Manadas Creek is an urban tributary of the Rio Grande that flows past a decommissioned antimony smelter and processing plant. This antimony plant is associated with heavy metal contamination in the creek and still pos...Manadas Creek is an urban tributary of the Rio Grande that flows past a decommissioned antimony smelter and processing plant. This antimony plant is associated with heavy metal contamination in the creek and still poses a threat to the surrounding aquatic environment. Corbicula fluminea was used to determine bioaccumulation from the water column and sediments in Manadas Creek. The metals arsenic (As), antimony (Sb) and thallium (Tl) were analyzed in the water, sediments, gills, mantle, foot, digestive (DI) tract, gonads and shell of clams being monitored at eight sites between March and August 2013. Sediment, water, and dissected Corbicula fluminea samples from different sites in the Creek were acid-digested and analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy. High levels of antimony (25.88 ug/L;75.96 mg/kg) and arsenic (8.26 ug/L;6.41 mg/kg) in the water and sediments were observed at the site downstream from the smelter. There were no detectable concentrations of arsenic, antimony, or thallium in the shell of C. fluminea. Arsenic and antimony were detected in the tissues of C. fluminea but thallium was not detected. Based on the results, the organotropism for arsenic is DI tract > gills > gonads > foot > mantle > shell and the organotropism for antimony is gills > DI tract > gonads > mantle > foot > shell. This study shows that the Asiatic clam (Corbicula fluminea) is a useful bio-monitor to provide data on the status of metal pollution in Manadas Creek, Laredo, Texas.展开更多
Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern...Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern New Mexico, USA. LAC contains legacy waste, including radionuclides and polychlorinated biphenyls, and occasionally discharges storm water and snowmelt flows to the Rio Grande. The Rio Grande is the major waterway that flows southward across the state. In 2009, rock baskets were placed in waters 61- to 76-cm-deep within each reach (five per reach), and, after approximately 6 weeks of colonization, the rock baskets were retrieved. All samples were sorted completely and organisms were identified to the lowest possible taxonomic level. Both reaches in 2009 were dominated by the collector filtering net-spinning caddisfly, Hydropsyche occidentalis. In 2011, benthic macroinvertebrates were collected using D kick nets from shallow riffle locations (15- to 31-cm depth) from each reach (six per reach). These samples were collected after post- (Las Conchas) fire flooding events moved sediment and ash through the two study areas—the downstream reach, however, was affected by higher flows and greater number of flooding events than those affecting the upstream reach. Each kick net sample consisted of ten 1-m (kick) samples. The 10 subsamples were composited and organisms were picked from randomly selected cells in a sorting pan until 500 organisms had been identified to the lowest possible taxonomic level. Both reaches in 2011 were dominated by the collector-gathering mayfly, Baetis tricaudatus. A bioassessment of the downstream reach compared with the upstream (reference) reach was conducted by scoring 10 metrics related to the structure and function of the benthic macroinvertebrate community. While 2009 ranked at the highest level (nonimpaired), 2011 ranked a level lower (slightly impaired). The slightly lower bioassessment score of the downstream reach in 2011 may be a result of flooding impacts following t展开更多
Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos C...Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos Canyon (LAC), Los Alamos National Laboratory (LANL), New Mexico, USA, from 2007 through 2013. Samples were also collected approximately 8 km downgradient of the retention structure in 2009 and 2013. LAC, a major drainage that crosses LANL lands, contains legacy waste, including PCBs, and occasionally discharges storm water and snowmelt flows to the Rio Grande approximately 8.8 km away from the weir. The Rio Grande is the major waterway that flows southward across the state. The weir was constructed across the channel on the northeastern boundary of LANL in late 2000 to help contain sediments mobilized by floodwaters as a result of a large wildfire in early 2000 that burned forest lands west and adjacent to LANL. Total PCBs in field mice directly upgradient of the sediment retention structure