An assessment of the risks associated with PCDDs and PCDFs following the application of sewage sludge to agricultural land in the UK

A model has been developed to describe the transfer of PCDDs and PCDFs from sludge-amended soils to the human foodchain. The model is conservative and assumes that all foods consumed by an individual are derived from sludge-amended soils. Predicted concentrations of PCDDs and PCDFs in potatoes, cereals, root vegetables and leafy vegetables were in close agreement with mean concentrations reported in the food survey conducted by MAFF in the UK. Predicted concentrations in milk were well below the Maximum Tolerable Concentration adopted by MAFF. Assuming a half-life of ten years in sludge-amended soils, the maximum estimated incremental daily intake (IDI) predicted by the model following ten applications of sludge to agricultural land was 0.80 pg I-TEQ kg⁻¹ day⁻¹, representing an increase of approximately 45% on current levels of background exposure. For an individual whose diet is solely derived from sludge-amended soils, the total exposure is predicted to be approximately 181 pg I-TEQ day⁻¹ or 2.6 pg I-TEQ kg⁻¹ day⁻¹. This compares with an average background exposure of approximately 2 pg I-TEQ kg⁻¹ day⁻¹, well within the TDI of 10 pg I-TEQ kg⁻¹ day⁻¹ and indicates that the application of sewage sludge to agricultural land under the conditions assumed would not appear to present a significant health risk under the conservative scenarios considered in this assessment.     

Cadmium content of shellfish of the South Carolina fishery

A survey of cadmium residues in shellfish from the Atlantic Coast of South Carolina was undertaken to see the magnitude of cadmium contamination in the South Carolina Fishery. The shellfish collected were oysters, clams, crabs, shrimps, and scallops. Shellfish samples were dissected and pieces of edible muscle tissue were incubated in reagent grade nitric acid, at a constant temperature shaking-water bath at 58°C. Cadmium levels were determined by flame atomic absorption. The distribution pattern of the element Cd in shellfish is different in various species. It seems that shellfish contained more Cd content levels than other saltwater boney fish. It was found that Cd levels were relatively higher in oysters, shrimps, and clams than crabs and scallops. Larger shellfish had higher Cd content than the smaller shellfish of the same species. Elevated levels of Cd found in these shellfish species of edible fish were not high enough to render them dangerous for human consumption.     

Rainforest composition and histories of human disturbance in Solomon Islands

On the basis of a Solomon Islands case study, we report that tropical rainforests hitherto perceived as untouched, pristine, virgin, etc., are actually sites of former settlement, extensive forest clearance, and irrigated/swidden agriculture. An unusually wide range of sources--rainforest ecology, forest classification and mapping, ethnobotany, land-use history, oral traditions, ethnographic and archaeological observations--supports our conclusions. These observations have bearings for contemporary perspectives on scenarios for rainforest regeneration after logging. They also force a revision of certain assumptions concerning Melanesian prehistory and historical demography, and indicate that interdisciplinary links between botany, archaeology and social anthropology are needed to achieve a better appreciation of rainforest dynamics.     

所罗门群岛的雨林组成与人类干扰的历史

通过对所罗门群岛的实例研究,我们发现迄今为止被认为是未经开发的、原始的、原生的热带雨林实际上是以前的定居点,而且存在着广泛的林木清除和灌溉/轮垦农业.多学科的观察,如雨林生态学、森林分类学和制图学、人类植物学、土地利用史、口头传说、人种学和考古学等方面都支持我们的结论.这些观察与有关伐木后雨林更新情况的现代观点有关系,也修正了某些关于美拉尼西亚史前史和历史的人口统计学假设,并意味着要较好地理解雨林动态,必须进行植物学、考古学和社会人类学等跨学科的联系.     

The potential to increase soil carbon stocks through reduced tillage or organic material additions in England and Wales: A case study

Results from the UK were reviewed to quantify the impact on climate change mitigation of soil organic carbon (SOC) stocks as a result of (1) a change from conventional to less intensive tillage and (2) addition of organic materials including farm manures, digested biosolids, cereal straw, green manure and paper crumble. The average annual increase in SOC deriving from reduced tillage was 310 kg C ± 180 kg C ha⁻¹ yr⁻¹. Even this accumulation of C is unlikely to be achieved in the UK and northwest Europe because farmers practice rotational tillage. N₂O emissions may increase under reduced tillage, counteracting increases in SOC. Addition of biosolids increased SOC (in kg C ha⁻¹ yr⁻¹ t⁻¹ dry solids added) by on average 60 ± 20 (farm manures), 180 ± 24 (digested biosolids), 50 ± 15 (cereal straw), 60 ± 10 (green compost) and an estimated 60 (paper crumble). SOC accumulation declines in long-term experiments (>50 yr) with farm manure applications as a new equilibrium is approached. Biosolids are typically already applied to soil, so increases in SOC cannot be regarded as mitigation. Large increases in SOC were deduced for paper crumble (>6 t C ha⁻¹ yr⁻¹) but outweighed by N₂O emissions deriving from additional fertiliser. Compost offers genuine potential for mitigation because application replaces disposal to landfill; it also decreases N₂O emission.     

