Influence of marine alga against mercury-induced biochemical changes,structural destabilization,and genotoxicity in marine tiger fish,Therapon jarbua

This study elucidated the protective role of alga against mercury (Hg)-induced toxicity in marine fish. Bath immersion with mercury chloride (HgCl) [0.125 and 0.25?ppm] in combination with the algal extract (3?ppm) to Therapon jarbua offered a significant protection against Hg only induced disturbed liver function, damaged histoarchitecture, elevated oxidative stress, and DNA fragmentation of tissues. Mercury exposure decreased hepatic superoxide dismutase (SOD), catalase (CAT) activities, and the level of nonprotein-soluble thiol (NPSH, GSH), with a concomitant increase in thiobarbituric acid reactive substances (TBARS) in the gill, kidneys, liver, and blood. Algal supplementation diminished the rise in TBARS restoring CAT, SOD, and GSH levels to control. Reduced generation of free radicals may be correlated to protect DNA stability and morphology. This study indicates the ability of alga to ameliorate Hg-mediated injuries. In conclusion, Kappaphycus alvarezii extract did not show any toxicity and its safety is suggestive for using as a supplement in fish food.     

Denitrification in bottom sediment near oil production facilities off the Louisiana Gulf Coast

There is little information on denitrification in Gulf of Mexico bottom sediment. Potential denitrification rates in surface sediment were measured along transects legs extending 0–800 m from two offshore oil production platforms. The average potential denitrification ranged from approximately 50 mg N m^?2 d^?1 in surface sediment near the platforms to 15 mg N m^?2 d^?1 in sediment 800 m from the platforms. Measured denitrification rates were correlated to a higher organic matter content in sediment nearer the platforms. This research examined only a small component of nitrogen processing in Gulf of Mexico sediment. Additional research should examine the effect of nitrogen loading and temporal and spatial variability on denitrification rate.     

Accumulation of Organochlorine Compounds in Oysters (Crassostrea Gasar) of an Estuarine Environment: Case of A Tropical Lagoon in the Gulf of Guinea

As part of a pollution monitoring study, oysters (Crassostrea gasar) were sampled in June 1996, in order to determine the concentrations and distribution of chlorinated hydrocarbons in two stations (near Boulay Island and Riviera Golf) of the Ebrie Lagoon, in the Abidjan area.

The chromatographic analysis of the oven dried samples revealed the presence of PCBs (2.13 to 86.22 ppb or ng/g dry weight), DDE (<0.48 to 169.55 ppb), DDD (<1.04 to 60.27 ppb), DDT (1.43 to 77.81 ppb, lindane (<0.22 to 91.64 ppb), aldrin (<0.30 to 154.1 ppb), endrin (<0.23 to 293.31 ppb) and dieldrin (<0.26 to 199.74 ppb). the results indicated high concentrations in oysters sampled near Boulay Island, due to industrial, agricultural and port activities going on in this area.

Compared to DDD/ΣDDT and DDT/ΣDDT, the DDE/ΣDDT ratios were high indicating old DDT inputs. the ΣDDT/PCBs ratios were higher than 1 illustrated the predominance of organochlorine inputs from agriculture activities. the presence of lindane in both stations illustrated the problem of fishing with toxic products.

Negative correlations found between dry tissue weight and organochlorine compounds concentrations showed that young oysters may concentrate more of these substances. More studies are needed in order to make any conclusions on their bioaccumulation trends.     

Horizontal Distribution of Some Artificial Radionuclides in Sediments Collected Off the Rhone Mouth (Gulf of Lions-Mediterranean Sea)

Abstract

The Rhône delta is a typical microtidal estuary. River runoff spreads out into the Gulf of Lions as a surface plume influenced by the prevailing N or NW wind and the Liguro-Provençal-Catalan current. in the prodelta, sediments form a filter that traps radionuclides released by the different nuclear installations on the Rhône River and which are associated with fine particles. the horizontal distribution of various artificial radionuclides shows the highest concentrations at the Rhône River mouth. There,¹³⁷Cs reaches 86.6 and 94.4 Bq·kg^?1 dry wt. and is still present 10 miles away (32.5 Bq·kg^?1 dry wt.) in the southwestward direction (influence of the general circulation). Data obtained in the sediment at Roustan station between 1980 and 1990 show that in 1990, ¹³⁷Cs levels were similar to those found previous to the Chernobyl accident.     

Total mercury content found in edible tissues of top predator fish from the Gulf of California,Mexico

Fish at the top of the food chain bioaccumulate and biomagnify toxic metals including mercury (Hg), at a higher rate than nonpredatory fish. However, although some top predator fish species are important in the human diet, the risks for consumers in Mexico are difficult to evaluate due to the scarce baseline information available. In the present article, data on the total mercury (THg) concentrations found in edible tissues of different species of sharks, rays, large pelagic fishes and groupers from the Gulf of California are presented and compared with national and international health guidelines. During 2003 and 2004, 73 shark dorsal tissue samples, 52 ray samples, 66 large pelagic fish samples and 16 grouper samples were collected at different sites along the Gulf of California. Samples were digested in a microwave system and analyzed by cold vapor atomic absorption spectrophotometry. Thirty samples (14%) showed concentrations of Hg above the national statutory limit of 1?mg?kg^?1, from which 25 samples were sharks and 3 were large pelagic fishes. A positive correlation was found between the natural log of THg [ln(THg)] and total length (TL cm) in species of sharks, rays and groupers. The Teacapán estuary in Sinaloa was detected as a possible source of Hg into the Gulf of California due to historic mining in the watershed. Mean Hg concentrations exceeded the regulatory limit of 1?mg?kg^?1 in the following highly commercial shark species: smooth hammerhead, pelagic thrasher, pacific sharpnose shark, dusky shark, scalloped hammerhead, and whitenose shark, in that order. It is recommended that preventive food advisories be issued with respect to these species until further investigations are conducted.     