from 2007 through 2012 were significantly greater (p 0.05) than in field mice collected from background locations but decreased in concentration over time;by 2013 the levels were statistically similar (p > 0.05) to background. The highest mean total PCB concentration in field mice was below the levels that may negatively impact field mice population attributes. Total PCBs in field mice collected 8 km below the sediment retention structure in 2009 were lower than field mice collected from behind the weir and decreased over time;also by 2013, the amount of PCBs in field mice 8 km below the sediment retention structure were not significantly different (p > 0.05) from background. The rank order of concentrations of ICES 7 PCB congeners in upgradient and downgradient field mice were: No. 153 > 180 > 138 > 118 > 28 > 101 > 52 and No. 153 > 180 > 138 > 52 > 101 > 118 > 28, respectively. Based on the PCB homolog distribution, the major formulation detected in field mice was Aroclor-1260. Overall, the reduction of PCBs in 展开更多
The Rio Grande variety of tomato is widely grown because of its high productivity during the cold and dry seasons, and its resistance to Verticillium wilt (caused by Fusarium oxysporium) and to stem canker (Alternaria...The Rio Grande variety of tomato is widely grown because of its high productivity during the cold and dry seasons, and its resistance to Verticillium wilt (caused by Fusarium oxysporium) and to stem canker (Alternaria). Grafting tomato onto compatible rootstocks resistant to these diseases offers a better potential to overcome soil-borne diseases, abiotic stresses, improve growth, yield and fruit quality. However, in Cameroon, there is little or no information on grafting between Rio Grande tomato and selected eggplant rootstocks. The objectives of this study were: 1) To determine the compatibility between Rio tomato grafting and a popular local eggplant (Nkeya) rootstock;2) To verify the effect of grafting on flowering time;3) To evaluate the effect of eggplant rootstocks on growth, fruit shelf life and fruit quality of Rio tomatoes. The trial was conducted in a randomized complete block design with 3 replications. Rio Grande (To) was the ungrafted treatment used as a control. To/Ko, To/To and To/Nk were the grafted treatments eventually transplanted to the field. Growth data were subjected to analysis of variance using SPSS software. Descriptive analyses were performed for the other parameters. The results revealed that, 1) The cleft grafting method used was successful with success rate varying between 90 and 100%;2) Grafting influenced flowering date (DAT, p = 0.05) as well as tomato growth parameters including stem height (H, 1.49 × 10<sup>-10</sup> p 0.00014) and collar diameter (SD, 4 × 10<sup>-1</sup><sup>4</sup> p 0.009). The To/To treatment was significantly different from the ungrafted cultivar To, which had no significant difference in stem diameter. A significant difference in plant height was also observed between the ungrafted treatment To and the To/Ko and To/Nk treatments. In addition, only the collar diameter of To/Nk was different from To. Also, there was no significant difference between To/To and To, but a significant difference between To/Ko and To/Nk compared to To. Conversely, grafting im展开更多
For more than 2500 years, soil tunnels have been used in warfare and smuggling. Initially tunnels were utilized to attack fortresses that were underlain by unconsolidated (non-bedrock) soil materials. Later tunnels pr...For more than 2500 years, soil tunnels have been used in warfare and smuggling. Initially tunnels were utilized to attack fortresses that were underlain by unconsolidated (non-bedrock) soil materials. Later tunnels provided housing and served as smuggling corridors. The medieval warfare undermining technique involved digging soil tunnels with wooden or beam props to hold up the soil ceilings. Then flammable material, such as hay or straw, was put in the tunnel and set on fire. The fire burnt the support beams which collapsed the soil tunnel ceilings and undermined the overlying perimeter wall. Later gunpowder and dynamite replaced fire when attempting to collapse a tunnel, fortress or perimeter defense. Modern warfare soil tunnels were the pathways used to move troops, weapons and supplies to the other side of a border or wall for surprise attacks. Most of the soil tunnels were placed in easy-to-dig unconsolidated soil materials that had a low water table and were not subject to flooding. Eventually, machinery was used to drill through bedrock permitting