residential areas, and there were no significant differences among ponds or seasons. Mean summation operatorPAH(16) values for sediments in Ponds 67, 100, and 37 were 184.7+/-101.3ng g(-1), 67.5+/-26.0ng g(-1), and 84.3+/-75.5ng g(-1), respectively. Mussel summation operatorPAH(16) concentrations from Pond 67 in August (mean 734.5+/-148.1ng g(-1)), and from Pond 37 in December (mean 1115.1+/-87.7ng g(-1)), were significantly higher than other ponds. Mean summation operatorPAH(16) values for mussels in Ponds 67, 100, and, 37 were 555.9+/-219.7ng g(-1), 312.5+/-99.1ng g(-1) and 737.8+/-419.8ng g(-1), respectively. The mean biota-to-sediment ratio was 7.6+/-8.1. Isomer ratios generally suggested pyrogenic sources. False dark mussels are a promising indicator species for PAH contamination because they are abundant, easy to sample, bioaccumulate PAH profiles representative of the time-integrated sediment profiles, and their PAH levels are less variable than either stormwater or sediment samples.     

从空间探测平流层上层臭氧长期趋势的方法

从沿轨道运行的遥测传感器探测平流层上层臭氧长期趋势的中心问题涉及到把仪器漂移从实际的地球物理变化中区分出来.航天飞机上携带的太阳后向散射紫外辐射仪(SSBUV)的定期飞行将使得检测业务卫星携带的光学特性相同的传感器(SBUV/2)的漂移成为可能.对SSBUV和SBUV/2数据集的详细模拟确定了从轨道上进行校准的程序所能达到的准确度.SSBUV从一次飞行到下一次飞行的校准的可重复性是分析中最关键的变量.约±1%的可重复性对于检测和订正SBUV/2辐射率测量中的漂移是必要的.模拟结果表明,在SSBUV每年约飞行一次、并对整个十年的SBUV/2数据集进行精确校准订正的情况下,人们可以推论出后向散射辐射率的真实地球物理趋势,其准确度可达约±1.0%/10年.     

Cellular diagnostics and coral health: declining coral health in the Florida Keys

Coral reefs within the Florida Keys are disappearing at an alarming rate. Coral cover in the Florida Keys National Marine Sanctuary declined by 38% from 1996 to 2000. In 2000, populations of Montastraea annularis at four sites near Molasses Reef within the Florida Keys National Marine Sanctuary and one reef within Biscayne National Park were sampled on a quarterly basis. Anecdotal observations showed corals at Alina's Reef in Biscayne National Park appeared healthy in March, but experienced an acute loss of coral cover by August. Cellular Diagnostic analysis indicated that Alina's Reef corals were in distress: they had been afflicted with a severe oxidative damaging and protein-denaturing stress that affected both the corals and their symbiotic zooxanthellae. This condition was associated with a significant xenobiotic detoxification response in both species, reflecting probable chemical contaminant exposure. These results demonstrate that applying a Cellular Diagnostic approach can be effective in helping to identify stress and its underlying causes, providing diagnostic and prognostic biomarkers of coral health.     

Toxicopathic liver lesions in English sole and chemical contaminant exposure in Vancouver Harbour,Canada

The prevalence of toxicopathic liver lesions in English sole (Pleuronectes vetulus) was determined along a presumed gradient of chemical contamination in Vancouver Harbour, Canada. Fish were captured from five sites in or near Vancouver Harbour, British Columbia, Canada. No toxicopathic lesions were observed in fish examined at the reference site (Howe Sound outside Vancouver Harbour), or at the outer harbour site. In contrast, 20-23% of the fish from three sites located in the central harbour, Indian Arm and Port Moody Arm had one or more types of toxicopathic lesions. Likewise, aromatic hydrocarbon (AH) metabolites measured in bile exhibited a gradient in levels from lower concentrations at the reference site to significantly higher levels in fish from Indian Arm and Port Moody Arm harbour sites. The occurrence of toxicopathic liver lesions was statistically associated with concentrations of AHs measured in sediment and AH metabolite levels measured in bile.     

Striped weakfish (Cynoscion guatucupa): a biomonitor of organochlorine pesticides in estuarine and near-coastal zones

The general goal of this study was to investigate the role of Cynoscion guatucupa as a biomonitor of organochlorine pesticides (OCP) contamination in Bahía Blanca estuary. Thus, we evaluated whether or not OCP fish distribution pattern reflects the OCP land sources, and if size-related bioaccumulation and biomagnification of these contaminants does occur by comparing different tissues of juvenile and adults of C. guatucupa (Cuvier, 1830). Size-related bioaccumulation in C. guatucupa was observed and it was more important for the more lipophilic and biomagnifying OCP, being determined over time by diet influence. Endosulfan sulfate, chlordanes, HCH isomers and DDT compounds predominated in tissues and ingested food of C. guatucupa, being alpha-chlordane, heptachlor and p,p'-DDE highly bioaccumulated and biomagnificated. Our findings also showed that male adults of C. guatucupa are biomonitors of OCP pollution so we propose this species for further investigations in other coastal zones of South America.     

Using PHREEQC to simulate solute transport in fractured bedrock

The geochemical computer model PHREEQC can simulate solute transport in fractured bedrock aquifers that can be conceptualized as dual-porosity flow systems subject to one-dimensional advective-dispersive transport in the bedrock fractures and diffusive transport in the bedrock matrix. This article demonstrates how the physical characteristics of such flow systems can be parameterized for use in PHREEQC, it provides a method for minimizing numerical dispersion in PHREEQC simulations, and it compares PHREEQC simulations with results of an analytical solution. The simulations assumed a dual-porosity conceptual model involving advective-reactive-dispersive transport in the mobile zone (bedrock fracture) and diffusive-reactive transport in the immobile zone (bedrock matrix). The results from the PHREEQC dual-porosity transport model that uses a finite-difference approach showed excellent agreement compared with an analytical solution.