Behavior of cesium in fish tissues from Savannah River

A survey of cesium residues in fish from the Savannah River near the Savannah River Nuclear Plant was undertaken in 1983. Fish tissues, bone, fin, and muscle were incubated by the wet disgestion method for analysis. Seventeen fish samples were analyzed by flame atomic absorption spectrophotometry procedure to determine cesium content. It was found that cesium concentration levels were consistently higher in the bones and fins than in muscles of all fish species. It seems that cesium concentration levels were relatively higher in fins than in bones. Cesium concentration levels in muscle tissues were negligible in all fish species.     

Trace elements in fish from the Savannah river near Savannah river nuclear plant

A survey of trace element residues in fish from the Savannah River near Savannah River Nuclear Plant was undertaken in 1982. Fish muscle tissue was incubated by the wet digestion method. Fifteen trace elements were determined by flame atomic absorption spectrophotometry analysi of the digests. It was found that As, Se, Mg, Hg, Ca, Zn, and Fe levels were relatively higher than Pb, Cd, Ni, Co, Cr, and Mn in all fish species. In addition, in all fish species it seems that Pb, Cd, Ni, Co, Cr, and Mn levels were relatively higher than Cs and Cu. Cs and Cu levels were negligible in all fish species analyzed. Trace element levels found in these fish species were not high enough to render them dangerous for human consumption.     

Estimation of upper centile concentrations using historical atrazine monitoring data from community water systems

A survey sampling approach is presented for estimating upper centiles of aggregate distributions of surface water pesticide measurements obtained from datasets with large sample sizes but variable sampling frequency. It is applied to three atrazine monitoring programs of Community Water Systems (CWS) that used surface water as their drinking water source: the nationwide Safe Drinking Water Act (SDWA) data, the Syngenta Voluntary Monitoring Program (VMP), and the Atrazine Monitoring Program (AMP).The VMP/AMP CWS were selected on the basis of atrazine monitoring history (CWS having at least one annual average concentration from SDWA ≥ 1.6 ppb atrazine since 1997 in the AMP). Estimates of the raw water 95th, 99th, and 99.9th centile atrazine concentrations for the VMP/AMP CWS are 4.82, 11.85, and 34.00 ppb, respectively. The corresponding estimates are lower for the finished drinking water samples, with estimates of 2.75, 7.94, and 22.66 ppb, respectively. Finished water centile estimates for the VMP/AMP CWS using only the SDWA data for these sites are consistent with the results. Estimates are provided for the April through July period and for CWS based on surface water source type (static, flowing, or mixed). Requisite sample sizes are determined using statistical tolerance limits, relative SE, and the Woodruff interval sample size criterion. These analyses provide 99.9% confidence that the existing data include the 99.9th centile atrazine concentration for CWS raw and finished water in the Midwest atrazine high-use areas and in the nationwide SDWA dataset. The general validity of this approach is established by a simulation that shows estimates to be close to target quantities for weights based on sampling probabilities or time intervals between samples. Recommendations are given for suitable effective sample sizes to reliably determine interval estimates.     

Comparative analysis of inorganic elements in the muscle and liver of some fish species

Four fish species were collected: brown trout, grouper, spotted tail bass, and black crappie. Fish samples were thawed and dissected. The pieces of edible muscle and liver tissues were digested in a reagent-grade nitric acid, in a constant temperature shaking-water bath at 58°C. Thirteen inorganic elements were determined by flame atomic absorption.The significant findings of this report are that inorganic elements, mercury, iron, copper, zinc, chromium, and nickel with the exception of magnesium show elevated levels in the livers than in the muscles of all the four fish species. It seems magnesium concentration levels were consistantly higher in the muscles than in the livers of all four fish species. It is found that calculations of muscle-liver ratios indicate that ratios in the range of 0.5 are preliminary indicative of environmental static conditions, whereas ratios in the range of more than one are indicative of environmental improvement.     

Comparison of indoor and outdoor residential levels of volatile organic chemicals in five U.S. geographical areas

Matched pairs of indoor and outdoor air samples from residences in Greensboro, NC; Baton Rouge/ Geismar, LA; Deer Park/Pasadena, TX; Elizabeth/Bayonne, NJ: Antioch/W. Pittsburg, CA; and several small communities in the Los Angeles area were collected and analyzed for over 20 volatile organic compounds during the period from 1981 to 1984. Indoor (I) medians and maximum levels were higher than the corresponding outdoor (O) concentrations over the large majority of chemicals studied. In some cases, e.g., chloroform, dichlorobenzenes, and tetrachloroethylene, the median ratios (I/O) were greater than 10.