deeper and longer tunnels for troop movement or smuggling. However, when drilling through bedrock under international borders, the process creates both noise and vibrations which were often detected by the enemy. Once discovered the tunnels were often collapsed by blowing up the tunnel, injection of gas, filling with water or wastewater, or inserting barriers. A series of case studies will be examined with the goal of determining soil and site criteria required to permit successful tunneling. The most restrictive soil and geologic conditions will be identified as well as potential mitigation methods used to overcome the site restrictions will be documented. Countries with warfare or smuggling issues along their borders, such as Israel and United States, need to identify the sections of the border most likely to be undermined by soil tunnels. In the case of Israel their entire border is susceptible as a result of the favorable arid climate, soils and geology. The 展开更多
Airborne pollutants such as SO42- and NO3- that cause acid rain may pollute water resources via acid deposition. However, such effects on the water quality of the upper Rio Grande River section in Texas have not been ...Airborne pollutants such as SO42- and NO3- that cause acid rain may pollute water resources via acid deposition. However, such effects on the water quality of the upper Rio Grande River section in Texas have not been systematically studied. The objective of this study is to collect and analyze field data, and perform hydrological and water chemistry analyses to assess acid deposition effects on the river water quality. The analysis of the precipitation data indicates that the concentrations of ions decrease as the quantity of precipitation increases. The precipitation with higher concentrations of SO42- and NO3- has a lower pH while that with higher concentrations of Ca2+ and Na+ has a relatively higher pH value. The analysis of river data demonstrates that the pH value, Dissolved Oxygen (DO), and Total Dissolved Solid (TDS) generally decrease when the flow rate increases immediately following precipitation events. The drop in pH following a precipitation event is due to the low pH in the precipitation. The DO and TDS decrease after the precipitation due to the increased flow rate. The slightly higher pH and lower DO values in the eastern section of the river (where the basin is limestone-dominated) as compared to the western section is due to the limestone erosion caused by the acid deposition. The annual stone loss by the acid deposition is about 72,000 m3. The fluctuation between the pH value and the temperature suggests the effect of CaCO3 solubility on the pH value. The water chemistry analysis using Geochemist’s Work Bench (GWB) has been performed to estimate the effect on the oscillation of CaCO3 dissolution-precipitation process. The equilibrium pH decreases with decreasing temperature, but increases as the CaCO3 concentration decreases. The effect of limestone on observed daily pH fluctuations appears to be supported by the simulation.展开更多
文摘Manadas Creek is an urban tributary of the Rio Grande that flows past a decommissioned antimony smelter and processing plant. This antimony plant is associated with heavy metal contamination in the creek and still poses a threat to the surrounding aquatic environment. Corbicula fluminea was used to determine bioaccumulation from the water column and sediments in Manadas Creek. The metals arsenic (As), antimony (Sb) and thallium (Tl) were analyzed in the water, sediments, gills, mantle, foot, digestive (DI) tract, gonads and shell of clams being monitored at eight sites between March and August 2013. Sediment, water, and dissected Corbicula fluminea samples from different sites in the Creek were acid-digested and analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy. High levels of antimony (25.88 ug/L;75.96 mg/kg) and arsenic (8.26 ug/L;6.41 mg/kg) in the water and sediments were observed at the site downstream from the smelter. There were no detectable concentrations of arsenic, antimony, or thallium in the shell of C. fluminea. Arsenic and antimony were detected in the tissues of C. fluminea but thallium was not detected. Based on the results, the organotropism for arsenic is DI tract > gills > gonads > foot > mantle > shell and the organotropism for antimony is gills > DI tract > gonads > mantle > foot > shell. This study shows that the Asiatic clam (Corbicula fluminea) is a useful bio-monitor to provide data on the status of metal pollution in Manadas Creek, Laredo, Texas.