北部湾潮间带波纹巴非蛤体内石油烃和多氯联苯的分布及风险评价

2011年春季在北部湾沿岸潮间带布设9个站位,采集双壳类动物波纹巴非蛤(Paphia undulata)并测定其软组织中的石油烃(TPH)和多氯联苯(PCBs)含量,研究两种污染物的分布特征、评价其生物质量并对巴非蛤体内残留PCBs可能造成的人体健康风险进行评价.结果表明,各站位TPH和∑PCBs含量范围分别为56.76—199.49μg.g-1和14.19—52.71 ng.g-1(干质量(dw)),就PCBs的组成而言,高氯代PCBs(PCB153、PCB180、PCB194)为优势同族体,所占比重较大.污染指数计算结果显示,除北海西场海域外,各站位的巴非蛤均受到TPH的重度污染,港口区尤为严重;而所有站位的巴非蛤均未受到PCBs污染.健康风险评价结果显示,所有站位的巴非蛤体内PCBs的非致癌风险处于可接受水平(RQ<1),但是,大多数站位的致癌风险指数(0.83×10-6—3.53×10-6)高于可接受的致癌风险低值(1×10-6),而存在一定的潜在致癌风险.     

A general process-based mass-balance model for phosphorus/eutrophication as a tool to estimate historical reference values for key bioindicators,as exemplified using data for the Gulf of Riga

This work describes how a general, process-based mass-balance model (CoastMab) for phosphorus for coastal areas may be used as a tool to estimate realistic values of “natural” or preindustrial reference levels of key bioindicators in coastal science, including the Secchi depth, a standard measure of water clarity, the chlorophyll-a concentration, an operational measure of phytoplankton biomass and the concentration of cyanobacteria, a measure of the concentration of harmful algae. The CoastMab-model is an ecosystem model giving monthly predictions to achieve seasonal variations of basin-wide properties. The selected case-study area, the Gulf of Riga, is sensitive to nutrient loading because of its shallowness and low openness towards the Baltic Proper. The morphometry of any coastal area, as given by the size and form parameters, influences all internal processes, such as sedimentation, resuspension, diffusion in water and from sediments to water, biouptake and retention in biota, stratification, mixing and outflow. There has been no mass-balance modeling for nitrogen (N) in this work because empirical data (from the HELCOM database) clearly indicate that the monthly primary production in the Gulf of Riga is regulated by phosphorus (P) – the mean monthly total-N to total-P ratios are well over 7.2 (the Redfield-ratio) and generally higher than 15 for the data used in this study (from 1992 to 2005). At present anthropogenic loads, the average modeled monthly values for Secchi depth, chlorophyll (Chl), cyanobacteria (CB) and total-P (TP) are 3.2 m, 3.8 μg/l, 78 μg/l and 31.3 μg/l, respectively. If 50% of all anthropogenic sources to the Gulf of Riga via rivers, point sources and diffuse sources were to be removed, these values would be 3.6 m, 3.4 μg Chl/l, 63 μg CB/l and 29.1 μg TP/l. If 60% of the anthropogenic phosphorus fluxes to the Baltic Proper were to be omitted and as well as 75% of all direct anthropogenic sources to the Gulf of Riga, the values would be 4.6 m, 2.7 μg Chl/l, 45 μg CB/l and 25.4 μg TP/l. These values represent the “natural” reference levels and it is not realistic to expect that remedial measures would improve the conditions more than that. Using the CoastWeb-model, similar calculations can be made for any given coastal area and the data necessary for such calculations are discussed in this work.     

基于山江海视角与SRP模型的桂西南-北部湾生态环境脆弱性评价

为揭示桂西南喀斯特-北部湾海岸带生态环境脆弱性,本研究基于山江海视角,采用生态敏感度-生态恢复力-生态压力度(SRP)模型、无纲量化模型、层次分析法,结合生态环境脆弱性指数,对该区域进行了生态环境脆弱性的评价,为该区域的生态环境治理和恢复提供科学的理论基础和技术指导.结果表明:(1)2000～2018年三期生态环境脆弱...     

Impacts of Variable Climate and Effluent Flows on the Transboundary Santa Cruz Aquifer

Assessing groundwater resources in the arid and semiarid borderlands of the United States and Mexico represents a challenge for land and water managers, particularly in the Transboundary Santa Cruz Aquifer (TSCA). Population growth, residential construction, and industrial activities have increased groundwater demand in the TSCA, in addition to wastewater treatment and sanitation demands. These activities, coupled with climate variability, influence the hydrology of the TSCA and emphasize the need for groundwater assessment tools for decision‐making purposes. This study assesses the impacts of changes in groundwater demand, effluent discharge, and climate uncertainties within the TSCA from downstream of the Nogales International Wastewater Treatment Plant to the northern boundary of the Santa Cruz Active Management Area. We use a conceptual water budget model to analyze the long‐term impact of the different components of potential recharge and water losses within the aquifer. Modeling results project a future that ranges from severe long‐term drying to positive wetting. This research improves the understanding of the impact of natural and anthropogenic variables on water sustainability, with an accessible methodology that can be globally applied.