文摘Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern New Mexico, USA. LAC contains legacy waste, including radionuclides and polychlorinated biphenyls, and occasionally discharges storm water and snowmelt flows to the Rio Grande. The Rio Grande is the major waterway that flows southward across the state. In 2009, rock baskets were placed in waters 61- to 76-cm-deep within each reach (five per reach), and, after approximately 6 weeks of colonization, the rock baskets were retrieved. All samples were sorted completely and organisms were identified to the lowest possible taxonomic level. Both reaches in 2009 were dominated by the collector filtering net-spinning caddisfly, Hydropsyche occidentalis. In 2011, benthic macroinvertebrates were collected using D kick nets from shallow riffle locations (15- to 31-cm depth) from each reach (six per reach). These samples were collected after post- (Las Conchas) fire flooding events moved sediment and ash through the two study areas—the downstream reach, however, was affected by higher flows and greater number of flooding events than those affecting the upstream reach. Each kick net sample consisted of ten 1-m (kick) samples. The 10 subsamples were composited and organisms were picked from randomly selected cells in a sorting pan until 500 organisms had been identified to the lowest possible taxonomic level. Both reaches in 2011 were dominated by the collector-gathering mayfly, Baetis tricaudatus. A bioassessment of the downstream reach compared with the upstream (reference) reach was conducted by scoring 10 metrics related to the structure and function of the benthic macroinvertebrate community. While 2009 ranked at the highest level (nonimpaired), 2011 ranked a level lower (slightly impaired). The slightly lower bioassessment score of the downstream reach in 2011 may be a result of flooding impacts following t
文摘Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos Canyon (LAC), Los Alamos National Laboratory (LANL), New Mexico, USA, from 2007 through 2013. Samples were also collected approximately 8 km downgradient of the retention structure in 2009 and 2013. LAC, a major drainage that crosses LANL lands, contains legacy waste, including PCBs, and occasionally discharges storm water and snowmelt flows to the Rio Grande approximately 8.8 km away from the weir. The Rio Grande is the major waterway that flows southward across the state. The weir was constructed across the channel on the northeastern boundary of LANL in late 2000 to help contain sediments mobilized by floodwaters as a result of a large wildfire in early 2000 that burned forest lands west and adjacent to LANL. Total PCBs in field mice directly upgradient of the sediment retention structure from 2007 through 2012 were significantly greater (p 0.05) than in field mice collected from background locations but decreased in concentration over time;by 2013 the levels were statistically similar (p > 0.05) to background. The highest mean total PCB concentration in field mice was below the levels that may negatively impact field mice population attributes. Total PCBs in field mice collected 8 km below the sediment retention structure in 2009 were lower than field mice collected from behind the weir and decreased over time;also by 2013, the amount of PCBs in field mice 8 km below the sediment retention structure were not significantly different (p > 0.05) from background. The rank order of concentrations of ICES 7 PCB congeners in upgradient and downgradient field mice were: No. 153 > 180 > 138 > 118 > 28 > 101 > 52 and No. 153 > 180 > 138 > 52 > 101 > 118 > 28, respectively. Based on the PCB homolog distribution, the major formulation detected in field mice was Aroclor-1260. Overall, the reduction of PCBs in
文摘The Rio Grande variety of tomato is widely grown because of its high productivity during the cold and dry seasons, and its resistance to Verticillium wilt (caused by Fusarium oxysporium) and to stem canker (Alternaria). Grafting tomato onto compatible rootstocks resistant to these diseases offers a better potential to overcome soil-borne diseases, abiotic stresses, improve growth, yield and fruit quality. However, in Cameroon, there is little or no information on grafting between Rio Grande tomato and selected eggplant rootstocks. The objectives of this study were: 1) To determine the compatibility between Rio tomato grafting and a popular local eggplant (Nkeya) rootstock;2) To verify the effect of grafting on flowering time;3) To evaluate the effect of eggplant rootstocks on growth, fruit shelf life and fruit quality of Rio tomatoes. The trial was conducted in a randomized complete block design with 3 replications. Rio Grande (To) was the ungrafted treatment used as a control. To/Ko, To/To and To/Nk were the grafted treatments eventually transplanted to the field. Growth data were subjected to analysis of variance using SPSS software. Descriptive analyses were performed for the other parameters. The results revealed that, 1) The cleft grafting method used was successful with success rate varying between 90 and 100%;2) Grafting influenced flowering date (DAT, p = 0.05) as well as tomato growth parameters including stem height (H, 1.49 × 10<sup>-10</sup> p 0.00014) and collar diameter (SD, 4 × 10<sup>-1</sup><sup>4</sup> p 0.009). The To/To treatment was significantly different from the ungrafted cultivar To, which had no significant difference in stem diameter. A significant difference in plant height was also observed between the ungrafted treatment To and the To/Ko and To/Nk treatments. In addition, only the collar diameter of To/Nk was different from To. Also, there was no significant difference between To/To and To, but a significant difference between To/Ko and To/Nk compared to To. Conversely, grafting im
文摘For more than 2500 years, soil tunnels have been used in warfare and smuggling. Initially tunnels were utilized to attack fortresses that were underlain by unconsolidated (non-bedrock) soil materials. Later tunnels provided housing and served as smuggling corridors. The medieval warfare undermining technique involved digging soil tunnels with wooden or beam props to hold up the soil ceilings. Then flammable material, such as hay or straw, was put in the tunnel and set on fire. The fire burnt the support beams which collapsed the soil tunnel ceilings and undermined the overlying perimeter wall. Later gunpowder and dynamite replaced fire when attempting to collapse a tunnel, fortress or perimeter defense. Modern warfare soil tunnels were the pathways used to move troops, weapons and supplies to the other side of a border or wall for surprise attacks. Most of the soil tunnels were placed in easy-to-dig unconsolidated soil materials that had a low water table and were not subject to flooding. Eventually, machinery was used to drill through bedrock permitting deeper and longer tunnels for troop movement or smuggling. However, when drilling through bedrock under international borders, the process creates both noise and vibrations which were often detected by the enemy. Once discovered the tunnels were often collapsed by blowing up the tunnel, injection of gas, filling with water or wastewater, or inserting barriers. A series of case studies will be examined with the goal of determining soil and site criteria required to permit successful tunneling. The most restrictive soil and geologic conditions will be identified as well as potential mitigation methods used to overcome the site restrictions will be documented. Countries with warfare or smuggling issues along their borders, such as Israel and United States, need to identify the sections of the border most likely to be undermined by soil tunnels. In the case of Israel their entire border is susceptible as a result of the favorable arid climate, soils and geology. The
文摘Airborne pollutants such as SO42- and NO3- that cause acid rain may pollute water resources via acid deposition. However, such effects on the water quality of the upper Rio Grande River section in Texas have not been systematically studied. The objective of this study is to collect and analyze field data, and perform hydrological and water chemistry analyses to assess acid deposition effects on the river water quality. The analysis of the precipitation data indicates that the concentrations of ions decrease as the quantity of precipitation increases. The precipitation with higher concentrations of SO42- and NO3- has a lower pH while that with higher concentrations of Ca2+ and Na+ has a relatively higher pH value. The analysis of river data demonstrates that the pH value, Dissolved Oxygen (DO), and Total Dissolved Solid (TDS) generally decrease when the flow rate increases immediately following precipitation events. The drop in pH following a precipitation event is due to the low pH in the precipitation. The DO and TDS decrease after the precipitation due to the increased flow rate. The slightly higher pH and lower DO values in the eastern section of the river (where the basin is limestone-dominated) as compared to the western section is due to the limestone erosion caused by the acid deposition. The annual stone loss by the acid deposition is about 72,000 m3. The fluctuation between the pH value and the temperature suggests the effect of CaCO3 solubility on the pH value. The water chemistry analysis using Geochemist’s Work Bench (GWB) has been performed to estimate the effect on the oscillation of CaCO3 dissolution-precipitation process. The equilibrium pH decreases with decreasing temperature, but increases as the CaCO3 concentration decreases. The effect of limestone on observed daily pH fluctuations appears to be supported by the simulation.
